COSEWIC Assessment and Status Report on the Deepwater Redfish/Acadian Redfish complex Sebastes mentella and Sebastes fasciatus in Canada – 2010

  • Deepwater Redfish Gulf of St. Lawrence – Laurentian Channel Population
  • Deepwater Redfish Northern Population
  • Acadian Redfish Atlantic Population
  • Acadian Redfish Bonne Bay Population

Table of Contents

Document Information

List of Figures

List of Tables

List of Appendices


Document Information

Deepwater Redfish/Acadian Redfish complex Sebastes mentella and Sebastes fasciatus

Line drawing of an Acadian Redfish Sebastes fasciatus.

  • Deepwater Redfish Gulf of St. Lawrence – Laurentian Channel Population – ENDANGERED
  • Deepwater Redfish Northern Population – THREATENED
  • Acadian Redfish Atlantic Population – THREATENED
  • Acadian Redfish Bonne Bay Population – SPECIAL CONCERN

2010

COSEWIC status reports are working documents used in assigning the status of wildlife species suspected of being at risk. This report may be cited as follows:

COSEWIC. 2010. COSEWIC assessment and status report on the Deepwater Redfish/Acadian Redfish complex Sebastes mentella and Sebastes fasciatus, in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. x + 81 pp.

Production note:

COSEWIC would like to acknowledge Red Méthot for writing the status report on the Deepwater Redfish/Acadian Redfish complex (Sebastes mentella and Sebastes fasciatus) in Canada, prepared under contract with Environment Canada. This report was overseen and edited by Alan Sinclair, Co–Chair of the COSEWIC Marine Fishes Specialist Subcommittee, and Howard Powles, previous Co–Chair of the COSEWIC Marine Fishes Specialist Subcommittee.

For additional copies contact:

COSEWIC Secretariat
c/o Canadian Wildlife Service
Environment Canada
Ottawa, ON
K1A 0H3

Tel.: 819–953–3215
Fax: 819–994–3684
E–mail
Website

Également disponible en français sous le titre Ếvaluation et Rapport de situation du COSEPAC sur le sébaste atlantique et le sébaste d’Acadie (Sebastes mentella et Sebastes fasciatus) au Canada.

Cover illustration/photo:

Deepwater Redfish/Acadian Redfish complex —

© Her Majesty the Queen in Right of Canada, 2010.
Catalogue CW69–14/603–2010E–PDF
ISBN 978–1–100–15989–8

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COSEWIC Assessment Summary

Assessment Summary – April 2010

Common name
Deepwater Redfish – Gulf of St. Lawrence – Laurentian Channel population

Scientific name
Sebastes mentella

Status
Endangered

Reason for designation
As with other members of the family Sebastidae, this species is long–lived (maximum age about 75 yr), late–maturing (generation time 18 yr), and highly vulnerable to mortality from human activities. Recruitment is episodic, with strong year–classes only occurring every 5–12 years. Abundance of mature individuals has declined 98% since 1984, somewhat more than one generation, and the decline has not ceased. Directed fishing and incidental harvest in fisheries for other species (bycatch) are the main known threats. Harvesting in parts of this population (Gulf of St. Lawrence) is currently limited to an index fishery, but commercial fisheries remain open in other areas (Laurentian Channel). Bycatch in shrimp fisheries has been substantially reduced since the 1990s by use of separator grates in trawls, but could still be frequent enough to affect recovery.

Occurrence
Atlantic Ocean

Status history
Designated Endangered in April 2010.

Assessment Summary – April 2010

Common name
Deepwater Redfish – Northern population

Scientific name
Sebastes mentella

Status
Threatened

Reason for designation
As with other members of the family Sebastidae, this species is long–lived (maximum age about 75 yr), late–maturing (generation time 23 yr), and highly vulnerable to mortality from human activities. Recruitment is episodic, with strong year–classes only occurring every 5–12 years. Abundance of mature individuals has declined 98% since 1978, somewhat over one generation. However, declines have stopped since the mid–1990s and increases have been observed in some areas. Directed fishing and incidental harvest in fisheries for other species (bycatch) are the main known threats. Fisheries in parts of this designatable unit are currently closed, but remain open in other areas. Bycatch in shrimp fisheries has been substantially reduced since the 1990s by use of separator grates in trawls, but could still affect population recovery.

Occurrence
Arctic Ocean, Atlantic Ocean

Status history
Designated Threatened in April 2010.

Assessment Summary – April 2010

Common name
Acadian Redfish – Atlantic population

Scientific name
Sebastes fasciatus

Status
Threatened

Reason for designation
As with other members of the family Sebastidae, this species is long–lived (maximum age about 75 yr), late–maturing (generation time 16–18 yr), and highly vulnerable to mortality from human activities. Recruitment is episodic, with strong year–classes only occurring every 5–12 years. Abundance of mature individuals has declined 99% in areas of highest historical abundance over about two generations. However, since the 1990’s, there has been no long–term trend in one area, and trends have been stable or increasing in other areas where large declines have been previously observed. Directed fishing and incidental harvest in fisheries for other species (bycatch) are the main known threats. Fisheries in parts of the range of this designatable unit (DU) are currently closed, but remain open in other areas. Bycatch in shrimp fisheries has been substantially reduced since the 1990s by use of separator grates in trawls, but could still be frequent enough to affect population recovery.

Occurrence
Atlantic Ocean

Status history
Designated Threatened in April 2010.

Assessment Summary – April 2010

Common name
Acadian Redfish – Bonne Bay population

Scientific name
Sebastes fasciatus

Status
Special Concern

Reason for designation
As with other members of the family Sebastidae, this species is long–lived (maximum age about 75 yr), late–maturing (females 50% mature at 8–10 yr in the adjacent Gulf of St. Lawrence/Laurentian Channel population), and highly vulnerable to mortality from human activities. Little is known of the biology of this designatable unit (DU). It has a small range of occurrence but there is no indication of decline. The population has been exploited by fishing in the past, but is currently closed to directed fishing. This DU is susceptible to extirpation by random events such as oil spills.

Occurrence
Atlantic Ocean

Status history
Designated Special Concern in April 2010.

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COSEWIC Executive Summary

Deepwater Redfish/Acadian Redfish complex Sebastes mentella and Sebastes fasciatus

  • Deepwater Redfish Gulf of St. Lawrence – Laurentian Channel Population
  • Deepwater Redfish Northern Population
  • Acadian Redfish Atlantic Population
  • Acadian Redfish Bonne Bay Population
Summary of species differences
Latin name Sebastes fasciatus Sebastes mentella

Common name

Acadian Redfish

Deepwater Redfish

Distinguishing characters (some overlap observed)

≤ 7 soft anal rays
Gas bladder muscle:
ribs 3–4

≥ 8 soft anal rays
Gas bladder muscle:
ribs 2–3

World distribution

Northwest Atlantic only: Hudson Strait to Gulf of Maine, Flemish Cap

Northwest and Northeast Atlantic: Scotian Shelf to Baffin Bay, Greenland, Iceland, southern Norway to Barents Sea

Canadian distribution

Hudson Strait to Gulf of Maine

Northeast Scotian shelf to Baffin Bay

Typical depth (some overlap observed)

150–300 m

350–500 m

DUs

1. Atlantic
2. Bonne Bay

  1. Northern
  2. Gulf of St. Lawrence/Laurentian Channel

Species information

Class: Actinopterygii
Order: Scorpaeniformes
Family: Sebastidae
Binomial Name: Sebastes mentella (Travins 1951) and Sebastes fasciatus (Storer 1854)
Common Names:
French: sébaste atlantique and sébaste d’Acadie
English: Deepwater Redfish and Acadian Redfish

Because these two species cannot be easily distinguished, fisheries management treats them as a single complex. For this reason the two species have been assessed together in this status report.

Designatable Units

Based on information from genetics, morphometric and meristic studies, and a parasite study, the following Designatable Units are proposed for these species.

Acadian Redfish Deepwater Redfish

1. Atlantic
2. Bonne Bay

  1. Northern
  2. Gulf of St. Lawrence/Laurentian Channel

Distribution

Redfish inhabit cold waters along slopes of banks and channels at depths of between 100 and 700 m.

Deepwater Redfishis found on both sides of the Atlantic Ocean. In Canadian waters, its range extends from the Grand Banks to Baffin Bay, and includes the Gulf of St. Lawrence, the Laurentian Channel and the Labrador Sea.

Acadian Redfish is only found in the western Atlantic. Its range extends from the Gulf of Maine to the southern Labrador Sea, and includes the Gulf of St. Lawrence, the Laurentian Channel and the Grand Banks.

Habitat

Larvae are found primarily in surface waters, although they are reported to make marked vertical migrations in some regions. Juveniles move below the thermocline upon reaching a length of 25 mm (in the Gulf of Maine). Juveniles remain pelagic for approximately 4–5 months. In general, depths inhabited by redfishes increase with increasing length. Deepwater Redfishgenerally live at depths from 350 to 500 m, whereas Acadian Redfishgenerally are found between 150 and 300 m. Redfishes are considered semi–pelagic species, because they make long daily vertical migrations.

Biology

Redfishes are viviparous: fertilization is internal, and females carry the young until they are released as larvae. Female fecundity is between 1,500 and 107,000 larvae, depending on length. Breeding occurs between September and December, and larvae are released at the end of spring and beginning of summer. Recruitment is highly variable in these species, with strong year–classes only produced every 5–12 years in unexploited or lightly exploited popuations.

These species have a long lifespan (up to 75 years) and exhibit slow growth. They can reach up to 60 cm in length.

Preferred temperature for larvae is between approximately 4°C and 11°C, varying across the range. Temperature preference of juvenile Acadian Redfishin the Gulf of Maine is between 5°C and 10°C, between 4.5°C and 7.0°C for adults.

Population sizes and trends

Abundance estimates for the mature population come from scientific surveys conducted by Fisheries and Oceans Canada (DFO). Abundance estimates are relative, since results may by affected by vessel, gear, surface and depth sampled, season, and time of day. The two redfish species are distinguished on survey cruises by sampling and examining individuals, which could add to uncertainty to trends by species.

Trends in survey abundance are presented for management units for which surveys are conducted. Both species have shown substantial (>95%) declines over 1–2 generations in areas where they were historically abundant, although in some areas abundance indices have been stable or increasing since the mid–1990s.

Deepwater Redfish

Gulf of St. Lawrence/Laurentian Channel DU:

Survey abundance of mature individuals in the Gulf of St. Lawrence has declined by 98% since 1984. No rate of decline has been estimated for the Laurentian Channel owing to incomplete survey coverage.

Northern DU

This DU is primarily distributed from the Grand Banks to the northern Labrador Sea. Available data show a decline in a single region, 2J3K, of 98% since 1978. In other parts of this DU, surveys between 1991 and the present do not show a declining trend. The information from 2J3K is given greatest weight because of relative abundance of Redfish here and the long duration of the time series.

Acadian Redfish

Atlantic DU:

Gulf of St. Lawrence and Laurentian Channel: Acadian Redfish in the Gulf of St. Lawrence have declined by 98.5% since 1984. No rate of decline has been assessed in the Laurentian Channel owing to a lack of relevant data.

Northern area: Available data show a decline in a single region, 2J3K, of 99.7% since 1978. In other regions, the surveys dating from 1991 to date do not show a declining trend. Survey information from 2J3K is given greatest weight because of relative abundance of Redfish in this area and long duration of the time series.

Southern area: Abundance indices in the Scotian Shelf fluctuate widely, but show no overall trends. In the Gulf of Maine, abundances are increasing and several significant year classes have appeared over the past few years.

Bonne Bay DU:

Given the small size of the fjord, the population is considered to be small. No abundance data are available for this population. Area of occupancy is estimated at 72 km².

Limiting factors and threats

Long life span, late maturation, and slow growth give this species low resilience and are considered limiting factors.

Directed fisheries have been the principal threat, with substantial catches taken in the various regions since the 1950s. Directed fisheries are closed in some areas but continue in others. Bycatches in other fisheries could also affect redfish populations; although the introduction of the Nordmore grate has considerably reduced the impact of shrimp fishing on redfishes, this fishery could affect population recovery. Unfavourable environmental conditions may have contributed to the decline of redfishes in certain regions, just as they have for other groundfish. Redfishes are a significant part of the diet of seals, and seal predation may be an important component of population mortality in some areas.

Special significance of the species

Deepwater and Acadian Redfish are (or have been) major commercial species. Moreover, given their large historical abundance, redfishes have an important place in marine ecosystems.

Existing protection and other status designations

The Acadian Redfishis on the IUCN Red List of Threatened Species. Management measures including catch quotas, size and mesh limits, and seasonal closures are used by management authorities to control fisheries. Management is under the responsibility of DFO for stocks in Canadian waters, NAFO for straddling stocks, and Canada–US for the Gulf of Maine. Stocks in the Gulf of St. Lawrence, NAFO 3LN, and NAFO 2J3K have been closed to directed fishing since the mid to late 1990s, although the 3LN fishery was reopened in 2010.

COSEWIC HISTORY
The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal–Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

COSEWIC MANDATE
The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC MEMBERSHIP
COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal entities (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non–government science members and the co–chairs of the species specialist subcommittees and the Aboriginal Traditional Knowledge subcommittee. The Committee meets to consider status reports on candidate species.

DEFINITIONS (2010)

Wildlife Species
A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for at least 50 years.

Extinct (X)
A wildlife species that no longer exists.

Extirpated (XT)
A wildlife species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)
A wildlife species facing imminent extirpation or extinction.

Threatened (T)
A wildlife species likely to become endangered if limiting factors are not reversed.

Special Concern (SC)*
A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.

Not at Risk (NAR)**
A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.

Data Deficient (DD)***
A category that applies when the available information is insufficient (a) to resolve a species’ eligibility for assessment or (b) to permit an assessment of the species’ risk of extinction.

* Formerly described as “Vulnerable” from 1990 to 1999, or “Rare” prior to 1990.
** Formerly described as “Not In Any Category”, or “No Designation Required.”
*** Formerly described as “Indeterminate” from 1994 to 1999 or “ISIBD” (insufficient scientific information on which to base a designation) prior to 1994. Definition of the (DD) category revised in 2006.

The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.

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COSEWIC Status Report on the Deepwater Redfish/Acadian Redfish complex Sebastes mentella and Sebastes fasciatus in Canada – 2010

Deepwater Redfish/Acadian Redfish complex Sebastes mentella and Sebastes fasciatus

  • Deepwater Redfish Gulf of St. Lawrence – Laurentian Channel Population
  • Deepwater Redfish Northern Population
  • Acadian Redfish Atlantic Population
  • Acadian Redfish Bonne Bay Population

SPECIES INFORMATION

Name and classification

  • Class: Actinopterygii
  • Order: Scorpaeniformes
  • Family: Sebastidae
  • Sub–family: Sebastinae
  • Binomial Name: Sebastes mentella (Travin, 1951) and Sebastes fasciatus (Storer, 1854)

Common Names:

English – Deepwater Redfish (Sebastes mentella) and Acadian Redfish (Sebastes fasciatus)

Other names in use: Ocean Perch, Beaked Redfish, Labrador Redfish, American Redfish

French – sébaste atlantique (Sebastes mentella) and sébaste d’Acadie (Sebastes fasciatus)

Other names in use: sébaste du Nord and sébaste rose (France), poisson rouge, sébaste à bec, sébaste américain

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Morphological description

The genus Sebastes comprises a hundred or so species, most of which are found in the Pacific Ocean. Redfish of the Atlantic Ocean are apparently descended from a common ancestor that came from the Pacific (Briggs 1995) some three million years ago.

Deepwater Redfish and Acadian Redfish are practically impossible to distinguish visually. Further, a third Redfish species—Golden Redfish Sebastes norvegicus (Ascanius, 1772), which is also found in the Northwest Atlantic—resembles the two others. Originally it was believed that the Northwestern Atlantic redfishes formed a single species. The species S. mentella and S. norvegicus were distinguished by Templeman and Sandeman (1957), while S. fasciatus was described by Barsukov (1968). Electrophoretic tests (Payne and Ni 1982; McGlade et al. 1983) were then used to confirm that Deepwater Redfish and Acadian Redfish are indeed two separate species.

Deepwater Redfish and Acadian Redfish are spiny–rayed fishes with a distinctive flame–red colouring, sometimes with a brownish cast. These species are characterised by the bony protrusion on the lower jaw, large eyes and fan of bony spines that radiates out from around the gill cover (Figure 1). The body shape of Deepwater Redfishis slightly more fusiform than that of Acadian Redfish(Valentin et al. 2002).

Figure 1. Acadian Redfish (Sebastes fasciatus).Note: It is impossible to visually distinguish it from Deepwater Redfish.

Line drawing of an Acadian Redfish.

