Science Advisory Report 2015/024
Assessment of Arctic Char (Salvelinus alpinus) in the Darnley Bay area of the Northwest Territories
Summary
- Biological and catch indices as well as modelling results indicate that the Hornaday River population is not experiencing overfishing and the current stock status is healthy.
- Data from community harvest surveys (1968-2013) and various sampling programs, most importantly the Hornaday River Char Monitoring Program (established in 1990) were incorporated into population models (depletion-based stock reduction analysis, surplus production and, statistical catch at age models) to estimate maximum sustainable yield (MSY) and population abundance, and evaluate stock status.
- Model estimates of the abundance of Arctic Char from the Hornaday River in 2013 ranged between approximately 17,000 and 33,700 for the fishable component of the population (≥440 mm), and 78,600 for the total population.
- The three models generated relatively similar estimates of MSY with the inverse weighted average among the estimates providing a value (± 1 standard deviation [SD]) of 2,496 (154) fish. Risk to the stock increases as harvest approaches MSY, therefore harvest should be kept below MSY to ensure a sustainable fishery. The voluntary total allowable harvest of 1,800 Arctic Char in 2013 is below MSY and appears to be sustainable.
- Two genetically distinct stocks of Arctic Char, one from the Hornaday River and the other from the Brock River, contribute to the summer coastal fishery in eastern Darnley Bay. Although both stocks are genetically distinct, a high degree of gene flow occurs between them, indicating some interbreeding. The contribution of the Hornaday River stock to the coastal fishery is consistently greater (average among sampling years was >80%) than the Brock River.
This Science Advisory Report is from the February 6-7, 2014 Assessment of Arctic Char in the Darnley Bay area of the Northwest Territories. Additional publications from this meeting will be posted on the DFO Science Advisory Schedule as they become available.
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