Microsatellite DNA markers for the study of population structure in the New Zealand fur seal

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Abstract

New Zealand trawl fisheries have accounted for an estimated 10 000 deaths of New Zealand fur seal (Arctocephalus forsteri) between 1990 and 2000, with over half occurring in the West Coast Hoki fishery. To assess the impact of bycatch on separate colonies, the effects of commercial fishing bycatch and environmentally driven fluctuations need to be disassociated by identifying the original breeding colony of individual fur seals subject to incidental bycatch.

Here we have identified 23 polymorphic loci from a battery of 31 seal-specific microsatellite markers. Using eight of these loci, we have examined the geneticvariability and relationships among seven A. forsteri breeding colonies around New Zealand. Colonies showed only low levels of genetic differentiation (all FST values <0.035), which is consistent with moderate levels of gene flow and an expanding population. Despite this limited genetic differentiation, assignment testing resulted in c. 42% of individuals being assigned to their colony of origin and c. 70% of individuals assigned to their region (West Coast versus East Coast). This study represents an essential first step towards the long-term goal
of determining the breeding colony provenance of A. forsteri killed as fisheries bycatch.