Assessment of ovulation of common carp (Cyprinus carpio) females selected for induced spawning on the basis of external morphological characteristics

Secondary sexual characteristics such as softening and rounding of the abdo men as well as reddening and protrusion of the anal papilla and vent can be of help to breeders in selecting common carp (Cyprinus carpio) females pre pared for propagation. To assess the reliability of this method, long-term data obtained on induced spawning of common carp at a large-scale fish hatc hery were evaluated. The average spawning ratio of 2,620 females receiving hormonal injections was 79.8%. The average pseudogonadosomatic index (PGSI) calculated fi om data on the egg production of 2,086 females was 16.3 +/- 5.87% (mean +/- SD) for the same period. There was a correlation between fi sh weight and the' time of induction determined by the breeder on the basis of external morphological characteristics. The similarity of the responses of females, including both spawning ratio and PGSI, among the different we ight categories proved the reliability of this method for identification.