Species Profile

Eastern Sand Darter Quebec populations

Scientific Name: Ammocrypta pellucida
Taxonomy Group: Fishes
COSEWIC Range: Quebec
COSEWIC Assessment Date and Status Change: November 2009
COSEWIC Status: Threatened
COSEWIC Status Criteria: B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v)
COSEWIC Reason for Designation: This species prefers sand bottom areas of lakes and streams in which it burrows. There is continuing decline in the already small and fragmented populations; three (of 18) have probably been extirpated, and the fate of five others is unknown due to lack of recent sampling.  The extent of occurrence of this species in Québec is approximately two-thirds of what it was in the 1970s, despite records at five new sites in two locations.  There is continuing habitat loss and degradation from historic and ongoing urban and agricultural development, stream channelization and competition with invasive alien species.
COSEWIC History of Status Designation: The species was considered a single unit and designated Threatened in April 1994 and November 2000. When the species was split into separate units in November 2009, the "Quebec populations" unit was designated Threatened.
SARA Status: Schedule 1, Threatened
Date of Listing (yyyy-mm-dd): 2003-06-05

Please note that this information is provided for general information purposes only. For the most up to date and accurate list of species listed under the Species at Risk Act, please see the Justice Laws Website.

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Quick Links: | Description | Habitat | Biology | Threats | Protection | Recovery Initiatives | Recovery Team | National Recovery Program | Documents

Description

The Eastern Sand Darter is a translucent fish of a yellowish or silvery shade with a series of 10-14 dark lateral spots. It is partially covered with scales. Adults range in length from 45 to 70 millimeters.

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Distribution and Population

The global range of Eastern Sand Darters is limited to North America. Their main range is located in eastern central United States to the southernmost part of Ontario, while a smaller area is mainly located in Quebec and includes a few tributaries in eastern Ontario and in Vermont and New York. In Quebec, Eastern Sand Darter populations occur in the St. Lawrence River and its tributaries, from Lac des Deux Montagnes to the west to Leclerville, downstream from Lac Saint-Pierre, to the east. The number of areas where Eastern Sand Darters are found, as well as the range, extent and quality of their habitats are declining. The species still occurs in about ten sites.

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Habitat

Eastern Sand Darters are usually found in sandy areas downstream from meanders in rivers and streams and on the sandy shoals of lakes. They are insectivorous with a well-developed burrowing behaviour, and feed mainly on midge and black fly larvae.

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Biology

Eastern Sand Darters spawn in late spring and summer at water temperatures between 14.4 and 25.5 degrees Celsius. Spawning is intermittent and females may lay eggs several times during the protracted spawning season. The slightly adhesive eggs are likely laid in sand and gravel substrates. Hatching occurs in 4 to 5 days at 20.5 to 23 degrees Celsius and larvae become benthic soon after emerging. Movements of the species are unknown, but it is expected to have limited dispersal abilities.

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Threats

In Quebec, the survival and recovery of the Eastern Sand Darter are primarily threatened by the disruption and deterioration of aquatic habitats caused by intensive agricultural activities. Other human activities such as commercial or recreational navigation, dam management, biting fly control, forestry activities, vacationing, stream channelization, fishing and industrial activities can negatively impact eastern sand darters or their habitat. The Eastern Sand Darter cannot tolerate pollution and has very specific requirements in terms of habitat. Thus, it is very vulnerable to any activity that could alter its habitat. These characteristics make the species a very good indicator of the quality of watercourses it inhabits.

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Protection

Federal Protection

The Eastern Sand Darter, Quebec populations, is protected under the federal Species at Risk Act (SARA). More information about SARA, including how it protects individual species, is available in the Species at Risk Act: A Guide.

Provincial and Territorial Protection

To know if this species is protected by provincial or territorial laws, consult the provinces' and territories' websites.

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Recovery Initiatives

Status of Recovery Planning

Recovery Strategies :

Name Recovery Strategy for the Eastern Sand Darter (Ammocrypta pellucida) in Canada, Quebec populations
Status Final posting on SAR registry

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Recovery Team

Quebec cyprinids and small percids recovery team

  • Marthe Bérubé - Chair/Contact -
    Phone: 877-775-0848  Send Email
  • Alain Kemp - Chair/Contact -
    Phone: 877-775-0848  Send Email

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Documents

PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.

