Foraging dynamics of Southern Brook Charr ( Salvelinus fontinalis )

Habitat selection in drift feeding fishes, the majority of stream fishes in North America, is strongly affected by velocity, as well as other environmental and intrinsic characteristics of an individual drift feeder (e.g., size and dominance status). Our study subject, the Brook Charr ( Salvelinus fontinalis Mitchill), is a widely distributed and economically important salmonid fish which exists in a variety of forms. We tested the effects of water velocity, fish size, days in captivity, dominance status, and size rank on prey capture success, holding velocity, and reactive distance of wild Southern Brook Charr (SBC), a rare subspecies. Mechanistic studies of foraging dynamics of drift feeders are not common. Prey capture success was negatively related to water velocity, holding velocity was positively related to water velocity, and larger, dominant fish had greater prey capture success than smaller subordinates. Prey capture success declined from 10 to 60 cm·s –1 . Reactive distances were not strongly or consistently affected by any treatment variables. Our data indicate that all else being equal, Southern Brook Charr will forage well in streams with abundant velocities up to 30 cm·s –1 .