The State of Char in the Arctic

C.D. Sawatzky and J.D. Reist

Freshwater Institute, Fisheries and Oceans Canada, Winnipeg, MB

Click to see Biology Summary

Introduction

The char species complex is made up of approximately 20 closely related taxa. Char are widely distributed throughout the circumpolar north (Figure C1) from northernmost areas south to temperate regions (e.g., Switzerland, Italy) (Johnson 1980), with a latitudinal distribution of approximately 40°N to 84°N.

Figure C1. Global distribution of Arctic char and Dolly Varden.

Arctic Char are the most northerly distributed freshwater fish species and occur in suitable habitats in all Arctic countries. The two most widely distributed groups are Arctic char (Salvelinus alpinus), a diverse primarily lake-adapted group (Figure C2), and Dolly Varden (Salvelinus malma), primarily a river-adapted group (Figure C3). Both occur as anadromous (sea-run) and freshwater resident forms. They are important components of northern aquatic ecosystems and are economically (subsistence food, commercial and sport fisheries) and culturally significant to northern communities (Conservation of Arctic Flora and Fauna 2001), particularly in Canada. For example, Arctic char made up approximately 45% by number of the top 15 species harvested in Nunavut between 1996 and 2001 (Priest and Usher 2004). The majority of the Canadian commercial Arctic char catch is taken in Nunavut fisheries at Rankin Inlet, Cambridge Bay, Pelly Bay and Nettilling Lake (DFO 2006).

Figure C2. An example of morphological diversity in Arctic char on a regional scale; these fish were sampled from one lacustrine and one marine site in northern Labrador, Canada. Photo by Wendy Michaud.		Figure C3. Adult male anadromous Dolly Varden char in spawning condition captured in the Firth River, Yukon Territory, Canada. Photo by Jim Johnson.

Status of Char in Northern Canada

Arctic char in the Northwest Territories has been ranked as Secure (not at risk of extinction or extirpation and not likely to become so in the foreseeable future) with the exception of the populations in the Hornaday and Kuujjua rivers which have been ranked as Sensitive (not at risk of extinction or extirpation but may require special attention or protection to prevent them from becoming at risk) (Working Group on General Status of NWT Species 2006). In Nunavut, Arctic char has been ranked as Sensitive (Canadian Endangered Species Conservation Council 2006). Dolly Varden in the Northwest Territories has been ranked as Sensitive (Working Group on General Status of NWT Species 2006) and is currently being assessed by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). Future updates will document the status of char in other Arctic countries as information becomes available.

Populations of both Arctic char and Dolly Varden inhabiting different systems have been shown to be genetically distinct (Reist 1989; Everett et al. 1998; Reist 2001; Rhydderch 2001; Bernatchez et al. 2002; Kristofferson 2002; among others) and are subject to different levels of biological (e.g., natural habitat change such as that caused by earthquakes) and anthropogenic (e.g., fisheries) stressors, thus summarizing population trends in a meaningful manner is a substantial endeavour. Furthermore, few long-term data sets exist for single populations or stock complexes and those that do deal exclusively with the effects of exploitation on population structure (Power et al. 2000). Prior to 2000, there had not been any Canadian studies that examined relationships between changes in stock characteristics and environmental variables. The first Canadian study of its kind examined a 20 year data set on Nain, Labrador char populations (Power et al. 2000). A similar recently conducted study examined a 15 year data set from the Hornaday River in the Northwest Territories (Chavarie 2008). Both studies found that environmental variables, including precipitation and temperature, influenced population characteristics such as mean length. Chavarie (2008) concluded that environmental changes predicted by climate change scenarios will significantly impact Hornaday River Arctic char and will likely affect other northern Arctic char populations.

As noted above, northern char population trends represent a significant gap in our knowledge of this species. To that end a char monitoring network is being developed within Canada and internationally as part of the International Polar Year (IPY) project Climate Variability and Change Effects on Char in the Arctic (Project Lead:Dr. James Reist, Fisheries and Oceans Canada; http://www.ipy.org/index.php?ipy/detail/arctic_biodiversity_of_chars/). This network will also contribute to the Circumpolar Biodiversity Monitoring Program (CBMP) of the Arctic Council.

Threats to Northern Char Populations

Potential threats to northern char populations include over-harvesting, habitat degradation/disruption, climate change, invasive species, and pollution among others. Perhaps the most urgent of these is climate change which is predicted to exacerbate existing stressors (ACIA 2005; Reist et al. 2006a). For example, rising temperatures may increase the level of contaminants, such as mercury, in Arctic freshwaters negatively affecting the health of the fish and the ecosystems they inhabit (ACIA 2005; Reist et al. 2006b). Their wide distribution, high level of diversity and significance to northern aquatic ecosystems make chars ideal for studying the effects of ecosystem change.

