BC Conservation Data Centre: Conservation Status Report
Entosphenus macrostomus
Cowichan Lake Lamprey
| Scientific Name: | Entosphenus macrostomus |
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| Scientific Name Synonyms: |
Lampetra macrostoma
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| English Name: | Cowichan Lake Lamprey |
| English Name Synonyms: |
Lake Lamprey
Vancouver Island Lake Lamprey Vancouver Lamprey |
| Provincial Status Summary | |
| Status: | S2 |
| Date Status Assigned: | May 15, 2019 |
| Date Last Reviewed: | May 15, 2019 |
| Reasons: | Cowichan Lake Lamprey is an endemic species restricted to three adjacent lakes within a small range on southern Vancouver Island (less than 200 km2). Major threats include bycatch, droughts, water management sedimentation and residential development. |
| Range | |
| Range Extent: | B = 100-250 square km |
| Range Extent Estimate (km2): | 176 |
| Range Extent Comments: | Cowichan Lake Lamprey is found only on Vancouver Island, within Cowichan, Bear and Mesachie Lakes and their tributaries. They have not been observed below the lake outlets even though there are no barriers (Beamish 1982, cited in COSEWIC 2017c). The known distribution is approximately 176 km2 (COSEWIC 2017c). |
| Area of Occupancy (km2): | E = 26-125 |
| Area of Occupancy Comments: | The index of area of occupancy, 176km2, was calculated using a 2km x 2km grid. (note that this area is same as the extent of occurrence/range) (COSEWIC 2017c). |
| Occurrences & Population | |
| Number of Occurrences: | A = 1 - 5 |
| Comments: | The Cowichan Lake lamprey occurs within Cowichan, Bear and Mesachie lakes and the lower parts of tributaries flowing into these two lakes (COSEWIC 2017c). |
| Number of Occurrences with Good Viability / Ecological Integrity: | Rank Factor not assessed |
| Number of Occurrences Appropriately Protected & Managed: | A = None |
| Comments: | Neither the two lakes and their tributaries, nor adjacent lands are currently in protected areas (COSEWIC 2008, 2017c). "Provincial legislation in BC (e.g., the Water Sustainability Act and Riparian Areas Protection Act) will offer some limited habitat protection and BC Sportfishing Regulations prohibit fishing for and retaining Vancouver Lamprey." (COSEWIC 2017c). |
| Population Size: | D = 1,000 - 2,500 individuals |
| Comments: | "Population size estimates for Vancouver Lamprey come from local experts (1000-2000 adults) and genetic data (65 to >2971 adults). However, more accurate estimates (e.g., from mark-recapture studies) are still needed." (COSEWIC 2008, 2017c). |
| Threats (to population, occurrences, or area affected) | |
| Degree of Threat: | C = Medium |
| Comments: |
2019 rank assessment: "Vancouver Lamprey, given its restricted distribution, is vulnerable to localized changes in habitat or other localized threats. Vancouver Lamprey habitat is threatened by droughts, dams and water management, increased sedimentation due to forestry, and residential development. As well, bycatch of Vancouver Lamprey adults in the recreational fishery may have an adverse effect on the adult population." (COSEWIC 2017c). " 2010 rank assessment: Presently, there are no major threats to Cowichan Lake lamprey, but given its restricted distribution, it is vulnerable to changes in water or habitat quality or other localized threats (COSEWIC 2008). Given the lack of knowledge on the general biology and habitat needs of the species, current threats are difficult to quantify. The significant decline of coho salmon, their most commonly observed host, is thought to directly impact the abundance of Cowichan Lake lamprey (COSEWIC 2008). For example, coho salmon escapement in the Cowichan Lake system (including Mesachie Lake) averaged 46,860 in the 1950s, 40,250 in the 1960s, 44,620 in the 1970s, and 20,550 in the 1980s, representing a decline of nearly 46% over the last 24 years (or 3 lamprey generations), and 73% since the 1950s (Baillie pers. comm. cited in COSEWIC 2008). Deliberate destruction of Cowichan Lake lamprey adults when caught by recreational anglers may have adverse effects on the population (COSEWIC 2008). Mortality rates for this threat are not quantified, but dwindling salmon stocks may lead to increased acrimony toward lampreys from anglers, who are known to kill lampreys in an effort to help declining salmon stocks. Siltation of littoral spawning areas caused by forestry activities or residential and commercial development is thought to be a minor threat to Cowichan Lake lamprey populations (COSEWIC 2008). |
| Trend (in population, range, area occupied, and/or condition of occurrences) | |
| Short-Term Trend: | U = Unknown |
| Comments: |