Golden Redfish (S. norvegicus) differs in certain morphological characteristics from Deepwater Redfish and Acadian Redfish. It is generally more orange in colour. Its eyes are also smaller than those of its congeners, and the small bony protrusion on its lower jaw is rounded and less pronounced. Moreover, this species is only abundant in the region of Flemish Cap (outside Canadian waters). Elsewhere in the Northwest Atlantic, its presence is marginal (Ni and McKone 1983).

A subspecies of the Acadian Redfish, S. fasciatus kellyi, has also been described (Litvinenko 1974). It lives in the shallow coastal waters of the Eastport region of Maine (United States), so is not found in Canadian waters. It is distinguished by, among other things, its colour, which ranges from dark green to black.

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Distinguishing species

Given their morphological resemblance and the major overlap in their distribution, several criteria have been used to distinguish between Deepwater Redfish and Acadian Redfish. Three characters described by acronyms are currently used: 1) AFC: soft anal fin ray counts (≥ 8 for Deepwater Redfish and ≤ 7 for Acadian Redfish (Ni 1981a; Kenchington, 1986; Rubec et. al 1991)); 2) GBM: gas bladder muscle insertion pattern (between the second and third ribs for Deepwater Redfish and between the third and fourth ribs for Acadian Redfish (Ni 1981a,1981b; Kenchington 1986)); 3) MDH, the genotype of the malate dehydrogenase locus (MDH–A*; Payne and Ni 1982; McGlade et al. 1983; Rubec et al. 1991; Sévigny and de Lafontaine 1992). Two alleles characterize the MDH–A* locus. A homozygote genotype for MDH–A*1 is most common in Deepwater Redfish, whereas a homozygote genotype for MDH–A*2 is typical of Acadian Redfish. Redfish with a heterozygote genotype (MDH–A* 12) could be interpreted as hybrids.

Genetic studies using ribosomal DNA (Desrosiers et al. 1999) and microsatellites (Roques et al. 2001) have demonstrated asymmetrical introgressive hybridization[1] between these two species. Hybridization, however, does not occur in the entire area of sympatry, but is limited to the Gulf of St. Lawrence and the Laurentian Channel (Roques et al. 2001; Valentin 2006).

An overlap exists between Deepwater Redfish and Acadian Redfish regarding AFCs. A certain percentage of Acadian Redfish have eight or more fin rays and, conversely, a proportion of Deepwater Redfish have seven or fewer fin rays (Valentin 2006). As for the GBM criterion, there are sometimes several branches to the gas bladder muscle, which are inserted between several ribs, making use of this criterion difficult. Of the usual identification criteria, MDH is considered to be the most reliable.

The congruence between the different identification criteria is high in the areas of allopatry, but lower in the areas of sympatry (Gulf of St. Lawrence and Laurentian Channel) where hybridization and introgression occur (Valentin 2006; Valentin et al. 2006). Moreover, intermediary characteristics such as a MDH–A*12 genotype or a GBM that is uncertain because of bifurcations between several ribs, are found in strong concentrations only in the Gulf of St. Lawrence and Laurentian Channel.

Certain meristic characteristics, such as the number of vertebrae and the dorsal fin ray count, have also been used along with the anal fin ray count to distinguish between the two Redfish species (Ni 1982; Morin et al. 2004).

Using these identification criteria on a large scale is difficult, given the associated costs and the time required. “Redfish” is therefore treated as a single species by the fishing industry. Development of a management strategy for each species has recently been recommended (DFO 2008) and feasibility of developing such a strategy is being examined.

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Genetic description

Genetic studies of redfish populations in the Northwestern Atlantic are relatively recent, but population structure of the two species has been relatively well documented.

Studies have shown that genetic structure was relatively weak in Northwestern Atlantic redfishes (Roques et al. 2001, 2002; Schmidt 2005; Valentin 2006). This is common in marine organisms, and is due to absence of effective barriers to larval drift or migration (Ward et al. 1994; Shaklee and Bentzen 1998; Ward 2000).

Roques et al. (2001, 2002) using microsatellite tags were the first to describe the genetic structure of redfish populations in the Northwestern Atlantic. Genotypes from eight loci were compared in 17 samples from regions ranging from the Gulf of Maine to the Labrador Sea, including the Gulf of St. Lawrence and the Laurentian Channel. Other samples taken further east as far as the Barents Sea were also included (Roques et al. 2002).

A second study also used microsatellites to describe the redfish populations in the Northwestern Atlantic (Valentin 2006), and combined genetic analyses with morphometric analyses. The number of microsatellites (13) and samples (36), as well as the type of statistical analyses, were revised to increase the accuracy of the comparisons. The samples for this study were taken in summer when redfish dispersion is considered to be highest, and in fall, during the mating season, when populations are considered to be well structured.

In addition to genetic studies, other types of analyses have been conducted to differentiate between redfish populations. One study examined parasites in Deepwater Redfish in five regions (Gulf of St. Lawrence, Laurentian Channel, Labrador Sea, Cabot Strait, Flemish Cap) in order to determine the population structure (Marcogliese et al. 2003). An analysis using trace elements of otoliths was also recently published (Campana et al. 2007).

Lastly, biological characteristics such as age or size at maturity can be compared between areas to differentiate populations.

Deepwater redfish

The results of the genetic analyses conducted by Roques et al. (2002) showed that Deepwater Redfish in the Gulf of St. Lawrence and the Laurentian Channel (GSL/LC) are homogeneous with respect to genetic diversity. The large majority of comparisons between pairs of samples in this region did not show any significant difference (Table 1) (origin of samples used by Roques et al. (2002) are found in Table 2). The average unbiased FST (θ) was 0.00028. There was also homogeneity seen within a group called “pan–oceanic" by the authors (average θ = −0.0004). It contained Deepwater Redfish from the Grand Banks to the Faroe Islands. A third group was identified during this study made up of individuals from the Norwegian and Barents seas. Each sample from the Gulf of St. Lawrence/Laurentian Channel was statistically different from those in other areas (average θ = 0.0127).

Table 1. Pairwise index of genetic differentiation between each of the 17 samples of Redfish. Dotted lines mark comparisons between Deepwater Redfish and Acadian Redfish. The degree of genetic exchange between samples was estimated using the unbiased FST (q) index (from Roques et al. 2001).
Sample FAA1 FAA2 FAS1 FAS2 FAS3 FAS4 MEA1 MEA2

FAA1

 

 

 

 

 

 

 

 

FAA2

0.0132*

 

 

 

 

 

 

 

FAS1

0.0091*

0.0196

 

 

 

 

 

 

FAS2

0.0185

0.0235

(−0.0050*)

 

 

 

 

 

FAS3

0.0196

0.0274

(−0.0003*)

(−0.0058*)

 

 

 

 

FAS4

0.0093*

0.0152

(−0.0043*)

(−0.0013*)

(0.0040*)

 

 

 

MEA1

0.1355

0.1636

0.1354

0.1219

0.1178

0.1255

 

 

MEA2

0.1154

0.1412

0.1113

0.1042

0.0991

0.1067

(−0.0039*)

 

MEA3

0.1189

0.1504

0.1145

0.1101

0.1023

0.1105

(−0.0008*)

(0.0026*)

MEA4

0.1085

0.1424

0.1125

0.1032

0.0974

0.1059

(0.0062*)

0.0014*

MES5

0.0830

0.1118

0.0817

0.0777

0.0741

0.0743

0.0063*

0.0153

MES6

0.0778

0.1095

0.0883

0.0846

0.0819

0.0792

0.0103

0.0154

MES7

0.1009

0.1313

0.1015

0.0977

0.0941

0.0927

0.0109

0.0167

MES1

0.0794

0.1135

0.0829

0.0829

0.0794

0.0766

0.0052*

0.0149

MES2

0.1035

0.1349

0.1016

0.1005

0.0962

0.0933

0.0077

0.0181

MES3

0.1065

0.1410

0.1035

0.1070

0.1027

0.0987

0.0078*

0.0224

MES4

0.0817

0.1143

0.0836

0.0865

0.0839

0.0793

0.0169

0.0274

Table 1. Continued

Sample

MEA3

MEA4

MES5

MES6

MES7

MES1

MES2

MES3

MES4

FAA1

 

 

 

 

 

 

 

 

 

FAA2

 

 

 

 

 

 

 

 

 

FAS1

 

 

 

 

 

 

 

 

 

FAS2

 

 

 

 

 

 

 

 

 

FAS3

 

 

 

 

 

 

 

 

 

FAS4

 

 

 

 

 

 

 

 

 

MEA1

 

 

 

 

 

 

 

 

 

MEA2

 

 

 

 

 

 

 

 

 

MEA3

 

 

 

 

 

 

 

 

 

MEA4

(−0.0006*)

 

 

 

 

 

 

 

 

MES5

0.0082

0.0044*

 

 

 

 

 

 

 

MES6

0.0096

0.0090

(0.0002*)

 

 

 

 

 

 

MES7

0.0156

0.0181

(0.0011*)

(−0.0005*)

 

 

 

 

 

MES1

0.0125

0.0103

(0.0020*)

(0.0020*)

(−0.0030*)

 

 

 

 

MES2

0.0117

0.0146

(0.0003*)

(0.0017*)

(−0.0046*)

(0.0000*)

 

 

 

MES3

0.0158

0.0163

0.0093

0.0043*

0.0038*

0.0101

0.0045*

 

 

MES4

0.0193

0.0213

0.0095

(0.0036*)

0.0057*

0.0098

−0.0094

0.0186

 

( ) Indicates the absence of significant heterogeneity in the frequency of alleles based on the Fisher method (a=0.001).
* No significant difference in the estimate q based on Bonferroni corrections (k=120, a=0.05/120=0.0004).

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Table 2. Origin of samples used by Roques et al. (2001).
Sample Geographic Origin Sample Geographic Origin
Acadian Redfish Deepwater Redfish

FAA1

Gulf of Maine

MEA1, MEA2

Grand Banks

FAA2

Nova Scotia

MEA3

2G

FAS1

South of Newfoundland

MEA4

2H

FAS2, FAS3, FAS4

Gulf of St. Lawrence

MES1, MES2, MES3

Gulf of St. Lawrence

 

 

MES4, MES5, MES6, MES7

South of Newfoundland

Valentin (2006) identified two groups of Deepwater Redfish in the Canadian Atlantic (Figs 2, 3): a Unit 1/Unit 2 (Figure 4) group (Gulf of St. Lawrence/Laurentian Channel) and a northern group consisting of individuals outside the former group. The FST varied from −0.003 to 0.008 in the comparison among the GSL/LC samples and no statistical test was significant (Table 3). The Deepwater Redfish in this region, however, were different from those in the Grand Banks region, Labrador Sea and Southern Greenland, as Roques et al. had observed (2002). All significant differences observed during this study were for comparisons of samples from the GSL/LC with samples from further north (Table 3). Moreover, statistics based on genetic distances (multi–dimensional statistical analyses and the Neighbor–Joining method), and cluster analyses also demonstrated homogeneity within the GSL/LC samples, and differences between GSL/LC and the Grand Banks and the northern part of the distribution (Figures 2, 3). Valentin’s (2006) genetic results were corroborated by morphometric analyses.

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Figure 2. Neighbour–joining tree illustrating the relationship between different samples of Acadian Redfish (Sebastes fasciatus), Deepwater Redfish (S. mentella) and S. norvegicus Source: DFO (2008) (modified from Valentin 2006).

Neighbour-joining tree diagram illustrating the genetic relationship between samples of Deepwater Redfish and Acadian Redfish.

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Figure 3. Graphical representation (stress value = 0.031) of the distances between the 36 samples after the MD analysis on the pairwise Cavalli–Sforza and Edwards (1967) chord distances:

Graphic representation of the distances between samples of Deepwater Redfish, Acadian Redfish and Golden Redfish after multi-dimensional statistical analyses on the pairwise Cavalli-Sforza and Edwards (1967) chord distances.

S. mentella samples (Orange triangle)

S. mentella samples showing introgression (Orange triangle with greeen dot in the middle.),

S. fasciatus samples (Green circle)

S. fasciatus samples showing introgression (Green circle with orange dot in the middle.)

S. norvegicus (Yellow square).

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Figure 4. DFO Redfish management units (modified from Morin et al. 2004). The black zone is included in Unit 1 from January to May, and in Unit 2 from June to December.

Map of Fisheries and Oceans Canada redfish management units.

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Table 3. Pairwise index of genetic differentiation between Deepwater Redfishsamples. The FST value is found above the diagonal, and test significance below the diagonal. (–) non–significant, (+) significant before correction, + significant after sequential Bonferroni correction (from Valentin 2006.

Sample

2J42

3L29

s1050

3PN1

3PN77

3PS133

4R48

4R51

4S35

2J42

 

0.012

0.027

0.039

0.033

0.043

0.041

0.041

0.040

3L29

(+)

 

0.007

0.025

0.018

0.027

0.027

0.025

0.022

s1050

+

 

0.016

0.012

0.014

0.016

0.018

0.012

3PN1

+

+

+

 

−0.001

−0.003

0.001

0.007

−0.003

3PN77

+

+

+

 

0.003

0.003

−0.001

0.001

3PS133

+

+

+

 

0.004

0.007

0.002

4R48

+

+

+

 

0.004

0.007

4R51

+

+

+

(+)

(+)

 

0.008

4S35

+

+

+

(+)

(+)

 

4S44

+

+

+

4VN12

+

+

+

4VN2

+

+

+

(+)

4VN77

+

+

+

4VS13

+

+

+

(+)

4VS147

+

+

+

(+)

(+)

Sag

+

+

+

Table 3. Continued

Sample 4S44 4VN12 4VN2 4VN77 4VS13 4VS147 Sag

2J42

0.037

0.039

0.034

0.043

0.040

0.033

0.042

3L29

0.02

0.025

0.021

0.024

0.022

0.019

0.025

s1050

0.012

0.016

0.015

0.014

0.013

0.013

0.015

3PN1

0.000

0.000

−0.002

−0.003

−0.001

−0.001

−0.001

3PN77

0.000

0.001

−0.003

−0.001

0.001

−0.002

0.002

3PS133

0.003

0.004

0.003

0.002

0.000

0.005

−0.001

4R48

0.001

0.005

0.005

0.001

0.004

0.006

0.004

4R51

−0.001

0.003

0.004

0.005

0.006

0.006

0.004

4S35

−0.002

0.001

−0.002

−0.002

0.005

−0.001

−0.003

4S44

 

0.000

−0.002

−0.002

0.003

0.001

−0.001

4VN12

 

0.001

0.000

0.004

−0.001

0.001

4VN2

 

−0.001

0.003

0.001

0.003

4VN77

 

0.000

0.002

−0.002

4VS13

 

0.005

0.005

4VS147

 

0.002

Sag

 

 

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The genetic differences observed between the Deepwater Redfish of the GSL/LC and the rest of the distribution were in large part due to introgressive hybridisation (Roques et al. 2001; Valentin 2006). According to Valentin (2006), other factors could however be responsible for these differences. In order for hybridisation alone to explain the genetic differences, the loci causing the difference between the populations should be the same as those responsible for the differences between species, which is only partially true. Moreover, analyses excluding individuals showing signs of introgression also demonstrated the same genetic heterogeneity (Valentin 2006). Introgression therefore was not the only factor causing genetic differentiation.

Oceanographic conditions found in the Gulf of St. Lawrence and the Laurentian Channel are different from those on the Grand Banks and Labrador Shelf. The GSL/LC is a relatively closed system where the environment is appropriate for all stages of life for the Redfish, including early stages. The Northwestern Atlantic is an open environment with few barriers, unlike the GSL/LC, and Deepwater redfish distribution appears more or less continuous from the Irminger Sea to Labrador/Grand Banks. The member/vagrant hypothesis was suggested to explain the genetic differentiation of Deepwater Redfish (Roques et al. 2002; Valentin 2006). Based on this theory, the number of distinct populations in a marine species is primarily determined by retention areas which retain the planktonic larval stages (Îles and Sinclair 1982). This weak genetic structure within the pan–oceanic population could therefore potentially be due to wide larvae dispersion.

No. samples of Deepwater redfishfrom the southern portion of the Grand Banks have yet been analysed. This region constitutes the southern limit of Deepwater Redfishdistribution, where this species is less abundant.

A study of parasites in Deepwater Redfish showed significant differences between samples from the Gulf of St. Lawrence and Laurentian Channel (Marcogliese et al. 2003). Conversely, samples from the Gulf of St. Lawrence and Labrador Sea could not be differentiated by parasite rate or occurrence.

Deepwater Redfish females in the Gulf of St. Lawrence (Unit 1) reach sexual maturity at a length and age similar to the females found in the Laurentian Channel (Unit 2) (10.4 and 10.6 yr respectively) (Morin et al. 2004; Table 5). However, the values calculated for the Grand Banks are higher (15 yr) than those for GSL/LC.

