Location: Warmwater Aquaculture Research Unit2011 Annual Report
1a. Objectives (from AD-416)
The objective of this cooperative research project is to test and further develop a novel incubator for use in commercial channel catfish hatcheries.
1b. Approach (from AD-416)
Catfish incubators have been largely unimproved since first developed in 1929. Egg masses are held in baskets made with ¼” mesh hardware cloth. Paddles held on a rotating shaft turn through the water between baskets, moving water through the baskets, aerating the eggs. As the eggs hatch, the sac fry pass through the mesh of the basket and sink to the bottom of the trough, where they are siphoned up. Farmers often experience problems (fungus and/or bacteria on eggs, resulting in poor hatch rates) during the peak of the spawning season when hatchery space is limited and egg masses are often crowded in the baskets at higher than desired densities. Recent research conducted by ARS has demonstrated that the oxygen requirements of catfish egg masses are higher than previously thought. This research has led to a preliminary design for a new hatchery system.
3. Progress Report
During the 2009 spawning season, sixteen standard hatchery troughs were equipped with the See-Saw incubation system. Most of this first season was used to design the system, purchase motors and material for fabrication of the supports, racks, and hatching baskets, and preliminary stress-testing of the system without live eggs. Near the end of the 2009 spawning season the first comparative trial was conducted. Survival to swim-up stage averaged 53.6 ± 7.1% in the See-Saw, versus 23.3 ± 6.5% for the control troughs, a 2.3-fold difference. Over-winter, an additional sixteen hatchery troughs were equipped with the See-Saw incubator, bringing the total to 32 troughs. In year 2 of the project (2010 spawning season) we measured the effect of egg loading density in See-Saw incubators on survival to hatch and swim-up. Further comparisons with the paddle-type incubators were not conducted. We loaded See-Saws (n=5 troughs for each treatment) with 15.0 ± 0.1 lb (220,300 eggs), 30.1 ± 0.1 lb (447,000 eggs), 45.1 ± 0.1 lb (669,600 eggs), and 60.1 ± 0.0 lb (893,100 eggs) of spawns. Water flow into the troughs averaged 2.1 gal/min, roughly half of the rate recommended for commercial hatcheries. The 15, 30, and 45 lb troughs produced an average of 132,700, 263,800, and 429,400 swim-up fry (survival from egg of 60 ± 9%, 59 ± 6%, and 64 ± 4%, respectively, similar to values reported in commercial hatcheries). However, the 60 lb treatment produced only 417,200 swim-up fry (survival of 46 ± 8%). The results of this year’s study indicate that both hatchery space and water use would be maximized with See-Saw incubators loaded at the 45 lb rate. Year three of the project will aim at further improvements in operational efficiencies. The results thus far indicate that the See-Saw incubator can be loaded with 45 lb of eggs per trough without impacting hatch rate or survival to swim-up. The use of this incubator across the commercial industry would result in considerable savings in water, and this would be particularly valuable for those hatcheries that need to heat their well water. This incubator may also have application in the numerous state and federal hatcheries which are tasked with hatching a growing number of fish species. The See-Saw can reduce both the space and water flow needed to meet their channel catfish production quota, making those resources available for other priority species. This project will continue through the 2011 spawning season. ADODR used site visit, email and telephone conferences to monitor activities of the project.