The mature part of the stock, consisting of fish 3-5 years and longer than 14 cm, migrate towards the coast and reaches the shores in the beginning of March, where it spawns along the coasts of Troms, Finnmark and the Kola peninsula. Usually, some spawning occurs also later in the year, mostly in eastern Finnmark and on the Russian side of the border.
The capelin spawns at the bottom, mostly at depths of 20-60 m, on sand and gravel. The eggs get attached to the bottom, where they hatch after one month. The larvae will ascend to the uppermost water layers and drift with the current from the coast towards the east and north. In the summer, the larvae will be spread over large parts of the central and southern Barents Sea.
During the first two years of life the juvenile capelin will be distributed further south than the adult capelin. During summer the capelin migrates northwards and forages in the ice-free plankton rich areas in the course of the autumn. The mature individuals start migrating towards the coast in late autumn or early winter. The distribution and migration are influenced by the abundance of the stock and of the climate in the Barents Sea.
The other important capelin stocks are found at Iceland, Newfoundland and in the Bering Sea.
There is one subspecies in the Atlantic and another in the Pacific. The largest capelin stock is found in the Barents Sea, but it’s abundance has varied much the latest 30 years, from a few hundred thousand tonnes to 7-8 million tonnes. There is another stock of capelin in the Iceland – East Greenland – Jan Mayen area. The capelin is a typical schooling fish that lives from plankton organisms.
The capelin is dark on the back with a light belly, which makes it difficult to see for predators from above (birds, seals, whales) or beneath (fish, whales). The capelin has a large mouth and well developed gill gitter and can therefore feed effectively on plankton organisms like copepods and krill. The male capelin develops a characteristic appearance towards spawning, with hairy protrusions along the side line (which has given the capelin both it’s scientific and Norwegian name) and an enlarged dorsal fin. In the northwest Atlantic the capelin cannot be mistaken for other species, except perhaps sandeel which has a resembling body form, but with a much more pointed head.
The capelin grows fast and reaches 14-18 cm in the course of 3-4 years. The males grow faster than the females, end become somewhat longer. Individuals that reach about 14 cm during autumn will start maturing and spawn the following spring.
