STRUCTURE, BIOMASS DISTRIBUTION, AND ENERGETICS OF THE PELAGIC ECOSYSTEM IN THE BARENTS SEA - A SYNOPSIS

Biomass distribution and energetics of trophic levels in the pelagic e cosystem of the Barents Sea are presented as averages over several yea rs for the whole Barents Sea using data from the research programme Pr o Mare in 1984-1989 and mathematical ecosystem models. Average biomass es range from more than 3 tonnes carbon km(-2) (zooplankton) to 0.1 kg C km(-2) (polar bears) and P/B ratios from 300 (bacteria) to 0.035 (m inke whales). However, the Barents Sea ecosystem is in a far from stea dy state with, for instance, capelin stocks ranging from 30-700 kg C k m(-2) between years and cod stocks from 150-700 kg C km(-2). As a gene ral rule, the various fish stocks grow adequately, albeit at different rates, in years characterized by large influxes of water and high zoo plankton productivity. The skewed populations distribution which arise s in ''warm'' years may lead to grave imbalances in ''cold'' years and even to the ''collapses'' of stocks, such as of capelin in the eighti es. The food requirements of average-sized stocks of cod, seabirds and marine mammals correspond to more than twice the average productivity of capelin. Thus other species of pelagic fish (herring, polar cod) a nd zooplankton obviously play major roles as prey for these animals.