A Comparison of New In-Pond Grading Technology to Live Car Grading for Food-Sized Channel Catfish, Ictalurus punctatus  

Jeremy Trimpey and Carole Engle  
Aquaculture/Fisheries Center, University of Arkansas at Pine Bluff
Mail Stop 4912, 1200 North University Drive, Pine Bluff AR, 71601

A series of grading trials were performed in experimental and commercial catfi°C, 13-26°C, < 13°C) with catfish size groups stocked in ratios of either 75:25, 50:50, or 25:75 sub-harvestable (<0.57 kg) to harvestable fish (>0.57 kg).  Commercial pond trials were replicated three times at each temperature range with a fish size range typical of ponds ready to harvest.  Stress experienced by fish during harvest and grading was measured by mean serum glucose and cortisol levels.  Grading speed was significantly greater (P<0.05) with the UAPB/Heikes grader (105-449 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.  In contrast, the traditional live car did not significantly reduce the proportion of sub-harvestable fish with the experimental methods used in this study during commercial trials or in the 25:75 distributions during hot and cold trials in experimental ponds.  The UAPB/Heikes grader returned an average 2-4 times (range of 2-52) more sub-harvestable fish by weight to the pond than the traditional live car method.  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.