The Effects of Harvesting and Hauling on the Blood Physiology and Fillet Quality of Market-Size Channel Catfish

Abstract

Commercially produced, food-size channel catfish Ictalurus punctatus that were harvested using routine procedures had significant elevations in plasma cortisol, glucose, and lactate compared with preharvest fish captured from open ponds. Blood samples were taken from 10 fish in each of two treatments (liquid oxygen diffuser- and paddlewheel-aerated holding socks) and four sampling periods (before harvest, after socking, before loading, and before unloading) during each of 10 harvest events. Water column temperatures averaged approximately 27°C during the study. Ten fillet samples were taken from fish held overnight in paddlewheel- and liquid oxygen-aerated holding socks during some harvest events. Mean plasma cortisol levels averaged 3.02 ng/mL before harvest, 84.38 ng/mL immediately after socking, 135.22 ng/mL after 18 h in the sock (i.e., before loading onto the truck), and 128.54 ng/mL after 2–3 h on the truck (i.e., before unloading). Mean plasma glucose levels averaged 34.7 mg/dL before harvest, 95.41 mg/dL after socking, 134.53 mg/dL before loading, and 134.86 mg/dL before unloading. Mean plasma lactate levels averaged 2.43 mmol/L before harvest, 13.24 mmol/L after socking, 11.53 mmol/L before loading, and 7.88 mmol/L before unloading. These results should not be considered maximal until additional studies are conducted with average water temperatures at their highest. There were significant changes within treatment over 7 d of refrigerated storage for fillet pH, color, and drip loss; however, there were no consistent trends between treatments. Results indicate that routine capture and hauling procedures are stressful to commercially produced, food-size channel catfish under the examined conditions and that using liquid oxygen for aerating fish in holding socks does not significantly improve fillet quality or reduce stress levels.