Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/25/2009
Publication Date: 9/3/2009
Publication URL: http://handle.nal.usda.gov/10113/55616
Citation: Torrans, E.L., Ott, B.D., Jones, R., Jones, Jr., R., Baxter, J., Mccollum, B., Wargo, III, A., Donley, J. 2009. A Vertical-Lift Incubator (The "Seesaw") Designed for Channel Catfish Egg Masses. North American Journal of Aquaculture. 71(4):354-359. Interpretive Summary: A new incubator for channel catfish eggs masses has been designed and tested on two commercial catfish hatcheries. Rather than hold spawns in mesh baskets and agitate water between the baskets, as is currently done in commercial hatcheries, the new incubator moves baskets holding the spawns up and down through the water. This provides better water circulation throughout the spawns, eliminating dead spots resulting from poor water flow (and reduced dissolved oxygen) often seen during the peak of the spawning season when hatchery troughs are often overloaded with eggs. The new incubator can hatch more eggs with less trough space and a reduced water flow when compared to traditional incubators.
Technical Abstract: Catfish spawns have been incubated the same way for nearly a century. Spawns are placed in baskets and agitated with rotating paddles. While this system is widely used, it has been recently determined that dissolved oxygen in the center of a spawn may be as much as 5 ppm less than air-saturated water, and that this oxygen stress can cause reduced survival. A new incubator was designed to improve water circulation through the spawns. Racks were suspended inside standard hatchery troughs and three baskets were placed in each rack and filled with spawns. The racks in a pair of troughs were connected to overhead bars which oscillated at six cycles per minute, resembling a playground “see-saw”. Eighteen lbs of spawns per trough (n=5) were incubated in the traditional system; the new system (n=5) incubated 18-47 lbs per trough. Survival through swim-up stage was similar in both incubators, averaging 85.9%. The traditional system produced an average of 82,000 fry per gal/min water flow; the new system produced 153,000 fry per gal/min water flow at the highest egg loading rate tested. The “see-saw” incubator could allow hatcheries to hatch more eggs using fewer troughs and less water than with traditional “paddle-agitation”.