Effects of Dissolved Oxygen Concentration on Oxygen Consumption and Development of Channel Catfish Eggs and Fry: Implications for Hatchery Management

Abstract

Eight channel catfish Ictalurus punctatus spawns were split into two similar portions and incubated under controlled conditions to determine the effect of dissolved oxygen (DO) concentration on the development and survival of eggs and fry. The DO concentration was 7.42 ± 0.03 mg/L (mean ± SD; 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 fry reached swim-up stage 31 h later. Survival to the swim-up stage in the low-oxygen treatment was 16.4 percentage points lower than in the high-oxygen treatment (72.5% versus 88.9%, respectively). The routine metabolic rate and limiting oxygen concentration were also determined for eggs, sac fry, and swim-up fry. Oxygen consumption increased through swim-up stage, as expected. However, the limiting oxygen concentration peaked during the last day of incubation at 88.1 ± 2.9% saturation and decreased to 40.1 ± 2.0% saturation upon hatching. Premature hatching observed in the low-oxygen treatment was apparently initiated when the limiting oxygen concentration approached the ambient oxygen saturation on the last day of incubation. A survey of DO management in 26 commercial catfish hatcheries in the Mississippi Delta revealed that 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 the time of hatching.