2011 Northern Fur Seal Pup Production Estimate on Bogoslof Island, Alaska
Northern fur seal pup production
Numbers of northern fur seal, Callorhinus ursinus, pups were estimated using a mark-recapture method, shearsampling, on Bogoslof Island (Figure 1) during August 2011. We estimated that 22,905 (SE = 921.5, Table 1) pups were born on Bogoslof Island. Dead pups were counted on all breeding areas of Bogoslof Island resulting in an observed pup mortality rate of 2.6%. The 2011 pup production estimate for Bogoslof Island is 30.3% greater than the estimate in 2007 (Figure 2). Since the first pup was observed on Bogoslof Island in 1980 pup production has increased at an annual rate of 38.2% (SE = 2.60) and at an annual rate of 11.7% (SE = 0.90) since 1997.