Theory of functioning of the Barents Sea ecosystem: fisheries and oceanographic aspects

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Management of resources in a marine ecosystem cannot be successful without understanding principles and specific features of its performance. The position of the Barents Sea between the Arctic and boreal oceanic systems determines the presence of extensive frontal zones. It is commonly accepted that owing to this peculiarity the Barents Sea is rich in various species of the commercial marine organisms. Results published earlier (Titov, 2001) and recent years’ investigations suggest that with transition from cold to warm climate conditions on the Barents Sea shelf, frontal zones in the pelagic and further in the bottom layer become sharpened. Correspondingly, the conditions formed are favourable at first for the pelagic (capelin) and then for the demersal (cod) fish species. These relationships correspond with the geographical areas of distribution of fish species. Catch statistics for capelin and cod summarized for the recent decades shows that concentrations of these species occur at the frontal zones in pelagic and bottom layers, correspondingly. On the basis of these data the main ideas of the theory of the Barents Sea ecosystem functioning were formulated: temporal variations of some characteristics of the Barents Sea ecosystem correspond to spatial peculiarities of their localization; climate variations influence the abundance of cod and capelin by modification of frontal zones parameters; abundance of cod and capelin is directly dependent on quality of the environmental conditions for these populations in general. An assessment of consequences of the global climate change for the populations of cod and capelin in the Barents Sea is presented.