84 record(s) found.

COSEWIC Status Reports

COSEWIC Assessments

  • COSEWIC Assessment Summary and Status Report: Eastern Sand Darter – Ontario and Quebec populations Ammocrypta pellucida (2010-09-03)

    Assessment Summary – November 2009 Common name Eastern Sand Darter – Ontario populations Scientific name Ammocrypta pellucida Status Threatened Reason for designation This species prefers sand bottom areas of lakes and streams in which it burrows. There is continuing decline in the already small and fragmented populations; four (of 11) have probably been extirpated. The extent of occurrence of this species in Ontario is approximately half of what it was in the 1970s as a result of habitat loss and degradation from increasing urban and agricultural development, stream channelization and competition with invasive alien species. Occurrence Ontario Status history The species was considered a single unit and designated Threatened in April 1994 and November 2000. When the species was split into separate units in November 2009, the "Ontario populations" unit was designated Threatened. Assessment Summary – November 2009 Common name Eastern Sand Darter – Quebec populations Scientific name Ammocrypta pellucida Status Threatened Reason for designation This species prefers sand bottom areas of lakes and streams in which it burrows. There is continuing decline in the already small and fragmented populations; three (of 18) have probably been extirpated, and the fate of five others is unknown due to lack of recent sampling. The extent of occurrence of this species in Québec is approximately two–thirds of what it was in the 1970s, despite records at five new sites in two locations. There is continuing habitat loss and degradation from historic and ongoing urban and agricultural development, stream channelization and competition with invasive alien species. Occurrence Quebec Status historyThe species was considered a single unit and designated Threatened in April 1994 and November 2000. When the species was split into separate units in November 2009, the "Quebec populations" unit was designated Threatened.

Response Statements

  • Response Statement - Eastern Sand Darter, Quebec populations (2010-12-02)

    This species prefers sand bottom areas of lakes and streams in which it burrows. There is continuing decline in the already small and fragmented populations; three (of 18) have probably been extirpated, and the fate of five others is unknown due to lack of recent sampling.  The extent of occurrence of this species in Québec is approximately two-thirds of what it was in the 1970s, despite records at five new sites in two locations.  There is continuing habitat loss and degradation from historic and ongoing urban and agricultural development, stream channelization and competition with invasive alien species.

Recovery Strategies

  • Recovery Strategy for the Eastern Sand Darter (Ammocrypta pellucida) in Canada, Quebec populations (2014-04-29)

    The eastern sand darter is a small, translucent freshwater fish of a yellowish or silvery shade with a series of 10-14 lateral dark spots. The global distribution of the eastern sand darter consists of two disjunct areas and is limited to North America. The species was designated as “threatened” and listed under Schedule 1 of the Species at Risk Act in June 2003. After the last assessment by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 2009, the Canadian populations of the eastern sand darter were divided into two separate units, both designated as "threatened": 1) Quebec populations (the unit subject to this recovery strategy); and 2) Ontario populations (DFO, 2012). In Quebec, the eastern sand darter is found in the St. Lawrence River and its tributaries between Lac des Deux Montagnes and Leclercville, downstream from Lake St. Pierre.

Action Plans

  • Multi-species Action Plan for La Mauricie National Park and National Historic Sites of La Mauricie and Western Quebec regions (2020-10-06)

    The Multi-species Action Plan for La Mauricie National Park and Canada's national historic sites (NHS) that are part of the Mauricie and Western Quebec Field Unit (MWQFU) applies to the land and waters within the boundaries of La Mauricie National Park (LMNP) and 13 NHSs in Quebec: Obadjiwan–Fort Témiscamingue; Forges-du-Saint-Maurice; Fort Chambly; Fort Lennox; Battle of the Châteauguay; Coteau-du-Lac; Carillon Barracks; Manoir Papineau; Louis-Joseph Papineau; Louis S. St-Laurent; Fur Trade at Lachine National Historic Site; Sir Wilfrid Laurier; and Sir George-Étienne Cartier. This plan meets the requirements for action plans set out in the Species at Risk Act (SARA; section 47) for species requiring an action plan that regularly occur on these sites. Measures described in this plan will also provide benefits for other species of conservation concern that regularly occur in LMNP and on associated NHSs.

