Microsoft word - ovaplant article.doc

EVALUATING SPAWNING INDUCTION IN CHANNEL CATFISH Ictalurus
punctatus USING sGnRHa AND DOMPERIDONE COMPOUNDS
Jeffrey Silverstein*, Jim Powell, and Anita Kelly Spawning success of channel catfish in ponds generally ranges from 30-50 %. This low spawning rate requires the maintenance of a large surplus of broodfish. To improve spawning success and predictability of spawning we have undertaken studies of induced spawning in the pond environment. Previous work showed that a combination of gonadotropin releasing hormone and dopamine antagonist rapidly induces final maturation and ovulation of channel catfish in spawning cages. To extend this work to pond spawning we treated channel catfish with slow release implants containing gonadotropin releasing hormone with or without a dopamine antagonist 3 weeks prior to the beginning of natural spawning. On April 20 implants containing sGNRHa, sGnRHa and domperidone or placebo implants were intramuscularly (i.m.) administered to channel catfish females. All males were treated with sGnRHa implants. These fish were stocked into 0.04 hectare ponds, 22 females and 12 males to a pond, all treatments were maintained in triplicate. There were no differences between the treatment groups for spawning rate, partly due to wide variation between replicate treatments. Nevertheless, the rise in cumulative percent spawning continued longer in the control group which had the highest mean spawning rate of the three treatments. The increase in percent spawning for both sGnRHa and sGnRHa+domperidone treated females slowed earlier than in the control treated females (see arrows). Treatment with slow release implants of sGnRHa and sGnRHa + domperidone appears to have sped the occurrence of spawning but not increased the percent success. Future work will focus on the rates of delivery of induction compounds. Literature References which you can use to guide you in the use of Ovaplant: 1. Alemandras, J.M., Duenas, C., Nacario, J., Sherwood, N.M. and Crim, L.W. 1988. Sustained hormone release – III: Use of gonadotropin-releasing hormone analogues to induce multiple spawnings in the sea bas, Lates calcarifer. Aquaculture. 74: 97-111. 1. Crim, L.W. 1985. Methods for acute and chronic hormone administration in fish. In: Reproduction and culture of milkfish. Proc. Workshop of the Tunkang Marine Laboratory, Taiwan. April 22-24, 1985. C.S. Lee and I.C.Liao eds. Tunkang Marine Laboratory and Oceanic Institute. Hawaii. Pp. 1-13. 1. Goudie, C.A., Simco, B.A., Davis, K.B. and Parker, N.D. 1992. Reproductive performance of pigmented and albino female channel catfish induced to spawn with HCG or Ovaprim. J. World. Aquacult. Soc. 23: 138-145. 1. Lee, C.-S., Tamaru, C.S., Banno, J.E., Kelley, C.D.,Bocek, A. and Wyban, J.A. 1986. Induced maturation and spawning of milkfish, Chanos chanos Forsskal, by hormone implantation. Aquaculture. 52: 199-205. 1. Marte, L.M., Sherwood, N., Crim, L. and Tan, J. 1988. Induced spawning of the maturing milkfish (Chanos chanos) using human chorionic gonadotropin and mammalian and salmon gonadotropin releasing hormone analogues. Aquaculture, 73: 333-340.Mason-Garcia, M., Vigh, S., Comura-Schally, A.M., Redding, T.W., Somomgyvari-Vigh, K., Horvath, J and Schally, A.V. 1985. Raidoimmunoassay for 6-D-tryptophan analog of luteinizing hormone-releasing hormone: Measurement of serum levels after administration of long-lasting microcapsule formulations. Proc. Natl. Acad. Sci. USA.88: 1547-1551. 1. Mylonas, C.C., Gissis, A., Magnus, Y. and Zohar, Y. 1997. Hormonal changes in male white bas (Marone chrysops) and eveluationof milt quality after treatment with sustained-relePowell, J.F.F., 1995. Gonadotropins I and II in Chinook salmon induced to spawn in seawater and freshwater with a salmon gonadotropin-releasing hormone (GnRH) analog In: 1994. Powell, J.F.F. 1994. The origin and evolution of gonadotropin-releasing hormone in boney fishes. Ph.D. Dissertation, University of Victoria, Victoria, British Columbia, Canada 1. Zohar, Y. New approaches for the manipulation of ovulation and spawning in farmed fish. 1996. Bull. Natl. Res. Inst. Aquacult. 0(Suppl. 2): 43-48.

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