Channel catfish Ictalurus punctatus strain comparison for induced ovulation in the early spawning season to produce channel catfish ♀ × blue catfish I. furcatus ♂ hybrid catfish embryos

The channel catfish (Ictalurus punctatus) ♀ × blue catfish (Ictalurus furcatus) ♂ hybrid catfish has superior performance in respect to survival, growth rate, feed conversion, low dissolved oxygen, and fillet yields compared to its parent species. Currently the demand for hybrid fingerlings is greater than available supply. Selective breeding for early spawning could extend the spawning season to partially address this problem. Under commercial conditions and using natural open pond spawning, the Thompson line of channel catfish spawns earlier at its location than other strains at their home farms. Over a 4-year period the Thompson line was compared to the Kansas strain and AR line for fry production in the early spawning season using induced spawning with luteinizing hormone-releasing hormone analogue implants to induce ovulation, followed by hand stripping, and in vitro fertilization techniques. Relative reproductive performance was variable among years, but in general, fry output of the three strains was similar and relatively high, with the 3-year average of both Thompson and Kansas strains being approximately 2500 fry/kg. The observed fry output of Thompson was about 15% higher than that for Kansas, which was not significantly different because of the high variation among years. The early spawning of the Thompson line appears to be due to an environmental effect, related to genotype-environment interactions or natural spawning and response to induced spawning are actually two different traits. Strains of more northerly origin might be evaluated to achieve the goal of better response to early induced spawning.