Orders

  • Order Acknowledging Receipt of the Assessments Done Pursuant to Subsection 23(1) of the Act(volume 146, number 14, 2012) (2012-07-04)

    His Excellency the Governor General in Council, on the recommendation of the Minister of the Environment, acknowledges receipt, on the making of this Order, of the assessments done pursuant to subsection 23(1) of the Species at Risk Act by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) with respect to the species set out in the annexed schedule.
  • Order Amending Schedule 1 to the Species at Risk Act (volume 147, number 7, 2013) (2013-03-27)

    This Order adds seven aquatic species to Schedule 1 of the Species at Risk Act (SARA) and reclassifies two species on Schedule 1 of SARA (Schedule 1). This Order also amends Schedule 1 by striking out one species previously listed as a single designatable unit and adding two new designatable units of the same species in its place. One designatable unit of a terrestrial species, currently also listed as part of a broader designatable unit, is struck out to eliminate duplication. These amendments are being made on the recommendation of the Minister of the Environment with advice from the other competent minister, the Minister of Fisheries and Oceans. A related Order under section 76 of SARA will exempt activities authorized under the Fisheries Act from the prohibitions of SARA for a period of one year for one of the species being added to Schedule 1 (Westslope Cutthroat Trout).

COSEWIC Annual Reports

  • COSEWIC Annual Report - 2010 (2010-09-03)

    Under Canada’s Species At Risk Act (SARA), the foremost function of COSEWIC is to “assess the status of each wildlife species considered by COSEWIC to be at risk and, as part of the assessment, identify existing and potential threats to the species”. During the past year, COSEWIC held two Wildlife Species Assessment Meetings and reviewed the status of 79 wildlife species (species, subspecies, populations). During the meeting of November 2009, COSEWIC assessed or reviewed the classification of the status of 28 wildlife species. COSEWIC assessed or reviewed the classification of an additional 51 wildlife species (species, subspecies and populations) during their April 2010 meeting. For species already found on Schedule 1 of SARA, the classification of 32 species was reviewed by COSEWIC and the status of the wildlife species was confirmed to be in the same category (extirpated - no longer found in the wild in Canada but occurring elsewhere, endangered, threatened or of special concern). The wildlife species assessment results for the 2009-2010 reporting period include the following: Extirpated: 6 Endangered: 39 Threatened: 16 Special Concern: 17 Data Deficient: 1 This report transmits to the Minister the status of 46 species newly classified as extirpated, endangered, threatened or of special concern, fulfilling COSEWIC’s obligations under SARA Section 24 and 25. A full detailed summary of the assessment for each species and the reason for the designation can be found in Appendix I of the attached report. Since its inception, COSEWIC has assessed 602 wildlife species in various risk categories, including 262 Endangered, 151 Threatened, 166 Special Concern and 23 Extirpated. In addition, 13 wildlife species have been assessed as Extinct. Also, to date, 46 wildlife species have been identified by COSEWIC as Data Deficient and 166 wildlife species were assessed as Not at Risk. This year has been a particularly productive year for COSEWIC’s Aboriginal Traditional Knowledge (ATK) Subcommittee. In April 2010 COSEWIC approved the Aboriginal Traditional Knowledge Process and Protocol Guidelines, providing clear and agreed principles for the gathering of Aboriginal Traditional Knowledge to carry out COSEWIC functions as required under Section 15(2) of SARA (See Appendix III of the attached report). We are grateful for the rich and enthusiastic contribution made by community elders and experts in helping the ATK Subcommittee prepare the ATK protocols.

