Submitted to: Book of Abstracts Aquaculture America
Publication Type: Abstract Only
Publication Acceptance Date: 10/9/2008
Publication Date: 2/1/2009
Citation: Weirich, C.R., Wills, P.S., Baptiste, R.M., Riche, M.A. 2009. Effect of culture density on production characteristics and body composition of market size cobia reared from juveniles in recirculating aquaculture systems [abstract]. Book of Abstracts Aquaculture America. p.371.
Technical Abstract: Interest regarding cobia Rachycentron canadum aquaculture in the US has increased greatly in the last decade due to their excellent consumer appeal, extremely rapid growth rates, and the observed success of rearing this species in Taiwan and other southeastern Asian countries. Because the principal culture system currently employed for farming this species is offshore net pens or cages, only limited information exists with respect to rearing juvenile cobia to marketable sizes using recirculating aquaculture systems (RAS). A 119-day trial to compare three rearing densities on production characteristics and body composition of sub-adult cobia was completed using four replicate 45-m3 RAS, each containing three experimental 8-m3 culture tanks (one tank/density/system) located within the USDA-ARS Sustainable Tank Aquaculture Recirculating Research (STARR) facility on the campus of Harbor Branch Oceanographic Institute at Florida Atlantic University. To initiate the trial juvenile cobia (initial weight = 322 g) were stocked into three tanks of each RAS, each at a different density: low (1.4 kg/m3, 35 fish); medium (2.8 kg/m3, 70 fish); or high (4.2 kg/m3, 106 fish). After stocking, fish were fed a commercial slow sinking pelleted diet (45% CP, 15% CL) twice daily at a targeted daily ration of 3 to 5 % bw/d. Initial pellet size was 5 mm and was increased as fish grew. At three week intervals 10% of the population in each tank was sampled to estimate mean weight, weight gain, specific growth rate (SGR), feed conversion efficiency (FCE), biomass, and survival. At termination of the trial, tanks were clean harvested to determine production characteristics and sufficient fish were processed to determine hepatosomatic index, % visceral fat, fillet yield, and proximate composition indices. Although tissue samples have not yet been analyzed, results indicate that rearing density had no effect on production throughout and at the conclusion of the trial. Fish reared at all three densities exhibited excellent growth, feed conversion, and survival. Final biomass of low, medium, and high density treatments was 9.0, 18.1, and 27.8 kg/m3, respectively. Across treatment fillet yield was 42.1% and average total fillet weight of each harvested fish was 884 g. Because no density effect was observed, higher densities are currently being evaluated. In addition, target harvest weight will be increased to 3 kg.