Skin injuries and serum enzyme activities of channel catfish ( Ictalurus punctatus) harvested by fish pumps

External injuries and the serum activities of two enzymes were determined for market-sized channel catfish moved from ponds to hauling trucks by either a conventional lift net attached to a boom, a turbine pump or a vacuum pump. One series of three harvests was conducted in cool weather (January–April), and the other in warm weather (June–September). Compared to other loading methods, the turbine pump caused significantly more reddened cutaneous abrasions, split fins, and broken fin spines in cool-weather experiments and caused more reddened abrasions, lacerations, and broken fin spines in warm-weather experiments. Histologically, reddened abrasions of the skin were inflamed or hemorrhagic. These abrasions involved removal of some or all of the epidermis, whereas portions of the dermis were removed as a result of more severe abrasions. Activities of both serum aspanate aminotransferase (AST) and lactate dehydrogenase (LDH) increased significantly ( P < 0.05) after the fish were loaded by any of the methods. Both serum AST and LDH activities of fish loaded by the turbine pump were significantly higher than for fish loaded by the vacuum pump or lift net.