FULL ARTICLES
The article provides data on the catch of the Northern Okhotsk, Eastern Kamchatka and Western Bering Sea walleye pollock stocks, fishery structure by the fishing gears in 2016–2019, size and age composition of the fish in the commercial trawl and Danish seine catches in 2010–2019. Data on the generation abundance and stock condition indices used in the stock assessment models are also demonstrated. Interannual dynamics of the total and spawning stock biomass, determinants of the dynamics and prospects of fishing are analyzed.
Data on the local distribution of capelin in the eastern part of the Sea of Okhotsk in 2000–2019 are very limited. Maps of the distribution were made based on results of complex pelagic surveys in 2000–2019. It is demonstrated, that spring distribution of capelin in the Eastern Sea of Okhotsk varied depending temperature conditions in each particular year. Major aggregations of capelin were observed within Shelikhov Gulf in spring. In the “cold” years these aggregations were in the south-western part of the West Kamchatkan shelf, and in the “warm” years – in the north-western part. In sense of bathymetric distribution the main body of the capelin aggregations was observed in the upper part of the shelf at the depth <125 m at the temperatures bit lower zero.
On the basis of the materials collected in the period of 2010–2018 the features of biology: the size-age structure, linear growth pattern and body mass growth of the stone cockscomb Alectrias alectrolophus from the Tauysk Bay, the Sea of Okhotsk, have been studied. In the intertidal zone, in the period from May to September, individuals of this species the body length 31.2–133.4 mm and body weight 0.1–12.8 g at the age of up to 6+ years are found in large quantities. The size and age characteristics, rates of growth of females and males are quite similar, but in general, females are slightly larger than males.
Some of biological traits of the Far Eastern sea cucumber from the Severnaya Bay were examined in 2016 and 2017. Body length of sea cucumber individuals varied from 3.6 to 23.4 cm. Dermo-muscular bag weight was higher in 2017 (137.5 g). Individual ages were 1–4 years in 2016 and 1–5 years in 2017. Sex ratio was near 1:1 in 2016 and 2017. During the period of the research gonad index was maximal in June – 10.6%. Spawning began in the 2nd decade of June and finished in the 2nd decade of July.
SHORT COMMUNICATION ARTICLES
Based on histological analysis of the ovaries of sockeye salmon spawners in the Kamchatka River, numerous abnormalities leading to resorption are shown in the structure of vitellogenic oocytes. Fertility of mature female sockeye salmon decreases due to the resorption of the vitellogenic oocytes. Presence of ovaries with abnormal oocytes implies oocyte resorption in fish being a phenomenon associated with mechanism of natural regulation of final fertility. Such mechanism is required in view of changing fish body length and weight in the sockeye salmon of the Kamchatka River. Numerous abnormalities in the ovaries indicate of a decreasing reproductive capacity of spawners and commercial quality of the eggs.
ISSN 2782-6236 (Online)