Campana et al. (2007) used otolith trace elements to show that Deepwater Redfish tend to leave the Gulf of St. Lawrence in winter to join aggregations in the Laurentian Channel. The results also indicated that Deepwater Redfish coming from the eastern Scotian Shelf (Unit 2 of DFO) or the southern part of the St. Pierre Bank do not overwinter with these aggregations.

A potentially isolated population is found in the Saguenay fjord (Quebec), but this does not appear to be distinct from the adjoining population. The fjord has a depth of up to 275 m and is separated from the estuary and the Gulf of St. Lawrence by a shallow sill (20 m) that limits exchanges between these two areas. Genetic analyses have not shown any difference between individuals in the Saguenay and those in the Gulf of St. Lawrence. The study of Roques et al. (2002) showed a θ of between −0.0005 and 0.0018 and Valentin’s study (2006) demonstrated an FST of between −0.001 and 0.004 during comparisons between Deepwater Redfish in the Saguenay and those in the Gulf of St. Lawrence. According to Fortin et al. (2006), there appeared to be Redfish larvae production in the Saguenay, but they only seemed to survive a few days, possibly due to the low salinity in the fjord’s surface waters. Therefore, recruitment had to come from the St. Lawrence estuary. The Saguenay Redfish would thus be considered a sink population. Because the sill could prevent adults from the estuary from moving into the Saguenay, it is probable that movements occur when the Redfish are juveniles. There are noticeable differences between the fjord Redfish and those found in the Gulf of St. Lawrence in terms of otolith trace element composition (Campana et. al 2007), and the morphometry of Saguenay Redfish is different from that of the Gulf of St. Lawrence (Valentin 2006). However these characteristics are likely due to growth in distinct environments.

Deepwater redfish are found as far north as Davis Strait and Baffin Bay off Nunavut (Northwest Atlantic Fisheries Organization (NAFO) Subdivision 0 (Figure 5)) (Treble 2002). Abundance data are limited here, and no quantitative analysis is possible. These fish could be associated with the northern population or with that of western Greenland.

Figure 5. Northwest Atlantic Fisheries Organization (NAFO) zones.

Map of Northwest Atlantic Fisheries Organization zones.

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Acadian redfish

The study of Roques et al. (2001) showed genetic homogeneity among samples of Acadian Redfish from the Gulf of St. Lawrence. The θ values varied between −0.005 and 0.004 in the three samples in this region (Table 1). Roques et al. (2001) reported a significant difference in the frequency of alleles between a sample from the Gulf of Maine and another from the Scotian Shelf (p < 0.05), but as indicated by Roques et al. (2003), this result should not be given much weight — only 30 individuals constituted the sample from the Gulf of Maine, and the difference in FST between the Gulf of Maine and the Scotian Shelf was not significant (Table 1; Roques et al. 2001). Further, samples were selected based on the congruence of the different distinguishing criteria (AFC, GBM and MDH) in order to ensure these were Acadian Redfishindividuals, which could have led to an underestimation of the genetic variability of the populations (Valentin 2006).

Valentin (2006) identified three groups of Acadian redfish: a Unit 1/Unit 2 (Figure 4) group, a northern group and a southern group (Figures 2, 3). Many of the differences between groups had FST values which were not significant (Table 4), although structure, MDS analyses and the neighbor–joining method show the various groups as being distinct. The presence of distinct groups is also supported by morphometric analyses. Further, little introgression is seen in samples from the northern region, in contrast to the region of the Gulf of St. Lawrence and the Laurentian Channel. Even the samples from the GSL/LC, which contain few individuals showing signs of introgression, can be differentiated from the northern samples. Therefore, processes other than introgressive hybridisation appear to be involved in the population differentiation process. This situation is similar to that of Deepwater Redfish. The specific oceanographic conditions of the Gulf of St. Lawrence could cause a certain isolation. Morphometric homogeneity was observed between Acadian Redfishsamples in the GSL/LC area. However, the samples exhibited genetic heterogeneity, the source of which remains unexplained.

Table 4. Pairwise index of genetic differentiation between Acadian Redfish samples. The FST value is found above the diagonal, and test significance below the diagonal. (–) non–significant, (+) significant before correction, + significant after sequential Bonferroni correction (from Valentin 2006).

Sample

3L65

3N23

3O44

3PS1

3PS138

3PS26

3PS114

3PS88b

4R107

4VN67

3L65

 

−0.002

0.006

0.001

−0.003

0.000

0.003

0.006

0.013

0.007

3N23

 

0.001

0.003

0.000

−0.003

0.004

0.004

0.008

0.006

3O44

 

0.001

−0.001

0.000

0.001

0.002

0.008

0.006

3PS1

 

0.000

−0.002

0.000

−0.003

0.006

0.004

3PS138

 

−0.003

−0.001

0.004

0.010

0.006

3PS26

 

0.002

0.004

0.010

0.008

3PS114

 

−0.004

0.002

−0.001

3PS88b

 

0.004

0.000

4R107

(+)

(+)

(+)

(+)

(+)

(+)

 

0.005

4VN67

(+)

(+)

(+)

 

4VS36

(+)

(+)

4R53

+

+

+

(+)

+

(+)

(+)

(+)

(+)

+

4VN5

+

+

+

(+)

+

+

+

+

+

+

BonBay

+

+

+

+

+

+

+

+

+

+

NS85

+

+

+

(+)

+

+

(+)

(+)

+

(+)

NS95

(+)

(+)

s261

(+)

(+)

(+)

s266

(+)

(+)

s327

(+)

(+)

(+)

(+)

(+)

(+)

(+)

(+)

Table 4. Continued

Sample

4VS36

4R53

4VN5

BonBay

NS85

NS95

s261

s266

s327

3L65

0.007

0.016

0.019

0.052

0.016

0.005

0.010

0.007

0.012

3N23

0.004

0.016

0.017

0.042

0.014

0.002

0.005

0.005

0.011

3O44

0.006

0.014

0.016

0.044

0.017

0.002

0.010

0.008

0.014

3PS1

−0.001

0.007

0.014

0.039

0.008

0.001

0.003

−0.001

0.001

3PS138

0.005

0.017

0.017

0.047

0.019

0.004

0.009

0.004

0.007

3PS26

0.002

0.012

0.018

0.051

0.016

0.004

0.003

0.001

0.006

3PS114

0.001

0.008

0.017

0.038

0.007

0.006

0.003

0.002

0.006

3PS88b

0.001

0.010

0.023

0.041

0.008

0.003

0.001

0.005

0.007

4R107

0.002

0.011

0.014

0.035

0.013

0.005

0.002

0.010

0.010

4VN67

0.001

0.015

0.019

0.044

0.010

0.008

0.005

0.003

0.009

4VS36

 

0.006

0.009

0.038

0.008

0.002

0.001

0.001

0.007

4R53

(+)

 

0.010

0.038

0.004

0.015

0.009

0.006

0.010

4VN5

(+)

(+)

 

0.029

0.007

0.017

0.019

0.010

0.012

BonBay

+

+

+

 

0.032

0.042

0.046

0.041

0.038

NS85

(+)

(+)

+

 

0.019

0.006

0.004

0.004

NS95

+

+

+

+

 

0.008

0.009

0.010

s261

(+)

+

+

(+)

 

0.000

0.001

s266

(+)

+

(+)

 

−0.005

s327

(+)

(+)

(+)

+

(+)

 

 

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Table 5. Length (L50) and age (A50) at maturity of females from different stocks (from Morin et al. 2004).
      Length Age
Species DU Stock L50 SE N A50 SE N

Acadian Redfish

Atlantic

Unit 1

20.17

0.169

210

7.67

0.126

86

Unit 2

25.64

0.036

309

10.31

0.029

304

 

 

Unit 3

22.37

0.112

204

8.03

0.147

193

 

 

3O

25.47

0.118

73

10.31

0.110

30

 

 

3LN

23.98

0.298

116

 

 

 

Deepwater Redfish

GSL/LC

Unit1

24.35

0.169

238

10.36

0.173

93

 

Unit 2

24.44

0.133

155

10.60

0.086

143

 

Northern

3O

33.13

0.325

25

15.08

0.380

19

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Table 6. Length (L50) and age (A50) at maturity of males from different stocks (from Morin et al. 2004).
      Length Age
Species DU Stock L50 SE N A50 SE N

Acadian Redfish

Atlantic

Unit 1

18.88

0.305

177

6.12

0.189

61

 

Unit 2

20.11

0.06

280

7.67

0.046

277

 

 

Unit 3

20.4

0.267

147

6.85

0.191

134

Deepwater Redfish

GSL/LC

Unit1

23.04

0.105

206

8.55

0.104

68

 

 

Unit 2

23.14

0.155

177

8.88

0.18

172

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Acadian Redfish in the southern part of the range (Gulf of Maine and Scotian Shelf) seem to be genetically different from those of the GSL/LC and the northern population, suggesting a restriction in the genetic exchange between these zones. Like the Gulf of St. Lawrence, the Gulf of Maine is a productive environment in which all stages of life for Redfish occur in a favourable habitat (Pikanowski et al. 1999; Sévigny et al. 2000). Immigration from other regions is only episodic in the Gulf of Maine (Valentin 2006).

Acadian Redfish in the Gulf of St. Lawrence (Unit 1) reach sexual maturity at a younger age than those in other areas (Tables 5 and 6; Morin et al. 2004): 50% of the females in the Gulf of St. Lawrence are mature at 7.6 years of age, whereas the maturity age is 8.0 in the Scotian Shelf and 10.3 the Laurentian Channel and Grand Banks/Labrador Shelf.

An isolated population is found in the Bonne Bay fjord on the west coast of Newfoundland (Figure 8; Currie et al. 2009). Individuals from this fjord showed notable genetic differences when compared with individuals from the Gulf of St. Lawrence as well as from other regions (Figs 2, 3) (Valentin 2006). The difference between the FST values was also significant for all comparisons involving the Bonne Bay sample (FST varying between 0.029 and 0.052, Table 4). The morphometric study conducted by Valentin (2006) also showed significant differences between the Bonne Bay Redfish and those in the Gulf of St. Lawrence. These morphological differences are apparent on visual inspection (Valentin 2006). The presence of a distinct population in Bonne Bay is consistent with the observation of limited water exchange between the Fjord and the Gulf of St. Lawrence. It is hypothesized that the population could have been even more isolated during the last deglaciation event that took place between 13,000 and 6,000 years ago.

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Designatable Units

Deepwater Redfish

Genetic studies, supported by morphometric analyses, strongly suggest that two populations of Deepwater Redfish are found in the Northwestern Atlantic. Only studies on parasite infestations show differences between the Deepwater Redfish in the Gulf of St. Lawrence and those in the Laurentian Channel.

The two genetic populations (Figs 2, 3) of Deepwater Redfish are clearly distinct geographically (Figure 6).

Figure 6. Deepwater Redfish (Sebastes mentella) genetic groups (as identified in Figure 2) and proposed boundary between the Northern DU and the Gulf of St. Lawrence/Laurentian Channel DU.

Map showing the location of Deepwater Redfish genetic groups and the proposed boundary between the Northern designatable unit and the Gulf of St. Lawrence - Laurentian Channel designatable unit.

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For the purposes of designating status, the report therefore proposes that Deepwater Redfish in Canadian waters be considered as two Designatable Units: the Northern DU, consisting of individuals of the Grand Banks, Labrador Shelf, Davis Strait and Baffin Bay, (NAFO Areas 0 and 2 plus Divisions 3KLNO, Figure 5); and the Gulf of St. Lawrence/Laurentian Channel (GSL/LC) DU (NAFO Divisions 3P4RST).

These DUs meet the “distinctness” criteria of COSEWIC’s DU Guidelines because of the genetic and morphometric differences between them, and because they are clearly geographically separated. They meet the “significance” criteria because elimination of one of these DUs would create a major gap in the distribution of the species.

The proposed boundary between the two DUs (Figure 6) is the boundary between NAFO Divisions 3LO and NAFO Subdivision 3Ps off southern Newfoundland, and between NAFO Divisions 4R and 3K between Newfoundland and Labrador. This is consistent with the genetic data and it conforms with the existing management framework for redfishes.

With respect to the northern boundary of the Northern DU, there is no information to indicate that the Northern DU does not extend to the northern limits of the distribution of the species in Canada; indeed the single sample from southern Greenland is genetically close to samples from Canadian waters on the Grand Banks and Labrador shelf. Accordingly the proposed DU would include all Canadian waters to the north, and its proposed eastern boundary is the boundary between Canadian and Greenland EEzs in the Davis Strait and Baffin Bay.

Acadian Redfish

For the purposes of designating status, this report proposes that the Acadian Redfish be divided into two Designatable Units: an Atlantic DU covering the Canadian distribution of the species except Bonne Bay and the Bonne Bay DU.

The Bonne Bay DU meets the “distinctness” criterion because its genetic and morphometric characteristics are very different from those of other Acadian redfish in Canada’s Atlantic. Experienced biologists and fishermen are able to distinguish Bonne Bay redfish from those originating outside the Bay. It meets the “significance” criteria because it has persisted in a unique setting for redfishes, a small fjord–like bay on the west coast of Newfoundland. This DU is separated from the Atlantic DU by the shallow waters of Outer Bonne Bay and the shallow sill (~50 m depth) at the entrance to East Arm, Bonne Bay (Figure 8). The majority of East Arm is greater than 150m in depth and this is where the Acadian Redfish are found.

The genetic differences between the other groups of Acadian redfish are small relative to those identified for Deepwater Redfish (Figs 2,3). Further, the three genetic groups identified are not clearly separated geographically (Figure 7). As such, there appears to be no basis for establishing more than one DU for Acadian Redfish outside Bonne Bay.

Figure 7. Acadian Redfish (Sebastes fasciatus) genetic groups from proposed Atlantic DU (solid symbols) and location of proposed Bonne Bay DU (cross). Genetic groups are as identified in Figure 2.

Map showing the location of Acadian Redfish genetic groups from the proposed Atlantic designatable unit, as well as the location of the proposed Bonne Bay designatable unit.

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Figure 8. Bonne Bay, Newfoundland. All Redfish were caught in the East Arm, east of the sill. Source: Currie et al. 2009.

Map of Bonne Bay on the Island of Newfoundland.

Because the proposed Atlantic DU covers the entire species distribution (other than Bonne Bay) in Atlantic Canada, the boundaries would be the boundaries of Canada’s Atlantic maritime waters and Extended Economic Zone.

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DISTRIBUTION

Global range

Deepwater Redfish is found on both sides of the North Atlantic at depths typically varying between 350 and 500 m (Atkinson 1987). However, Deepwater Redfish has been observed at much greater depths (as far down as 910 m) (Whitehead et al. 1986). On the western side of the Atlantic, this species is found from the south of Newfoundland north to Baffin Bay (Figure 9). The distribution of this species extends east, from an area south of Greenland and off the coast of Iceland to the northern coast of Europe. In Europe, Deepwater Redfish occurs from the western Barents Sea to the Norway Sea (Whitehead et al. 1986).

Figure 9. North Atlantic distribution of Deepwater Redfish.

Map of the North Atlantic distribution of Deepwater Redfish.

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The distribution of Acadian Redfish, which is found only in the Northwestern Atlantic, is more limited than that of Deepwater Redfish. This species occupies shallower depths than Deepwater Redfish, generally between 150 and 300 m (Atkinson 1987). The distribution of the Acadian Redfish extends from the Gulf of Maine to the Labrador Sea (Figure 10). A few individuals (18 in total) of Acadian Redfish have been reported east of Greenland and near Iceland (Whitehead et al. 1986).

Figure 10. Global distribution of Acadian Redfish.

Map of the global distribution of Acadian Redfish.

The distributions of these two redfish species in the Northwestern Atlantic follow a north–south gradient: Deepwater Redfishis more abundant in the north, whereas Acadian Redfish is more prevalent in the south. The vast majority of Redfish occupying the north of the Labrador Sea are Deepwater Redfish, whereas Acadian Redfish is found almost alone in the Gulf of Maine and the Scotian Shelf (Valentin et al. 2006). In the intermediate zones, both species are present.

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Canadian range

In Canadian waters, Deepwater Redfish is primarily found along the edge of the banks of the continental slope and in deep channels. The Canadian range extends from the area south of Newfoundland to Baffin Bay, and includes the Gulf of St. Lawrence and Labrador Sea (Figure 11). Deepwater Redfish also occurs in the St. Lawrence estuary and can be found as far as the Saguenay fjord.

Figure 11. Canadian distribution of Deepwater Redfish.

Map of the Canadian distribution of Deepwater Redfish.

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A large portion of the range for Acadian Redfish is found in Canadian waters. This species is found on the Scotian Shelf, along the continental slope of the Grand Banks of Newfoundland, in the Gulf of St. Lawrence and south of Newfoundland (Figure 12). Acadian Redfish also occurs in the Bonne Bay fjord.

