RNA:DNA ratio
for diagnosis of the nutritional condition of Japanese anchovy Engraulis
japonicus larvae during the first-feeding stage
N. Kono, Y. Tsukamoto, H. Zenitani-2003
Fisheries
Science, 69(6):
1096-1102
Abstract:
In order to establish criteria with which
to evaluate the nutritional condition of wild first-feeding 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.
(National Research Institute of Fisheries and
Environment of Inland Sea, Saeki, Hiroshima 739-0452, Japan, Tel:
81-829-55-3563,
Fax: 81-829-54-1216. Email: nkono@fra.affrc.go.jp)