ARS | Publication request: Comparison of Three Methods of Grading Stocker Catfish

Submitted to: Catfish Farmers of America Research Symposium
Publication Type: Abstract Only
Publication Acceptance Date: January 9, 2003
Publication Date: February 21, 2003
Citation: GREEN, B.W., HEIKES, D., GOODWIN, A. COMPARISON OF THREE METHODS OF GRADING STOCKER CATFISH. CATFISH FARMERS OF AMERICA RESEARCH SYMPOSIUM. 2003. p.35. Abstract No. 32.

Technical Abstract: Technical Abstract: Channel catfish fingerlings and stockers generally are sold by size or weight, and pond-stocking recommendations are based on fish size. Farmers commonly separate fingerlings and stockers by size using passive in-pond sock grading or box grading. An in-pond, mechanical grader, developed at University of Arkansas at Pine Bluff (UAPB), should expedite size grading of fish. This study compared the efficiency of three different size-grading technologies used to obtain 11-12-inch channel catfish stockers. Three 0.25-acre ponds located at the UAPB Aquaculture Research Station and stocked with a mixed population of stocker channel catfish were used for this study. The sock grader, equipped with a 1 3/8" mesh, was stocked with fish at 20.8 lb/ft3 and fish were left to grade passively for 24 hours. The sock grader was placed inside a larger live car (3/8"mesh) to capture fish exiting the sock grader. Box graders were equipped with a #70 (70/64") or a #88 (88/64") grader basket. The bar spacing on the UAPB grader were set at 70/64" or 88/64". The sock grader, box grader, and UAPB grader were equally effective in sorting stocker catfish by size. The average size of the target population was 11.7 ± 1.04", 11.2 ± 0.89", and 10.6 ± 0.81" for the sock, box, and UAPB graders, respectively. Grading fish with the box grader involved the most fish handling and manual labor, but allowed for grading fish within tight size limits. Minimal fish handling and moderate labor were required for the sock grader, but the fish population tended to be larger and have higher size variability. The UAPB grader required an intermediate amount of fish handling and labor, required less time than either of the other two methods, but allowed fish to be graded to tight size limits.