Review of the results of common carp (Cyprinus carpio) breeding at a large-scale hatchery

Long-term data on the induced spawning of common carp (Cyprinus carpio) at a large-scale hatchery were evaluated. Breeders at the farm prefer medium-s ize fish with body weights between 4 and 8 kg. The number of females select ed for propagation in the first period of the spawning season made up about half of the total number of females (47.5%). The average spawning ratio fr om the data of 2620 females receiving hormonal injections was 79.8%. From t he egg production data of 2086 females, the average pseudogonadosomatic ind ex (PGSI) was calculated as 16.3 +/- 5.87% (mean +/- SD) for the same perio d. There was a high correlation between fish weight and the time of inducti on, determined by the breeder on the basis of secondary sexual characterist ics. The similarity of the responses of females among the different weight categories proved the reliability of this method for identification. The ti me of induction has a significant effect on both the responsiveness of the females and the relative quantity of eggs released. Spawning ratio was sign ificantly lower in the third period of the reproductive season, compared wi th those in the first and second period. Mean PGSI for the third period was significantly lower than that for the first period. The considerable decre ase of both reproductive parameters by the end of the spawning season is at tributed to ovarian atresia. The spawning ratio and the mean PGSI for the m irror and scaled varieties were similar.