Enos Lake Benthic Threespine Stickleback
Scientific Name: Gasterosteus aculeatus
Other/Previous Names: Enos Lake Benthic Stickleback ,Gasterosteus sp.
Taxonomy Group: Fishes
COSEWIC Range: British Columbia
COSEWIC Assessment Date and Status Change: May 2012
COSEWIC Status: Endangered
COSEWIC Status Criteria: A2ace; B1ab(iii,v)+2ab(iii,v); C2a(ii)
COSEWIC Reason for Designation: This small fish occurs in a single lake in south coastal British Columbia where it has now formed a hybrid swarm with a co-existing stickleback. Although it is possible that a small number of genetically-pure fish still exist in the lake, the ongoing presence of an invasive crayfish, and associated habitat degradation, continue to place this species at a high risk of extinction.
COSEWIC History of Status Designation: Original designation (including both Benthic and Limnetic species) was Threatened in April 1988. Split into two species when re-examined in November 2002 and the Enos Lake Benthic Threespine Stickleback was designated Endangered. Status re-examined and confirmed in May 2012.
SARA Status: Schedule 1, Endangered
Date of Listing (yyyy-mm-dd): 2005-01-12
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.
|Enos Lake Threespine Sticklebacks||Non-active||Threatened|
Image of Enos Lake Benthic Threespine Stickleback
Enos Lake Benthic and Limnetic Threespine Sticklebacks (Gasterosteus aculeatus) are one of several unique Stickleback Species Pairs that live in sympatry. Two species are sympatric when they exist in the same area and evolved together from a common ancestor. The two species of Enos Lake Sticklebacks descended from the marine Threespine Stickleback and evolved into separate species by living in different habitats. The benthic species lives in nearshore areas. The limnetic species lives in open water. The divergence from their common ancestor is thought to have occurred because of the limited competition and predation in their habitat after the last glaciation. Habitat or environmental changes can disrupt mating barriers within a species pair and lead to a collapse of the pair into a single hybrid population. This hybrid population is sometimes referred to as a hybrid swarm. In Enos Lake, morphological and genetic studies suggest that Benthic and Limnetic Sticklebacks are no longer distinct species. They collapsed into a hybrid population in the late 1990s. This happened because of habitat changes following the invasion of American Signal Crayfish (Pacifastacus leniusculus). The Enos Lake Benthic Stickleback was a small, dark fish. Enos Lake Benthic Sticklebacks had larger and deeper bodies than the Limnetic species. During breeding season, males would turn black. Enos Lake Benthic Sticklebacks were less heavily armoured than the Limnetic species. They had fewer bony rays in their anal fins, and fewer gill rakers. (Updated 2017/07/19)
Distribution and Population
The Enos Lake Stickleback Species Pair is found only in Enos Lake on Vancouver Island in British Columbia, Canada. In 2001, a study found approximately 26,000 mature sticklebacks in Enos Lake. There is substantial hybridization between Enos Lake Benthic and Limnetic Sticklebacks. (Updated 2017/07/19)
Enos Lake is a small coastal lake that covers 17.6 hectares. Its maximum depth is 11 metres. There is no permanent surface drainage into the lake. An outlet drains the lake towards the northwest in the rainy season. Enos Lake Benthic Sticklebacks lived close to shore in aquatic vegetation. Both the Limnetic and Benthic species nested in nearshore beaches. Natural light was necessary for the species to recognize their mates. Enos Lake Benthic Sticklebacks preferred to spawn in more protected areas under aquatic plants. Both the Limnetic and Benthic species moved to deeper water habitats to overwinter. After the introduction of American Signal Crayfish, inshore habitat changed drastically. The invasive crayfish removed almost all aquatic vegetation. This likely had a significant effect on the mating barriers between the Benthic and Limnetic species and promoted the collapse of the pair into a single hybrid population. (Updated 2017/07/19)
Reproduction in the two species was separated through different spawning areas and breeding times. Enos Lake Benthic Sticklebacks tended to spawn earlier in the spring and in more protected areas under vegetation cover than the Limnetic species. These barriers and mate recognition resulted in little hybridization. Enos Lake Benthic Stickleback males constructed nests. Females produced several clutches of eggs. Benthic females tended to produce fewer egg clutches than Limnetic females. Males mated with several females and nested more than once in one breeding season. Eggs took up to one week to hatch into larvae. The larvae were free-swimming after another three to five days. Male Enos Lake Benthic Stickleback guarded their nests until fry were about one week old. Enos Lake Benthic Sticklebacks matured at two years old. They could live through several breeding seasons. Their lifespan was about five years. Fry, juveniles and adults fed on inshore invertebrates from the lake bottom. Their mouths were adapted for this feeding style. Predators of the Enos Lake Benthic Stickleback included fish-eating birds such as Great Blue Heron (Ardea herodias) and Belted Kingfisher (Megaceryle alcyon), and Coastal Cutthroat Trout (Oncorhynchus clarkii clarkii). Young Enos Lake Benthic Sticklebacks were also preyed on by invertebrates. Few, if any, pure Enos Lake Benthic Stickleback currently exist in Enos Lake. (Updated 2017/07/19)