Figure 12. Canadian distribution of Acadian Redfish.

Map of the Canadian distribution of Acadian Redfish.

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Extent of occurrence and area of occupancy

The area of occupancy was evaluated by DFO using data from scientific surveys (Sévigny et al. 2007). Three indices were produced: the design–weighted area of occupancy (DWAO) index, the D95 and the GINI index of aggregation. The DWAO is the area of occupancy (A) weighted by sampling:
 
Math equation
where Whis the area of stratum h, Nh is the number of tows in stratum h, and Ihi = 1 if the catch in stratum h and set i is > 0. Ihi= 0 if the

catch = 0.

The D95 and GINI are indices of fish concentrations. However, of the three indices presented by DFO, the DWAO is the one that comes closest to the definition of “area of occupancy” as proposed by COSEWIC. This index will therefore be presented for the different areas of occupancy covered by each survey. It should be noted that the DFO surveys used in this analysis do not include NAFO Area 0 where Deepwater Redfish are known to occur.

Using DFO’s catch data, the COSEWIC Secretariat has also calculated the area of occupancy of Redfish species. Unlike the DWAO, the calculation method used by COSEWIC is based on presence in 2 km by 2 km grid squares. The two values for the area of occupancy (DWAO and COSEWIC) are presented in this report.

The COSEWIC Secretariat also calculated the extent of occurrence. This index is obtained from the minimum area occupied by a convex polygon covering all sites for the listed catches.

The extents of occurrence for Deepwater Redfish and Acadian Redfish are evaluated respectively at 511 x 103 km² and 553 x 103 km² in the Gulf of St. Lawrence/Laurentian Channel. The area occupied by redfish species in this region has remained constant over the period studied (Figure 13). Although the abundance indices have declined substantially (see later section), the distribution of redfishes has remained the same. Between 1996 and 2002 (years in which sampling was carried out in both units 1 and 2), the surface occupied varied between 144 000 and 149 000 km². Note that identification by species was not carried out due to the imprecise methods of differentiation (Morin et al. 2004). As well, sampling does not cover the entire redfish range. Based on the 2 km x 2 km COSEWIC method, the areas occupied by Deepwater Redfish and Acadian Redfish in this area are 16 x 103 km² and 31 x 103 km² respectively.

Figure 13. Area of occupancy (DWAO) for redfish populations in the Gulf of St. Lawrence and the Esquiman Channel. Aire échantillonnée = area sampled. Aire d’occupation = area of occupancy. Unité = Unit.

Chart showing area of occupancy for redfish populations in the Gulf of St. Lawrence and the Esquiman Channel.

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In northern areas (Newfoundland Grand Bank, Labrador Shelf and Sea), the extent of occurrence has been evaluated at 1431 x 103 km² for Deepwater Redfish and 785 x 103 for Acadian Redfish. The area of occupancy (DWAO) was calculated by DFO for each management zone (Sévigny et al. 2007). The areas occupied by Sebastes sp. in each management unit were added to Figure 14. Note that the area covered by the surveys varied enormously from year to year. Note that the survey season is not the same for all areas between 1973 and 1990. Zones 3O and 3LN were visited in the spring, whereas zones 2J3K and 2GH were seen in the fall. From 1991 to 2006, the values were calculated on the basis of the fall surveys for all zones. Note as well that certain surveys (especially 2GH) were not done for each year. As with the Gulf of St. Lawrence/Laurentian Channel populations, Redfish distribution seems to be relatively stable over time. The DWAO index increased, based on surface sampled. Moreover, the surveys did not cover the entire area occupied by the northern Redfish population. The actual zone occupied is therefore higher than the maximum value of 104 000 km² as measured in the surveys. Based on the 2 km x 2 km COSEWIC method, the areas occupied by the northern populations of Deepwater Redfish and Acadian Redfish are 21 x 103 km² and 20 x 103 km² respectively.

Figure 14. Area of occupancy (DWAO) for redfishes in the northern area (Grand Banks, Labrador Shelf). Aire échantillonnée = area sampled. Aire d’occupation = area of occupancy.

Chart showing area of occupancy for redfish in the northern area (Grand Banks, Labrador Shelf).

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In the southern area, Unit 3 of DFO (Scotian Shelf and Gulf of Maine), the extent of occurrence for Acadian Redfish has been evaluated at 173 x 103 km². In spite of fluctuations that may be attributed in part to variabilities in sampling, no long–term trend was seen (Figure 15). Based on the 2 km x 2 km COSEWIC method, the area occupied by the southern population of Acadian Redfish is 5.6 x 103 km².

The east arm of Bonne Bay has a surface area of 26.1 km² based on a polygon that encloses the fjord (Joe Wroblewski, pers. comm. 2009). The extent of occurrence is estimated to be 72 km² using a 2 km x 2 km grid of the area. Area of occupancy would probably be somewhat less than this since redfish occupy only the deeper fraction of the fjord.

Figure 15. Area of occupancy (DWAO) for Acadian Redfish in Unit 3, the Scotian Shelf. Aire d’occupation = area of occupancy. Unité = Unit.

Chart showing area of occupancy for Acadian Redfish in Unit 3, the Scotian Shelf.

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Habitat

Habitat requirements

The habitat requirements of Atlantic Redfish species are incompletely known. Knowledge of the requirements of Acadian Redfish in the Gulf of Maine were summarized by Pikanowski et al. (1999). Certain aspects of redfish biology and requirements were also described by Gascon (2003).

Redfishes are born as larvae, which are found primarily in surface waters. In the Gulf of Maine, newly released larvae are mainly found in the first 10 m of the water column, whereas larvae measuring between 10 and 25 mm are found in the thermocline (10–30 m) (Pikanowski et al. 1999). Unlike larvae in the Gulf of Maine and the Scotian Shelf (Kelly and Barker 1961; Sameoto 1984; cited by Kenchington 1991), larvae in the Gulf of St. Lawrence undertake a marked vertical migration. The preferred depth of Redfish larvae (regardless of the species) was evaluated at between 11 and 30 m by day and 10 metres or less at night (Kenchington 1991). Despite the preference for certain depths larvae were observed throughout the upper 200 m of the water column. Some observations suggest that Deepwater Redfish larvae make larger vertical migrations than Acadian Redfish larvae (Kenchington 1991).

In the Gulf of Maine, Acadian Redfish juveniles move below the thermocline upon reaching a length of approximately 25 mm. The juveniles remain pelagic until they reach 40–50 mm, i.e. for a period of approximately 4 to 5 months (Kelly and Barker 1961). In general, smaller redfishes live in shallower waters, while larger individuals occupy deeper waters. The preferred zone for younger individuals is between 75 and 175 m. Some evidence suggests that redfishes use rocks or anemones as shelter from predators (Shepard et al. 1986; Auster et al. 2003). Because the smaller redfishes stay in shallower habitats, it is likely that their need for shelter (macro–vegetal or anemone) is greater than that of the adults. Coastal habitats are more commonly occupied by Acadian Redfish than by Deepwater Redfish.

Adults prefer cold waters (approximately 5°C) along the slopes of banks and deep channels. Acadian Redfish generally live at depths varying from 150 to 300 m, whereas Deepwater Redfish are found between 350 and 500 m (Atkinson 1987). Although these are consistent depth preferences, and depth can be used to help separate the two species, overlap in depth distribution is such that depth alone cannot be used to separate species. Redfish are considered to be semi–pelagic species because they make large–scale daily vertical migrations (Gauthier and Rose 2002).

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Trends

The proportion of habitat made up of anemones or coral or having an irregular bed may have declined in recent decades due to the increased use of bottom trawling. However, no studies have been carried out to evaluate the effects of trawling on these habitats. If this type of habitat is important for the survival of Redfish, the possible reduction of the habitat could have an adverse impact on the abundance of the species.

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BIOLOGY

Information on the biology of Deepwater Redfish and Acadian Redfish is limited. As a result of the multidisciplinary research program on redfishes carried out between 1995 and 1998 by Fisheries and Oceans Canada (DFO) (Gascon 2003), knowledge of redfish biology has improved. Modelling marine ecosystems has also been useful in understanding the different trophic interactions of Redfish (e.g. Savenkoff et al. 2006).

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Life cycle and reproduction

The redfishes of the Northwestern Atlantic differ from most other marine fishes because females are viviparous. Fertilization is internal, and the female carries the young until they are released as larvae. According to Saint–Pierre and de Lafontaine (1995) and Lambert et al. (2003), the absolute fecundity of females varies between 1500 and 107 000 larvae, and fecundity increases as a power function of fish length or mass. According to the results of these studies, Acadian Redfish seems to have greater fecundity than Deepwater Redfish. Breeding (transfer of male gametes to the female) occurs between September and December (Ni and Templeman 1985; Lambert et al. 2003). The female carries the embryos until the larvae are released, for a period that varies with region and species. In the Gulf of St. Lawrence, the larvae appear to be released in late spring and early summer, but release seems to take place sooner in the waters south of Newfoundland (Ni and Templeman 1985). Larval release in Deepwater Redfish appears to occur 15 to 25 days earlier than for Acadian Redfish (Sévigny et al. 2000). The larvae measure 6–9 mm at birth (Penny and Evans 1985).

Recruitment is highly variable in these species. An interval of between 5 and 12 years has been observed between each of the major year classes (Morin et al. 2004) during periods when populations were relatively lightly exploited and abundant. Some year classes that appeared particularly strong at young ages have disappeared without reaching larger sizes, for unknown reasons. This phenomenon was observed during the 1990s when the abundant 1988 year class apparently disappeared before reaching commercial size (Lambert et al. 2003).

Redfish differ from most other marine fishes in their slow growth and long life expectancy. Specimens at least 75 years old have been reported (Campana et al. 1990). The two species have similar growth, although Acadian Redfish grows more slowly starting from age 10 (Morin et al. 2004). Further, after age 10 females grow faster than males in both species. Growth is quicker in the southern part of the range than in the northern part (Gascon 2003).

Deepwater Redfish males generally reach a maximum length of 40 to 45 cm, whereas females may grow to between 45 and 60 cm in length. A 58–cm specimen was described by Coad and Reist (2004). Acadian Redfish commonly reaches a size of 45 cm in the Gulf of Maine (Mayo et al. 1990).

“Generation time” is defined by COSEWIC as the average age of the parents of the current cohort. The same calculation that is applied to cod was used to determine the generation time for the different species and populations of Redfish (COSEWIC 2003). This was done to take into account the effects of fishing pressures on age at maturity.

Gt= Afemale + 1/M

where Afemale (or A50) is the age at which 50% of adult females are mature, and M is the instantaneous rate of natural mortality. The natural mortality rate used in this report is 0.125, as adopted by Bundy et al. (2000). This involves an average of the values estimated by Rikhter (1987). Because redfish have a long life expectancy, this value is considered more appropriate than the 0.2 value used for several marine species (e.g. cod: Smedbol et al. 2002). The A50s of the different stocks, based on Morin et al. (2004), are found in tables 5 and 6, and generation times are summarized in Table 7.

Table 7. Age at maturity, generation time, and summary of decline rates for the number of mature individuals for Deepwater Redfish and Acadian Redfish in different areas. Age at maturity is for females. For the rates of decline, NA indicates no data, and None indicates there was not a decline.
Species DU Stock Age at Maturity Generation Time (yr) Period Rate of Decline

Deepwater Redfish

GSL/LC

Unit 1

10.4

18.4

1984−2007

− 98.4%

Unit 2

10.6

18.6

1994−1997; 2000; 2002

NA

Northern

3O

15.1

23.1

1991−2006

None

3LN

1991−2006

None

2J3K

1978−2006

− 98.0 %

2GH

1987−2006

None

Acadian Redfish

Atlantic

Unit 1

7.7

15.7

1984–2007

− 98.5%

Unit 2

10.3

18.3

1994−1997; 2000; 2002

NA

3O

10.3

18.3

1991−2006

None

3LN

1991−2006

None

2J3K

1978−2006

− 99.7%

2GH

1987−2006

None

Unit 3

8.0

16.0

1984−2006

None

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Predators

Redfishes are preyed upon by Harp Seals (Phoca groenlandica), Hooded Seals (Cystophora cristata), Grey Seals (Halichoerus grypus), and large piscivorous fish. These fish include Greenland Halibut (Reinhardtius hippoglossoides), Thorny Skate (Raja radiata), Atlantic Cod (Gadus morhua), Black Dogfish (Centroscyllium fabricii), Monkfish (Lophius americanus), Pollock (Pollachius virens) and Wolffishes (Anarhichas sp.) (Konchina 1986; Berestovskiy 1990; Pikanowski et al. 1999, Hammil and Stenson 2000).

Based on modelling conducted by Savenkoff et al. (2006), the Harp Seal and skates have been the main predators of redfishes over the past few years in the Gulf of St. Lawrence. Before stocks collapsed, Atlantic Cod was the main predator. On the Newfoundland and Labrador Shelf, Greenland Halibut and skates appear to be the main predators of redfishes (Savenkoff et al. 2001). In the eastern part of the Scotian Shelf, Pollock, Grey Seals and Haddock are the most common predators of redfishes (Bundy 2004).

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Diet

At the larval stage, Acadian Redfish in the Gulf of Maine feed on the eggs of fish and invertebrates. The largest larvae also feed on copepods and euphausiids (Anderson 1994; Pikanowski et al. 1999). When redfishes reach juvenile and adult sizes, the prey size increases, and the redfishes may then feed upon copepods, euphausiids and fish. Deepwater Redfish and Acadian Redfish seem to have a similar diet (Dutil et al. 2003a).

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Physiology

The preferred temperature of Acadian Redfish larvae at the southern limit of their range (Gulf of Maine) was evaluated at between 4 and 11°C (Pikanowski et al. 1999). The preliminary results of the laboratory studies carried out as part of the DFO multidisciplinary project on Redfish (Dutil et al. 2003b) show that the mortality rate is higher in Acadian Redfish larvae at low temperatures (0.3 to 1.6°C) and at temperatures above 14°C than at temperatures between these values.

The temperature preference of Acadian Redfish juveniles in the Gulf of Maine is between 5 and 10°C (Pikanowski et al. 1999). In the Gulf of St. Lawrence and the Laurentian Channel, the temperature preference for adult Redfish is between 4.5 and 6.0°C, whereas it is between 5.5 and 7.0°C off Nova Scotia (Morin et al. 2004).

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Movements/dispersal

Dispersal in redfish species has not been well documented. Dispersal probably mainly occurs at the larval and juvenile stages. The larvae are extruded in the spring and the juveniles only settle on the bottom at the beginning of the fall (Kenchington 1984), which leaves considerable time for dispersal by currents.

Once redfishes reach the bottom, it is believed that their movements are limited. Given their exceptionally long life, however, the adults could undertake major long–term movements. Redfishes very rarely survive capture due to the gas bladder’s rupture (lethal trauma) on being brought to the surface. It is therefore virtually impossible to conduct tagging studies on these species unless tagging is done at depth (and Redfish live too deep to be tagged by divers). For these reasons, redfish movements are not as well documented as for some other species.

Redfish in the Gulf of St. Lawrence move in winter to the Laurentian Channel south of Newfoundland. Analyzing industry catch rates first revealed this movement (Atkinson and Power 1989). A study using the composition of otolith trace elements also supports these conclusions (Campana et al. 2007).

Given its more fusiform morphology, it is believed that Deepwater Redfish may move farther than Acadian Redfish (Valentin et al. 2002).

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POPULATION SIZE AND TRENDS

Search effort

DFO trawl surveys are the main method used to follow changes in redfish abundance. Surveys have been conducted based on management units defined by the Northwest Atlantic Fisheries Organization (NAFO) (Figure 5): 1) West Greenland (Subarea 1); 2) the Labrador Sea (Subarea 2+Division 3K); 3) the Flemish Cap (Division 3M); 4) the eastern and northern Grand Banks (Divisions 3LN); 5) the southwestern Grand Banks (Division 3O); 6) the Gulf of St. Lawrence (an area defined by DFO as Unit 1, comprising NAFO 4RST + 3Pn4Vn, January to May); 7) the Laurentian Channel (an area defined by DFO as Unit 2, comprising NAFO 3Ps4Vs4Wfgj + 3Pn4Vn, June to December); 8) the Scotian Shelf (DFO Unit 3 comprising NAFO 4WdehklX); and 9) the Gulf of Maine (NAFO Subarea 5). Each of the DUs proposed in the present report (other than Bonne Bay for Acadian Redfish) therefore groups together several management areas. The abundance indices presented in this section were calculated by DFO and details are presented in Sévigny et al. (2007).

Abundance estimates of Sebastes spp. for each management area as well as the related confidence intervals are in Appendices 1 and 2.

