Population genetic structure of walleye pollock <Emphasis Type="Italic">Theragra chalcogramma</Emphasis> (Gadidae,Pisces) from the Bering Sea and Sea of Okhotsk |
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Authors: | E A Shubina E V Ponomareva A I Glubokov |
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Institution: | (1) Institute of Marine Biology, Vladivostok, Russia;(2) Pacific Research Fisheries Centre (TINRO-Centre), Vladivostok, Russia |
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Abstract: | Walleye pollock Theragra chalcogramma Pallas occupies a central place in ecosystems of the North Pacific and is an important target species of fisheries. The species
is characterized by daily vertical, spawning, feeding, and wintering migrations and spawning occurring under the sea ice.
Since population structure estimation by the tagging with recapture is inefficient in walleye pollock, the pollock resources
are difficult to estimate by conventional methods, requiring population genetic studies with molecular markers. The population
genetic structure of five spawning aggregations from the Bering Sea was for the first time studied with ten microsatellite
loci: Tch5, Tch10, Tch11, Tch12, Tch14, Tch16, Tch17, Tch19, Tch20, and Tch22. A spatially distant sample from the Sea of
Okhotsk was used as a reference group. Polymorphism for the markers reached 100%, and heterozygosity of individual loci ranged
from 41 to 95% in different populations. It was shown the aggregations of interest are in goodness-to-fit the Hardy-Weinberg
equilibrium (HWE) at hole, while the Sea of Okhotsk sample demonstrated a sex bias: the heterozygosity at Tch16 in males was
significantly lower than in females. The highest discriminative power was observed for Tch10, Tch20, and Tch22. F
ST genetic distances between populations were typical for marine fishes. A mixed composition was supposed for the sample from
the region of the underwater Shirshov Ridge, which serves as a natural partial geographic barrier between the Olyutor-Karagin
and Koryak walleye pollock stocks. With the Shirshov sample excluded, F
ST scatter plots and the spatial autocorrelation approach supported isolation by distance for the aggregations. An influence
of abiotic factors on the population structure was assumed for walleye pollock of the Bering Sea. |
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