Absolute and relative fecundity, egg weigt and influebce of egg weight on body weight of larvae and alevins in rainbow trout (Onchorynchus mykiss) at first and second stripping
2006
Pohar, J.
From a certain number of females, eggs were collected during their first and second spawning. Body mass at spawning (MPlm) and absolute fecundity (PAbs) was registered for each female. On the basis of these data the relative fecundity was calculated (PRel). For each female 50 eyed eggs as well as 50 offspring at different stages of growth were individually weighted. Weightings were done 11 days (T1), 6 weeks (T2) and 10 weeks (T3) after hatching. By such procedure mean weight of the eggs (MIker) and the mean body mass of alevins attained at T1, T2 in T3 (MRib1, MRib2 and MRib3) were obtained. The statistical model of partial regression including PRel and MIker as independent variables was used to evaluate the influence of MIker on MRib1, MRib2 and MRib3. Results indicate that from heavier eggs heavier larvae are hatched. Nevertheless, the influence of egg weight on body mass is only short termed. Partial regression coefficient of MIker on MRib3 is not statistically significant regardless whether relation between eggs and alevins at first or second spawning is observed. According to our results it is suggested that eggs collected at first spawning should not be discarded even they appear to be too small for production. At age of 10 weeks after hatching, average size of alevins hatched from small eggs collected at first spawning did not to essentially differ from average size of alevins hatched from large eggs collected at second spawning.
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