Seasonal changes in pelagic fish biomass around the Chiswell Island Steller sea lion rookery in 2003

Seasonal changes in the diel vertical migration of walleye pollock (Theragra chalcogramma) in the northern Gulf of Alaska

“…1) was centered around Chiswell Island (59°36′N, 149°34′W), a Steller sea lion (Eumetopias jubatus) rookery in the northern GOA, located offshore of the Kenai Peninsula (Adams et al 2008). Bottom topography in the area includes submarine canyons and ridges.…”

“…Differential global positioning system position and Greenwich Meridian Time from the ship's navigation system were appended to each record before writing the data to disk. Details of echosounder calibration can be found in Adams et al (2008).…”

“…This abundance estimate was then converted to kg nmi −2 using the length-weight regressions for pollock, herring and eulachon reported in Adams et al (2008), while the equation in Brown (2002) was used for capelin and surf smelt. Radiometric data were processed with Profiler software (Biospherical Instruments, Inc., San Diego, California, U.S.A.).…”

Scientific inference and experiment in Ecosystem Based Fishery Management, with application to Steller sea lions in the Bering Sea and Western Gulf of Alaska

“…The frequency of occurrence of herring and Pollock in the diet of Steller sea lions did not differ significantly between seasons, although that of other prey species did [52]. In [53] it is concluded that Steller sea lions in the Northern Gulf of Alaska (the eastern population) are not food limited during summer months. A bioenergetics model used to investigate the hypothesis that competition between the Western population of Steller sea lions and the commercial ground-fishery for walleye pollock gave rise to the decline of the population [54] predicted population trends of Steller sea lions under a variety of scenarios of continued pollock harvest.…”

Milk fatty acid composition of perinatal and foraging Steller sea lions (Eumetopiasjubatus): examination from pup stomachs

“…Changes in milk FA composition between maternal states in other pinniped species are caused by differences in overall diet pre-and post-birth (Iverson et al 1997a, Smith et al 1997. SSL prey species near the Chiswell Island rookery fluctuate seasonally (Adams et al 2008), and therefore differences in milk FA composition between perinatal and pinnipeds (Prime & Hammond 1990, Pierce et al 1991, Beck et al 1993, and for SSLs in Alaska , Sinclair & Zeppelin 2002, Womble & Sigler 2006. Therefore, in this study it is likely that milk FAs of perinatal SSLs are influenced by feeding on pollock and herring, which are dominant prey species nearby the Chiswell rookery during spring (Adams et al 2008), while milk FAs of foraging SSLs primarily arise from feeding on pollock and salmon, which are dominant prey species nearby the rookery during summer.…”