Distribution of pacific salmons Oncorhynchus spp. and dynamics of their catch by gill-nets within the exclusive economic zone of Russia in the period of prespawning migration
Distribution and catch of pacific salmons are investigated for the spring-summer period (May-August), when the maturing or mature fish have the highest concentration in the Bering Sea and adjacent Pacific, on the data of control samplings by gill-nets (mesh size 55 mm) obtained in 1995-2008 (7208 net settings) in the research cruises conducted by the fisheries research institutes: KamchatNIRO (Petropavlovsk-Kamchatsky), SakhNIRO (Yuzhno-Sakhalinsk), TINRO (Vladivostok) and its Chuckchee branch (Anadyr), MagNIRO (Magadan), and VNIRO (Moscow). The surveyed area is divided onto three districts: the southwestern Bering Sea, the Pacific waters adjacent to Kamchatka, and the Pacific waters adjacent to northern Kuril Islands. All regional stock complexes of pacific salmons are represented in these districts during their prespawning migration. Besides, more than 70 % of all Russian gill-nets samples were collected within these districts. General scheme of pacific salmons aggregations distribution in the period of their intense prespawning migration is designed. Spatial structure of the aggregations reflects the main regularities of the migration process development. Dynamics (by 5-days) of the salmon catches in these three districts is presented. Both the scheme of distribution and catch dynamics are generalized for two periods: the 1990s (1995-2000) and the 2000s (2001-2008), the main features of these periods are compared.