Reducing size variation in hybrid catfish culture through graded partial harvest

Authors: MISCHKE, CHARLES - Mississippi State University; Torrans, Eugene; Brown, Travis; Tucker, Craig; WISE, DAVID - Mississippi State University

Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/5/2016
Publication Date: 1/1/2017
Citation: Mischke, C.C., Torrans, E.L., Brown, T.W., Tucker, C.S., Wise, D. 2017. Reducing size variation in hybrid catfish culture through graded partial harvest. North American Journal of Aquaculture. 79:84-89.

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. Overall, partial harvest of faster-growing fish in mid-summer reduced the overall biomass of discounted, out-of-size fish. Higher production in control ponds resulted in greater net revenue.

Technical Abstract: Hybrid Catfish (' Channel Catfish Ictalurus punctatus x ' Blue Catfish I. furcatus) 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 year-class 1 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 removed ~25% of fish from ponds in August. Removal of faster-growing fish resulted in 0.9% of the total crop considered “out-of-size” (> 4 lb/fish) and subject to discounts, compared with 2.1% of the fish from the control ponds. However, reduction of fish numbers by mid-summer partial harvest reduced overall production by an average of 16% in the partial-harvest treatment compared with control ponds. Overall, partial harvest of faster-growing fish in mid-summer reduced the overall biomass of discounted, out-of-size fish. Higher production in control ponds resulted in greater net revenue.