For an unknown reason, the Steller sea lion population in Alaska has declined by 80% over the past three decades. In 2001, the National Research Council began a study to assess the many hypotheses proposed to explain the sea lion decline including insufficient food due to fishing or the late 1970s climate/regime shift, a disease epidemic, pollution, illegal shooting, subsistence harvest, and predation by killer whales or sharks. The report's analysis indicates that the population decline cannot be explained only by a decreased availability of food; hence other factors, such as predation and illegal shooting, deserve further study. The report recommends a management strategy that could help determine the impact of fisheries on sea lion survival -- establishing open and closed fishing areas around sea lion rookeries. This strategy would allow researchers to study sea lions in relatively controlled, contrasting environments. Experimental area closures will help fill some short-term data gaps, but long-term monitoring will be required to understand why sea lions are at a fraction of their former abundance.This comparison indicated that the current availability of fish biomass is higher for the 1999 population than for the prefishery population ... Steller sea lion counts correspond to index sites in the Gulf of Alaska and Aleutian Islands, as there are no index rookeries in the Bering Sea. ... In the Bering Sea and Aleutian Islands, Steller sea lion 120 DECLINE OF THE STELLER SEA LION IN ALASKAN WATERS.
|Title||:||The Decline of the Steller Sea Lion in Alaskan Waters:|
|Author||:||Committee on the Alaska Groundfish Fishery and Steller Sea Lions, Division on Earth and Life Studies, Polar Research Board, Ocean Studies Board, National Research Council|
|Publisher||:||National Academies Press - 2003-04-04|