The American Signal Crayfish got established in Enos Lake in the 1990s. Following their invasion, aquatic vegetation disappeared from the lake and the number of Limnetic-Benthic hybrids increased in the lake. The species pair now exists as a single hybrid population. The American Signal Crayfish may have affected the Enos Lake Stickleback Species Pair through changing vegetated habitat, displacement from nesting habitat, predation and competition. Current threats to the species include more invasive species, water use and land use. Additional introductions of species are possible. For example, Brown Bullhead (Ameiurus nebulosus), Largemouth and Smallmouth Basses (Micropterus salmoides and M. dolomieu), Pumpkinseed (Lepomis gibbosus), and Yellow Perch (Perca flavescens) may be spread by anglers and other members of the public. In most regions of British Columbia, the probability of invasive species becoming established after release to a new location is high or very high. Existing water licences allow both water storage and diversion from Enos Lake. These have raised lake levels because of a dam at the outlet and increased annual drawdowns. This could threaten the species by reducing spawning and feeding habitat. Also, the Enos Lake watershed is currently being developed for residential use. Increases in sedimentation and loss of riparian habitat associated with these developments are a concern for the species. Use of water from the lake by a nearby golf course may also have negative effects on the volume of water in the lake and the quality of the habitat. The amount of limnetic habitat is also being decreased because of accumulation of sediment. (Updated 2017/07/19)
The Enos Lake Benthic Threespine Stickleback 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
Status of Recovery Planning
Recovery Strategies :
Name Recovery Strategy for Paxton Lake, Enos Lake, and Vananda Creek Stickleback Species Pairs (Gasterosteus spp.) in Canada
Status Final posting on SAR registry
Pacific Region Species at Risk Program - Enos Lake Benthic Threespine Stickleback
DFO Pacific Region - MPO région du Pacifique - Chair/Contact - Fisheries and Oceans Canada
Recovery Progress and Activities
The Enos Lake Benthic Stickleback was assessed as Endangered in 2002 and reassessed as Endangered in 2012 by COSEWIC. The species was listed under the Species at Risk Act in January 2005. A Recovery Strategy that addresses the Paxton Lake, Vananda Creek, and Enos Lake Stickleback Species Pairs was posted in 2007. The Recovery Strategy identifies threats, population and distribution objectives and broad approaches to recovery for the six species. Researchers have investigated the relationship between American Signal Crayfish and the Enos Lake Sticklebacks. Stewardship groups also contribute outreach and education activities, and management activities to recovery of the Enos Lake Stickleback Species Pairs. For example, the Nanoose Naturalists developed and submitted an Enos Lake Water Management Plan to the key landowner in the watershed. They also developed a management plan that addresses water quality for the Enos Lake Stickleback Species Pair. (Updated 2017/07/19)
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.
26 record(s) found.
- Reports on the Progress of Recovery Document Implementation (1 record(s) found.)
- COSEWIC Status Reports (2 record(s) found.)
- Response Statements (2 record(s) found.)
- Recovery Strategies (1 record(s) found.)
- Orders (3 record(s) found.)
- COSEWIC Annual Reports (2 record(s) found.)
- Permits and Related Agreements (14 record(s) found.)
- Consultation Documents (1 record(s) found.)
Reports on the Progress of Recovery Document Implementation
Report on the Progress of Recovery Strategy Implementation for the Paxton Lake, Enos Lake, and Vananda Creek Stickleback Species Pairs (Gasterosteus aculeatus) in Canada for the Period 2007 – 2015 (2016-10-12)The Paxton Lake and Vananda Creek Stickleback Species Pairs were assessed as Endangered in 2000, and again in 2010 by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC 2010a and 2010b). The Enos Lake Stickleback Species Pair was assessed as Endangered in 2002, and again in 2012 (COSEWIC 2012). The Enos Lake, Paxton Lake, and Vananda Creek Stickleback Species Pairs were listed under the Species at Risk Act as Endangered in June of 2003. In October of 2007 the final Recovery Strategy for Paxton Lake, Enos Lake, and Vananda Creek Stickleback Species Pairs (Gasterosteus spp.) in Canada (NRTSSP 2007) was posted to the Species at Risk Public Registry. Fisheries and Oceans Canada, in cooperation with the Province of British Columbia’s Ministry of Environment, is developing an Action Plan for the Paxton Lake and Vananda Creek Stickleback Species Pairs as part of the Government of Canada’s ongoing commitment to the conservation of species at risk through the implementation of the Species at Risk Act.
COSEWIC Status Reports
Response Statements - Benthic Enos Lake Stickleback (2004-04-21)A response statement is a communications document that identifies how the Minister of the Environment intends to respond to the assessment of a wildlife species by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). The document provides a start to the listing and recovery process for those species identified as being at risk, and provides timelines for action to the extent possible.
COSEWIC Annual Reports
COSEWIC Annual Report - 2003 (2003-10-01)May 2003 Annual Report to the Canadian Endangered Species Conservation Council by the Committee on the Status of Endangered Wildlife in Canada.
COSEWIC Annual Report - 2011-2012 (2012-10-05)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”. COSEWIC held two Wildlife Species Assessment Meetings in this reporting year (September 1, 2011 to September 30, 2012) from November 21 to 25, 2011 and from April 29 to May 4, 2012. On February 3, 2012, an Emergency Assessment Subcommittee of COSEWIC also assessed the status of the Tri-colored Bat (Perimyotis subflavus), the Little Brown Myotis (Myotis lucifugus), and the Northern Myotis (Myotis septentrionalis). During the current reporting period COSEWIC assessed the status or reviewed the classification of 67 wildlife species. 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 2011-2012 reporting period include the following: Extinct: 1 Extirpated: 4 Endangered: 29 Threatened: 10 Special Concern: 15 Data Deficient: 2 Not at Risk: 6 Total: 67 Of the 67 wildlife species examined, COSEWIC reviewed the classification of 49 species that had been previously assessed. The review of classification for 26 of those species resulted in a confirmation of the same status as the previous assessment (see Table 1a).