2010 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.
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. Pairs of troughs (one control and one test) were sequentially loaded with eggs. See-Saw and control troughs (n=4 of each) were loaded with 25.6 ± 0.5 egg masses per trough (474,947 ± 3002 and 472,878 ± 3892 eggs per trough, respectively). This is 1.5 – 2.0 X higher than recommended loading rates. Water quality (water flow, dissolved oxygen (DO), pH, total ammonia nitrogen, and nitrite nitrogen) were measured in the water supply and in each trough daily. Survival to swim-up stage was significantly higher in the See-Saw than the traditional control troughs. 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. While survival in the See-Saw was lower than expected, that was attributed to the generally poor egg quality from eggs collected at the end of the season (June 17-20, 2009). Over-winter, an additional sixteen hatchery roughs were equipped with the See-Saw incubator, bringing the total to 32 troughs. During the 2010 spawning season a test of egg loading rates was conducted in the new incubators. Egg loading rates of 15, 30, 45, and 60 pounds of egg masses per trough were tested with six replicate troughs per treatment. Data are being analyzed. This project will continue through the 2011 spawning season. Additional details can be found in the report for the parent project 6402-13320-004-00D. The ADODR monitors this project through site visits, telecoms and e-mails to the collaborator, and through ann. reports from the collaborator.