Knowledge Gaps

In order for char to be used to monitor Arctic change and attribute cause(s) to that change, several obstacles must be overcome. These include:

1. Char biodiversity and geographically wide distribution: As noted previously, this is one aspect of char biology that makes them ideal for studying effects of ecosystem change. However, it is also problematic as their high level of diversity creates difficulties in interpretation of results. Chars occur in rivers, lakes, and seasonally in the sea. Their diversity includes adaptations to all of these environments and to moving between freshwater and marine systems. In freshwater, different species are adapted to specific habitat types (e.g., lakes versus rivers). Each species, and in some cases population, is also inherently diverse. This includes differences such as anadromy versus freshwater residency and diversity of forms in some situations (e.g., ecological types within many lakes). These diverse forms may be seen as size variants, morphological variants, ecological forms or some combination of the above. A key component in our understanding is therefore to develop basic knowledge of the range and geographic distribution of this diversity to provide a baseline for future comparisons and thus for documenting change.
2. Role(s) of char(s) in the ecosystems: The roles performed by chars, how these change with life history, and how these differ among char forms are keys to understanding any observed changes and addressing consequences of the changes.
3. Indicators to monitor: What are the best parameters to monitor for chars to document short-term change, medium-term change and long-term change in both the chars and their supporting ecosystems? How best should such monitoring be developed in the long-term?
4. Char responses to stressors: Is most of the observed variation genetically based (and therefore can only shift in small increments over longer time frames) or is it environmentally driven and thus can we expect rapid char responses to rapid changes in stressors and environments? What surprises may exist concerning local responses of chars and how may we best prepare for such?
   

References

ACIA. 2005. Arctic Climate Impact Assessment. Cambridge University Press, New York. 1042 p.

Bernatchez, L., Rhydderch, J.G., and Kircheis, F.W. 2002. Microsatellite gene diversity analysis in landlocked Arctic char from Maine. Transactions of the American Fisheries Society 131(6): 1106–1118.

Canadian Endangered Species Conservation Council (CESCC). 2006. Wild Species 2005: The general status of species in Canada. Minister of Public Works and Government Services Canada, Ottawa, ON. 141 p. [report and searchable database available from: http://www.wildspecies.ca/wildspecies2005/index.cfm?lang=e; accessed 06 August 2008].

Chavarie, L. 2008. Changes in the biological characteristics of Canadian Arctic charr (Salvelinus alpinus) populations in response to climate-induced environmental variation. M.Sc. Thesis, University of Waterloo, Waterloo, Ontario. viii + 71 p. [available from: http://uwspace.uwaterloo.ca/bitstream/10012/3628/1/General%20thesis%20final%20version.pdf; accessed 06 August 2008].

Conservation of Arctic Flora and Fauna (CAFF). 2001. Arctic flora and fauna: status and conservation. Arctic Council Program for the Conservation of Arctic Flora and Fauna, Helsinki, Finland. 272 p.

Everett, R.J., Wilmot, R.L., and Krueger, C.C. 1998. Population genetic structure of Dolly Varden char from Beaufort Sea drainages of northern Alaska and Canada. In Genetics investigations of Dolly Varden char (Salvelinus malma) of the North Slope of Alaska, Part I. Alaska Fisheries Technical Report 43, p. 1–16. [available from: http://alaska.fws.gov/fisheries/genetics/pdf/1001_rf_1998_EverettWilmotKrueger_t_1998_43.pdf; accessed: 23 July 2008].

Fisheries and Oceans Canada [DFO]. 2006. Underwater World: Arctic char. 2 p. [available from: http://www.dfo-mpo.gc.ca/zone/underwater_sous-marin/omble/char-omble_e.htm; accessed 21 July 2008].

Johnson, L. 1980. The Arctic charr, Salvelinus alpinus. In: Charrs: Salmonid fishes of the genus Salvelinus. Edited by: E.K. Balon. Dr. W. Junk Publishers, The Hague, The Netherlands, p. 15–98.

Kristofferson, A.H. 2002. Identification of Arctic char stocks in the Cambridge Bay area, Nunavut Territory, and evidence of stock mixing during overwintering. Ph.D. Thesis, University of Manitoba, Winnipeg, MB. 255 p.

Power, M., Dempson, J.B., Power, G., and Reist, J.D. 2000. Environmental influences on an exploited anadromous Arctic charr stock in Labrador. Journal of Fish Biology 57: 82–98.