Abundance estimates in these surveys are relative. Catchability of redfishes varies depending on the fishing gear used, and the power or speed of the vessel, so abundance estimates from different areas or years cannot be directly compared. Moreover, because redfishes are semi–pelagic species, bottom trawls (as used in DFO surveys) may not sample the entire population, and abundances would therefore be underestimated. Sampling can also only be partial when redfishes occupy areas beyond depths covered by the surveys, so presence of redfishes in deep waters may thus lead to abundance being underestimated. The bed topography may differ between areas, and can also introduce bias. Certain areas have very steep slopes or a rocky bed, which complicates or prevents the use of bottom trawling. Lastly, the data series available are, for the most part, of short duration, and generally do not cover the three generations usually needed for application of the COSEWIC decline criterion.

Given the impossibility of rapidly differentiating between Deepwater Redfish and Acadian Redfish, particularly in commercial catches, redfish stock assessments have always been done for all species combined. However morphological and genetic characteristics collected during the various surveys permit differentiating the species in trawl survey catches (Morin et al. 2004; Méthot et al. 2004).

In Units 1 and 2 (Gulf of St. Lawrence and Laurentian Channel), anal fin ray count and MDH analyses were used to evaluate total and mature abundance for each genotype (Deepwater Redfish, Acadian Redfish and heterozygotes). In this report, the heterozygote individuals were treated separately. However, data on these individuals are presented in the sections on Deepwater Redfish. Although introgressive hybridation is bidirectional, it is asymmetrical toward Deepwater Redfish (Roques et al. 2001). Several characteristics, including fecundity and sexual maturity, show this asymmetry (Gascon 2003), as well as distribution (Morin et al. 2004) and depth occupied (Méthot et al. 2004). Although some of heterozygotes are closer to Acadian Redfish, the majority are related to Deepwater Redfish.

In surveys in NAFO 3O, 3LN and 2+3K (Grand Banks and Labrador Sea), differentiation by species was done by number of vertebrae, and anal and dorsal fin ray counts (Morin et al. 2004)). Next, the percentages of Deepwater Redfish and Acadian redfish were estimated by depth zone and applied to the abundance indices of Sebastes sp. This assessment by depth is based on data used by Ni (1982), and the estimates therefore do not take into account the potential variations in the percentages of the species by depth over time.

Abundance indices for mature individuals for each population were based on size class. Individuals equalling or exceeding L50 females in size (Table 5) were considered mature in each region.

The decline rate was determined using the following equation:

Gdecline  = 1−exp(T*b)
where T is the number of survey years and b the slope of linear regression for abundance in loge.

Redfishes have an exceptionally long lifespan, and surveys covered only a short period relative to this. Thus, recruitment variability must be considered when evaluating the status and rate of decline in this species.

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Abundance

All decline rates presented in this section, along with generation time and age at maturity for each population are summarised in Table 7. Abundance indices by species and population are shown in table form in Appendix 1.

Deepwater redfish

Gulf of St. Lawrence/Laurentian Channel DU

The proposed Gulf of St. Lawrence/Laurentian Channel DU includes two management units, Units 1 and 2 (Figure 4), which were put in place in 1993 (Atkinson and Power 1991). Unit 1 corresponds to NAFO Divisions 4RST, and has been covered by a DFO summer scientific survey since 1984. Two changes were made to the vessel and fishing gear during this series. Correction factors had to be determined to allow comparisons among the different survey years.

Before 1993, Unit 2 was made up of more than one management unit, and no survey fully covered Unit 2. Complete surveys of the area were carried out between 1994 and 1997, in 2000 and in 2002. Partial surveys have been done over a longer period of time: since 1972 in Subdivision 3Ps, and since 1970 in Subdivision 4V. These surveys were carried out using different gear and for a different period, and thus the data obtained from these surveys cannot be compared with data from directed Redfish surveys. Further, no identification information was collected during these surveys so abundance indices by species are not available from these surveys (see “Pooled Species” section below).

In Unit 1, abundance indices of mature Deepwater Redfish were stable until the end of the 1980s, after which they declined between 1989 and 1994 (Figure 16). The estimate went from 2293 million mature individuals to a minimum of 34 million in 2004. The Deepwater Redfish abundance index in 2007 is an all–time low (36 million). The rate of decline between 1984 and 2007 was assessed at 98.6%. Abundance indices for heterozygotes follow the same pattern as those for Deepwater Redfish (Figure 16).

Figure 16. Survey abundance of mature Deepwater Redfish and heterozygotes in Unit 1, proposed Gulf of St Lawrence/Laurentian Channel DU, from 1984 to 2007, ln transformed.

Chart showing survey abundance for mature Deepwater Redfish and heterozygotes in Unit 1, Gulf of St Lawrence - Laurentian Channel designatable unit, from 1984 to 2007.

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Little information is available for Unit 2. As in Unit 1, the abundance index appeared to remain stable between 1996 and 2002 (Figure 17), varying between 169 and 245 million mature individuals (Morin et al. 2004). The abundance index series available for Unit 2 is insufficient for evaluating the changes that have occurred over the past decades.

Figure 17. Survey abundance of Deepwater Redfish and heterozygotes in Unit 2, Gulf of St Lawrence/Laurentian Channel DU, from 1994 to 2002.

Chart showing survey abundance for Deepwater Redfish and heterozygotes in Unit 2, Gulf of St Lawrence - Laurentian Channel designatable unit, from 1994 to 2002.

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The lack of significant recruitment of Deepwater Redfish is a concern in the Gulf of St Lawrence/Laurentian Channel population (Figure 18). Redfish populations are characterized by the appearance of strong year classes between 5 and 12 years of age (Morin and Bernier 1994). These populations will thus support fishing activities for many years to come. The last significant year class for Deepwater Redfish may have been produced at the beginning of the 1980s (Sévigny et al., in progress). Therefore, there has been no major recruitment of Deepwater Redfish for more than 25 years. Note that, in Unit 1, a year class has appeared for the first time in the 2007 catches (Figure 18). Tests will be carried out to establish to which species this cohort belongs.

Figure 18. Length frequency of Sebastes sp. in Unit 1, Gulf of St. Lawrence/Laurentian Channel DU. From Sévigny et al. 2007.

Chart showing length frequency for Sebastes species in Unit 1, Gulf of St. Lawrence - Laurentian Channel designatable unit. From Sévigny et al. 2007.

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Northern DU

Abundance indices by species are available for NAFO 3O, 3LN and 2+3K (Sévigny et al. 2007).

Surveys have been carried out in the spring in divisions 3O and 3LN since 1973 and in the fall since 1991. However, due to the use of different gear and variations in the area covered, only 1991 to 2005 are directly comparable. Note that the 2006 survey in Divisions 3O and 3N did not cover the depths in which redfishes would normally be found. Surveys have been conducted in NAFO 2J3K since 1978. From 1978 to 1991, depths to 1000 m were covered, while maximum depths have been increased to 1500 m since 1996. A survey was also carried out more sporadically in Divisions 2GH, with variable coverage and no survey in 2G in 2001, 2004 or 2006. Since 1996, surveys have been carried out down to a depth of 1500 m.

The difference in areas covered by the surveys adds variability to abundance estimates. However, the additional area that has been fished since 1996 covers deeper areas (1000 to 1500 m) in which Redfish are not abundant. The often rocky bed of a steep slope provides additional variability, because no two hauls have the same catch performance. Species were differentiated based on meristic characteristics (number of vertebrae, anal and dorsal ray fin count (Morin et al. 2004), which adds additional uncertainty.

In Division 3O, abundance indices from 1973 to 1982 were variable without showing any trend (Figure 19). Variability may be explained by the fact that the surveys only cover depths shallower than 200 fathoms (366 m), such that Deepwater Redfish population was not sampled in its entirety. From 1984 to 1990, the estimates were also variable, with a declining trend, decreasing from 2.1 million in 1984 to 0.4 million in 1990. Since 1991, in spite of the wide variability, a generally increasing trend has been observed in the abundance index. The estimated number of mature individuals went from 3.1 million in 1992 to 20.8 million in 2005 during the spring survey, and from 1.2 million in 1992 to 33.5 million in 2006 during the fall survey.

Figure 19. Survey abundance of mature Deepwater Redfish in Division 3O, Northern DU, ln transformed. Printemps = spring; automne – fall.

Chart showing survey abundance for mature Deepwater Redfish in Division 3O, Northern designatable unit, ln transformed.

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In Divisions 3LN, there was considerable variation between 1973 and 1982 (Figure 20). Higher estimates at the end of the period may be attributable to better distribution coverage (Morin et. al 2004). Indices for mature Deepwater Redfish declined between 1985 and 1990 (1.9 to 0.5 million). An increase in the abundance index was noted in the spring between 1991 and 2004, followed by a decline. The values calculated in 2006 are similar to those observed in 1991 (10.4 and 8.1 million, respectively). Lastly, a slight increase was seen during the fall survey between 1991 and 2006. Note that this management unit was under a moratorium for Redfish from 1998 but a fishery was recently reopened.

In Divisions 2J3K, the Deepwater Redfish substantially decreased in numbers between 1983 and 1995 (Figure 21), going from 3752 million to 14 million. The abundance index has dropped by 98.3% since 1978. The abundance estimates however have shown a tendency to increase over the past few years.

Figure 20. Survey abundance of mature Deepwater Redfish in Division 3LN, Northern DU, ln transformed. Printemps = spring; automne = fall.

Chart showing survey abundance for mature Deepwater Redfish in Division 3LN, Northern designatable unit, ln transformed.

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Figure 21. Survey abundance of mature Deepwater Redfish in divisions 2J3K and 2GH, Northern DU, ln transformed. Note: Division 2G was not sampled in 2001, 2004 and 2006.

Chart showing survey abundance for mature Deepwater Redfish in divisions 2J3K and 2GH, Northern designatable unit, ln transformed.

The surveys conducted in Division 2GH have shown a certain amount of variability without revealing any trends.

In summary, the portion of the population found in Division 2J3K has declined substantially, although an increase has been observed since 2000. The abundance indexes for divisions 3O, 3LN and 2GH do not appear to show similar declines, although changes in gear make long–term index comparisons difficult; in 3LN and 3O an increasing trends has been observed since the early 1990s.

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Acadian Redfish

Atlantic DU

Although a single DU is proposed for Acadian Redfish outside of Bonne Bay, abundance indices for this DU are presented by geographical region.

a) Gulf of St. Lawrence/Laurentian Channel

This region includes Management Units 1 and 2. The same surveys as those described for the Deepwater Redfish in the Gulf of St. Lawrence/Laurentian Channel are used for Acadian Redfish.

The Gulf of St. Lawrence (Unit 1) included over 70% of the total abundance in the Atlantic DU in the early 1980s. The abundance index for mature individuals was relatively stable during the 1980s but plummeted between 1988 and 1996 (Figure 22), going from 2500 million to 39 million during this period. Abundance has remained low ever since; the abundance index was 50 million in 2007. The rate of decline in the mature population between 1984 and 2007 was evaluated at 99.5% in the Gulf of St. Lawrence.

Because Unit 2 is a recent management unit, very few data are available for the entire zone. No trends are apparent in this short series (1994 to 2002; Figure 23). Data for 3Ps and 4V for Sebastes sp. presented below in the section on pooled species have shown however a certain stability in the abundance indices since the 1970s. Moreover, the indices for these last two surveys have been increasing since 2004.

Figure 22. Survey abundance of mature Acadian Redfish in Unit 1, Gulf of St. Lawrence, ln transformed.

Chart showing survey abundance for mature Acadian Redfish in Unit 1, Gulf of St. Lawrence, ln transformed.

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Figure 23. Survey abundance of mature Acadian Redfish in Unit 2, Laurentian Channel, from 1994 to 2002.

Chart showing survey abundance (millions) for mature Acadian Redfish in Unit 2, Laurentian Channel.

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Cohorts which appeared to be abundant when they were first observed in surveys have subsequently disappeared before recruiting to the fishery. In Unit 1, the 1988 year class disappeared from survey catches after only a few years (Figure 18). This year class was mainly made up of Acadian Redfish. The most plausible hypothesis for this disappearance is a high mortality rate. The lack of major recruitment over the past few years has kept the population at a low level of abundance. A large new cohort of Acadian Redfish however appeared in the 2005 surveys (Figure 18). This cohort was still apparent in the 2007 survey, but preliminary analysis of the 2008 survey shows that it has now disappeared (DFO pers. comm.).
 
b) Northern area

Surveys in Divisions 3O, 3LN, 2J3K and 2GH described for Deepwater Redfish were used to examine abundance trends.

In Division 3O, surveys conducted in the spring from 1973 to 1982 showed considerable variability in the abundance index, without revealing any definite trend (Figure 24). The values varied between 6.4 and 135 million. That variability could be explained by the incomplete coverage of areas occupied by Acadian Redfish. The 1984 to 1990 spring surveys also revealed fluctuations. The values were higher in 1990 (439 million) than at the beginning of the survey in 1984 (41 million). Between 1991 and 2007, two surveys were carried out annually in this area (spring and fall). An increase in the abundance index occurred between 1991 and 1998 in the spring survey. The values thereafter fluctuated without any definite trends. The 1997 spring survey is considered to be an anomaly (Morin et al. 2004). The 1991 to 2006 fall surveys showed more stable abundance indices, with the exception of the high values recorded in the late 1990s.

Figure 24. Survey abundance of mature Acadian Redfish in Division 3O, ln transformed. Printemps = spring; automne = fall

Chart showing survey abundance for mature Acadian Redfish in Division 3O, ln transformed.

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In Division 3LN, the abundance indices varied greatly between 1973 and 1982 (7.5 to 161 million; Figure 25). The variation in the area sampled over the years could explain the higher values over the last few years (Morin et al. 2004). From 1985 to 1990, the abundance indices also varied without showing any definite trends. Lastly, the abundance indices seemed to have increased between 1991 and 2006 in the spring and fall surveys. The values in the fall were 33 million in 1991 and 252 million in 2006. In the spring, the abundance index was 17.1 and 95 million for these same years. Directed Redfish fishery has been prohibited in this division since 1998.

Figure 25. Survey abundance of mature Acadian Redfish in Division 3LN, ln transformed. Printemps = spring, automne = fall.

Chart showing survey abundance for mature Acadian Redfish in Division 3LN, ln transformed.

In 2J3K, the Acadian Redfish population started to decrease in the mid–1980s, and then dropped substantially in the 1990s (Figure 26). From 4001 million in 1983, the abundance index decreased to 1.2 million in 1994. The values remained low until 2004 and increased in 2005 and 2006 to 71 million. The rate of decline between 1978 and 2007 was 99.8%.

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Figure 26. Survey abundance of mature Acadian Redfish in divisions 2J3K and 2GH, ln transformed.

Chart showing survey abundance for mature Acadian Redfish in divisions 2J3K and 2GH, ln transformed.

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Surveys conducted in 2GH were discontinued and no trend appeared.

To conclude, the Acadian Redfish abundance index dropped substantially in Division 2J3K, but has shown some increase in the most recent years. In other areas, the data between 1991 and 2007 showed no decline. Unfortunately, the complete series cannot be compared given the changes to the fishing gear. The northern area made up less than 20% of the Acadian Redfish abundance in the Atlantic DU in the early 1980s.

c) Southern area

The southern area includes the Scotian Shelf and Gulf of Maine. The Scotian Shelf constitutes Management Unit 3, and is made up of NAFO subdivisions 4X and 4Wdehlk. NAFO Division 5 in the Gulf of Maine is almost entirely located in American territory. Because only Acadian Redfish is found in this zone, no classification by species was necessary to interpret survey results.

A scientific survey has been conducted annually by DFO in Unit 3 since 1970. However, the vessel and fishing gear were changed in 1982 and no conversion factor could be calculated. Consequently, only the data series from 1982 to date are comparable. Large variations in abundance indices were seen in Unit 3 (Figure 27), from 29 to 343 million mature individuals between 1982 and 2006, but with no long–term trend. Therefore, there has been no evidence of decline in Unit 3 and the average abundance between 1970 and 2006 is 207 million.

Figure 27. Survey abundance of mature Acadian Redfish in Unit 3, Scotian Shelf, ln transformed.

Chart showing survey abundance for mature Acadian Redfish in Unit 3, Scotian Shelf, ln transformed.

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Scientific surveys have been conducted since 1963 by American authorities in the Gulf of Maine. A decline in the average numbers per tow was recorded in this region until the mid–1990s (Mayo et al. 2006). Subsequently, the numbers increased considerably to reach levels in 2005 similar to those seen at the beginning of the historical series of fall surveys. It would seem that several major year classes may have appeared over the past few years (Mayo et al. 2002). However, the rate of increase is not consistent with the low growth rate seen in this species (Mayo et al. 2002).
In summary, in the southern area there has been no indication of major decline. Abundance indices in Unit 3 fluctuate widely, but without showing any specific trend. In the Gulf of Maine, abundance indices are increasing and several significant year classes have appeared over the past few years. The southern area made up less than 10% of the Acadian Redfish abundance in the Atlantic DU in the early 1980s.

