| Popis: |
Domestic x Domestic, Domestic x Wild, and Wild x Wild channel catfish (Ictalurus punctatus) were paired in individual spawning pens and subsequent egg masses were artificially incubated. Domesticated catfish originated from 5 different hatcheries located in Georgia, Alabama, and Mississippi and since 1974 had undergone selective breeding for 2 generations for multiple traits. Wild catfish were collected from Carlyle and Shelbyville reservoirs in Illinois and were transferred to Tifton, Georgia, for this study. None of the 8 Wild x Wild pairs spawned in captivity, but the 8 Wild ♂ x Domestic ♀ and the 8 Domestic ♂ x Wild ♀ produced 3 and 6 egg masses, respectively. The fry hatched from each of the 14 egg masses (5 from Domestic x Domestic) were standardized to 2 tanks of 500 fish each at 4 weeks of age where one tank received 22°C well water and the other 28°C from 4–12 weeks. The fish from both tanks were grown in a constant 22°C water temperature from 12–40 weeks. The objective was to produce crossbreds superior to both parents in growth and survival in 22°C well water. An increment of 6°C in water temperature for a period of 8 weeks increased body weights of both straightbred and crossbred catfish by 100%. Domestic x Domestic catfish outperformed the Domestic x Wild crossbreds in both temperature regimes. These results suggest a stronger need for growth improvement through selective breeding of channel catfish than crossbreeding with wild strains. |
