DOES OTOLITH STRUCTURE REFLECT THE NUTRITIONAL CONDITION OF A FISH LARVA - COMPARISON OF OTOLITH STRUCTURE AND BIOCHEMICAL (RNA DNA RATIO) DETERMINED ON COD LARVAE/

Cod larvae from laboratory rearing experiments aged from 1 to 12 d aft er hatching, both fed and deprived of food, were analysed. The number of increments on the otolith and the width of these increments were de termined together with the RNA/DNA ratios on the same individual larva . Alizarin marking of the otoliths was performed to confirm the format ion of daily increments. Cod larvae reared at 6 degrees C formed the f irst ring right after hatching and deposited increments on a daily bas is. A comparison of the measurements between the right and the left la pillus showed that these can differ, if the radius is taken. The lapil lae core showed especially high individual variability, whereas the su m of the increments did not differ between both lapilli. Until Day 10 alter hatching, while the larvae were still feeding on their yolk, the external food situation did not affect the increment width of the lap illi or the RNA/DNA ratios. In larvae older than 10 d the width of the daily increments was dependent on the nutritional situation and RNA/D NA ratios decreased in starving larvae in comparison to feeding larvae . RNA/DNA ratios and increment widths were correlated.