Assessing overall status of Acadian Redfish in the Atlantic DU requires that abundance indices from individual parts of the range be considered in the context of overall abundance trends. There is no easy way of combining indices from surveys using different methods in different areas. Greater weight should be given to indices from the northern and Gulf of St. Lawrence/Laurentian Channel areas than to the southern area, because the former areas have had greater abundance of the species (based on relative fishery catches and relative abundance indices).

Accordingly, it can be concluded that the species has declined substantially over a period of roughly 1.5 generations. A decline of the order of 98% was observed over something greater than one generation in the Gulf of St. Lawrence, the area representing over 70% of the historical abundance. However, in northern and southern areas, abundance indices have been stable or increasing since the 1990s. An overall decline of roughly 75% is evident for the DU.

Bonne Bay DU

Little information is available on the isolated population in the Bonne Bay fjord on the west coast of Newfoundland. Given the small size of the fjord, the population can only be a small one. No abundance data however exists on this population.

Pooled species

Gulf of St Lawrence/Laurentian Channel (Unit 2)

The partial survey of Unit 2 conducted by DFO in NAFO 3Ps (Figure 28) did not collect information to separate the two redfish species, so this information is presented for pooled species. Given the similarity in abundance trends in other areas, it is probably valid to consider this information as representing the situation for each species, although uncertainty would be increased by using the information in this way.

Changes were made in vessels and fishing gear during this series, which complicates analysis of the results. In 1983, the vessel A. T. Cameron, equipped with a Yankee trawl, was replaced by the vessels Wilfred Templeman and Alfred Needler, equipped with an Engel trawl and, since 1996, the Campelen trawl has been used on these two last vessels. It was noted regarding cod that the Campelen trawl was more effective for catching small individuals, while being just as efficient with the larger fish (DFO 1998). Determining abundance trends during the period covered by these surveys is difficult (Figure 5); each vessel–gear combination can be considered a single series (1973–83, 1984–1995, 1996–2007) but the relative abundance between these three series is unknown. There is some indication of an increasing trend in the most recent years. In 1991, a strong year class of Redfish probably appeared, consistent with this increase in the abundance index.

Figure 28. Survey abundance of Sebastes sp.in Division 3Ps, Gulf of St. Lawrence/Laurentian Channel DU, ln transformed. The type of gear used is indicated in the legend.

Chart showing survey abundance for Sebastes speciesin Division 3Ps, Gulf of St. Lawrence - Laurentian Channel DU, ln transformed.

As with the partial survey for NAFO 3Ps, no identifying criteria were available to classify the abundance indices by species in the survey of NAFO 4V (Figure 29). This survey was conducted using a Western IIA trawl, and the vessel Alfred Needler was used during most of these surveys. However, between 2004 and 2007, the survey was carried out by the vessel Teleost, and no comparative information has been collected in order to take vessel changes into account. There appears to be no decline throughout the entire period (Figure 29). The indices were especially high during the 1980s, but comparable between 1970 and 1990. Note that the indices increased between 2004 and 2007.

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Figure 29. Survey abundance of Sebastes sp. in Division 4V, Gulf of St. Lawrence/Laurentian Channel, ln transformed. The vessel used is indicated in the legend.

Chart showing survey abundance for Sebastes species in Division 4V, Gulf of St. Lawrence - Laurentian Channel, ln transformed.

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Rescue effect (immigration from an outside source)

As described in the section on Distribution, Deepwater Redfish is distributed continuously along both sides of the Atlantic. There appear to be no genetic differences in the Deepwater Redfish from the Grand Banks to the Faroe Islands according to Roques et al. (2002). The distribution of Acadian Redfish however is more limited, and this species tends to travel less and stay in a more coastal habitat. The main zones from which potential contributions to Canadian Redfish populations could come the region of Flemish Cap to the east of the Grand Banks for both species, the region of Greenland to the north for Deepwater Redfishalone, and the Gulf of Maine for Acadian Redfish.

Roques et al. (2002) suggested that the middle of the North Atlantic could form a single larval retention area. The arguments put forth are the lack of genetic differentiation between samples from the different regions, as well as ocean current patterns that may disperse the larvae over a greater distance. As Valentin (2006) mentioned, there is remarkable environmental continuity throughout the distribution of Deepwater Redfish in this region. However, Schmidt (2005) showed genetic heterogeneity between the Irminger Sea, Greenland and Iceland.

Migrations could also be made by adult individuals. Because Redfish have a very long lifespan, movements may happen over a long period. Potential migrations remain speculative because no study to date has dealt with this issue.

Flemish Cap (NAFO Div. 3M) is located entirely outside Canadian waters. Schmidt (2005), based on microsatellites, indicated that Deepwater Redfishin the Flemish Cap region could represent a distinct population. For example, samples from the Flemish Cap were genetically different from those in Division 2J (FST = 0.00989). Moreover, only two of the samples from the different regions of the Northern Atlantic (Irminger Sea, Greenland, Iceland, Division 1F) were not significantly different from the samples of Flemish Cap (FST between 0.00521 and 0.01839). As the author pointed out, these results are in line with the hypotheses already formulated that the Flemish Cap populations are relatively isolated from those of the Grand Banks (Templeman 1976). Note that, according to surveys done by the European Union (de Melo et al. 2007), the abundance indices for Deepwater Redfish and Acadian Redfish (combined) seem to have remained stable from the late 1980s to the beginning of 2000. However, abundance estimates appear to have risen considerably since 2003.

Exchanges between the Deepwater Redfish of west Greenland (NAFO Subarea 1) and those of western Davis Strait (NAFO Subarea 0) and the Labrador Sea are possible. However, No. study has quantified the potential exchanges between these areas. Abundance evaluated by surveys conducted on the west Greenland shelf since 1982 show greater variation in indices without revealing any definite trends (Fock et al. 2006).

In US waters of the Gulf of Maine, Acadian Redfish were at low abundance from the early 1980s to the mid–1990s but biomass per tow increased substantially in the late 1990s and has remained high relative to earlier periods in the time series since then (Miller et al. 2008). Variability in annual abundance estimates is high. Redfish in this area since the increase in abundance have been smaller than those seen historically, most at lengths below those taken by the fishery (Miller et al. 2008).

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LIMITING FACTORS AND THREATS

Limiting factors

Given their long lifespan, slow growth and late maturity, Redfishes are considered to have very low resilience. As well, recruitment is highly variable in this species, with good year–classes only appearing every five to 12 years (Morin and Bernier 1994) under normal conditions. Reduction of spawning abundance could have the effect of decreasing the frequency of strong year–classes on which the persistence of populations may depend.

The difficulty in differentiating between the two species complicates stock assessments and management. Changes in abundance for each species are not necessarily the same and managing Redfish as a single species could result in fishing pressures that are excessive for a particular species. Discussions are under way in DFO on how to set up management by species.

Certain environmental factors have been cited to explain the declines in abundance and lack of increase in certain Redfish stocks. It has been suggested that the particularly cold conditions observed in the Gulf of St. Lawrence since the end of the 1980s could have had an adverse effect on the survival of Deepwater Redfish larvae (DFO 2000), through adverse impacts on the physical condition of larvae, and the abundance and quality of their prey.

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Threats

Directed fisheries

Directed fisheries have been and are the principal threat.

In the Gulf of St. Lawrence/Laurentian Channel, two periods of heavy fishing occurred, coinciding with recruitment of strong year–classes: one at the beginning of the 1970s and the other during the 1990s (Figure 30). Interest in harvesting Redfish increased in the 1990s following collapse of other groundfish populations. Average annual catches were 123,000 tonnes between 1970 and 1976. In 1992, more than 90,000 tonnes were landed in these same areas, 78,000 of which came from Unit 1. Catches then fell to under 10,000 tonnes, coming primarily from Unit 2, following the moratorium imposed in the Gulf of St. Lawrence.

Figure 30. Redfish (Sebastes sp.) landings (metric tons) in the Gulf of St. Lawrence (Unit 1) and the Laurentian Channel (Unit 2). Étrangers = foreign. Unité = Unit.

Chart showing landings of Sebastes species (tonnes) in the Gulf of St. Lawrence (Unit 1) and the Laurentian Channel (Unit 2).

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In the northern area, the largest landings occurred at the end of the 1980s and the beginning of the 1990s (Figure 31). Only Division 2+3K had larger catches before this period, with heavy fishing occurring from 1950 to 1960. In 1959, 187,000 tonnes were caught in this sector. Catches dropped considerably in divisions 3LN and 2+3K starting at the beginning of the 1990s, whereas they remained high in Division 3O. Divisions 3LN and 2+3K have been under a moratorium but the Redfish fishery was reopened in 3LN in 2010. Note that a large proportion of landings in these regions have been by countries other than Canada.

Figure 31. Redfish (Sebastes sp.) landings (metric tons) in the Grand Banks and the Labrador Sea. Étrangers = foreign.

Chart showinglandings of Sebastes species (tonnes) in the Grand Banks and the Labrador Sea.

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In the southern area for Acadian Redfish, catches have been more modest in Unit 3 than in areas further north, varying between 1,900 and 6,700 tonnes between 1977 and 2006 (Figure 32). As well, no decline was recorded in this area. Since 1994, the landings have been limited to 500 tonnes in the Gulf of Maine (Mayo et al. 2002).

Figure 32. Acadian Redfish landings (metric tons) on the Scotian Shelf (Unit 3). Although landings are classified as “redfish” (Sebastes sp.), essentially all would be Acadian Redfish in this area. Étrangers = foreign.

Chart showing Acadian Redfish landings (tonnes) on the Scotian Shelf (Unit 3).

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Fishing may have contributed to the disappearance of apparently strong year–classes. In the Gulf of St. Lawrence; no major year class has reached a fishable size for more than 30 years. An apparently strong year class, which first appeared in 1988 (assumed to be primarily composed of Acadian Redfish) disappeared in 1992–3 when individuals would have been 14–16 cm in length, below the size taken by gear with current mesh size limits. A similar phenomenon was reported in 1966 and 1974 in the Gulf of St. Lawrence (Morin et al. 2004). The disappearance of the 1974 year–class coincided with periods of high fishing pressure and a drop in catches (the same is true for the 1988 year–class but this disappeared before reaching fishable size, so the fishery is unlikely to have been the principal cause).

The fishery could also affect recruitment by reducing the average size of females and their fecundity, which increases with length (Saint–Pierre and de Lafontaine 1995). In the Gulf of St. Lawrence, the size at maturity of 50% of females decreased from 29 cm from 1957 to 1969 (Ni and Sandeman 1984) to 25 cm in 1990 (Saint–Pierre and de Lafontaine 1995), similar to the decline in size at age observed in cod following great fishing pressure (Dutil et al.  1999). Moreover, it has hypothesized that stress from fishing on Redfish females before expulsion could affect larvae survival (DFO 2000).

Incidental and unreported catch

Bycatch from other fisheries may also contribute to mortality, in particular the shrimp fishery, because distributions of Redfishes and the northern shrimp Pandalus borealis overlap. Since the introduction of the Nordmore grate in the 1990s, which limits fish bycatches in shrimp trawl gear, the impact of this fishery on Redfish has declined substantially (DFO 2006). Removals due to shrimp bycatch were estimated at less than 1% of the directed fishery removals of Redfish in 2J3K in 2000 (Power 2001). The low recent bycatches may in part be due to the depleted state of Redfish in shrimp fishing areas, and the potential impact of the shrimp fishery should Redfish begin to recover is not well known.

Undeclared catches in fisheries for Redfish and other groundfish species may also represent a major source of mortality in Redfish. This factor is obviously difficult to quantify, although the general decline in trawl fisheries off Canada’s Atlantic may have acted to reduce this threat in recent years.

Bonne Bay Acadian redfish are taken as bycatch in mackerel and other fisheries which are prosecuted in the Bay.

Seal consumption

Redfish consumption by seals could be a major cause of mortality. The northern populations (2J3KL) are preyed upon by both Harp and Hooded Seals. These two species were estimated to have consumed 35,000 t of redfish in 1996 with approximately equal proportions by both species (Hammil and Stenson 2000). The abundance of the Harp Seals has probably increased since then and is considered to be very high. The Harp Seal is also a major predator of redfish in the Gulf of St. Lawrrence where the consumption in 1996 was estimated to be 95,000 t. Most of the redfish consumed were thought to be juvenile fish less than 25 cm in length (Hammil and Stenson 2000).

Other threats

The Bonne Bay population could be subject to environmental threats such as oil or effluent spills from a highway along the north shore of the fjord.

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SPECIAL SIGNIFICANCE OF THE SPECIES

Deepwater Redfish and Acadian Redfish are (or have been) major commercial species. In 2006, Redfish species generated revenues of $9,431,000 in the Atlantic region (DFO Statistical Services 2007). Revenues were $28,062,000 in 1992, when quotas were high in most areas. The current depleted status of Redfish populations has thus had major negative economic impacts on some fishing fleets.

Given their high abundance (at least in unstressed conditions), these species have an important place in the trophic ecosystem of the Northwestern Atlantic. When abundant in the mid–1980s, Redfish were both dominant predators and prey. According to the ecosystem models of Savenkoff et al. (2006), redfishes represented 8% of the prey consumed in the northern Gulf of St. Lawrence. As well, after Atlantic Cod, redfishes were the most prevalent predator. The situation has changed since the collapse in populations in the northern Gulf, where the ecological role of redfishes has diminished greatly.

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Existing PROTECTION or other status

The Acadian Redfish is on the IUCN’s Red List of Threatened Species (Sobel 1996). Its status is qualified as EN A1bd.

Redfish fisheries in the Northwestern Atlantic are managed by DFO, NAFO or the US government and American states. Gulf of St. Lawrence/Laurentian Channel populations are located in exclusively Canadian waters and are therefore managed by DFO. To the north, stocks in NAFO Div. 3O and Divs. 3LN are managed by NAFO, while the remainder, SA2+Div3K, is managed by DFO. The Acadian Redfish population of the southern Scotian Shelf/Gulf of Maine is jointly managed by the United States and Canada.

Moratoria on directed fishing for redfishes are in place for Unit 1 since 1995 and in NAFO 2J3K since 1998. The fishery in NAFO 3LN reopened in 2010 following a moratorium in 1998. Redfish fisheries continue under quota limits in Unit 3 and in NAFO 3O.

In addition to catch limits, minimum legal catch sizes and minimum mesh sizes are in place to reduce fishing pressure on immature redfish populations. The minimum legal catch size for redfish is 22 cm in stocks managed by DFO. Minimum mesh size is 130 mm in areas managed by NAFO, and 90 mm (Unit 1, Unit 2, DFO–managed parts of NAFO 3M and 3O) or 110 mm (Unit 3) for stocks managed by DFO. To protect spawners, fishing is prohibited in May and June in Unit 2 of DFO and the season opens June 15 in Unit 1. There is also a protected area for juvenile redfish to protect the Acadian Redfish southern population (Browns Bank).

Use of the Nordmore grate, which has been mandatory since 1994 in the northern shrimp fishery, allows fish to escape the trawl and has considerably reduced incidental catches of redfishes.

Commercial fishing for groundfish species is currently not permitted in Bonne Bay. Recreational fishing is permitted but it is not directed at redfish.

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Technical summary – Deepwater Redfish Gulf of St. Lawrence – Laurentian Channel Population

Sebastes mentella

Deepwater Redfish
Gulf of St. Lawrence – Laurentian Channel population

sébaste atlantique
Population du golfe du Saint–Laurent et du chenal Laurentien

Range of Occurrence in Canada: Atlantic Ocean (Gulf of St. Lawrence, Laurentian Channel)

Demographic Information

Generation time (average age of parents in the population)

18.4–18.6 yrs

Population trend and dynamics

 

Observed percentage of reduction in total number of mature individuals over the last 10 years.

−97% in key abundance index since 1984

Projected percentage of reduction in total number of mature individuals over the next 10 years.

Unknown

Observed percentage reduction in total number of mature individuals over any 10 years period, over a time period including both the past and the future.

N/A

Are the causes of the decline clearly reversible?

No

Are the causes of the decline clearly understood?

Yes; fishing and poor recruitment are the likely causes

Are the causes of the decline clearly ceased?

No

Observed trend in number of population

Single population

Are there extreme fluctuations in number of mature individuals?

No

Are there extreme fluctuations in number of populations?

No

Number of mature individuals in population
Population

79 m Mature Individuals in last 5 years

Extent and Area Information

Estimated extent of occurrence (km²)

511 x 103 km²

Observed trend in extent of occurrence

Stable

Are there extreme fluctuations in extent of occurrence?

