Atlantic Whitefish (Coregonus huntsmani): COSEWIC rapid review of classification

Official title: COSEWIC Rapid Review of Classification on the Atlantic Whitefish (Coregonus huntsmani) in Canada

Endangered

2022

COSEWIC assessment summary

Assessment summary – December 2022

Common name: Atlantic Whitefish

Scientific name: Coregonus huntsmani

Status: Endangered

Reason for designation: This landlocked anadromous fish species is endemic to Canada. It once migrated between fresh water and the Atlantic Ocean, but it is now restricted to three interconnected lakes in southwestern Nova Scotia. It is threatened by illegally introduced predatory fishes, water-control structures that impede movement, municipal alteration of water levels, and declining habitat quality. If these threats are not reversed, they will lead to the extinction of this unique Canadian species.

Occurrence: Nova Scotia

Status history: Designated Endangered in April 1984. Status re-examined and confirmed in November 2000, November 2010, and December 2022.

COSEWIC rapid review of classification

Preface

Atlantic Whitefish (Coregonus huntsmani) is a landlocked fish species that was historically anadromous, but it now occurs only in southwestern Nova Scotia. Reproduction is largely restricted to three small, partially interconnected, semi-natural lakes (Hebb, Milipsigate, and Minamkeak) in the upper Petite Rivière drainage area near Bridgewater. Some historical connections between these lakes have been blocked by water control structures. The species is believed to be extirpated from the Tusket River, where it was once reportedly abundant. It was almost certainly more widespread before European colonization (DFO 2018a). Wild Atlantic Whitefish is not found anywhere else in the world.

The exact size of the remaining population is not known but is believed to be small (DFO 2018a,b). Cook (2012) estimated contemporary effective population size (N_e), defined as the size of an ideal population experiencing the same rate of genetic change as the focus population, to be 18 and 38 using two different methods. Comparisons of N_e and census population size (N_c) show that the ratio between N_c and N_e averages approximately 10:1, although the relationship varies considerably. For example, if there are wide fluctuations in population size, N_e may be very much smaller than N_c (Frankham 1995). Nevertheless, the N_e observed in Atlantic Whitefish is among the lowest of any fish species examined (Cook 2012) and is cause for concern.

In the previous status report, non-native predatory Smallmouth Bass (Micropterus dolomieu) was reported to be reproducing in Minamkeak and Milipsigate lakes, and it was thought that it would almost certainly be reproducing in Hebb Lake in the near future (COSEWIC 2010). As of 2013, Smallmouth Bass reproduction has been confirmed in all three lakes (DFO 2018b). Chain Pickerel (Esox niger) was previously not known to be present within the Petite Rivière system (COSEWIC 2010), but it was reported in both Hebb and Milipsigate lakes in 2013 (Themelis et al. 2014; Feener et al. 2021). Introduction of Chain Pickerel into the Tusket-Annis system in the 1970s may have played a role in the extirpation of Atlantic Whitefish from this system. Negative effects from these illegally introduced predatory fishes could take the form of direct predation on Atlantic Whitefish, habitat displacement, and trophic disruption; and water control structures that impede movement, municipal alteration of water levels, and pollution also appear to be causing a decline in habitat quality (COSEWIC 2010).

Captive-reared Atlantic Whitefish were introduced into a small (<1 km²) lake, Anderson Lake (2005–2008, 2012) in Dartmouth, Nova Scotia, as part of an experiment to evaluate the feasibility of using captive-reared fish to establish successfully reproducing lake-resident populations of Atlantic Whitefish (Bradford et al. 2015). Environmental DNA (eDNA) work done in 2017 indicates that it is unlikely that the species persists in Anderson Lake (Dillon Consulting 2018).

Starting in 2018, larvae have been collected and housed at the Dalhousie Aquatron Laboratory and form the only captive stock of the species. Dalhousie Aquatron Laboratory, the Nova Scotia Salmon Association (NSSA), and Coastal Action are working to construct a streamside rearing trailer with the purpose of introducing young Atlantic Whitefish to a potential new waterbody. DFO, NSSA, and Coastal Action are also surveying Nova Scotia lakes to determine their suitability as Atlantic Whitefish habitat (Species at Risk Public Registry 2021).

