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Submitted to: Journal of the World Aquaculture Society
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 2/16/2017 Publication Date: 3/30/2018 Citation: Bosworth, B.G., Quiniou, S., Chatakondi, N.G. 2018. Effects of season, strain and body weight on testes development and quality in three strains of blue catfish, Ictalurus furcatus. Journal of the World Aquaculture Society. 49(1):175-182. Interpretive Summary: Commercial production of channel catfish (Ictalurus punctatus) female x blue catfish (I. furcatus) male hybrids has increased dramatically in the U.S. during the last 10 years. Hybrid fry production requires fertilization of channel catfish eggs with blue catfish sperm obtained by surgical removal and maceration of testes. Farmers report large individual and seasonal variation in blue catfish testes development and quality and understanding factors influencing blue catfish testes development could improve hybrid catfish fry production efficiency. A study was conducted to determine the effects of season (mid-May vs. mid-June), strain (D&B, Missouri and Texas) and body weight on testes development in 5 year old blue catfish males. Results showed that fish weight, strain and season all affected testes development and quality in blue catfish. D&B strain catfish had larger testes and better quality sperm (more sperm with higher motility) and had a higher percent of mature fish than the Texas and Missouri strains. Fish from all strains had larger testes, better sperm quality and a higher percent maturity in May than in June, although there were males with good testes development in all three strains in June. Larger fish tended to have larger testes, better quality sperm and were more likely to be mature than smaller fish, suggesting a size-threshold required for maturity of blue catfish males. Information from this study will be important in development of strategies to enhance and control timing of blue catfish testes development and quality to improve efficiency of hybrid catfish fry production. Technical Abstract: Commercial production of channel catfish (Ictalurus punctatus) female x blue catfish (I. furcatus) male hybrids has increased dramatically in the U.S. during the last 10 years. Hybrid fry production requires fertilization of channel catfish eggs with blue catfish sperm obtained by surgical removal and maceration of testes. Farmers report large individual and seasonal variation in blue catfish testes development and quality and understanding factors influencing blue catfish testes development could improve hybrid catfish fry production efficiency. A study was conducted to determine the effects of season (mid-May vs. mid-June), strain (D&B, Missouri and Texas) and body weight on testes development in 5 year old blue catfish males. Males from each strain were measured in mid-May (n = 85) and mid-June (n = 100) for total length, total weight, testes weight and GSI. Fish with testes weight < 0.2 g were classified as immature. Testes from mature fish were crushed in HBSS to release sperm and total sperm/g of testes, percent motility and motile sperm/g of testes were determined. D&B strain males weighed more, had larger testes with higher sperm density and motility, and had a higher percent maturity than Missouri or Texas strain males both months. Mature Texas strain males were larger than immature Texas strain males both months, but weight was not different among immature and mature D&B or Missouri strain males. Testes development and quality were better in May than in June for all strains, however there were males from each strain with large, good quality testes in June. GSI, sperm/g of testes, percent motility and motile sperm/g of testes were positively correlated. Information from this study will be important in development of strategies to enhance and control timing of blue catfish testes development and quality to improve efficiency of hybrid catfish fry production. |