Permits and Related Agreements

  • Explanation for issuing permit(# 20-PQUE-00032 ), persuant to the provisions of section 73 of SARA (2020-09-24)

    Surveys of Eastern Sand Darters are part of an overall project to protect biodiversity in the upper St. Lawrence River valley, with a focus on aquatic species at risk (Channel Darter, Eastern Sand Darter, Bridle Shiner, etc.) and their habitat through stewardship, habitat restoration and outreach activities. This project requires a qualitative survey of the fish present on the property of participating riparian landowners in order to provide them with recommendations for maintaining or improving water quality and fish habitat. The activities authorized by this permit are as follows: Surveys of Eastern Sand Darters at three electrofishing stations or using minnow seines. Surveys will be conducted using electrofishing or minnow seines in accordance with the protocols set out by Couillard et al. (2011) and will include the modifications proposed by the Cyprinidae and Small Percidae (CSP) recovery team.
  • Explanation for issuing permit(# MPO-LEP-QC-15-004), persuant to the provisions of section 73 of SARA (2015-08-03)

    The goal of this project is to estimate the area of suitable habitat for the eastern sand darter and the channel darter in the Rivière Bécancour, as well as the number of individuals per species using the catch per unit effort (CPUE) index. Sampling will be performed using 20 m by 2 m beach seines with 3 mm mesh for the entire net and 2 mm for the pocket. Up to 30 individuals of both the eastern sand darter and the channel darter species will be recorded and measured. They will then be photographed and returned to the water as quickly as possible.
  • Explanation for issuing permit(#18-HQUE-00096), persuant to the provisions of section 73 of SARA (2019-08-01)

    The project involves installing sheet-piling cofferdams to dewater an area of the L'Assomption river estimated at 345 m2. This area is located within the boundaries of critical habitat for the channel darter and the eastern sand darter. The activity involves catching fish that may get caught inside the cofferdam enclosures, before the work begins, and relocating them to an area promoting their survival in the L'Assomption river.
  • Explanation for issuing permit(#20-PQUE-00008 ), persuant to the provisions of section 73 of SARA (2020-05-19)

    The activity authorized by this permit consists of the incidental capture of Copper Redhorse, Eastern Sand Darter and Striped Bass during sampling for tench (Tinca tinca). This activity is part of a three-year research project aimed at studying the extent of competition for resources between tench, an aquatic invasive species, and target native fish species present in rivers in Quebec. The types of fishing gear that will be used are as follows: gillnet, fyke net, minnow seine, beach seine, kick net and electrofisher. The effects that this activity may have on the listed wildlife species, their critical habitats and the residences of their individuals, and the impacts of the changes authorized by this permit are as follows: No impacts on the habitats of aquatic species at risk are anticipated. Sampling may result in incidental captures of Copper Redhorse, Eastern Sand Darter or Striped Bass; however, non-lethal fishing methods will be used and in the event of any incidental captures of aquatic species at risk, the fish will be returned to the water alive as soon as measurements are completed.
  • Explanation for issuing permit(#20-PQUE-00009 ), persuant to the provisions of section 73 of SARA (2020-05-25)

    The activity authorized by this permit consists of the capture of Striped Bass (eggs, larvae and juveniles) from the St. Lawrence River population as part of a project to locate and document spawning grounds and juvenile movement areas. There is a risk of incidental capture of Copper Redhorse or Eastern Sand Darter which is covered by this permit. The inventories will be carried out in the Richelieu River and a portion of the St. Lawrence (between the mouth of the Richelieu River and the centre of Ile d'Orléans).
  • Explanation for issuing permit(#20-PQUE-00021 ), persuant to the provisions of section 73 of SARA (2020-08-03)

    The activity authorized under this permit is the capture and handling of eastern sand darter, Quebec population, as part of the second year of a project to inventory and characterize the habitat in the small tributaries of the headwaters of the Bécancour River as well as the Blanche and Du Portage rivers. The inventories will be carried out via beach seine and electrofishing outside of sensitive periods (spawning, rearing), i.e., during the month of August, at a total of 28 stations. All captured individuals will be released alive after being handled. The changes that the activity may cause to the listed wildlife species, its critical habitat or the residences of its individuals and the effects of those changes authorized under this permit are as follows: No impact on eastern sand darter habitats is anticipated. Although the capture and handling protocol used is considered non lethal, the capture may cause some stress over a short period (a few days) and possibly the mortality of a few small fish.
  • Explanation for issuing permit(#20-PQUE-00024 ), persuant to the provisions of section 73 of SARA (2020-08-20)

