In winter, and cooler parts of the spring and autumn season, these marine mammals populate the Northern Caspian. In the first days of April, spring migration to the southern part of the Caspian Sea begins with mature female seals and their pups, during this migration hungry seals eat the fish in the nets. Male mature seals stay in the northern Caspian Sea longer and wait until the moulting is completed. In summer, seals find empty places in the western part of Apsheron for resting. In the eastern part, the most crowded place used to be the Ogurchinskiy Island, but by 2001, fewer than 10 pups were recorded on Ogurchinsky, some of which were killed by people on the island.