Genetic Effects on the Production of Channel Catfish (Ictalurus punctatus) Female X Blue Catfish (Ictalurus furcatus) Male Hybrid Fry
Type of DegreeThesis
Fisheries and Allied Aquacultures
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The hybrid from the mating of a female channel catfish (Ictalurus punctatus) with a male blue catfish (Ictalurus furcatus) exhibits heterosis for various performance traits which would make it attractive to the commercial aquaculture industry. However, the widespread use of the hybrid in the aquaculture industry has been impeded by reproductive isolating mechanisms that prohibit the adequate production of fry. The primary research objective was to evaluate various genotypes of channel catfish females to determine if certain genotypes with blue catfish produced increased numbers of fry when hybridized. Fry output and other reproductive traits of seventeen genotypes of channel catfish females when crossed with blue catfish males were evaluated. The effect of crossbreeding or selection for body weight for channel catfish females was evaluated to determine heterosis, correlated responses or inbreeding depression for hybrid fry production. No clear effect of strain on percent ovulation, latency period, egg quality, or fecundity was observed, thus any observed differences among strains are likely due to age effects. Strain of female did affect the most important trait, fry/kg female body weight, with genotypes low (162 ± 280 fry/kg) and AU-7 (801 ± 793 fry/kg) being poor performers. Season affected strain differences, and the best channel catfish strain to use during different portions of the spawning season varies. Three-year-old crossbred females exhibited negative heterosis for ovulation percentage (52.1%) which could be the result of late sexual maturity of the crossbreed. However, earlier experiments indicated that these same fish have early sexual maturity so early sexual maturity for more conventional reproduction does not equate to good reproductive performance. The crossbreed did not exhibit any heterosis for latency period, egg quality, or fecundity. With regards to percent hatch and fry/kg, the crossbreed exhibited performance equal to (4 years of age; 27.4% and 3,393 fry/kg) or less than (3 years of age; 8.4% and 880 fry/kg) the best performing adult. Results indicate no advantage of using this crossbreed to produce hybrid fry compared to the best parental line, AU-1. Selection for increased body weight had variable effects on reproduction and hybrid fry production. Various lines had increased, decreased, or no change in reproductive output compared to randomly bred controls.