Effect of Increased Egg Stocking Density in Existing and Experimental Catfish Incubators

Channel catfish egg masses are typically incubated in stationary wire mesh baskets suspended in metal troughs with flow-through water that is agitated and circulated between the baskets and around the eggs with rotating paddles. A limiting factor in the successful incubation of channel catfish egg masses is the absorption of oxygen by the developing embryos; low levels of dissolved oxygen in the water result in premature hatching and increased fry mortality. We modified and tested a vertical-lift incubator (the “See-Saw”) for incubating channel catfish egg masses. Both the See-Saw and control (paddle-type) troughs were loaded with 26 egg masses (13.2 kg) per trough which is 1.5-2.0 times higher than recommended loading rates. Swim-up fry survival was 2.3-fold higher for the See-Saw than the control troughs. Many of the sac-fry produced in the control troughs were either dead when removed or died prior to reaching swim-up stage, presumably due to oxygen stress. The See-Saw incubator increases fry survival while simultaneously using less water and hatchery space per unit fry produced.

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