No

Estimated area of occupancy (km²)
 

144 x 103 km² (survey estimate)

16 x 103 km²
(2x2 km grid)

Observed trend in area of occupancy

Stable

Are there extreme fluctuations in area of occupancy?

No

Is the total population severely fragmented?

No

Number of current locations

N/A

Trend in number of locations

N/A

Are there extreme fluctuations in number of locations?

N/A

Observed trend in area of habitat

Stable

Quantitative Analysis

 

Not carried out

Threats (actual or imminent, to populations or habitats)

Fishing (directed and bycatch) and poor recruitment are the principal known threats

Rescue Effect (immigration from an outside source)

Status of outside population(s)?
Adjacent DU (Newfoundland–Labrador) is similarly depleted; not found in USA

Is immigration known or possible?

 Possible

Would immigrants be adapted to survive in Canada?

 Probably

Is there sufficient habitat for immigrants in Canada?

 Yes

Is rescue from outside populations likely?

 No

Current Status
COSEWIC: Endangered (April 2010)

Status and Reasons for Designation

Status:
Endangered

Alpha–numeric code:
A2b+4b

Reasons for Designation:
As with other members of the family Sebastidae, this species is long–lived (maximum age about 75 yr), late–maturing (generation time 18 yr), and highly vulnerable to mortality from human activities. Recruitment is episodic, with strong year–classes only occurring every 5–12 years. Abundance of mature individuals has declined 98% since 1984, somewhat more than one generation, and the decline has not ceased. Directed fishing and incidental harvest in fisheries for other species (bycatch) are the main known threats. Harvesting in parts of this population (Gulf of St. Lawrence) is currently limited to an index fishery, but commercial fisheries remain open in other areas (Laurentian Channel). Bycatch in shrimp fisheries has been substantially reduced since the 1990s by use of separator grates in trawls, but could still be frequent enough to affect recovery.

Applicability of Criteria

Criterion A (Decline in Total Number of Mature Individuals): Meets Endangered, A2b+4b because abundance has declined more than 50% in less than two generations and the decline has not ceased.

Criterion B (Small Distribution Range and Decline or Fluctuation): Does not apply because the range of occurrence exceeds 20,000 km² and the area of occupancy is greater than 2,000 km².

Criterion C (Small and Declining Number of Mature Individuals): Does not apply because the estimated population size exceeds 10,000 individuals.

Criterion D (Very Small Population or Restricted Distribution): Does not apply because the number of mature individuals exceeds 1,000 and area of occupancy is greater than 20 km².

Criterion E (Quantitative Analysis): Not undertaken.

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Technical summary – Deepwater Redfish Northern Population

Sebastes mentella

Deepwater Redfish
Northern population

sébaste atlantique
Population du Nord

Range of Occurrence in Canada: Atlantic Ocean (Northern Grand Banks of Newfoundland, Labrador Shelf)

Demographic Information

Generation time (average age of parents in the population)

23 yrs

Population trend and dynamics

Observed percentage of reduction in total number of mature individuals over the last 10 years or 3 generations.

  • NAFO 2J3K: 98% decline since 1978, given greatest weight because of relative abundance of redfish in this area
  • NAFO 3O, 3 LN – increasing since 1990s but these stocks had a much lower historical abundance than 2J3K

98% decline in 2J3K abundance index since 1978, but the indices in 3O and 3LN increased since 1991

Projected percentage of reduction in total number of mature individuals over the next 10 years.

Unknown

Observed percentage reduction in total number of mature individuals over any 10 years period, over a time period including both the past and the future.

N/A

Are the causes of the decline clearly reversible?

No

Are the causes of the decline clearly understood?

Yes; fishing and poor recruitment are the likely causes

Are the causes of the decline clearly ceased?

No

Observed trend in number of population

Single population

Are there extreme fluctuations in number of mature individuals?

No

Are there extreme fluctuations in number of populations?

No

Number of mature individuals in population
Population

140 million Mature Individuals in last 5 years

Extent and Area Information

Estimated extent of occurrence (km²)

1431 x 103 km²

Observed trend in extent of occurrence

Stable

Are there extreme fluctuations in extent of occurrence?

No

Estimated area of occupancy (km²)

104 x 103 km² (survey estimate)
21 x 103 km²
(2x2 km grid)

Observed trend in area of occupancy

Stable

Are there extreme fluctuations in area of occupancy?

No

Is the total population severely fragmented?

No

Number of current locations

N/A

Trend in number of locations

N/A

Are there extreme fluctuations in number of locations?

N/A

Observed trend in area of habitat

Stable

Quantitative Analysis

 

Not carried out

Threats (actual or imminent, to populations or habitats)

Fishing (directed and bycatch) and poor recruitment are the principal known threats

Rescue Effect (immigration from an outside source)

Status of outside population(s)?
No recent trend in Greenland; recent abundance increase on Flemish Cap

Is immigration known or possible?

 Possible

Would immigrants be adapted to survive in Canada?

 Probably

Is there sufficient habitat for immigrants in Canada?

 Yes

Is rescue from outside populations likely?

 Possible but uncertain

Current Status

COSEWIC: Threatened (April 2010)

Status and Reasons for Designation

Status:
Threatened

Alpha–numeric code:
Met criterion for Endangered, A2b, but designated Threatened, A2b, because the species is widely distributed, includes several million mature individuals, and has been stable or increasing since the mid–1990s

Reasons for Designation:
As with other members of the family Sebastidae, this species is long–lived (maximum age about 75 yr), late–maturing (generation time 23 yr), and highly vulnerable to mortality from human activities. Recruitment is episodic, with strong year–classes only occurring every 5–12 years. Abundance of mature individuals has declined 98% since 1978, somewhat over one generation. However, declines have stopped since the mid–1990s and increases have been observed in some areas. Directed fishing and incidental harvest in fisheries for other species (bycatch) are the main known threats. Fisheries in parts of this designatable unit are currently closed, but remain open in other areas. Bycatch in shrimp fisheries has been substantially reduced since the 1990s by use of separator grates in trawls, but could still affect population recovery.

Applicability of Criteria

Criterion A (Decline in Total Number of Mature Individuals): Meets Endangered, A2b because abundance has declined more than 50% in less than two generations.

Criterion B (Small Distribution Range and Decline or Fluctuation): Does not apply because the range of occurrence exceeds 20,000 km² and the area of occupancy is greater than 2,000 km².

Criterion C (Small and Declining Number of Mature Individuals): Does not apply because the estimated population size exceeds 10,000 individuals.

Criterion D (Very Small Population or Restricted Distribution): Does not apply because the number of mature individuals exceeds 1,000 and area of occupancy is greater than 20 km².

Criterion E (Quantitative Analysis): Not undertaken.

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Technical summary – Acadian Redfish Atlantic Population

Sebastes fasciatus

Acadian Redfish
Atlantic population

sébaste d’Acadie
Population de l'Atlantique

Range of Occurrence in Canada: Atlantic Ocean (ocean waters of Atlantic Canada, other than Bonne Bay)

Demographic Information

Generation time (average age of parents in the population)

16–18 yrs

Population trend and dynamics

 

Observed percentage of reduction in total number of mature individuals over the last 10 years or three generations.

  • −99.8% since 1978, northern area
  • −99.5% since 1984, Gulf of St. Lawrence/Laurentian Channel
  • no trend, Scotian Shelf

greater than 99% over about 2 generations in areas of greatest historical abundance, but some indices are stable or increasing since mid–1990s

Projected percentage of reduction in total number of mature individuals over the next 10 years.

Unknown

Observed percentage reduction in total number of mature individuals over any 10 years period, over a time period including both the past and the future.

N/A

Are the causes of the decline clearly reversible?

No

Are the causes of the decline clearly understood?

Yes; fishing and poor recruitment are the likely causes

Are the causes of the decline clearly ceased?

No

Observed trend in number of population

Single population

Are there extreme fluctuations in number of mature individuals?

No

Are there extreme fluctuations in number of populations?

No

Number of mature individuals in population

Population

565 m Mature Individuals in last 5 years

Extent and Area Information

Estimated extent of occurrence (km²)

1511 x 103 km²

Observed trend in extent of occurrence

Stable

Are there extreme fluctuations in extent of occurrence?

No

Estimated area of occupancy (km²)

322 x 103 km² (survey estimate)

57 x 103 km²
(2x2 km grid)

Observed trend in area of occupancy

Stable

Are there extreme fluctuations in area of occupancy?

No

Is the total population severely fragmented?

No

Number of current locations

Not applicable – continuous distribution

Trend in number of locations

Not applicable

Are there extreme fluctuations in number of locations?

Not applicable

Observed trend in area of habitat

Stable

 

Quantitative Analysis

 

Not carried out

Threats (actual or imminent, to populations or habitats)

Fishing (directed and bycatch) and poor recruitment are the principal known threats

Rescue Effect (immigration from an outside source)

Status of outside population(s)?
Adjacent population (Gulf of Maine) is not depleted

Is immigration known or possible?

 Possible

Would immigrants be adapted to survive in Canada?

 Probably

Is there sufficient habitat for immigrants in Canada?

 Yes

Is rescue from outside populations likely?

 Possible

Current Status

COSEWIC: Threatened (April 2010)

Status and Reasons for Designation

Status:
Threatened

Alpha–numeric code:
Met criterion for Endangered, A2b, but designated Threatened, A2b, because the species is widely distributed, the population includes several hundred million mature individuals, and abundance indices are stable or increasing since the 1990s in some areas.

Reasons for Designation:
As with other members of the family Sebastidae, this species is long–lived (maximum age about 75 yr), late–maturing (generation time 16–18 yr), and highly vulnerable to mortality from human activities. Recruitment is episodic, with strong year–classes only occurring every 5–12 years. Abundance of mature individuals has declined 99% in areas of highest historical abundance over about two generations. However, since the 1990’s, there has been no long–term trend in one area, and trends have been stable or increasing in other areas where large declines have been previously observed. Directed fishing and incidental harvest in fisheries for other species (bycatch) are the main known threats. Fisheries in parts of the range of this designatable unit (DU) are currently closed, but remain open in other areas. Bycatch in shrimp fisheries has been substantially reduced since the 1990s by use of separator grates in trawls, but could still be frequent enough to affect population recovery.

Applicability of Criteria

Criterion A (Decline in Total Number of Mature Individuals): Meets Endangered, A2b because abundance has declined more than 50% in less than two generations.

Criterion B (Small Distribution Range and Decline or Fluctuation): Does not apply because the range of occurrence exceeds 20,000km² and the area of occupancy is greater than 2,000 km².

Criterion C (Small and Declining Number of Mature Individuals): Does not apply because the estimated population size exceeds 10,000 individuals.

Criterion D (Very Small Population or Restricted Distribution): Does not apply because the number of mature individuals exceeds 1,000 and area of occupancy is greater than 20 km².

Criterion E (Quantitative Analysis): Not undertaken.

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Technical summary – Acadian Redfish Bonne Bay Population

Sebastes fasciatus

Acadian Redfish
Bonne Bay population

sébaste d’Acadie
Population de la baie Bonne

Range of Occurrence in Canada: Atlantic Ocean (Bonne Bay fjord, western Newfoundland)

Demographic Information

Population trend and dynamics

 

Observed percentage of reduction in total number of mature individuals over the last 10 years.

Unknown

Projected percentage of reduction in total number of mature individuals over the next 10 years.

Unknown

Observed percentage reduction in total number of mature individuals over any 10 years period, over a time period including both the past and the future.

N/A

Are the causes of the decline clearly reversible?

N/A

Are the causes of the decline clearly understood?

N/A

Are the causes of the decline clearly ceased?

N/A

Observed trend in number of population

Single population

Are there extreme fluctuations in number of mature individuals?

No

Are there extreme fluctuations in number of populations?

No

Number of mature individuals in population

Population

Unknown

Extent and Area Information

Estimated extent of occurrence (km²)

72 km²

Observed trend in extent of occurrence

Stable ?

Are there extreme fluctuations in extent of occurrence?

No

Estimated area of occupancy (km²)

Unknown, less than 72 km²

Observed trend in area of occupancy

Unknown

Are there extreme fluctuations in area of occupancy?

No

Is the total population severely fragmented?

No

Number of current locations

N/A

Trend in number of locations

N/A

Are there extreme fluctuations in number of locations?

N/A

Observed trend in area of habitat

Stable

Quantitative Analysis

 

Not carried out

Threats (actual or imminent, to populations or habitats)

This is a relatively small area in an accessible and populated area. Bonne Bay could be subject to environmental threats such as oil or effluent spills from a highway along the north shore of the fjord.

Rescue Effect (immigration from an outside source)

Status of outside population(s)?
No rescue possible since this is a distinct Designatable Unit within Canada

Is immigration known or possible?

No

Would immigrants be adapted to survive in Canada?

Not applicable

Is there sufficient habitat for immigrants in Canada?

Not applicable

Is rescue from outside populations likely?

Not possible

Current Status
COSEWIC: Special Concern (April 2010)

Status and Reasons for Designation

Status:
Special Concern

Alpha–numeric code:
N/A

Reasons for Designation:
As with other members of the family Sebastidae, this species is long–lived (maximum age about 75 yr), late–maturing (females 50% mature at 8–10 yr in the adjacent Gulf of St. Lawrence/Laurentian Channel population), and highly vulnerable to mortality from human activities. Little is known of the biology of this designatable unit (DU). It has a small range of occurrence but there is no indication of decline. The population has been exploited by fishing in the past, but is currently closed to directed fishing. This DU is susceptible to extirpation by random events such as oil spills.

Applicability of Criteria

Criterion A (Decline in Total Number of Mature Individuals): Does not apply, no information on population trends.

Criterion B (Small Distribution Range and Decline or Fluctuation): Does not apply; although extent of occurrence is less than 20,000 km² and the area of occupancy is less than 2,000 km², there is no information to indicate decline or fluctuation.

Criterion C (Small and Declining Number of Mature Individuals): Does not apply because the population size probably exceeds 10,000 individuals.

Criterion D (Very Small Population or Restricted Distribution): Does not apply because the number of mature individuals exceeds 1,000 and area of occupancy is greater than 20 km².

Criterion E (Quantitative Analysis): Not undertaken.

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Acknowledgements And Experts Consulted

The report writer would like to thank Jean–Marie Sévigny from DFO for his valuable assistance. DFO scientists Don Power, Peter Comeau and Brigitte Bernier provided the data required for this report. Interviews with Nadia Ménard from the Parc marin du Saguenay and Alexandra Valentin of DFO also provided the author with many clarifications. Gloria Goulet from the COSEWIC Secretariat was also contacted about Aboriginal traditional knowledge. Finally, Alain Filion and Jenny Wu, also from the COSEWIC Secretariat, prepared the distribution maps for the Redfish species.

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Sources of Information

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Atkinson, D.B. and D. Power. 1989. Redfish in NAFO Division 3P.CAFSAC Res. Doc. 1989/048. 37 p.

Auster, P.J., J. Lindholm and P.C. Valentine. 2003. Variation in habitat use by juvenile Acadian redfish Sebastes fasciatus. Env. Bio. Fish. 68:381−389.

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Berestovskiy, E.G. 1990. Feeding in the skates, Raja radiata and Raja fyllae, in the Barents and Norwegian Seas. J. Ichthyol. 29(8):88−96.

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Gauthier S. and G.A. Rose. 2002. Acoustic observation of diel vertical migration and shoaling behaviour in Atlantic redfishes J. Fish. Biol. 61: 1135−1153.

Hammil, M.O. and G.B. Stensen 2000. Estimated Prey Consumption by Harp seals (Phoca groenlandica), Hooded seals (Cystophora cristata), Grey seals (Halichoerus grypus) and Harbour seals (Phoca vitulina) in Atlantic Canada. J. Northw. Atl. Fish. Sci. 26: 1–23.

Kelly, G.F. and A. M. Barker. 1961 Vertical distribution of young redfish in the Gulf of Maine. ICNAF Spec. Pub., 3: 220−233.

Kenchington, T.J. 1991. Vertical distribution and movements of larval redfishes (Sebastes spp.) in the southern gulf of St. Lawrence. J. Northw. Atl. Fish. Sci. 11: 43−49.

Kenchington, T.J. 1984. Population structures and management of the redfishes (Sebastes spp.: Scorpanidae) of the Scotian Shelf. Thèse de doctorat, Dalhousie University, 491 p.

Konchina, V.Y., 1986. Fundamental trophic relationships of the rockfishes Sebastes mentella and Sebastes fasciatus (Scorpaenidae) of the northwestern Atlantic. J. Ichthyol. 26(1):53−65.

