Distribution and population genetic structure of sibling rougheye rockfish species

Distribution and population genetic structure of sibling rougheye rockfish species

A.J. Gharrett, A.P. Matala, E.L. Peterson, A.K. Gray, Z. Li, and J. Heifetz

Distribution and population genetic structure of sibling rougheye rockfish speciesThis is part of Biology, Assessment, and Management of North Pacific Rockfishes
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Description

Rougheye rockfish (Sebastes aleutianus) includes two genetically distinct species, type I and type II. We examined their spatial distributions, population genetic structures, and the effects of fish size, depth, and capture gear (trawl or longline) on their distributions from samples collected on the continental shelf and upper slope from the south end of the Queen Charlotte Islands to the western Aleutian Islands and the Bering Sea. Type I fish occurred throughout the Alaskan range, but type II fish were not abundant west of Kodiak Island. Their distributions overlapped in the northeastern Gulf of Alaska. Collections were pooled for genetic analysis into geographically defined groups. We examined allelic variation at seven microsatellite loci in 710 type I fish and 510 type II fish and restriction site variation in the ND3/ND4, 12S/16S, and ND5/ND6 mtDNA regions in 666 type I and 400 type II fish. Tests of homogeneity and adjacency tests that partitioned heterogeneity showed that both species have genetic structure that is consistent with a neighborhood model of dispersion. For both species, population divergence was apparent at the edges of the range, but divergence in the northeastern Gulf of Alaska was more pronounced in type II populations, which suggests structure on a finer scale than the management area boundaries. Analysis of the effect of fish size, depth, and capture gear (trawl or longline) on distributions of the species suggests that the species differ in habitat preference. In addition, numerous small type II fish were captured by trawl in relatively shallow water, but large numbers of small type I fish were not observed, which suggests that young fish have different habitat preferences.

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