Largemouth bass Micropterus salmoides were reared over their first 8 weeks of free‐swimming life in uncontaminated control water or in water containing one of five concentrations of pentachlorophenol (PCP) ranging from 1.6 to 88 μg/L. Over the final 3 weeks of the study, fish reared in concentrations of 67 and 88 μg PCP/L performed significantly fewer feeding acts (orientations, bites) and had a lower rate of prey capture than did control fish. However, fish in high concentrations spent significantly more time swimming than did control fish, which indicated that exposure to PCP made them hyperactive. By inhibiting energy intake while inducing higher energy expenditures, PCP may reduce survival of young largemouth bass over the winter.
The study took place at the Queen's University Biological Field Station located on Lake Opinicon. Largemouth bass were collected as eleutheroembryos (Balon 1975) from nests and were placed immediately in wooden 90-L glass-fronted tanks, which were supplied with a continuous flow of lake water under a natural photoperiod. During the period May-September 1983, methods for exposing fish to PCP were established and determinations of the median lethal concentration (LC50) for young largemouth bass and suitable long-term PCP exposure concentrations were made (Johansen et al. 1985). The following protocols were used during the period May-September 1984.