Lambert, Y., Dutil, J.–D., Sévigny, J.–M. 2003. Variability in the reproductive characteristics and larvae production of redfish (Sebastes fasciatus) in the Gulf of St. Lawrence. Pages 99−118 dans Redfish multidisciplinary research zonal program (1995−1998). Gascon (éditeur). Final report. Can. Tech. Rep. Fish. Aquat. Sci. No. 2462: xiii+155 p.

Litvinenko, N. I. 1974. On the systematic position of Sebastes from the waters of Eastport (Maine, USA). In: Otchetnaya nauchn. Sessiya po itogam rabot 1973 g. Zool. In–t AN SSSR. Tez dokl. (Review session on the results of the work in 1973 of the Zoological Institute of the USSR Academy of Sciences. Proceedings). Leningrad, Nauks Press. –1974a. Coloration and other morphological characters distinguishing juvenile Sebastes fasciatus from juvenile Deepwater Redfish (Scorpaenidae). Vopr. Ikhtiol., 14, No. 4.

Marcogliese, D.J., E. Albert, P. Gagnon and J.–M. Sévigny. 2003. Use of parasites in stock identification of the deepwater redfish (Sebastes mentella) In the Northwest Atlantic. Fish. Bull. 101: 183−188.

Mayo, R.K., J. Brodziac, M. Thompson, J. Burnett and S.X. Cadrin. 2002. Biological characteristics, population dynamics and current status of redfish, Sebastes fasciatus Storer, in the Gulf of Maine–Georges bank region. NMFS, Northeast Fisheries Sciences Center Reference Document 02−05, 130 p.

Mayo, R.K., J. Burnet, T.D. Smith and C.A. Muchant. 1990. Growth–maturation interactions of Acadian Redfish (Sebastes mentella) in the Gulf of Maine–Georges Bank region of the Northwest Atlantic. J. Cons. Int. Explor. Mer. 46:287−305.

Mayo, R.K., L. Col and M. Traver. 2006. Acadian redfish. Status of Fishery Resources off the Northeastern US. NEFSC – Resource Evaluation and Assessment Division.

McGlade, J.M., M.C. Annand and T.J. Kenchington. 1983. Electrophoretic identification of Sebastes and Helicolenus in the northwest Atlantic. Can. J. Fish. Aquat. Sci. 40: 1861−1870.

Méthot, R., B. Morin and D. Power. 2004. Description of the methods used to discriminate Sebastes fasciatus and Deepwater Redfish in Units 1 and 2. CSAS Res. Doc. 2004/092.

Miller, Timothy J., Ralph K. Mayo, Michelle L. Traver and Laurel A. Col. 2008. N. Gulf of Maine/Georges Bank Acadian redfish. Pages 2–658 – 2–692 in Assessment of 19 Northeast Groundfish Stocks through 2007, Northeast Fisheries Science Center Reference Document 08–15. National Marine Fisheries Service, USA.

Morin, B. and B. Bernier. 1994. Le stock de redfish (Sebastes spp.) du golfe du Saint–Laurent (4RST + 3Pn4Vn [Jan.Mai]) : État de la ressource en 1993. MPO Pêche Atl. Doc. Rech. 94/24, 62 p.

Morin, B., R. Méthot, J.–M. Sevigny, D. Power, B. Branton and T. McIntyre. 2004. Review of the structure, the abundance and distribution of Sebastes mentella and Acadian Redfish in Atlantic Canada in a species–at–risk context. CSAS Res. Doc. 2004/058.

MPO. 2006. Proceedings of the Zonal Workshop on new evidence regarding the issue of redfish stock discrimination between Units 1 and 2 in the context of the current management practice. February 9, 2006. Secr. Can. Consulted. Sci. DFO, Report 2006/019.

Ni, I.–H. 1982. Meristic variation in beaked redfish, Sebastes mentella and Acadian Redfish, in the Northwest Atlantic. Can. J. Fish. Aquat. Sci. 52:1274−1285.

Ni, I.–H. 1981a. Numerical classification of sharp–beaked redfishes, Sebastes mentella and Acadian Redfish, from Northeastern Grand Bank. Can. J. Fish. Aquat. Sci. 38:873−879.

Ni, I.–H. 1981b. Separation of sharp–beaked redfish, Sebastes fasciatus and Deepwater Redfish, from northeastern Grand Bank by the morphology of extrinsic gasbladder musculature. J. North. Atl. Fish. Sci. 2: 7−12.

Ni, I–H and W. Templeman. 1985. Reproductive Cycles of Redfishes (Sebastes) inSouthern Newfoundland Waters. J. North. Atl. Fish. Sci. 6(1): 57−63.

Ni, I.–H. and W.D. McKonne. 1983. Distribution and concentration of redfishes in Newfoundland and Labrador waters. NAFO Scientific Council Studies 6: 7−14.

Ni, I.–H. and E.J. Sandeman. 1984. Size at maturity for Northwest Atlantic redfishes (Sebastes). Can. J. Fish. Aquat. Sci. 41: 1753−1762.

Payne, R. H. and I.–H. Ni. 1982. Biochemical population genetics of redfishes (Sebastes) off Newfoundland. J. Northw. Atl. Fish. Sci. 3: 169−172.

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Power, 2001. An assesment of the status of the redfish ressource in NAFO divisions 3LN. NAFO SCR. Doc. 01/62, Ser. No. N4440, 22 p.

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Biographical Summary Of Report Writer

Red Méthot earned a master’s degree in oceanography from the Institut des Sciences de la Mer (ISMER) in 2002. His thesis was on the spatial and temporal aspects of cod reproduction in stock management. He then worked for Fisheries and Oceans Canada (DFO) on fisheries–related projects. One of his achievements is the development of an analytical method for classifying Redfish catches by species during scientific surveys. He is currently an ichthyologist at Alliance Environnement/Tecsult.

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Appendix 1. Abundance indices for Redfish populations from Sévigny et al. 2007.

Abundance indices for Acadian Redfish, Deepwater Redfish and heterozygotes in Unit 1 of DFO.

Survey Year

Abundance Indices (106)

Total Population

Mature Population

Acadian Redfish Deepwater Redfish Heterozygote Acadian Redfish Deepwater Redfish Heterozygote

1984

3162

2826

952

1813

2002

645

1985

3824

1751

670

1327

1013

346

1986

2832

1705

628

1640

935

314

1987

3378

2453

846

2161

1506

492

1988

3256

3103

1031

2500

2293

739

1989

2894

2456

830

2327

2165

713

1990

1633

797

278

345

563

166

1991

1808

649

265

381

418

131

1992

441

224

82

451

332

116

1993

323

361

109

186

306

88

1994

187

136

47

117

106

36

1995

94

119

37

41

97

28

1996

92

99

31

39

75

22

1997

123

106

34

51

81

24

1998

338

111

42

140

58

20

1999

205

113

40

35

60

17

2000

320

142

52

41

65

19

2001

196

111

38

36

61

17

2002

139

119

38

36

87

24

2003

344

287

92

158

216

64

2004

189

68

26

57

34

11

2005

3822

587

304

66

59

18

2006

1662

334

161

91

50

16

2007

1967

437

203

50

36

11

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Abundance indices for Acadian Redfish, Deepwater Redfish and heterozygotes in Unit 2 of DFO.

Survey Year

Abundance Index (106)

Total Population

Mature Population

Acadian Redfish Deepwater Redfish Heterozygote Acadian Redfish Deepwater Redfish Heterozygote

1994

565

279

75

225

245

62

1995

445

273

74

131

231

58

1996

322

218

60

149

204

55

1997

535

259

71

238

214

54

2000

578

272

74

253

223

57

2002

561

206

56

226

169

43

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Abundance indices for Acadian Redfish in Unit 3 of DFO.

Survey Year

Abundance Index (106)

Total Population

Mature Population

Acadian Redfish

Acadian Redfish

1970

402

233

1971

428

275

1972

521

445

1973

526

499

1974

172

82

1975

572

564

1976

80

59

1977

299

288

1978

434

430

1979

50

46

1980

49

45

1981

81

77

1982

208

186

1983

330

317

1984

244

191

1985

49

29

1986

195

162

1987

157

143

1988

248

222

1989

79

51

1990

222

172

1991

104

56

1992

324

316

1993

206

177

1994

208

137

1995

166

119

1996

217

143

1997

586

302

1998

125

64

1999

329

248

2000

282

183

2001

352

331

2002

151

118

2003

392

189

2004

195

125

2005

446

343

2006

645

294

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Abundance indices for Acadian Redfish and Deepwater Redfish in Unit 3O of DFO.

Year

Abundance Index (106)

Spring

Fall

Total Population

Mature Population

Total Population

Mature Population

Acadian Redfish

Deepwater Redfish

Acadian Redfish

Deepwater Redfish

Acadian Redfish

Deepwater Redfish

Acadian Redfish

Deepwater Redfish

1973

11.8

0.1

9.7

0.0

 

 

 

 

1974

 

 

 

 

 

 

 

 

1975

72.9

0.1

38.4

0.0

 

 

 

 

1976

33.4

0.6

6.4

0.2

 

 

 

 

1977

239.1

0.5

134.8

0.4

 

 

 

 

1978

26.7

1.5

20.1

0.9

 

 

 

 

1979

86.3

3.9

62.8

2.4

 

 

 

 

1980

19.0

0.4

12.7

0.2

 

 

 

 

1981

 

 

 

 

 

 

 

 

1982

188.3

1.9

79.4

1.0

 

 

 

 

1983

 

 

 

 

 

 

 

 

1984

899.1

10.4

40.5

2.1

 

 

 

 

1985

241.0

3.6

46.7

1.1

 

 

 

 

1986

925.7

9.4

342.4

1.2

 

 

 

 

1987

243.5

4.7

126.1

1.8

 

 

 

 

1988

358.9

4.6

100.7

0.8

 

 

 

 

1989

84.5

0.6

44.5

0.4

 

 

 

 

1990

529.4

0.6

438.9

0.4

 

 

 

 

1991

141.3

14.1

19.2

9.5

326.7

9.6

75.1

2.8

1992

123.7

23.1

30.9

3.1

413.3

8.5

153.2

1.2

1993

555.3

13.0

275.9

8.8

262.7

39.5

140.5

18.4

1994

1430.0

29.6

380.8

23.2

296.0

25.4

117.1

15.9

1995

2152.8

44.8

275.4

11.9

955.2

64.9

186.1

25.2

1996

756.4

25.4

204.8

9.7

130.7

22.6

52.2

9.8

1997

81.0

36.2

32.6

7.8

952.8

106.7

442.9

39.8

1998

1008.1

24.7

530.8

16.8

336.5

61.5

252.6

36.9

1999

651.1

67.8

415.1

38.8

249.8

18.5

162.4

11.6

2000

422.4

50.1

291.4

31.8

300.6

58.2

210.8

32.8

2001

148.8

20.5

88.9

12.4

329.4

26.3

87.7

7.7

2002

112.0

11.5

67.0

5.9

232.7

39.9

77.4

11.8

2003

202.9

15.1

107.5

7.3

92.1

21.4

49.2

8.1

2004

485.7

19.4

354.4

16.2

130.4

28.5

76.5

15.0

2005

400.0

26.8

206.2

20.8

190.1

43.7

120.5

22.3

2006

ND

ND

ND

ND

260.1

71.7

190.0

33.5

Top of Page

Abundance indices for Acadian Redfish and Deepwater Redfish in Unit 3LN of DFO.

Year

Abundance Index (106)

Spring

Fall

Total Population

Mature Population

Total Population

Mature Population

Acadian Redfish

Deepwater Redfish

Acadian Redfish

Deepwater Redfish

Acadian Redfish

Deepwater Redfish

Acadian Redfish

Deepwater Redfish

1973

47.4

1.7

23.1

0.5

 

 

 

 

1974

8.9

0.4

7.5

0.3

 

 

 

 

1975

16.5

0.7

9.6

0.3

 

 

 

 

1976

164.2

7.6

160.9

7.3

 

 

 

 

1977

51.0

2.0

41.3

1.5

 

 

 

 

1978

29.2

1.1

24.4

0.8

 

 

 

 

1979

361.0

12.2

154.4

3.5

 

 

 

 

1980

35.3

1.4

23.7

0.8

 

 

 

 

1981

130.5

6.3

98.1

3.3

 

 

 

 

1982

58.5

2.6

45.2

1.9

 

 

 

 

1983

 

 

 

 

 

 

 

 

1984

 

 

 

 

 

 

 

 

1985

113.6

10.8

27.8

1.9

 

 

 

 

1986

54.2

2.3

16.0

0.6

 

 

 

 

1987

134.6

4.1

51.5

1.0

 

 

 

 

1988

89.1

3.5

39.0

1.0

 

 

 

 

1989

46.5

2.1

18.6

0.6

 

 

 

 

1990

34.3

1.4

13.4

0.5

 

 

 

 

1991

41.2

24.9

17.1

8.1

369.5

52.5

33.1

26.5

1992

35.1

19.4

13.0

9.9

1014.7

115.5

280.6

45.6

1993

81.8

28.9

28.7

20.0

30.3

58.3

12.7

30.0

1994

16.2

8.1

5.7

4.2

112.5

62.7

24.7

44.6

1995

19.8

12.2

7.4

5.3

307.9

124.4

84.8

91.8

1996

72.5

51.5

41.5

23.9

34.7

38.8

18.9

21.1

1997

50.5

32.6

31.4

19.5

241.5

113.6

160.1

88.7

1998

185.5

63.6

145.0

55.3

485.9

106.0

346.7

74.7

1999

226.8

58.5

186.3

49.1

159.0

128.0

122.2

111.5

2000

233.8

140.6

189.2

102.9

384.7

102.2

275.3

79.0

2001

111.9

75.2

74.6

51.2

736.3

145.0

425.9

94.4

2002

101.6

58.9

59.7

35.0

159.2

85.7

94.3

60.7

2003

129.0

46.6

53.5

20.5

324.7

88.7

146.2

54.5

2004

200.2

117.8

143.7

103.3

111.5

83.2

80.8

56.6

2005

322.1

62.4

151.0

43.7

216.5

80.0

114.1

51.3

2006

196.0

21.1

95.0

10.4

428.4

97.5

252.1

61.6

Top of Page

Abundance indices for Acadian Redfish and Deepwater Redfish in DFO surveys conducted in the fall in divisions 2J3K, 2GH (1987–1999) and 2H only (2001–2006)

Year

Abundance Index (106)

2J3KL

Fall

Total Population

Mature Population

Total Population

Mature Population

Acadian Redfish

Deepwater Redfish

Acadian Redfish

Deepwater Redfish

Acadian Redfish

Deepwater Redfish

Acadian Redfish

Deepwater Redfish

1978

3253.1

5386.9

1297.9

4238.2

 

 

 

 

1979

817.2

1322.3

481.9

1055.6

 

 

 

 

1980

1361.7

1617.1

1130.7

1431.0

 

 

 

 

1981

2304.1

1503.7

2224.8

1307.0

 

 

 

 

1982

431.0

1469.7

388.9

1172.8

 

 

 

 

1983

4024.6

4260.1

4001.2

3751.9

 

 

 

 

1984

316.9

799.1

270.3

723.2

 

 

 

 

1985

236.5

965.2

213.4

901.3

 

 

 

 

1986

186.1

651.9

154.6

593.0

2GH

1987

61.4

275.1

44.8

234.6

1.4

37.4

0.7

20.7

1988

168.5

689.7

137.7

585.5

7.1

101.6

0.7

15.3

1989

58.6

250.9

40.1

170.2

 

 

 

 

1990

106.9

469.1

96.5

398.2

 

 

 

 

1991

29.8

134.4

16.5

84.7

1.0

28.9

0.0

0.6

1992

12.9

73.3

2.7

27.2

 

 

 

 

1993

6.5

35.7

1.7

16.8

 

 

 

 

1994

4.0

32.3

1.2

16.8

 

 

 

 

1995

25.0

123.0

1.7

13.9

 

 

 

 

1996

62.3

178.0

7.3

59.2

9.1

321.9

1.1

24.2

1997

46.5

178.6

5.6

93.8

13.9

367.9

2.8

42.9

1998

76.3

236.0

9.9

99.0

4.9

150.8

0.9

27.2

1999

56.2

224.6

7.2

100.2

7.5

212.9

1.2

26.6

2000

64.6

160.2

4.1

37.3

2H Only

2001

145.2

268.8

6.8

91.1

3.0

96.4

0.4

5.4

2002

109.9

265.0

5.5

62.7

 

 

 

 

2003

178.2

366.4

2.6

42.0

 

 

 

 

2004

325.6

520.3

8.4

103.3

6.0

129.2

0.2

16.4

2005

305.3

559.5

35.4

81.6

 

 

 

 

2006

286.6

790.5

71.1

263.0

9.7

148.8

0.6

20.1

1 Introgression: incorporation of a gene from one species into another species. It occurs in the Redfish when a fertile hybrid mates with an individual from the parental species.

Date modified: