The catfish sector is a large contributor to the US aquaculture industry, as it processed 335 million pounds foodsize fish on 63,000 water acres of ponds in 2018 (NASS Catfish Production, April 2019). The majority of production ponds are located in rural counties of the southeastern US states of Mississippi, Alabama, Texas, and Arkansas. Fish health and disease mortality reduction are essential to this industry's profitability, success and sustainability.
Effective fish health and disease treatment begins with good farm management. Feed restriction is a common practice used to reduce disease transmission between actively feeding catfish. Use of medicated feed is popular, but it is expensive and requires a veterinary feed directive (VFD). Bath treatments, such as copper sulfate against columnaris, are often costly and require additional labor as well. Vaccines are an emerging treatment option, which could reduce medicated feed use. In addition, vaccines can be delivered through a variety of methods, including bath immersion, injection, or coated feed.
Three major diseases affecting US catfish production are enteric septicemia of catfish (Edwardsiella ictaluri; ESC), virulent Aeromonas hydrophila (vAh), and columnaris (Flavobacterium columnare, COL). In this project, a live-attenuated COL vaccine is being compared against a non-vaccinated control channel catfish (Ictalurus punctatus) treatment. If this vaccine trial is successful, it is hoped that its future use could lower the 2018 annual loss of 1.5 million pounds of catfish to COL in Alabama. Another goal of this project is to identify factors affecting COL vaccine adoption by producers in the US catfish industry.
COL vaccine efficacy will be evaluated through an on-going pond trail. Channel catfish fingerlings were stocked into ten 0.1-acre ponds, with five ponds stocked with COL vaccinated catfish via a one-hour bath immersion at stocking and the other five ponds of catfish being a control with no vaccine. Seven monthly samplings of catfish from each pond will provide data for growth rate, feed conversion ratio (FCR), and survival analyses. Blood samples taken at 30 days and 90 days post-stocking will be analyzed for IgG antibody concentration using an ELISA test. Factors affecting COL vaccine adoption will be identified by reviewing the history of the previously available COL vaccine (AQUAVAC-COL).