Status history

Designated Endangered in April 1984. Status re-examined and confirmed in November 2000, November 2010, and December 2022.

Updated map

▢ Required
▣ Not required

No change in distribution known; see previous assessment (COSEWIC 2010).

Technical summary

Atlantic Whitefish

Corégone de l’Atlantique

Coregonus huntsmani

Range of occurrence in Canada (province/territory/ocean): Nova Scotia

Quantitative analysis

Is the probability of extinction in the wild at least [20% within 20 years or 5 generations whichever is longer up to a maximum of 100 years, or 10% within 100 years]? Unknown; analysis not conducted

Threats and limiting factors

Was a threats calculator completed for this species?

No, but threats were most recently reviewed during a DFO Regional Science Advisory Process meeting undertaken by DFO (2009) and updated in DFO (2018b)

Key threats identified in the previous status report (COSEWIC 2010), with impact inferred here from the wording of that text, can be classified as (numbers refer to IUCN threats classification system):

8. Invasive and other problematic species and genes = High Impact

7. Natural system modifications = Medium Impact (water control structures and dams and anthropogenic alteration of water level (i.e., water supply for Town of Bridgewater))

9. Pollution = Low Impact (forestry runoff, leachate from historical mine sites and land development) based on current levels and if properly mitigated (DFO 2018a)

11. Climate Change = Unknown Impact (thermal suitability of egg incubation conditions (ice cover and duration), oxythermal constraints (i.e., reduced volume of coldwater refugia), changes in lake primary productivity)

What additional limiting factors are relevant? Very small population and limited range

Occurrence data sensitivity

Are occurrence data of this species sensitive? No

Status and reasons for designation

Status: Endangered

Alpha-numeric codes: B1ab(iii)+2ab(iii)

Reasons for designation: This landlocked anadromous fish species is endemic to Canada. It once migrated between fresh water and the Atlantic Ocean, but it is now restricted to three interconnected lakes in southwestern Nova Scotia. It is threatened by illegally introduced predatory fishes, water-control structures that impede movement, municipal alteration of water levels, and declining habitat quality. If these threats are not reversed, they will lead to the extinction of this unique Canadian species.

Reason for change of status: Not applicable

Applicability of criteria

A: Decline in total number of mature individuals
Not applicable. Timing and magnitude of past decline have not been documented, but likely occurred prior to the last three generations. Data are lacking on recent population trends.

B: Small distribution range and decline or fluctuation
Meets Endangered, B1ab(iii)+2ab(iii), as EOO (76 km²) and IAO (76 km²) are below thresholds for Endangered, the population (a) exists at no more than three locations (most likely a single location), and (b) there is a continuing decline in quality of habitat.

C: Small and declining number of mature individuals
Not applicable. Data on number of mature individuals are lacking.

D: Very small or restricted population
Meets Threatened, D2. Number of locations 1–3 (most likely 1), and prone to substantial decline from effects of human activities or stochastic events within 1–2 generations.

E: Quantitative analysis
No quantitative analysis of extinction risk was conducted.

Acknowledgements

Funding for the preparation of this report was provided by Environment and Climate Change Canada. The authorities listed below provided valuable data and/or advice. Special thanks to Mark Ridgway for reviewing an earlier draft of this rapid review of classification. Anonymous reviewer(s) from DFO provided additional useful recent information on the species and recovery efforts.

Authorities contacted

Drs. Allen Curry, Margaret Docker, Nicholas Mandrak, and John Post, COSEWIC Freshwater Fishes Species Specialists Committee

Dr. Donna Hurlburt, Manager of Biodiversity, Wildlife Division, Department of Lands and Forestry, Kentville, Nova Scotia

Information sources

Bradford, R.G., D. Themelis, P. LeBlanc, D.M. Campbell, S.F. O’Neil, and J. Whitelaw. 2015. Atlantic Whitefish (Coregonus huntsmani) stocking in Anderson Lake, Nova Scotia. Canadian Technical Report of Fisheries and Aquatic Sciences 3142, Dartmouth, Nova Scotia. vi + 45 pp.

Cook, A.M. 2012. Addressing key conservation priorities in a data poor species. PhD thesis, Dalhousie University, Halifax, Nova Scotia. 214 pp.

