Evaluation of RNA concentration as an indicator of growth in young-of-the-year winter flounder Pseudopleuronectes americanus and tautog Tautoga onitis

Abstract

White muscle tissue RNA concentration was evaluated as an indirect measure of fish growth. Young-of-the-year winter flounder Pseudopleuronectes americanus and tautog Tautoga onitis were grown in short-term caging experiments conducted during 1994 and 1995 within 3 geographically distinct estuarine systems in the NE of the USA; the Hammonasset River along the Connecticut coast of Long Island Sound, the Navesink River located in the Hudson-Raritan Bay estuary in northern New Jersey, and Great Bay-Little Egg Harbor estuary in southern New Jersey. Fish were caged in each of 5 habitat types including: eelgrass, macroalgae, unvegetated areas adjacent to eelgrass, unvegetated areas adjacent to macroalgae, and tidal marsh creeks. White muscle tissue RNA concentration (μg per mg wet tissue wt) was measured in winter flounder and tautog recovered from the cages and compared to instantaneous growth rate measurements of these same fish. RNA concentration was significantly correlated with growth rate measured as length (r = 0.83) and weight (r = 0.79) in winter flounder and length (r = 0.69) and weight (r = 0.73) in tautog. In most cases, estuary- and habitat-specific differences in growth rate, as determined by RNA concentration, were similar to those determined by measuring instantaneous growth. These results validate the use of RNA concentration as an indirect measure of growth in young-of-the-year winter flounder and tautog.