Practical Application of a Bioenergetic Model to Inform Management of a Declining Fur Seal Population and Their Commercially Important Prey

摘要: Food availability is a key concern for the conservation of marine top predators, particularly during time when they face rapidly changing environment and continued pressure from commercial fishing activities. Northern fur seals (Callorhinus ursinus) breeding on Pribilof Islands in eastern Bering Sea have experienced an unexplained population decline since late-1990s. Dietary overlap with large U.S. fishery walleye pollock (Gadus chalcogrammus) combination changes maternal foraging behavior pup growth has led to hypothesis that food limitation may be contributing decline. We developed age- sex-specific bioenergetic models estimate seal energy intake May - December six target years, which were combined diet data quantify prey consumption. There was considerable sex- age-specific variation because differences body size, energetic costs, behavior; net lowest juveniles (18.9 MJ sea-day-1, 1,409.4 season-1) highest adult males (66.0 7,651.7 season-1). Population-level consumption ranged 255,232 t (222,159 350,755 t), 95% CI) 2006 500,039 (453,720 555,205 t) 1996, comprising between 41.4 76.5% this biomass. Interannual size-specific appeared largely driven by juvenile fish, up 81.6% biomass coming mature years poor age-1 recruitment. Relationships among metabolic rates, trip durations, lactating females suggest most feasible mechanism increase rates increasing efficiency through reductions effort, unlikely occur without increases localized density. By quantifying year-specific pollock, our study provides pathway incorporate into multispecies stock assessment models, critical management given significant source mortality both pollock.