Research Document - 2009/011
Spatiotemporal distribution of beluga stocks (Delphinapterus leucas) in and around Hudson Bay: Genetic mixture analysis based on mtDNA haplotypes
By J. Turgeon, P. Duchesne, L.D. Postma and M.O. Hammill
Abstract
Stocks of belugas have been defined on the basis of summer aggregations in distinct areas. In the vicinity of Hudson Bay, the Western Hudson Bay (WHB), the Southeastern Baffin Island (SB), and the threatened Eastern Hudson Bay (EHB) stocks may contribute to the harvest by northern Nunavik communities. The contribution of the endangered Ungava Bay stock is also possible despite the very low census estimates for this population. Here, a genetic mixture analysis was performed with 37 mitochondrial haplotypes distributed among 1432 belugas caught in the Hudson Bay - Hudson Strait - Baffin Island geographical complex between 1984 and 2004. Genetic differentiation validated the traditional definition of beluga stocks in this area. The probabilistic estimation of stock contribution to mixed samples was heterogeneous among sectors and seasons. Contributions of the WHB and SB extended into Hudson Strait and Ungava Bay, but generally decreased further away from the summering grounds. Overall, the EHB stock contributed to an estimated 11 % of all mixed samples. EHB was best represented in spring and fall along the northeastern coast of Hudson Bay and in Ungava Bay, respectively. The array of haplotypes is unusual and very variable at Sanikiluaq, with the spring composition suggesting, as per other studies, a distinct, fluid population in the vicinity.
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