Rainbow trout performance in food-limited environments: implications for future assessment and management

Abstract

We evaluated the performance of rainbow trout in food-limited lake and hatchery environments using whole-body water content as a proxy for fish energy reserves and lipid content. Relative abundance of rainbow trout stocked in an oligotrophic lake from 2002 to 2006 decreased by 88% in 145 days. Whole-body water content of rainbow trout increased following stocking in the lake and similar increases in water content were observed in fish from a food-deprived hatchery treatment. Water content in the fed hatchery fish was significantly lower than water content observed in stocked lake fish. Traditional metrics of body condition (i.e., Fulton's K and relative weight) based on length–weight relationships were insufficient to detect the observed changes in whole-body water content for all lake and hatchery treatments. We conclude that depletion of energy reserves contributed to poor survival and low angling returns of stocked rainbow trout in the study lake.