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Project Description

The National Marine Mammal Laboratory (NMML) of the Alaska Fisheries Science Center is responsible for providing scientific information as a basis for managing seals in Alaska under the Marine Mammal Protection Act. The genetic structures of seal populations are critical pieces of information for this purpose. Though some basic research has been conducted, relatively little is known of the genetic discreteness and stock structure of bearded, ribbon, ringed, and spotted seals (collectively called ice seals) in the Bering, Chukchi and Beaufort Seas. Previous work has focused on collecting tissue samples that can be used in genetic analyses. This project will involve collaborating with various researchers and institutions to collectively analyze the microsatellite and mtDNA markers in these tissue samples to begin addressing questions of possible subdivisions in ice seal populations.

Issues & Justification

Despite the fact that ice seals represent important subsistence resources for the native peoples of northern and western Alaska, and are key ecological components of the arctic and sub-arctic marine ecosystems, relatively little is known of their genetic discreteness and stock structure. An understanding of their population subdivisions and dispersal patterns and of the genetic components of their fitness and population viability is essential to managing their populations. It is also important in predicting how these pagophilic species might deal with potential changes in their environment. As such, information on stock structure is critical for NMFS to fulfill its stewardship mandates described by the Marine Mammal Protection Act. This project is aimed at addressing this lack of basic knowledge of ice seal ecology

Goals

  • Complete the mtDNA analysis of recently acquired seal samples from across Alaska to fill in critical sampling gaps.
  • Screen 100 bearded seal samples for variation in 16 polymorphic microsatellite loci.
  • Screen 100 spotted seal samples for variation in 20 polymorphic microsatellite loci.

Methods

The technically specialized work of analyzing seal population structure has been conducted through various collaborations between NMML, the NMFS Southwest Fisheries Science Center and the Alaska Department of Fish and Game. Previous, research efforts focused on: 1) the collection of tissue samples from breeding locations throughout the Bering-Chukchi-Beaufort region, 2) the extraction of total DNA and 3) an analysis of mtDNA variation. The screening of 33 variable loci revealed a subset of 16 that may be informative in population genetics studies of bearded seals, and a set of 20 that may be informative in studies of spotted seals. Our objectives for 2008 are to mount a region-wide study of population structure in bearded seals and spotted seals using these markers and to test for hybridization between the spotted seal and its sibling species the harbor seal. We will continue to collect additional tissue samples in the Bering, Chukchi and Beaufort Seas.
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