Fat content and fatty acid composition of forage fish and invertebrates in Prince William Sound, Alaska: factors contributing to among and within species variability

摘要: We determined the fat content and fatty acid composition of 26 species fish inver- tebrates (n = 1153) that are primary forage piscivorous seabirds marine mammals in Prince William Sound (PWS), Alaska. Flatfish, shrimps octopus had lowest average con- tents (~1.0%), although some cods, as well juvenile walleye pollock Theragra chalcogramma, Pacific herring Clupea harengus pallasi pink salmon Oncorhynchus gorbuscha also ranged low 0.5 to 0.7% fat. The highest contents were found eulachon Thaleichthys pacificus (25%), adult (21%) squid Berrytheuthis magister (5 13%). Within species, var- ied mostly with season, but size. Fatty signatures generally distinguished spe- cies, up 95% individuals correctly classified using either discriminant or classification regression tree (CART) analyses. Discriminant plots provided insight into relationships between different species. Species similar life histories diets clustered closer together, while those greatest differences ecology differed most their pat- terns. changes apparent increasing size consistent known dietary shifts reported from stomach Furthermore, Age 0 (yr) PWS previous analysis indicated annual timing eating zoo- plankton piscivory. Overall, when size/age classes taken account, was improved. Our findings have important implications for evaluating food web interactions stocks, at higher trophic levels. Despite individual variation within our results indicate accurately characterize this ecosystem, consequently can be used study perhaps estimate predators.