Seasonal patterns in white crappies' consumption and growth: Influences of varying water temperatures and prey availability

Crappies Pomoxis spp. are popular sport fishes but often fail to achieve sizes that are acceptable to anglers. While many factors may contribute to episodes of suboptimal growth in crappies, insufficient densities of prey fish and high summer water temperatures (>27°C) have been considered to be key underlying causes. We examined the influences of prey fish size, prey availability, and water temperature on the consumption and growth of white crappies P. annularis (ages 1-3) in three Missouri reservoirs over five successive years. Monthly growth rates were estimated using aging analyses, while consumption was estimated using a bioenergetics model. All age-groups grew fastest in the reservoir that was warmest but in which prey fish availability was the highest. Diet analyses coupled with bioenergetics modeling suggested that white crappies were able to maintain positive growth rates at temperatures exceeding 27°C by maximizing consumption rates when adequate prey fish resources were available. When sufficient prey fish resources were unavailable, white crappies fed on invertebrates and often ceased growing or lost weight, even during periods with suitable water temperatures. Our study documents the importance of adequate prey fish resources for maintaining positive growth rates of white crappies, especially during periods of adverse temperature conditions.