Reconstruction of Arctic char biomass dynamics by Bayesian state-space assessment model

Arctic char, Salvelinus alpinus, is endemic to the islands of Canadian Arctic archipelago with an average annual total harvest of 40900kgs round weight for six of the primary fisheries in Cambridge Bay Nunavut since 1960. Accumulative evidence indicated that the supportive stocks and fishery are periodically stable, although a consistent decline in modal age and increase in condition factor and growth rate was noted for one of the fisheries. We constructed a Bayesian state-space surplus-production model to rebuild Arctic char population dynamics given limited data and uncertainty about char demography. Data series comprised commercial landings of Arctic char from Cambridge Bay (1960-2009) and experimental survey of commercial harvests by indexed gillnet and weirs (1971–2009). The results derived from MAMC simulations revealed that the char stocks showed somewhat explicit vulnerability for exploitation and sensitivity to the variable Arctic carrying capacity. Estimated fishing mortality for char stocks is influenced by prior knowledge, population biology and prior assumptions about exploitation rates. It is concluded that current practices of fisheries management should incorporate with precautionary measures to ensure population sustainability and intact arctic ecosystem stability simultaneously.