A B S T R A C TThe Barents Sea, a large, high-latitude shelf sea, has been monitored and investigated for more than a century. More than 1800 occasional expeditions have been organized both by Norway and Russia, and since the1960s the collaboration between the Institute of Marine Research (IMR, Bergen) and the Knipovich Polar Research Institute of Marine Fisheries and Oceanography (PINRO, Murmansk) has been strengthened by developing and carrying out joint surveys. Monitoring changes in the Barents Sea fish stocks and collecting information needed for stock assessments and advice for fisheries management were the driving forces behind the increased effort spent on marine research. This triggered the development of sampling and observation methodology, the design of scientific research vessels for using various equipment and gear, and the development of new technologies for processing several types of samples. Increased data collection generated a need for the development of complex database systems and software that, could analyze larger data sets. Joint large-scale monitoring over the last 50 years, together with joint management of living marine resources during the last 20 years, resulted in high stock biomasses of commercially important fish stocks and thus the successful development of fisheries in the Barents Sea. Here, we describe the development of Barents Sea monitoring from single species (or fishery) surveys that were focused on target species/groups to integrated ecosystem surveys that aim to describe the status and main changes in the Barents Sea ecosystem.

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The assessment of the stock status and prospects for the fishery of the Barents Sea cod is characterized by significant uncertainty caused by the peculiarities of the age structure, which often led to significant differences in the results obtained using different models. As a result, this caused intense discussions both within the framework of the International Council for the Exploration of the Sea (ICES) and at the meetings of the Joint Norwegian-Russian Fisheries Commission. In 2021, at a specialized ICES workshop («benchmark» group), the input data and configuration of the main assessment model - SAM, were refined, related to the inclusion of additional information on older age groups. As a result, two models currently used by the ICES working group to estimate cod stock (SAM and TISVPA), which are very different in their approaches, showed that the number of generations born in 2004–2005 significantly decreased, which led to a decrease in cod biomass. An assessment of the prospects for the state of the stock, performed both on the basis of calculations using the SAM model and on the basis of an alternative approach using the AMO (Atlantic Multidecadal Oscillation Index), showed a high probability of further decline and stabilization of the spawning stock biomass (and catches) in the next 2–3 years, after which restoration of spawning stock biomass is likely due to sufficiently abumdante generations born in 2011 and 2014.

In order to assess the optimum red king crab's landing size in the Barents Sea, concept of maximum sustainable yield was chosen which could be reached at different levels of fisheries exploitation and values of the minimum landing size. At maximum allowable level of fisheries exploitation of 30% the optimum red king crab's landing size should be 170 mm in carapace width. Though this increase is reasonable only provided that economic indicator (cost of production) is included in calculation and set of assumptions on equilibrium state of «stockfishery» system is accepted, correlation stock-recruitment and traumatic mortality value are correctly chosen.

Аннотация. В 2010 г. был снят мораторий на коммерческий промысел черного палтуса Баренцева моря. На данный момент управление промыслом осуществляется на основе трендового метода. Это связано с плохой настройкой на входные данные ранее использовавшейся модели оценки величины запаса, которая показала свою несостоятельность. В работе проведены расчеты величины запаса черного палтуса Баренцева моря при помощи продукционной модели Шефера и сделаны выводы об ее применимости.Abstract. In 2010 commercial fishing of Greenland halibut in the Barents Sea was reopened. But due to poor fitting of the previous model to input data, management of fishery is currently being performed using the survey trends. In this paper, the calculations of the Barents Sea halibut stock based on the Schaefer production model have been presented and some conclusions about the applicability of this model have been made.Ключевые слова: черный палтус, оценка запаса, продукционная модель, Шефер, биомасса.