Некоторые предварительные результаты биологических исследований в Карском море на НИС «Профессор Леванидов» в сентябре 2019 г.

Abstract

Results of biological studies conducted at RV “Professor Levanidov” in September 2019 in the Kara Sea at depths of 18-533 m presented. During the research period, phytoplankton blooms were not observed, almost no meroplankton, eggs, and crustacean nauplia were found in samples. The bulk of communities was formed by copepods, euphausiid and chaetognaths, jellyfish and snow crab larvae were widely met. Increased biomass was observed in deep-water areas in the north, and minimal biomass was found in desalinated shelf areas in the south of the sea. In trawl catches among invertebrates, snow crab dominated with maximum catches in the north off Cape Zhelaniya and in the southwest near Kara Strait. Echinoderms and coral polyps made a significant contribution to benthic biomass. Maximum catches of invertebrates were recorded in deep-sea areas: in the north near Cape Zhelaniya (south of the St. Anna Trench) and southwest (south of Novaya Zemlya Trough). In trawl catches, Liparidae, Zoarcidae, and Cottidae were most species diverse. Dominant species in terms of occurrence and abundance was Polar cod with maximum concentrations recorded in the southern part of the sea off Kara Strait. Its abundance in 2019 compared to previous studies increased according to bottom trawl surveys and remained almost the same according to acoustic data. The most catches included American plaice with biomass 190 thousand tons. In the southeastern part of the sea near Yamal Peninsula, Pacific herring with a biomass of 214 thousand tons has been recorded. Increased concentrations of navaga with catches up to 115 specimens per haul were found near the coasts of Yamal Peninsula and Baydaratskaya Bay. Feeding habits of common fish species were studied. Diet composition and high feeding intensity indicated favorable forage conditions. Ontogenetic changes of diet composition of individual species were revealed. An extremely high level of Polar cod cannibalism observed.