|Green, Bartholomew - Bart|
Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2007
Publication Date: 9/17/2007
Citation: Minchew, D.C., Beecham, R.V., Pearson, P.R., Green, B.W., Kim, J.M., Bailey, S.B. 2007. The effects of harvesting and hauling on the blood physiology and fillet quality of market-size channel catfish. North American Journal of Aquaculture. 69:373-380. Interpretive Summary: Results of this study indicate that routine harvest procedures can significantly increase levels of chemicals and hormones known to indicate stress in adult channel catfish. These elevated blood chemical levels may affect fillet quality and shelf life. Aeration using diffusion of pure oxygen gas instead of aeration by a tractor-powered paddlewheel did not affect stress levels of channel catfish placed in holding nets overnight, nor was fillet quality improved.
Technical Abstract: Commercially produced adult channel catfish harvested using routine procedures had significant elevations in plasma cortisol, glucose, and lactate compared to pre-harvest fish captured from open ponds. Blood samples were taken from ten fish in each of the two treatments (liquid oxygen and paddlewheel aerated holding socks) at three sampling periods (after-socking, pre-loading, and pre-unloading) during each of 10 field trials. Water column temperatures averaged about 80oF during the study. Ten fillet samples were taken from fish held overnight in paddlewheel and liquid oxygen aerated socks during some field trials. Mean plasma cortisol levels averaged 3.02 ng/mL before harvesting, 84.38 ng/mL immediately after-socking, 135.22 ng/mL after 18 h in the sock, and 128.54 ng/mL after 2-3 h on the truck. Mean plasma glucose levels averaged 34.7 mg/dL before harvesting, 95.41 mg/dL immediately after-socking, 134.53 mg/dL after 18 h in the sock, and 134.86 mg/dL after 2-3 h on the truck. Mean plasma lactate levels averaged 2.43 mmol/L before harvesting, 13.24 mmol/L immediately after-socking, 11.53 mmol/L after 18 h in the sock, and 7.88 mmol/L after 2-3 h on the truck. These results should not be considered maximal until additional studies are conducted with average water temperatures at their highest. Aerating the fish held overnight with liquid oxygen instead of a tractor-driven paddlewheel did not result in significant reductions in stress levels or significant improvements in the fillet quality. There were significant changes within treatment over 7 days of refrigerated storage for fillet pH, color, and drip-loss; however, there were no consistent trends between treatments. Results from this study indicate that routine capture and hauling procedures are stressful to commercially produced adult channel catfish under the conditions of this study and that using liquid oxygen for aerating fish in holding socks does not significantly improve fillet quality or reduce stress levels.