Assessment of the regional composition of juvenile chum salmon mixed aggregations in the Sea of Okhotsk based on results of genetic assay

Abstract

Genetic differentiation of chum salmon in the basin of the Sea of Okhotsk is demonstrated. Eight microsatellite loci (Ssa20.19, One101, Oke3, Oki1b, Oki23, Ogo2G, Oke11, Ots102) were used as genetic markers. Four original genetic regions of chum salmon reproduction have been figured out: West Kamchatka and northern part of the continental coast of the Sea of Okhotsk, Sakhalin, Ithurup (the Kuril Islands), the Amur basin, where the part of juvenile fish was found as a result of genetic identification in the mixed aggregations in the early period of marine feeding. The resolution ability of the reference database was within the limits 74.9–94.6 %. It was demonstrated based on results of the genetic identification, that juveniles from West Kamchatka and northern part of the continental coast of the Sea of Okhotsk dominate in the northern part of the Sea of Okhotsk. Majority of individuals examined in the central zone of the survey area (54 %) was from the Kuril Islands. A number of juvenile chum salmon from the Amur River basin and Sakhalin were recorded at the stations in vicinity of Sakhalin coast.