Concentrations of nucleic acids and protein as indices of nutritional status for recently emerged brook trout (Salvelinus fontinalis)

Abstract

We examined whether concentrations of nucleic acids and protein sampled from muscle tissue were useful indicators of nutritional status for recently emerged brook trout (Salvelinus fontinalis). Trout collected from the field were maintained in the laboratory under two food treatments: fed versus food deprived. Concentrations of RNA and DNA, and RNA/DNA ratio did not differ significantly between fed and food-deprived trout, but fed trout had higher concentrations of protein and were 20% heavier at a given fork length than food-deprived trout. Wild trout fed in the laboratory had lower concentrations of RNA, DNA, and protein, and lower RNA/DNA ratios than did trout in the field, but were significantly heavier for their fork length. Tissue concentrations of protein may provide an index of nutritional status for recently emerged brook trout while concentrations of nucleic acids apparently do not. It is important to ensure that concentrations of nucleic acids and protein reflect nutritional status adequately for the species and life stage of interest before using these indices to assess the condition of fish in the field.