Seasonal proximate composition and food source comparisons of Dolly Varden char in the Kugururok River, Alaska

Abstract

The Kugururok River on the Noatak River System is an important spawning tributary for Dolly Varden char (Salvelinus malma), an important subsistence resource, occur bycatch in commercial fisheries, and are the basis of a sport fishery. The feeding habits and energetic condition of two spawning run patterns in the Noatak River Drainage were studied. Isotope ratio analysis revealed a predominantly marine carbon and nitrogen composition in all adult char. No internal isotopic fractionations were found either between tissues or seasons in any tissue. Proximate analysis revealed patterns of lipid and protein utilization characteristic of periodic starvation in fishes. Significant shifts of energy between key tissues were noted during the production of gonads. Data suggest that energetic minimums must be reached at sea before char can enter freshwater and successfully spawn.