The Steller's sea eagle is a sentinel species in the natural environment of the Russian far east and northern Japan. It’s existence is threatened by declines in its food supply, habitat changes, and pollution. The Steller’s sea eagle is one of the largest eagles in the world, and, to many people, is a symbol of the wildness associated with the Russian Far East. Beyond the emotive response to these species, they are important because they are also top predators in their environment. As such their ecology positions them at the center of their ecosystems, and their long-term health is dependent upon the natural function of their environment. Although the population is not considered endangered at this time, it is listed as ‘vulnerable’ because of the relatively small size and because of its limited range.
The ecology of Steller's sea eagles varies across its range, and
the potential impact of human activities and the conservation
challenges change from region to region and from season to season.
Habitat changes, declining populations of salmon due to overfishing, and environmental contaminants all are threats faced by Steller's sea eagles.
Abundant food is important for survival and breeding. Long-term declines in salmon runs can be caused by human activities many kilometers from the rivers in which they spawn, and can have a deleterious effect upon eagle populations. Declines in salmon and other fisheries can impact eagles on their wintering and summering grounds, as well as on migration.
Pollution has possibly direct and indirect effects on eagles.
Documented and undocumented oil spills have occurred on in the
region. The experience of the spill in the Prince William Sound,
Alaska suggests that no matter how well prepared emergency services
are for such a spill, weather conditions are most influential
in determining the extent of spills. It is probably not a case of
‘if‘ a spill will occur, but ‘when’, ‘where’, and
‘in what conditions’
DDT, PCB phenol contamination
Wide-spread, and large-scale timbering and gold mining operations could be a source of long-term pollution and siltation of water that may compromise the health of salmon spawning grounds. Timber operations in particular might remove the large trees in which eagles nest
Steller's sea eagles migrate along two basic routes: one that follows the western shore of the Okotsk sea to Sakhalin and onto Hokkaido, and another that funnels to the Kuril Lake in Southern Kamchatka, with some birds continuing south to the Kuril Island chain and Hokkaido. Strategies for managing resources along migration routes are not developed , but it is important that general environmental quality be maintained. Some areas, like Sakhalin, support their own breeding population, but also are migratory habitat for about 60% of the entire population. Hydrocarbon pollution in Sakhalin could have wide reaching effects on breeding eagles from Magadan, Amur and Sakhalin.
Traditionally, much of the Steller's sea eagle population has wintered in northern Hokkaido and on the southern most Kuril Islands, where the eagles would feed off the by-catch and fish lost from nets of commercial fisherman. Walleye pollack was particularly important, but over the past 5 years this fishery has declined. As the fishery has declined, eagles have turned to using the remains of Sika deer left by hunters. In doing so, the Steller’s sea eagles are now exposed to the threat of lead poisoning from ingesting bullet fragments in the deer carcasses. Over the past three years, 47 eagles have been diagnosed to have died from lead poisoning. These probably represent the ‘tip of the iceberg’ of dead Steller’s sea eagles.
Because immature eagles are rarely seen on breeding territories, they must take at least six years to enter the breeding population. In general it is thought that pre-breeding eagles inhabit the edges of the breeding range and in interstitial areas between breeding territories. Because pre-breeding eagles probably do not congregate, it is less easy to identify critically important areas and try to manage them, although it is important for the survival of the species to conserve these areas used by the pre-breeding portion of the population.