Influence of age of wild ide Leuciscus idus (L.) female on spawning effectiveness under controlled conditions

The aim of this study was to determine the effect of age of female ide on spawning success under controlled conditions. All ide breeders were collected from one wild population. Data concerning reproductive parameters were collected during induced spawning under hatchery conditions. The age of mature females ranged from 4 (average weight 504 g) to 9 years (average weight 2540 g) and the youngest collected females (3+) (average weight 330 g) were immature. The females from group 4+ produced smaller oocytes (1.28 mm diameter after hydration) than older fish (1.44-1.57). There were no differences in oocyte sizes in females 6+ and older. The highest relative fecundity (mean 44,621 eggs kg-1) was noted for fish aged from 5 to 7. Eggs obtained from the oldest females had the lowest biological quality: the highest percentage of dead embryos during incubation (49.9) and the highest percentage of morphological abnormalities in hatched larvae (5.6%). In addition, in the group of the oldest females, only 67% of fish produced eggs.