Submitted to: Aquaculture America Conference
Publication Type: Abstract Only
Publication Acceptance Date: 8/9/2005
Publication Date: 2/13/2006
Citation: Peterson, B.C., Bates, T.D., Bosworth, B.G. 2006. Effects of confinement bags in raceways on the production of hybrid catfish (channel female x blue male) embryos and fry. Aquaculture America Conference. Las Vegas, NV 13-16, 2006. p. 232.
Technical Abstract: Over the past thirty years there has been interest in the production of F1 hybrids of female channel catfish (Ictalurus punctatus) and male blue catfish (I. furcatus). Hybrid catfish have been shown to exhibit faster growth and uniformity in body conformation as well as being more disease resistant compared to channel catfish. Some of the disadvantages of producing hybrids are the labor and low reproductive success associated with induced spawning. The reduction in handling stress of the female may improve the reproductive rate in producing hybrid catfish. Gravid, mature female channel catfish were seined from earthen ponds and allowed to acclimate in a concrete raceway. Female channel catfish (n = 7) were placed individually in nylon mesh confinement bags (24” x 36”) in the raceway while other female catfish (n = 5) were left free to swim in the raceway. The fish were injected with carp pituitary extract (CPE; 2 mg/kg body weight) and re-injected approximately 18 hr after the initial injection with CPE (8 mg/kg body weight). Females were examined approximately 24 hr after the second injection, and if eggs could be expressed with minimal pressure to the abdomen females were anesthetized with 100 ppm MS-222, strip-spawned, and eggs were collected in Hank’s Buffered Salt Solution (HBSS). Testes were surgically removed from mature blue male catfish that were euthanized by a percussive blow to the cranium. Testes were macerated in HBSS and sperm was pooled from 2 males. The pooled sperm solution was diluted to approximately 2 L with HBSS and stored at 4 C until use. Sperm solution was added to eggs (approximately 25 mL of sperm solution/400 g of eggs), fresh water was added to initiate sperm motility, and fertilized eggs were transferred to hatching baskets. A sub-sample of each of the spawns was examined to determine percent fertility. Results showed that fertility was reduced by 65% (P = 0.001) in fish that were placed in bags while percent hatch was similar (P > 0.10) between treatments (Table 1). The total number of fry produced in the control fish tended (P = 0.053) to be higher (Table 1). No mortalities were observed due to confinement. Placing the fish in nylon bags made it convenient to handle the fish but may have negative effects on producing hybrid catfish. Table 1. Percent fertile and hatch of catfish placed in nylon bags (BAG) versus catfish left free in the raceway (CON). Treatment %Fertile %Hatch Total Fry BAG 40.0* 21.1 2217.1** CON 66.0 33.4 3968.0 *P = 0.001; **P < 0.10