Priest, H., and Usher, P.J. 2004. The Nunavut Wildlife Harvest Study, August 2004. Nunavut Wildlife Management Board, Iqaluit, NU. 814 p. + CD. [available from: http://www.nwmb.com/english/resources/publications.php; accessed: 24 July 2008].

Reist, J.D. 1989. Genetic structuring of allopatric populations and sympatric life history types of charr, Salvelinus alpinus/malma, in the western Arctic, Canada. Physiology and Ecology Japan 1: 405–420.

Reist, J. 2001. Taxonomic issues, life history and stock discrimination – Rat River Dolly Varden. Canadian Science Advisory Secretariat (CSAS) Research Document 2001/091: 5 p. [available from: http://www.dfo-mpo.gc.ca/csas/Csas/DocREC/2001/RES2001_091e.pdf; accessed: 24 July 2008].

Reist, J.D., Wrona, F.J., Prowse, T.D., Power, M., Dempson, J.B., Beamish, R.J., King, J.R., Carmichael, T.J., and Sawatzky, C.D. 2006a. General effects of climate change on Arctic fishes and fish populations. Ambio 35(7): 370–380.

Reist, J.D., Wrona, F.J., Prowse, T.D., Dempson, J.B., Power, M., Köck, G., Carmichael, T.J., Sawatzky, C.D., Lehtonen, H., and Tallman, R.F. 2006b. Effects of climate change and UV radiation on fisheries for Arctic freshwater and anadromous species. Ambio 35(7): 402–410.

Rhydderch, J.G. 2001. Population structure and microphylogeographic patterns of Dolly Varden (Salvelinus malma) along the Yukon North Slope. M.Sc. Thesis, University of Guelph, Guelph, ON. v + 128 p.

Working Group on General Status of NWT Species. 2006. NWT species 2006-2010 – General status ranks of wild species in the Northwest Territories. Department of Environment and Natural Resources, Government of the Northwest Territories, Yellowknife, NT. 111 p. [available from: http://www.nwtwildlife.com/monitoring/speciesmonitoring/2006.htm; accessed: 24 July 2008].

Additional Resources

Selected Recent Publications on Trends in Canadian Populations of Arctic Char

Dempson, J.B., Shears, M., Furey, G., and Bloom, M. 2004. Review and status of north Labrador Arctic charr, Salvelinus alpinus. Canadian Science Advisory Secretariat (CSAS) Research Document 2004/070: 46 p. [available from: http://www.dfo-mpo.gc.ca/Library/284126.pdf; accessed: 24 July 2008].

DFO [Department of Fisheries and Oceans]. 2004a. Cambridge Bay Arctic char. Canadian Science Advisory Secretariat (CSAS) Stock Status Report 2004/10: 15 p. [available from: http://www.dfo-mpo.gc.ca/Library/284796.pdf; accessed: 24 July 2008].

Tallman, R. 2005. Stock assessment report on Kipisa Arctic char. Canadian Science Advisory Secretariat (CSAS) Science Advisory Report 2005/028: 14 p. [available from: http://www.dfo-mpo.gc.ca/csas/Csas/status/2005/SAR-AS2005_028_E.pdf; accessed: 24 July 2008].

Selected Recent Publications on Trends in Canadian Populations of Dolly Varden

DFO [Department of Fisheries and Oceans]. 2001. Rat River Dolly Varden. DFO Science Stock Status Report D5-61: 15 p. [available from: http://www.dfo-mpo.gc.ca/Library/264842.pdf; accessed: 24 July 2008].

DFO [Department of Fisheries and Oceans]. 2002a. Babbage River Dolly Varden. DFO Science Stock Status Report D5-62: 12 p. [available from: http://www.dfo-mpo.gc.ca/csas/Csas/status/2002/SSR2002_D5-62_e.pdf; accessed: 24 July 2008].

DFO [Department of Fisheries and Oceans]. 2002b. Big Fish River Dolly Varden. DFO Science Stock Status Report D5-60: 15 p. [available from: http://www.dfo-mpo.gc.ca/csas/Csas/status/2002/SSR2002_D5-60_e.pdf; accessed: 24 July 2008].

DFO [Department of Fisheries and Oceans]. 2002c. Firth River Dolly Varden. DFO Science Stock Status Report D5-63: 12 p. [available from: http://www.dfo-mpo.gc.ca/csas/Csas/status/2002/SSR2002_D5-63_e.pdf; accessed: 24 July 2008].

September 29, 2008

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