Theses and Dissertations


Title: Influence of vertical substrate on the production of Australian redclaw crayfish, Cherax quadricarinatus (Von Martens), in earten bottom ponds

Name: Sayles, Christopher Richard

Degree: MS

Chair: David B. Rouse

Resides:

University: Auburn University

Location: Auburn, Alabama

Date: 2003

Pages: 49

Keywords: Australian red claw crayfish, Cherax quadricarinatus, earthen-bottom ponds

Abstract:

Australian redclaw crayfish, Cherax quadricarinatus, is a relatively new aquaculture species in the southeastern United States. Economic returns are a function of final animal size and total yield of ponds. Growth rates and survival are currently limited by animal density. Previous work with a similar cultured crustacean, freshwater prawn, Machrobrachium rosenbergii, suggested that adding artificial vertical substrate in prawn ponds increases yield and economic returns. Hence, the objective of this research was to determine the effects of artificial substrate, applied vertically, on average final size, survival, and total yield of crayfish reared in outdoor ponds. Redclaw crayfish were cultured in nine 0.02 ha earthen-bottom ponds. Control habitat was provided by 15-cm lengths of 2" PVC pipe. Artificial substrate was provided by construction barrier netting. Two densities of vertical substrate were tested, increasing surface area by 25% and 50%. Crayfish were stocked at 4/m2 and had an average size of 1.4 g at stocking, A commercial sinking shrimp feed was administered six nights per week at rates calculated to provide 3% estimated total biomass. Harvest was accomplished by the use of flow traps. Control, low-density substrate, and high-density substrate ponds showed no significant differences in survival, average size, or total yield. Survivals were 31%, 39%, and 40%, respectively. Average crayfish weights were 44.5g, 42.5g, and 47.6g, respectively, and total yields were 578 kg/ha, 673 kg/ha, and 764 kg/ha, respectively. Based on known biological traits and observations, the redclaw crayfish were presumed to have not taken advantage of the upper heights of the vertically oriented netting. This study indicates that the use of vertical substrate can be used as a replacement for standard PVC tube refuges, but should not be expected to provide an increase in growth, survival, or yield, as has been seen with its use in freshwater prawn culture.

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