Submitted to: North American Journal of Aquaculture
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/7/2007
Publication Date: 4/14/2008
Citation: Torrans, E.L., Steeby, J. 2008. Effects of Dissolved Oxygen Concentration on Oxygen Consumption and Development of Channel Catfish Eggs and Fry: Implications for Hatchery Management. North American Journal of Aquaculture 70(3):286-295. Accepted Aug. 7, 2007; Published on-line Apr. 14, 2008. Interpretive Summary: Channel catfish eggs were incubated, hatched and reared through swim-up stage under high (18.4 mg/L) and low (7.4 mg/L) dissolved oxygen concentrations. Additionally, oxygen consumption and minimum oxygen requirements were determined for all stages. It was determined that eggs require water nearly saturated with oxygen (over 7.4 mg/L) in order to fully develop before hatching. While oxygen consumption increases rapidly through sac and swim up fry stages, the oxygen concentration required for those stages is less than for eggs. A survey of 26 commercial catfish hatcheries revealed that most (65%) maintained a dissolved oxygen concentration too low to optimize embryo development. Recommendations were made which could increase fry production of existing hatcheries by over 300 million fry per year.
Technical Abstract: Channel catfish spawns were incubated under controlled conditions to determine the effect of dissolved oxygen (DO) concentration on development and survival. Routine metabolic rate and limiting oxygen concentration were determined on eggs, sac fry and swim-up fry. Eight channel catfish spawns were split into two equal portions and aerated with either air supplied by a blower or with liquid oxygen (LOX). Dissolved oxygen concentration averaged 7.42 ± 0.03 (92.5% saturation) and 18.40 ± 0.28 mg/L (230% saturation) through hatching in the low and high oxygen treatments, respectively. Eggs hatched 6 h earlier in the low oxygen treatment but reached swim-up stage 31 h later. Survival to swim-up stage in the low oxygen treatment was 16.4% lower than in the high oxygen treatment (72.5% vs. 88.9%, respectively). Oxygen consumption increased through swim-up stage as expected. However, the limiting oxygen concentration peaked during the last day of incubation at 87% saturation and decreased to 40.1% saturation upon hatching. Premature hatching was observed in the low oxygen treatment during the last day of incubation, when the limiting oxygen concentration approached the ambient oxygen saturation. A survey of DO management in 26 commercial catfish hatcheries in the Mississippi delta was conducted. DO saturation in the hatching troughs ranged from 45.2% to 100.2%, with only nine hatcheries (35% of the hatcheries sampled) having a DO saturation greater than 95%. Seventeen hatcheries (65%) had a DO saturation less than that maintained in the low oxygen treatment in our hatching experiment and could experience greater mortality through swim-up than we observed. We recommend that hatcheries initially run well water through a packed column, and use blowers or liquid oxygen to maintain the DO concentration in hatching troughs at or above air saturation as eggs near hatching.