    The activity authorized by this permit is the capture and handling of eastern sand darters, Quebec population, as part of a project to survey and characterize habitat in the Noire River and David Creek sub-basins, located upstream of the Yamaska River. Surveys will be conducted using electrofishing and beach seines outside of sensitive periods (i.e. spawning and rearing) in August and October, for a total of 25 stations. All captured individuals will be released alive after handling. Changes that the activity may cause to the listed wildlife species, its critical habitat or the residences of its individuals and the effects of such changes authorized by this permit are as follows: No impact on eastern sand darter habitat is expected. The capture and handling protocol used is considered non lethal; however, capture could cause some stress for a short period.
  • Explanation for issuing permit(#20-PQUE-00034 ), persuant to the provisions of section 73 of SARA (2020-10-13)

    Activity objectives: Validate the presence of Cutlip Minnow within its known range in five watercourses (the Chaloupe, Bayonne, Chicot, Maskinongé and Yamachiche Rivers) where Cutlip Minnow has been historically observed and characterize the habitat of this species. Description of the activity: The activity authorized by this permit is the incidental capture of Eastern Sand Darter using electrofishing during inventories of Cutlip Minnow. In total, 35 stations will be fished for a maximum duration of 15 minutes or along a 100 m long stretch, whichever situation occurs first, or until a Cutlip Minnow is captured.
  • Explanation for issuing permit(#2013-005), persuant to the provisions of section 74 of SARA (2013-09-01)

    The emergency stabilisation works of two sections of the bank of the Richelieu River in order to mitigate scouring of route 133 in Saint-Denis-sur-Richelieu, through the installation of a counterweight rockfill. The stabilisation works are planned to occur at two locations: 1) site 133-6a for 60 linear meters; and 2) site 133-8/9 for 320 linear meters. The works will harm the Copper redhorse, Channel darter and Eastern sand darter by affecting a part of their critical habitat as identified in their respective final recovery strategy, proposed recovery strategy or draft recovery strategy.
  • Explanation for issuing permit(#21-PQUE-00012 ), persuant to the provisions of section 73 of SARA (2021-05-01)

    The activity authorized by this permit consists of the incidental capture of Copper Redhorse, Eastern Sand Darter and Striped Bass during sampling for tench (Tinca tinca). This activity is part of a three-year research project aimed at studying the extent of competition for resources between tench, an aquatic invasive species, and target native fish species present in rivers in Quebec. The types of fishing gear that will be used are as follows: gillnet and fyke net. The effects that this activity may have on the listed wildlife species, their critical habitats and the residences of their individuals, and the impacts of the changes authorized by this permit are as follows: No impacts on the habitats of aquatic species at risk are anticipated. Sampling may result in incidental captures of Copper Redhorse, Eastern Sand Darter or Striped Bass; however, non-lethal fishing methods will be used and in the event of any incidental captures of aquatic species at risk, the fish will be returned to the water alive as soon as measurements are completed.
  • Explanation for issuing permit(#CCHM-(895) - autorisation no.2), persuant to the provisions of section 73 of SARA (2019-06-10)

    As part of the federal wharf rehabilitation project in Chambly, sheet piles were installed all around the current wharf. Relocation of possibly captive fish (due to increased water levels in winter) behind the federal wharf sheet pile wall. Species of fish at risk could possibly be present inside the sheet pile wall (Copper Redhorse, Eastern Sand Darter, Channel Darter).
  • Explanation for issuing permit(#COUR-(1525)), persuant to the provisions of section 73 of SARA (2019-08-01)

    The Vianney-Legendre fish ladder must be dewatered to allow some repair work. Relocation of potentially captive fish (due to dewatering of the work area) by electric fishing, nets, scoop, bait trap or any other relevant method. Species of fish at risk could possibly be present inside the work area (Copper Redhorse, Eastern Sand Darter, Channel Darter).
  • Explanation for issuing permit(#DFO-17-HQUE-00116), persuant to the provisions of section 73 of SARA (2017-08-01)

    The Department of National Defence will remove and dispose of 150 UXO (unexploded ordnance) within the former firing range (CYR 606) near Landroche Channel at Baie-du-Febvre in Lake St. Pierre. The 150 UXOs cannot be safely moved and will be detonated on site, in the aquatic environment. Notwithstanding mitigation measures, the explosions could cause fish to die, including some species at risk near the explosion sites.
  • Explanation for issuing permit(#DFO-18-HQUE-00096), persuant to the provisions of section 73 of SARA (2018-08-16)

