The numbers of seabirds breeding in the Barents Sea Region have changed dramatically over the last 50 years. Increase in numbers of several species were associated with a recovery from an excess harvest of eggs and adults in the first half of the century, e.g. on Svalbard and Novaya Zemlya (Barrett and Krasnov, 1996). The changes seen in several populations in the second half of the 20th century can be explained by several factors. After 1950 there have been great fluctuations in all three primary prey fish stocks; herring, capelin and polar cod.