Using Fisheries Techniques to Estimate the Age and Growth of Hybrid Catfish (Ictalurus punctatus ♀ X I. furcatus ♂) in West Alabama Commercial Ponds

Abstract

In west Alabama, catfish producers routinely face the challenge of fish that exceed market size (aka “Big Fish”) in their commercial ponds. These fish are skilled at evading seine nets during harvest and can increase in size significantly before subsequent harvests occur. This is problematic for catfish producers because processing plants prefer catfish within the 0.45 – 1.81 kg range, and farmers are paid a premium price for catfish of this size. Depending on the market and processing plant, a catfish producer can receive little-to-no monetary value for an oversized catfish. Due to their larger size and growth potential, hybrid catfish (Ictalurus punctatus ♀ × I. furcatus ♂) can become a more significant issue than Channel Catfish if they evade harvest. Unfortunately, little is known about the age structure and growth rate of hybrid catfish that repeatedly evade capture and remain in commercial ponds for extended periods or multiple production seasons. The objectives of this study were to quantify the age structure and growth of hybrid catfish that evade capture, remain in commercial ponds following harvest, and grow beyond acceptable market size as defined by catfish processing plants (i.e., Big Fish). From December 2021 to August 2022, twelve recently harvested hybrid catfish ponds were sampled prior to re-stocking fingerlings using an electrofishing boat. Lapilli otoliths were removed from 1,005 hybrid catfish to estimate the total length and weight at age from seven commercial catfish farms in west Alabama, with the successful aging of 1,001 fish. Results of this study indicate that hybrid catfish exceeded the premium size threshold at age 2.72 years and should be harvested after one production cycle. Additionally, from age 2 to age 3, hybrid catfish can gain 2.9 kg, growing from an average of 0.4 kg to 3.3 kg.