Steller sea lion feeding habits in the Russian Far East, 2000-2003

Abstract

During the breeding seasons of 2000-2003 we collected 1,724 scats from seven rookeries and eighteen haul-outs on the Kamchatka Peninsula and in the Kuril Islands, Okhotsk Sea, and Commander Islands to analyze the diet of Steller sea lions (Eumetopias jubatus) in the Russian Far-East. The most frequently encountered prey items in all scats combined were Atka mackerel (Pleurogrammus monopterygius), walleye pollock (Theragra chalcogramma), salmon (Oncorhynchus sp.), sculpins (Cottidae), cephalopods, Pacific sand lance (Ammodytes hexapterus), Pacific herring (Clupea pallasii), Northern smoothtongue (Leuroglossus stilbius), snailfish (Liparidae), and Pacific cod (Gadus macrocephalus). Spatial differences were analyzed by comparing frequency of occurrence (FO) values on a site-by-site basis for each year and all years combined. Breeding-season collection sites were grouped into seven geographic regions based on FO similarities using cluster analysis. Diet diversity was calculated for each of these geographic regions. No significant relationship was found between diet diversity and population trend (P = 0.886). Significant differences in diet composition were found between geographic regions (P < 0.001 for all regions). Significant seasonal differences were also detected at two haul-outs on the Kamchatka Peninsula from which an additional 93 scats were collected during the fall molt (P < 0.001 for both locations). Sea Lions of the World Alaska Sea Grant College Program • AK-SG-06-0 , 2006