Does High Stocking Density Reduce Cannibalism in Alligator Gar Propagation?

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Title: Does Culture Density Reduce Cannibalism in Alligator Gar Propagation?

 

Format: Oral

 

Authors:

Perschbacher, Peter. Aquaculture/Fisheries Center, University of Arkansas at Pine Bluff, currently 210 River Gate Lane, Wilmington, NC 28412; 870 534-0650; pwpersch@gmail.com

 

Presenter: Peter Perschbacher

 

Abstract:  Alligator gar fry to fingerling hatchery survival is limited by severe cannibalism. Westers suggested to increase hatchery survival of highly cannibalistic escoids, pond culture should provide high numbers of forage fish, and intensive tank culture should provide frequent feeding. Adapting these methods to alligator gar fingerling production proved successful in a 1999 trial at UAPB. By ensuring constant availability of forage at a ratio of 3-4 cyprinid forage for each cultured fish, and of a size one fourth of the cultured fish, survival in replicated outdoor pools was as high as 100% and averaged 65-72 % from 3 cm to a target of 250 cm. In addition, all treatments received a floating steelhead pellet at approximately 10% bw/d. Of two densities per treatment, 3 and 5/m³, the higher density had higher survivals. Trials in ponds with forage or feeding and at densities of 0.3-0.5/m³ had significantly lower survivals than the previous trial. A third trial was conducted in indoor aquaria at 66/m³, comparing forage or multiple, ad libitum feeding. Survivals were slightly lower than in the pool trial, but not significantly so. High survivals are proposed to result from the ready and easily accessible food and forage at high densities of gar, and perhaps a breakdown in territoriality. Multiple, automated feedings with floating pellets, constant availability of forage, and stocking densities in the range of 5-66/m³ may prove optimal for reducing labor and facilities while maintaining 60-70% survival, and without the need for grading.

 

Student presenter: No