WINTER FLOUNDER LARVAE REARING: OPTIMIZATION OF FOOD
CONDITIONS BY ACCLIMATIZATION OF THE ROTIFER BRACHIONUS PLICATILIS
L.
Mercier, B. Parent, R. Fournier, J. De La Noüe, C. Audet
Abstract :
Winter flounder (Pseudopleuronectes americanus) is a
common inshore finfish, which was identified as a candidate for cold-water
marine aquaculture few years ago. Today, its larval rearing are mastered but
not optimised. The winter flounder larvae are fed on two live preys: a
rotifer first (Brachionus plicatilis) and then a brine shrimp (Artemia
salina). The 24°C “thermal preferendum” of these two preys is not
adapted to the 10°C of larvae water tank. When live preys are given to
larvae, they receive a thermic shock that is thought to reduce their
nutritional value and vigor. Inert food was attempted as a total replacement
of live preys but it was not digested by larvae until their gut loop
development was completed. The aim of this study was to improve the quality
of the live prey Brachionus plicatilis before the reliable use of inert
food. Brachionus plicatilis were reared at 24°C but acclimated at 10°C
before being given to larvae. A Brachionus plicatilis non-acclimated diet
was compared to the acclimated one. The study was conducted from mouth
opening to complete larvae gut loop development. Growth performance and
nutritional condition of larvae were compared with morphometric
measurements, total and soluble protein concentrations, trypsin activity,
and RNA/DNA ratios.
(Institut
des Sciences de la Mer à Rimouski (ISMER), Université du Québec à
Rimouski, Rimouski, QC G5L 3A1, Canada)