The Barents Sea is located on top of a shelf, implying relatively shallow waters. Average depth is 230 meters, and rarely in excess of 300 meters. Instantly west of Spitsbergen, the shelf ends and the ocean depth rapidly increases to more than one thousand meters.
The warm Gulf Stream comes in from the south, spreading further east to the Barents Sea, where it changes name to the Murmansk Stream. From the opposite direction (north-east) come cold, southbound streams, moving rapidly, resulting in thorough blending of the water masses. In springtime, water, rich on nutrition, flows to the lightened surface, and as the ice retreats, it becomes available for plankton. The recently melted ice water lays upon the the more saline sea water, and creates a bright and good environment for phytoplankton.
The large, shallow ocean area, the blending of the water masses, cold and warm streams meeting, the ice melting and retreating, are all factors forming the basis for the production that makes the the Barents Sea one of the worlds richest ocean areas. A strong bloom of phytoplankton in the spring and early summer is the nutritional basis for a vast production of zooplankton. The zooplankton is nutrition for larvals and the spawn from all the fish populations.
The Barents Sea is capable of maintaining large fish populations. Cod, Capelin and herring are key species, but all together, there are approximately 150 species of fish in the area. All the fish populations in the Barents Sea utilize Norwegian waters in their adolescence. Eggs and spawn drift into the Barents Sea with the streams along the Norwegian coast. The fish grow up here, and make the Barents Sea fisheries significant, perhaps the most important in the North Atlantic.
The large occurrence of plankton and plankton-eating fish throughout the year, forms the basis for an abundant and varied animal life further up in the food chain. The most numerous group is the seabirds. They nest in several bird mountains around the whole sea, some places together with more than 100 000 other individuals on the same mountain. The Barents sea is one of the worlds richest seabird areas. It is estimated to accommodate 13 -15 million seabirds in the summer. Also in the dark period, millions of birds live here, and auks can be observed far into the drift ice areas. Common birds at all times are fulmars, cormorants, terns and arctic goose. Totally, there are 26 species of international conservation significance in the area, and further 9 species of national significance.
Among the mammals, seals dominate in numbers, with among 1,3 million specimen. The most significant species are ringed seal, bearded seal, and walrus. The sea is also estimated to accommodate 55 000 whales, especially mink whale. Apart from humans, the polar bear is on top of the food chain. In the Spitsbergen area, among two thousand polar bears have seals on their menu.