Effects of hatchery rearing on Florida largemouth bass Micropterus floridanus resource allocation and performance under semi-natural conditions

This study examined the growth, activity, metabolism and post-release survival of three groups of Florida largemouth bass Micropterus floridanus: wild-caught fish, hatchery fish reared according to standard practice (hatchery standard) and hatchery fish reared under reduced and unpredictable food provisioning (hatchery manipulated). Hatchery-standard fish differed from wild-caught fish in all measured variables, including survival in semi-natural ponds. Hatchery-standard and hatchery-manipulated fish showed higher activity levels, faster growth and lower standard metabolic rates than wild-caught fish in the hatchery. Fish reared under the manipulated feeding regime showed increased metabolic rates and increased post-release growth, similar to wild-caught fish. Their activity levels and post-release survival, however, remained similar to those of hatchery-standard fish. Activity was negatively correlated with post-release survival and failure of the feed manipulation to reduce activity may have contributed to its failure to improve post-release survival. Activity and post-release survival may be influenced by characteristics of the rearing environment other than the feeding regime, such as stock density or water flow rates.