Influence of temperature, water current, illumination, and time on activity and substrate selection in juvenile smallmouth bass (Micropterus dolomieui)

Abstract

Behaviour of wild juvenile smallmouth bass, Micropterus dolomieui, in the laboratory was significantly influenced by water temperature, current, and illumination. Activity increased with increasing water temperature and (or) water current. When exposed to black and white substrate, selection of black was inversely dependent on temperature and current, and highly correlated with fish activity (r = 0.995, P < 0.001, inverse cubic relation). Substrate pattern influenced fish activity, aggregation, and social interaction. Activity levels increased with increasing incident illumination whereas selection of black substrate declined, particularly at higher water temperatures. Older juveniles became less active with age and preferred black substrate when available, thereby indicating a developing behavioural pattern which favours survival and energy conservation under natural nursery conditions by the discrete use of available cover.