REDUCED BODY-SIZE OF FEMALE STELLER SEA LIONS FROM A DECLINING POPULATION IN THE GULF OF ALASKA

Nutritional stress is a leading hypothesis behind the decline in numbe rs of Steller sea lions in the Gulf of Alaska, the Aleutian Islands, a nd the Bering Sea. To evaluate this hypothesis we compared body growth of female Steller sea lions 1.0-13.9 yr of age collected in the Gulf of Alaska during two time periods, 1975-1978 just prior co or early in the decline and 1985-1986 when the decline was well established. We f ound that growth, as measured by standard length, axillary girth, and mass, was reduced during the 1980s, supporting the undernutrition hypo thesis. We also found a suggestion of reduced growth in our 1970s and 1980s samples when compared to a collection of Steller sea lions obtai ned from the Gulf of Alaska in 1958. However, no direct link has been demonstrated between undernutrition and the actual decline in numbers.