Effects of a graded partial-harvest on hybrid catfish size variation

Authors: MISCHKE, CHARLES - Mississippi State University; BROWN, TRAVIS - Brunswick Community College; Tucker, Craig; Torrans, Eugene

Submitted to: NWAC (National Warmwater Aquaculture Center) Aquaculture Newsletter
Publication Type: Experiment Station
Publication Acceptance Date: 4/15/2017
Publication Date: 12/1/2017
Citation: Mischke, C., Brown, T., Tucker, C.S., Torrans, E.L. 2017. Effects of a graded partial-harvest on hybrid catfish size variation. NWAC (National Warmwater Aquaculture Center) Aquaculture Newsletter. 14(1):2-3.

Interpretive Summary: Hybrid Catfish have quickly become a major contributor to ictalurid catfish aquaculture in the United States. Hybrid Catfish have unique production characteristics compared with Channel Catfish, and rapid farmer adoption of the hybrid has outpaced research on appropriate management practices. This study was conducted to determine the effect of mid-summer partial harvest of faster-growing fish on production characteristics in ponds with Hybrid Catfish in single-batch culture. Twelve, 1.0-acre ponds were stocked with 10,000 Hybrid Catfish (~ 0.12 lb/fish) in mid-March 2015. In August 2015, six random ponds were partially harvested to remove fish larger than ~ 1.25 lb using an in-pond, flexible-panel grading sock. In October 2015, all ponds were completely harvested. Partial harvest of faster-growing fish in mid-summer reduced the overall biomass of discounted, out-of-size (i.e., too large) fish but higher production in non-harvested control ponds resulted in greater net revenue. However, if larger fish are used to initiate culture or if harvest is delayed by market conditions or flavor problems, removal of larger fish using graded partial harvest would have a greater effect on net revenues.

Technical Abstract: Hybrid Catfish have quickly become a major contributor to ictalurid catfish aquaculture in the United States. Hybrid Catfish have unique production characteristics compared with Channel Catfish, and rapid farmer adoption of the hybrid has outpaced research on appropriate management practices. This study was conducted to determine the effect of mid-summer partial harvest of faster-growing fish on production characteristics in ponds with Hybrid Catfish in single-batch culture. Twelve, 1.0-acre ponds were stocked with 10,000 Hybrid Catfish (~ 0.12 lb/fish) in mid-March 2015. In August 2015, six random ponds were partially harvested to remove fish larger than ~ 1.25 lb using an in-pond, flexible-panel grading sock. In October 2015, all ponds were completely harvested. Partial harvest of faster-growing fish in mid-summer reduced the overall biomass of discounted, out-of-size (i.e., too large) fish but higher production in non-harvested control ponds resulted in greater net revenue. However, if larger fish are used to initiate culture or if harvest is delayed by market conditions or flavor problems, removal of larger fish using graded partial harvest would have a greater effect on net revenues.