Submitted to: Aquacultural Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/19/2004
Publication Date: 10/1/2004
Citation: Trimpey, J., Engle, C., Heikes, D., Davis Jr, K.B., Goodwin, A. 2004. A comparison of new in-pond grading technology to live car grading for food-sized channel catfish (Ictalurus punctatus). Aquacultural Engineering. 31:276. Interpretive Summary: The efficiency and performance of a new in-pond horizontal floating bar grader (Heikes/UAPB grader) for channel catfish was compared with current live car grading techniques. Comparisons were made on experimental ponds stocked with known compositions of harvestable and non-harvestable size fish and on commercial ponds during three different temperature ranges (>260C. 12.8-260C and < 130C). The efficiency at grading harvestable fish from non-harvestable fish was compared between the two techniques and stress to the fish was determined by plasma glucose and cortisol concentrations. Plasma glucose and cortisol levels in fish graded with the two grading techniques were not significantly different. The Heikes/UAPB grader was faster and graded out non-harvestable fish better than live car grading. The UAPB/Heikes grader sorted fish faster, more accurately and consistently than the live car technique at all temperatures in both the experimental and commercial ponds. Additional research is needed to evaluate the economic feasibility of this new technique.
Technical Abstract: A series of grading trials were performed at the University of Arkansas at Pine Bluff and on commercial catfish ponds to determine if a new in-pond horizontal floating bar grader is more efficient and outperforms current live car grading techniques. Three replicate trials were conducted at UAPB with three fish size distributions (75:25, 50:50, 25:75 sub-harvestable to harvestable fish) during three different temperature ranges (> 26°C, 12.8-26°C, < 12.8°C). Commercial trials were replicated three times during each temperature range with the size distribution of fish in the pond at harvest time. Stress was measured by mean glucose and cortisol levels. Grading speed was significantly greater (P<0.05) with the UAPB/Heikes grader (105-219 kg/min) than the traditional live car (0.5-0.6 kg/min). The UAPB/Heikes grader significantly decreased the proportion of sub-harvestable fish during all trials. However, the traditional live car did not significantly grade fish during commercial trials nor in the 25:75 distributions during hot and cold trials. The UAPB/Heikes grader returned from 2-52 times more sub-harvestable fish by weight to the pond than the traditional live car grader. Glucose and cortisol levels in fish graded with the two grading technologies were not significantly different. The UAPB/Heikes grader sorted fish more accurately and consistently than the live car at all temperatures in both experimental and commercial trials. Additional research is needed to evaluate the economic feasibility of this new grading technology.