COSEWIC. 2010. Update COSEWIC status report on the Atlantic Whitefish (Coregonus huntsman) in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vii  + 35 pp.

DFO. 2006. Recovery Strategy for the Atlantic Whitefish (Coregonus huntsmani) in Canada. Species at Risk Act Recovery Strategy Series. Fisheries and Oceans Canada, Ottawa. xiii  + 42 pp.

DFO. 2009. Proceedings of the 2009 Recovery Potential Assessment for Atlantic Whitefish (Coregonus huntsmani); 24–25 March 2009. DFO Canadian Science Advisory Secretariat Proceedings Series 2010/021.

DFO. 2018a. Action Plan for the Atlantic Whitefish (Coregonus huntsmani) in Canada. Species at Risk Act Action Plan Series. Fisheries and Oceans Canada, Ottawa. ix + 39 pp. Website: https://www.canada.ca/en/environment-climate-change/services/species-risk-public-registry/action-plans/atlantic-whitefish-final.html [accessed February 2022].

DFO. 2018b. Recovery strategy for the Atlantic Whitefish (Coregonus huntsmani) in Canada. Species at Risk Act Recovery Strategy Series. Fisheries and Oceans Canada, Ottawa. xiii + 62 pp. Website: https://www.canada.ca/en/environment-climate-change/services/species-risk-public-registry/recovery-strategies/atlantic-whitefish-amended-final.html#_1.6 [accessed February 2022].

DFO. 2018c. Strategies for the establishment of self-sustaining Atlantic Whitefish population(s) and development of a framework for the evaluation of suitable lake habitat. Canadian Science Advisory Secretariat Maritimes Region Science Advisory Report 2018/045. Website: https://waves-vagues.dfo-mpo.gc.ca/library-bibliotheque/40738176.pdf [accessed February 2022].

Dillon Consulting. 2018. Environmental Assessment Highway 107 Burnside to Bedford: Additional Information – Anderson Lake. Report for Nova Scotia Ministry of Transportation. 17 pp. Website: https://novascotia.ca/nse/ea/highway-107-burnside-to-bedford/TIR_Highway_107_EA_Additional_Info_8Jun2018.pdf [accessed February 2022].

Feener, S., M. Leblanc, M. Risto, S. Reeves, and Z. Lamontagne. 2021. 2020-21 Review of Fisheries Activities for the Atlantic Whitefish Recovery Project. Mahone Bay, NS: Coastal Action. 22 pp. Website: https://www.coastalaction.org/uploads/1/2/2/2/122203881/2020_atlantic_whitefish_field_report.pdf [accessed September 2022].

Frankham, R. 1995. Effective population size / adult population size ratios in wildlife: a review. Genetic Research 66:95–107.

IUCN Standards and Petitions Committee. 2022. Guidelines for Using the IUCN Red List Categories and Criteria. Version 15. Prepared by the Standards and Petitions Committee. Website: https://www.iucnredlist.org/documents/RedListGuidelines.pdf. [accessed February 2022].

Mitchell, S.C., J.E. LeBlanc, and A.J. Heggelin. 2010. Impact of introduced Chain Pickerel (Esox niger) on lake fish communities in Nova Scotia, Canada. Unpublished report. Inland Fisheries Division, Nova Scotia Department of Fisheries and Aquaculture, Pictou, Nova Scotia. 18 pp. [accessed February 2022].

Species at Risk Public Registry. 2021. Atlantic Whitefish. (Coregonus huntsmani). Website: https://species-registry.canada.ca/index-en.html#/species/64-47 [accessed February 2022].

Themelis, D.E., R.G. Bradford, P.H. LeBlanc, S.F. O’Neil, A.P. Breen, P. Longue, and S.B. Nodding. 2014. Monitoring activities in support of endangered Atlantic Whitefish (Coregonus huntsmani) recovery efforts in the Petite Rivière lakes in 2013. Canadian Manuscript Report of Fisheries and Aquatic Sciences 3031, Dartmouth, Nova Scotia. v + 94 pp.

Writer of rapid review of classification:

• David F. Fraser. RAMAS input by Dwayne Lepitzki, updated by David F. Fraser

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 (2022)

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 and Climate Change Canada, provides full administrative and financial support to the COSEWIC Secretariat.