O. Rochemayzaud et al., CHANGES IN LIPID CLASSES AND TRYPSIN ACTIVITY DURING THE EARLY DEVELOPMENT OF BROOK CHARR, SALVELINUS-FONTINALIS (MITCHILL), FRY, Aquaculture research, 29(2), 1998, pp. 137-152
Fertilized eggs of brook charr, Salvelinus fontinalis (Mitchill), (Nas
hua x Baldwin domestic strains) held for 86 days under laboratory cond
itions from eggs to fry were split into three groups: FWF2, FWF3 and S
WF2, Breeders originated from the same broodstock, but rearing procedu
res were different; FWF2 and FWF3 were always kept in fresh water, whe
reas SWF2 had spent the previous summer in sea water, The SWF2 and FWF
Z females were sexually mature before the FWF3 females, The feeding ex
periment started 16 weeks after fertilization. Juveniles were fed with
the same commercial pellets at three different levels, a complete rat
ion (R1) and two restricted rations, 50% and 25% of R1, Eggs and fry w
ere analysed for size, dry weight, total lipids, lipid classes (polar
lipids, cholesterol and triglycerides), soluble proteins and trypsic a
ctivity, Although dry weight, mean length, and trypsic activities incr
eased availability, lipid changes showed a permanent use of the endoge
nous reserve. No lipid synthesis was detected in any developmental sta
ge, even though exogenous food sources were used. When the 25% restric
ted ration was given, fry mortality increased, Unexpectedly, fry survi
val tended to increase in individuals from small eggs. The data from t
his study showed that reserve distribution and its use can improve the
resistance of fry hatching from small eggs and prompt better survival
despite changes in the nutritional environment, The two factors relat
ed to the breeders, summer environmental rearing conditions and sexual
maturation time, had significant effects on the response of progeny t
o feeding conditions.