Responses of Brook Trout and Creek Chubs to Turbidity

The influence of red-clay turbidity on behavior and distribution of brook trout Salvelinus fontinalis and creek chubs Semotilus atromaculatus was measured in the laboratory. Creek chubs preferred highly turbid water (56.6 formazin turbidity units—FTU) over moderately turbid water (5.8 FTU) but brook trout did not show a preference. In moderately turbid water, both species were more active, and used overhead cover less, than in clear water. The results indicate turbidity may represent an important isolating mechanism that promotes production of creek chubs.