What Has Put Alaska on the Skids?

by Kieran Mulvaney and Bruce McKay

Originally published in BBC Wildlife, October 1996.

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Alaska has an image problem. Widely perceived as being a relatively pristine, unspoiled wilderness, the state is experiencing precipitous declines in coastal and marine wildlife populations. A new report from the US Fish and Wildlife Service (FWS), detailing dramatic reductions in numbers of sea ducks throughout much of the state, is just the latest addition to a series of surveys providing evidence for similar trends in a wide variety of populations.

For example, harbor seal numbers in the Gulf of Alaska declined by as much as 57% from 1984 to 1992; on southeastern Tugidak Island, once home for one of the largest concentrations of harbor seals in the world, the population has fallen from some 6,900 animals in 1976 to under 700 in 1994, a decline of over 90%. Steller sea lions in Alaskan waters have dropped from approximately 236,000 during the 1960s to under 59,600 by 1994, a decline of 75%.

Since 1976, the abundance of thick-billed and common murres and red- and black-legged kittiwakes on the Pribilof Islands has declined by an average of about 40%; a large colony of red-legged kittiwakes on Middleton Island has regularly experienced total reproductive failure since 1981, causing the colony's numbers to drop by half.

A 1994 review of sea duck numbers in the North Pacific Rim found apparent declines in 13 of 17 species. A survey in1971 of spectacled eider populations in the Yukon-Kuskokwim Delta produced a figure of approximately 100,000, which was then half the estimated world population; the next survey, in 1992, estimated just 1,721 nesting pairs. The Steller's eider, once a common and regular breeder on the delta, has not been found nesting there since 1975.

Despite widespread efforts to determine whether these declines share an underlying cause, there is no smoking gun and no obvious, overall suspect. One immediately apparent possibility was that at least some of the populations concerned might be suffering from food shortages. The marine mammals and seabirds are fish-eaters and the waters around Alaska are host to some of the most intensive fisheries in the world. Groups such as Greenpeace have expressed concern about possible over-exploitation of, for example, pollock stocks and the possible repercussions for the region's wildlife; and reviews of declines in northern fur seals, Steller's sea lions and black-legged kittiwakes have all pointed to food shortages as a likely cause. A 1991 workshop at the University of Alaska, convened to look at possible causes for marine mammal and seabird declines, tentatively agreed that in at least some cases - particularly for some seabird populations - food shortages were likely to blame; but there was not enough evidence to conclude definitively whether such shortages were the result of over-fishing or natural, or human-induced, climate change.

One problem is that there is no overall pattern. Most seabird populations are in decline in the Pribilofs, but very few, except kittiwakes, are declining in the Gulf of Alaska. Amongst waterfowl, red-throated loons have dwindled drastically in numbers; common and Pacific loons have not. And food shortages would seem an unlikely explanation for the declines in sea ducks, which are benthic feeders, concentrating on shellfish from the sea floor - unless climate change or over-fishing has resulted in unknown, widespread ecosystem changes.

A multiplicity of causes may be at play. One FWS researcher suggested to BBC Wildlife that the sea duck declines might be caused, at least in part, by the birds ingesting lead shot from illegal hunting, or eating mussels which have accumulated high levels of contaminants over their 60-year life spans. They could be related to habitat destruction or low-level pollution in their winter breeding grounds, or to increased predation by foxes.

The only certainty is that there is uncertainty. Scientists are lobbying for more funding for more research. And meanwhile, the marine and coastal wildlife of a supposedly pristine wilderness continues to disappear.