THE EFFECT OF FOOD AVAILABILITY, AGE OR SIZE ON THE RNA DNA RATIO OF INDIVIDUALLY MEASURED HERRING LARVAE - LABORATORY CALIBRATION/

RNA/DNA ratios in individual herring (Clupea harengus) larvae (collect ed from Kiel Bay, Baltic Sea, in 1989) were measured and proved suitab le for determining nutritional status. Significant differences between fed and starving larvae appeared after 3 to 4 d of food deprivation i n larvae older than 10 d after hatching. The RNA/ DNA ratio showed an increase with age or length of the larvae and was less pronounced in s tarving larvae compared to fed larvae. The individual variability of R NA/ DNA ratios in relation to larval length of fed larvae and of larva e deprived of food for intervals of 6 to 9 d is presented. Based on th e length dependency and the individual variability found within the RN A/DNA ratios, a laboratory calibration is given to determine whether a larva caught in the field has been starving or not. An example for a field application is shown.