Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Three potential pheromones were evaluated to determine their effect on blue and channel catfish and their reproductive success. In two trials female channel catfish were injected intraperitoneally with an ethanol solution containing either 0.0 mg/kg or 0.5 mg/kg of one of the following: 17,20-P; 17,20-P-Glucosiduronate; or PGF-2a. Females were held separately in large traps in a common pond. Channel males were attracted to PGF-2a injected females on 22.9% of their given opportunities, and were attracted to control females only 1.4% of the time. Blue males responded to 17,20-P-Glucosiduronate and PGF-2a injected females 8.3% of their given opportunities for each treatment, but were not attracted to the control females. There was significant variation in response among individual fish. One PGF-2a injected female attracted 66.7% of the channel males trapped in that trial. Only 15% of blue males used were attracted to channel females, but those blue males were attracted on multiple occasions. When male blues were injected with the above chemicals and held in traps, no female channel catfish were attracted to the males. Channel catfish females were injected with LH-RH and PGF-2a, or only LH-RH and the spawning successes compared. When females given only LH-RH were paired with channel males, the spawning frequency was 31.2% and when paired with blue males it was 12.5%. When females given both LH-RH and PGF-2a were paired with blue males, the spawning frequency was 25.0%, however, half the spawns were not fertilized. PARTICIPANTS: As PIs, were R. Phelps, J. Chappell, and R.Dunham. J. Broach, a MS degree student, was the lead student on this project with support from S. England, an undergraduate. TARGET AUDIENCES: The directly targeted audience was the US catfish industry who would benefit greatly from the improved availability of hybrid catfish fingerlings. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
These results suggest that PGF-2a injections into channel females may enhance a blue and channel male's attraction to channel females. The frequency of ovulation by channel females in the presence of a blue male can be improved using PGF-2a but male fertilization success rates need to be improved on.
Publications
- No publications reported this period
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Progress 10/01/06 to 09/30/08
Outputs
OUTPUTS: Traditional catfish spawning methods have had limited success in producing a hybrid between channel and blue catfish. Lack of the male blue's interest and attraction to the female channel is though be an issue. Studies were conducted to determine if a blue male's attraction to channel females could be increased via pheromonal steroid injections of either 17alpha, 20beta-dihydroxy-4-pregenene-3-one (17,20beta-P) or its glucorinated form (17,20beta-P-Glucosiduronate), or prostaglandin F-2alpha (PGF-2alpha). Blue and channel males were stocked into separate 644 square meter ponds at 20 males per pond. In each trial, four sets of six channel females were injected intraperitoneally with an ethanol solution containing either 0.0 mg/kg or 0.5 mg/kg of one of the following: 17,20beta-P; 17,20beta-P-Glucosiduronate; or PGF-2alpha. Females were held separately in large traps constructed from 121 L plastic barrels spaced 6.4 m apart in the ponds for a total of 12 females per pond. Traps were checked at 6, 12, 24, 48, 72, and 96 hours post-injection, and the number of males caught per female recorded. Logistic regression analysis was used to generate maximum likelihood estimates of a male being captured based upon male species, female strain, hormone injected, and post-injection time. Channel males were attracted to PGF-2alpha injected females on 22.9% of their given opportunities, and were attracted to control females only 1.4% of the time. Blue males responded to 17,20beta-P-Glucosiduronate and PGF-2alpha injected females 8.3% of their given opportunities for each treatment, but were not attracted to the control females. Males were 9.8 times more likely to be captured at 48 hours post-injection than at either 12 or 24 hours post-injection. There was significant variation in response among individual fish. One PGF-2alpha injected female attracted 66.7% of the channel males trapped in that trial. Only 15% of blue males used were attracted to channel females, but those blue males were attracted on multiple occasions. These results suggest that PGF-2alpha injections into channel females may enhance a blue male's attraction to channel females. The effects of prostaglandin F-2alpha (PGF-2alpha) given along with LH-RHa used for induced spawning of channel catfish, Ictalurus punctatus, were investigated to determine if pen spawning hybridization success between female channel catfish and male blue catfish, Ictalurus furcatus, could be increased. PGF-2alpha was injected into channel females at 