Sea otters numbers grow in Southeast Alaska after extirpation by the fur trade
January 04, 2012
In 2010 and 2011 the U.S. Fish and Wildlife Service conducted an aerial survey in Southeast Alaska to estimate sea otter abundance in all known otter habitat and to document range expansion into new areas. We found that the sea otter population has increased in both range and number, but the animals have not yet fully re-colonized all of Southeast Alaska. We now estimate that there are a total of 19,989 sea otters in the Southeast Alaska population. Otter numbers have increased by 4% per year in the northern area of Southeast Alaska and by 12% per year in the southern area since they were last surveyed in 2002 and 2003, respectively. We know that population densities of sea otter in Southeast Alaska are still generally below those in other areas (including Prince William Sound), but, conversely, we don’t know what densities would be appropriate to the habitat found in Southeast Alaska.
Although the sea otter population has not expanded its range in northern Southeast Alaska since 2002, otters have occupied appreciable new habitat in southern SE AK since 2003. Sea otter re-colonization in Southeast Alaska has resulted in changes to the ecosystem. Kelp forests are regulated by the presence or absence of sea otters due to their predation on sea urchins, which forage on the kelp. Therefore, species that depend on kelp forests for part of their life history, such as Pacific herring or rock fish, may be positively affected by sea otter presence and the resulting kelp-dominated ecosystem. On the other hand, there is little question that the return of this predator to areas from which it was once eliminated will impact the abundance of species that thrived in the sea otters’ absence.
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