RNA:DNA ratio for diagnosis of the nutritional condition of Japanese anchovy Engraulis japonicus larvae during the first-feeding stage

In order to establish criteria with which to evaluate the nutritional condition of wild firstfeeding larvae of Japanese anchovy Engraulis japonicus, the whole body RNA:DNA ratio and daily protein growth rate of reared larvae were individually determined.Anchovy larvae were reared for up to 9 days after the first-feeding day at 20∞C and 25∞C under various feeding conditions.Percent survival of the group starved for 2 days after the first-feeding day was extremely lower than that of those fed from the first-feeding day and 1 day starved groups at the two temperatures, even if they were supplied with food thereafter.Therefore it was concluded that the point of no return (PNR) was between 1 and 2 days after the first-feeding day within this temperature range.The RNA:DNA ratio of the PNR criterion was determined.Also, a 0% growth formula was established representing the relationship between the daily growth rate in protein, RNA:DNA ratio and temperature for first-feeding larvae.