Reproductive behaviors of SSLs were studied at the Forrester Island rookery in the eastern stock and the Sugarloaf Island rookery in the western stock during 1994 and 1995 in order to compare behaviors that might be affected by nutritional status. Both perinatal periods and trips to sea were shorter at Sugarloaf Island in the area of Decline. There were differences between years at both sites in length of perinatal period, trips to sea and visits ashore. 1996 at Timbered Island, Alaska. Male pups spend more time involved in play than female pups, while females are more likely to rest.
Male pups suckle significantly longer per bout than females.
No diurnal haulout pattern was observed. This suggests a high proportion of immatures are not fully behaviorally or physiologically weaned 3-5 months prior to breeding. Nutritional stress is a leading hypothesis behind the decline in numbers of Steller sea lions in the Gulf of Alaska, Aleutian Islands and Bering Sea. We found that growth, as measured by standard length, axillary girth. and mass, was reduced during the 1980s supporting the undernutrition hypothesis. We also found a suggestion of reduced growth in our 1970s and 1980s samples when compared to a collection of Steller sea lions obtained from the Gulf of Alaska in 1958.