Kuril Islands - Marine Ecology

Marine Ecology

Owing to their location along the Pacific shelf edge and the confluence of Okhotsk Sea gyre and the southward Oyashio Current, the Kuril islands are surrounded by waters that are among the most productive in the North Pacific, supporting a wide range and high abundance of marine life.

Invertebrates: Extensive kelp beds surrounding almost every island provide crucial habitat for sea urchins, various mollusks and countless other invertebrates and their associated predators. Many species of squid provide a principal component of the diet of many of the smaller marine mammals and birds along the chain.

Fish: Further offshore, walleye pollock, Pacific cod, several species of flatfish are of the greatest commercial importance. During the 1980s, migratory Japanese sardine was one of the most abundant fish in the summer and the main commercial species, but the fishery collapsed and by 1993 no sardines were reported caught leading to significant economic contraction in the few settlements on the islands. Several salmon species, notably pink and sockeye, spawn on some of the larger islands.

Pinnipeds: The Kuril islands are home to two species of Eared Seal, the Steller Sea Lion and northern fur seal, both of which aggregate on several smaller islands along the chain in the summer to form several of the largest reproductive rookeries in Russia. A distinct Kuril island subspecies of the Common Seal (Phoca vitulina stejnegeri) and Largha are also abundant.

Pinnipeds were a significant object of harvest for the indigenous populations of the Kuril islands, both for food and materials such as skin and bone. The long term fluctuations in the range and distribution of human settlements along the Kuril island presumably tracked the pinniped ranges. In historical times, fur seals were heavily exploited for their fur in the 19th and early 20th centuries and several of the largest reproductive rookeries, as on Raykoke island, were extirpated. In contrast, commercial harvest of the true seals and Steller Sea Lions has been relatively insignificant on the Kuril islands proper. Since the 1960s there has been essentially no additional harvest and the pinniped populations in the Kuril islands appear to be fairly healthy and in some cases expanding. The notable exception is the now extinct Japanese Sea lion which was known to occasionally haul out on the Kuril islands.

Sea otters were exploited very heavily for their pelts in the 19th century. Indeed, the pursuit of the valuable otter pelts drove the expansion of the Russians onto the islands and much of the Japanese interest. Their numbers consequently dwindled rapidly. A near total ban on harvest since the mid 20th century has allowed the species to recover and they are now reasonably abundant throughout the chain.

Cetaceans: The most abundant cetaceans include Orcas, Harbor and Dall's Porpoises. Baird's and Cuvier's Beaked Whales, Minke Whales, Fin Whales, and Sperm Whales are also observed regularly. The surrounding water is considered as the major habitat for North Pacific Right Whales, one of the most endangered of all whale species.

Seabirds: The Kuril islands are home to many millions of seabirds, including Northern Fulmars, Tufted Puffins, Murres, Kittiwakes, Guillemots, Auklets, Petrels, Gulls, Cormorants. On many of the smaller islands in summer, where terrestrial predators are absent, virtually every possibly hummock, cliff niche or underneath of boulder is occupied by a nesting bird.