2019 rank assessment: "NatureServe (2015) stated that the short-term trend of the population is unknown (but fluctuations seem to occur)..." (COSEWIC 2017c; NatureServe ND, accessed 30 January 2019). "Without a more accurate method of measuring lamprey abundance (e.g., markrecapture studies), it is difficult to draw firm conclusions about population trends. As an alternative method of examining population trends, MacConnachie and Wade (2016) suggest electroshocking the same areas for ammocoetes every two to three years and comparing counts over time." (COSEWIC 2017c). 2010 rank assessment: The current population of Cowichan Lake lampreys in British Columbia is thought to be stable (COSEWIC 2008). However, the population appears to fluctuate from year-to-year. Changes in salmonid scarring rates may provide an index of the number of adult lampreys per year. The magnitude and frequency of such fluctuations have not been sufficiently quantified, but data from Mesachie Lake suggest that the number of lampreys between 1987-1996 was lower than that prior to 1982 (COSEWIC 2008). The number of juvenile or adult lampreys caught during the same time period in the downstream trap at the Mesachie Creek enumeration fence ranged from 4 (in 1991) to 60 (in 1995), while the number of coho salmon smolts recorded with lamprey wounds ranged from 139 (in 1989) to 1982 (in 1996). In both datasets, numbers varied by more than an order of magnitude, but no statistically significant population decline or increase was evident over the 10-year period (COSEWIC 2008). |
| Long-Term Trend: | U = Unknown |
| Other Factors | |
| Intrinsic Vulnerability: | Rank Factor not assessed |
| Environmental Specificity: | A=Very narrow. Specialist or community with key requirements scarce. |
| Comments: | Cowichan Lake lampreys are inferred to be dependent on a narrow suite of habitat types due to its restricted distribution. |
| Other Rank Considerations: | The Cowichan Lake lamprey is endemic to British Columbia (COSEWIC 2008). The species was first described in 1982 (Beamish 1982); previously, it was thought to be a dwarf race of Pacific lamprey (COSEWIC 2008). |
| Information Gaps | |
| Research Needs: | 2010 rank assessment: Further research is required to identify biological and taxonomic relationships to its close relative the Pacific lamprey and three other freshwater derivatives found in Village Bay Lake (Quadra Island), West Lake (Nelson Island) (Beamish 2001), and on the Sechelt Peninsula on British Columbia's mainland coast (Baillie pers. comm. 2007; Taylor pers. comm. 2007; both cited in COSEWIC 2008). General biology of the Lake Cowichan lamprey is poorly known and should be further studied. To determine the severity of the threat imposed by declines in target host species, particularly coho salmon, the lamprey's behavioural, numerical and life history responses should be studied. Although there is indirect evidence to suggest that the Cowichan Lake lamprey moves between Cowichan and Mesachie lakes, this needs to be studied and quantified. Little is known about dispersal within each of the two lakes, further study is required to identify seasonal movements among habitats. |
| Inventory Needs: | No quantified population estimates exist. Regular monitoring of the population should be continued and expanded. |
| Stewardship | |
| Protection: | Spawning habitat (shallow water gravel areas near creek mouths) and important seasonal areas should be considered for protection. |
| Management: | |
| Version | |
| Author: | Chytyk, P. and L. Gelling |
| Date: | May 15, 2019 |
| References | |
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Beamish, R.J. 1982. Lampetra macrostoma, a new species of freshwater parasitic lamprey from the west coast of Canada. Can. J. Fish. Aquat. Sci. 39:736-747.
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Beamish, R.J. 1984. Status report on the lake lamprey (Lampetra macrostoma) in Canada. Comm. on the Status of Endangered Wildl. in Can., Ottawa.
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Beamish, R.J. 1987.Status of the lake lamprey, Lampetra macrostoma, in Canada. Can. Field-Nat.101:186-189.
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Beamish, R.J. 2001. Updated status of the Vancouver Island Lake Lamprey, Lampetra macrostoma, in Canada. Can. Field-Nat. 115(1):127-130.
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COSEWIC. 2008v. COSEWIC assessment and update status report on the Vancouver Lamprey Lampetra macrostoma in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 39 pp.
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COSEWIC. 2017c. COSEWIC assessment and status report on the Vancouver Lamprey Entosphenus macrostomus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xi + 67 pp.
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Fisheries and Oceans Canada. 2018d. Action Plan for the Vancouver Lamprey (Lampetra macrostoma) in Canada [Proposed]. Species at Risk Act Action Plan Series. Fisheries and Oceans Canada, Ottawa. iv + 36 pp.
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NatureServe. ND. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available http://explorer.natureserve.org.
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Please visit the website Conservation Status Ranks for information on how the CDC determines conservation status ranks. For global conservation status reports and ranks, please visit the NatureServe website http://www.natureserve.org/.
Suggested Citation:
B.C. Conservation Data Centre. 2019. Conservation Status Report: Entosphenus macrostomus. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jan 24, 2025).