Proximate composition of some north-eastern Pacific forage fish species

To understand the relative dietary value of forage fish as prey in the Beri ng Sea and Gulf of Alaska, whole organisms of 13 species were analysed for proximate composition (protein, oil, ash and moisture content). Eulachon (T haleichthys pacificus) were high in oil (total lipid) (16.8% to 21.4%) and low in moisture (64.6% to 70.8%). Oil in capelin (Mallotus villosus) ranged from 2.1% to 14.0%. Juveniles of walleye pollock (Theragra chalcogramma), Atka mackerel (Pleurogrammus monopterygius), Pacific herring (Clupea pallas ii), and prowfish (Zaprora silenus) had low oil contents (< 1.8%) and high moisture contents (> 80.3%). Rankings of median proximate values illustrate the similarities. Surf smelt (Hypomesus pretiosus), rainbow smelt (Osmerus mordax), pricklebacks (Lumpenus spp.), Atka mackerel, Pacific sand lance ( Ammodytes hexapterus) and Pacific sandfish (Trichodon trichodon) ranked hig h in median protein content (> 15.4%). Median ash content for all species r anged from 0.6% to 3.3%. Total wet mass caloric content (kcal g(-1)) was ca lculated for the four main species and a linear model was developed for cal oric content as a function of moisture. The linear models (caloric content = b(0) + b(1) x moisture) were Pacific sand lance and Pacific sandfish (b(0 ) = 7.82, b(1) = - 0.09); eulachon (b(0) = 7.97, b(1) = - 0.08); and capeli n (b(0) = 9.70, b(1) = - 0.11).