    The project involves installing sheet-piling cofferdams to dewater an area of the L'Assomption river estimated at 345 m2. This area is located within the boundaries of critical habitat for the channel darter and the eastern sand darter. The activity involves catching fish that may get caught inside the cofferdam enclosures, before the work begins, and relocating them to an area promoting their survival in the L'Assomption river.
  • Explanation for issuing permit(#DFO-2016-001), persuant to the provisions of section 73 of SARA (2016-02-23)

    Four offsetting projects must be implemented to counterbalance the serious harm to fish and impacts to aquatic species at risk (Copper Redhorse, Channel Darter and Eastern Sand Darter) resulting from bank stabilization at five sites along the Richelieu River. These projects consist of the creation of a floodplain in the Huron River at Sainte Marie Madeleine, the removal of a barge and fill in the Richelieu River at the Saint Marc sur Richelieu wharf, the restoration of Parc de la Pointe Valaine in Otterburn Park and the restoration of Île Deschaillons channel in Saint Roch de Richelieu. These actions will restore, improve or create breeding, rearing, shelter, feeding and migration areas especially, and as applicable, for the Yellow Perch, Smallmouth Bass, Northern Pike, Copper Redhorse, Channel Darter and Eastern Sand Darter. While implementing these offsetting projects and carrying out follow-ups, it may be necessary to catch and relocate fish, including the Copper Redhorse, Channel Darter and Eastern Sand Darter.
  • Explanation for issuing permit(#DFO-MPO SARA-LEP QC 14-007), persuant to the provisions of section 73 of SARA (2014-09-08)

    As part of the critical habitat review schedule in the Recovery Strategy for the Eastern Sand Darter, the purpose of the project is to characterize the habitat and conduct an Eastern Sand Darter survey in six rivers in southern Quebec. Fish sampling will be done using a seine and the method established by Faune Québec to survey small fish at risk (Couillard et al. 2011). During fishing, up to 30 Eastern Sand Darters will be weighed and measured. Excess specimens will be weighed and counted in groups. This will be done quickly and the specimens will be kept in water freshly collected from the river. These specimens will then be quickly released. Any species at risk caught accidentally, particularly the Channel Darter, will be identified and put back into the water.
  • Explanation for issuing permit(#DFO-MPO SARA-LEP QC 14-008), persuant to the provisions of section 73 of SARA (2014-09-26)

    This permit authorizes the holder to catch or take individual Channel Darters or Eastern Sand Darters. The activities authorized under this permit are carried out as part of a project designed to teach watershed organization members various techniques for the safe capture of Channel Darter, Bridle Shiner and Eastern Sand Darter as part of a workshop organized by the Regroupement des Organismes de Bassins Versants du Québec. The study technique is entirely based on the protocol of the Ministère des Forêts, de la Faune et des Parcs (Couillard et al. 2011, Protocole d'échantillonnage du fouille-roche gris, du dard de sable et du méné d'herbe). The main fishing gear used for this project is a portable electrofisher (Smith-Root LR-24). A beach seine will also be used in habitats with a smooth or homogeneous substrate. The procedure consists of catching, identifying and measuring a sub-sample of the specimens caught, then releasing them into the stream once they have gone through the sampling station. The samples will be taken at sites where they have been observed historically, as well as sites suitable for these species.
  • >> See more Permits and Related Agreements documents

Critical Habitat Orders

  • Critical Habitat of the Eastern Sand Darter (Ammocrypta pellucida) Quebec Populations Order (2018-07-25)

    The objective of the Recovery Strategy over the long term (20 years) is to promote the growth of existing populations to ensure their viability and, wherever possible, to restore historical populations that have disappeared. The short-term (within five years) objective of the Recovery Strategy is to maintain Eastern Sand Darter populations throughout the species’ distribution in Quebec and prevent their decline. Efforts to meet the short- and long-term goals are ongoing and supported by the measures described in the Recovery Strategy. Current threats to the Eastern Sand Darter (Quebec populations), as identified in the Recovery Strategy, include increased sediment input and siltation, alteration of flow regimes and fluctuation in water levels, presence of contaminants, nutrient loading and barriers to movement.
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