There must be other people on this site who share the concern about the uncontrollable expanding sea otter population. The shellfish in southeast alaska are on the way of being completely wiped out. Years ago when there used to be a sea urchin fishery in Sitka, when the otters made their way into the Sitka area, in one year they consumed 16,000,000 sea urchins closing the fishery instantly.
Abalone are basically non-existent anymore and this year they have been proposed to be put on the endangered species list. This is not only because of sea otters, but also due to a poorly regulated fishery, and overharvest of the animal, but otters played a significant role in keeping the abalone from repopulating. As the otters continue to migrate to inside waters, they have begun to decimate important subsistence and commercial shellfish harvesting. Otters are starting to heavily effect Dungeness crab fishing, Sea cucumber and Geoduck harvesting, not to mention the harvest of clams and scallops.
A sea otter consumes 23% of it's body weight a day in shellfish, so in a year one 50lb sea otter will consume roughly 4,200lbs of various shellfish. With an estimated population of 25,000 sea otters in southeast alone, and a population increase of 8% in northern southeast, and an outrageous 12% population increase in southern southeast, it's not long until the otters eat themselves out of house and home. If nothing is done to slow the population, Important shellfish commercial fisheries and subsistence opportunities for the people of southeast will be gone.
Diving around Sitka Sound now is a graveyard of abalone and shellfish shells. It's not uncommon to see over 50 otters a day on an hour long skiff cruise. The hunting harvest by Alaska natives for otters is not enough to effect the population at all, and if nothing is done soon to address this problem, I can't imagine what it's going to be like 5-10 years from now. If anyone is interested, below is a great link discussing the effect of sea otters on southeast Alaska's ecosystem.