Fish diets and food webs in the Northwest Territories : Dolly Varden (Salvelinus malma) / by D.B. Stewart, N.J. Mochnacz, T.J. Carmichael, C.D. Sawatzky, and J.D. Reist. : Fs97-4/2912E-PDF

"Dolly Varden prey on a variety of aquatic invertebrates and fishes, and on terrestrial invertebrates when the opportunity presents. They forage near the surface of the substrate and seldom feed on infaunal benthos, or on midwater or surface taxa. Small fish in fresh water eat predominately immature stages of aquatic insects. Prey size and the proportion of fish in the diet increases as the Dolly Varden grow larger. Anadromous Dolly Varden do not feed extensively in fresh water. In coastal waters they eat mostly amphipods, mysids and fish, although insects—predominately chironomid larvae, are eaten in areas strongly influenced by freshwater. The diet of anadromous fish in fresh water is similar to that of juveniles and residuals that remain there year-round, except that a higher proportion of the anadromous fish have empty stomachs. Humans are a key predator on larger anadromous Dolly Varden that are predictably available in confined areas of fresh water and vulnerable to mixed-stock coastal fisheries. Piscivorous fishes, including larger Dolly Varden, may be the key predators on smaller juveniles and eggs. The ability of northern-form Dolly Varden to withstand competition from other species is not well understood. This document provides generalized freshwater and marine food webs for the species and reviews knowledge of its interactions with predators, prey, and competitors. Dietary differences related to geographical location, habitat type, life history stage, season, predation, and competition are discussed"--Abstract, page v.

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