0.5 mg/kg during priming dose injections of LH-RHa. Females receiving the additional PGF-2 were paired with blue males in concrete tanks, and spawning success was compared between this spawning group as well as channel females (not receiving additional PGF-2alpha) paired with channel males and blue males. PGF-2alpha appeared to have no effect on spawning success; however, ovulation as well as hatch rates appeared to be influenced by the additional injections. PARTICIPANTS: Ronald P. Phelps. P.I. Department of Fisheries and Allied Aquacultures, Auburn University, Auburn AL. Jason S. Broach. Graduate Student. Department of Fisheries and Allied Aquacultures, Auburn University, Auburn AL. The project supported his degree program and the subject of his research. Shelly E. England. Undergraduate student. Department of Fisheries and Allied Aquacultures, Auburn University, Auburn AL. The project provided the basis for a Special Problems topic as part of her academic program and assisted in covering related costs. TARGET AUDIENCES: The primary focus of the research effort was the commercial catfish industry, specifically those involved in hatchery operations. The thrust of the work was to develop spawning techniques to produce hybrid catfish that are more compatible with conventional hatchery procedures. The secondary audiences included researchers focusing on animal behavior, animal reproduction and the impact of chemicals such as pheromones on animal behavoir and reproduction. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The results of the research demonstrate that catfish respond to particular pheromones but much additional work is needed to refine procedures to optimize spawning success. The methodology developed for evaluation of phermones under field conditions has application to the evaluation of other chemicals as to their impact on fish reproductive behavior. With further refinement, the successful use of pheromones to stimulate the natural hybridization between channel and blue catfish will eliminate the current need to sacrifice male blue catfish to obtain sperm for egg fertilization. Improved success in natural spawning as the result of pheromone use will increase the availability of hybrid fingerlings and in-turn increase the profitability of the catfish industry. Results of this work have been presented at professional meetings and has provided the basis for a Master of Science thesis, a manuscript being submitted to a professional journal and additional grant proposals.
Publications
- Broach, J.S., S. E. England, and R. P. Phelps. 2009. Effects of pheromonal steroids or prostaglandin given to female channel catfish Ictalurus punctatus on attracting male blue catfish Ictalurus furcatus or male channel catfish. Published abstract, Aquaculture America 2009. Seattle WA , Feb. 15-18, 2009.
- Broach, J.S. 2009. Effects of steroid and prostaglandin injections on hybridization success between female channel catfish and male blue catfish. Master of Science Thesis, Auburn University.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: Four spawning protocols of: channel female & blue male with no hormone administration; channel female & blue male with hormone administration; channel female & channel male with no hormone administration; and Blue female & blue male with no hormone administration were be compared. Spawning success rates were low across all treatments with even the channel X channel cross giving less than 20% spawning success. The effect of flowing water vs. a static setting on spawning success was studied in 20 m 2. tanks. A channel female was paired with a blue male in each tank. Males were given an LH-RHa implant and stocked into the tank three days prior to the female. Females were given 120 ug LH-RHa in a two injection sequence then stocked. Ten tanks were static and ten tanks had a continuous water exchange. Spawning success rates were low across all treatments and no conclusions could be drawn.
PARTICIPANTS: As PIs, were R. Phelps, J. Chappell, G. Whitis, and R.Dunham. . Shelly England was the lead student on this project.
TARGET AUDIENCES: The directly targeted audience was the US catfish industry who would benefit greatly from the improved availability of hybrid catfish fingerlings.
PROJECT MODIFICATIONS: None
Impacts
Continued effort is needed to improve the natural hybridization rates between channel and blue catfish. When hybrids are made by artificial fertilization, hatching rates of 10 to 30% are common A major handicap to this approach is that the male must be sacrificed before sperm can be obtained. Hatch rates of naturally spawned hybrid eggs is similar to that of channel catfish but the frequency of such natural spawns is low. Much additional work is required to understand the natural spawning process and to improve spawning rates.
Publications
- No publications reported this period
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