Laboratory studies on RNA/DNA ratios of starved and fed herring (Clupea harengus) and turbot (Scophthalmus maximus) larvae

Abstract

Dry weight, RNA, DNA, protein content, and RNA/DNA ratios of starving and fed laboratory-reared herring ( Clupea harengus ) and turbot ( Scophthalmus maximus ) larvae were evaluated for diagnosis of nutritional status. Starving larvae had lower protein concentrations, lower RNA concentrations, and slightly higher DNA concentrations (in percentage of dry weight) than fed larvae. The RNA/DNA ratio proved to be the most sensitive parameter for determining nutritional status. Significant differences between fed and starving larvae appeared after four to five days of food deprivation. In both species the RNA/DNA ratio was linearly correlated with the length of the starvation interval regardless of larval age (after the yolk-sac stage). Multiple regression analysis showed that the log dry weight per larva and the RNA/DNA ratio explained 62% of the observed variation in the starvation interval in degree-days.