Research Document - 2013/068
Information to support an updated stock status of commercially harvested Arctic Char in the Cambridge Bay region of Nunavut, 1960-2009
By A.C. Day and L.N. Harris
Abstract
Harvest (1960 to 2009) and biological data (1971 to 2009) are presented for the commercial Arctic Char (Salvelinus alpinus) fishery of Cambridge Bay, Nunavut. Various aspects of Arctic Char biology and their response to harvest are also assessed and summarized. Since the inception of the fishery in 1960, total commercial landings from the seven primary fisheries (Lauchlan (Byron Bay), Halovik (Thirty Mile), Surrey (Paliryuak), Ekalluk, Jayco, Ellice and Perry rivers), have averaged 41,290 kg round weight per year with total landings exceeding 2,000,000 kg round weight from 1960 to 2009. The subsistence harvest of char is substantial, estimated to equal approximately half that of the commercial harvest. Trends in mean age and fork length appear stable although they exhibited a high amount of annual variation which was somewhat synchronous among locations. Several of the fisheries demonstrated increasing trends in mean round weight and mean condition factor. Pooled maturity data suggested that 64 % of females and 70 % of males harvested by the fishery were immature. However, recent maturity assessments at other locations suggest this may not be accurate and a higher percentage of mature fish are actually being harvested. For the examination of long term growth trends, length at age was analyzed separately for each of four decadal periods and for all fisheries, growth rate did not differ among these periods. All of the primary stock complexes were considered to have a low level of risk of overexploitation under current harvest regimes, with the exception of the Ellice River stock complex. The Ellice River stock complex is considered to have a moderate level of risk of overexploitation due to a decline in mean age, a consistent increase in mean condition factor and round weight, and a faster growth rate in comparison to growth rates of char from other fisheries. This level of risk, however, is lessened by the fact that this river has not been fished since 1999. Overall, the Cambridge Bay Arctic Char fishery and its supportive stocks are considered stable and fished at or below their sustainable rates of harvest.
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