INFLUENCE OF EGG SIZE ON GROWTH AND SURVIVAL OF EARLY STAGES OF SIBERIAN STURGEON (ACIPENSER BAERI) UNDER SMALL SCALE HATCHERY CONDITIONS
E. Gisbert, P. Williot, F. Castelló-Orvay-2000
Aquaculture, 183 (1-2): 83-94
Abstract:
A study was conducted to determine the relationships between egg and newly hatched larvae sizes and growth and survival of Siberian sturgeon (Acipenser baeri) during early stages of development. We hypothesised that this may lead to improved rearing techniques and hatchery management. Eggs (mean size 2.8-4.1 mm) were obtained from 20 cultured 13-14 years old females. There was a positive correlation between egg size and total length (TL), body weight (BW) and yolk sac volume of newly hatched larvae. Mortality during the endogenous feeding phase were less than 3.6% and occurred among morphologically deformed fish. First feeding age (9-11 days post-hatch) correlated significantly with egg and newly hatched larvae size (P<0.05). At the onset of the exogenous feeding, mortality sharply increased in all experimental groups and represented 2.1%-23.5%. Losses were attributed to the change from endogenous nutrition to exogenous feeding based on an artificial commercial diet. Cannibalism was common between 9 and 15 days post-hatch, but was not an important source of larval mortality (2.0%-5.4%). Mortality substantially declined after the transition to exogenous feeding. At the end of the rearing period (20 days post-hatch), the effects of egg and newly hatched larvae sizes were still evident on the TL and BW of larvae (P<0.05). However, no significant differences (P>0.05) were found when larval specific growth rates (SGRs) were compared between progeny from different females, revealing the ability of smaller specimens of Siberian sturgeon to grow at the same rate as initially larger fish. Egg size did not provide any advantage for survival of young fish (P>0.05). We conclude that under generally favourable rearing conditions, egg size has no direct implications for larval survival of Siberian sturgeon.
(Laboratori d'Aqüicultura, Departament de Biologia Animal, Facultat de Biologia, Universitat de Barcelona, Av. Diagonal, 645, 08028 Barcelona, Spain)