Title: Effect of chronic, nightly hypoxia on growth and yield of channel x blue hybrid catfish Authors
Submitted to: Catfish Farmers of America Research Symposium
Publication Type: Abstract Only
Publication Acceptance Date: November 16, 2011
Publication Date: February 17, 2012
Citation: Green, B.W., Rawles, S.D., Beck, B.H. 2012. Effect of chronic, nightly hypoxia on growth and yield of channel x blue hybrid catfish [abstract]. Catfish Farmers of America Research Symposium. p.19. Technical Abstract: Performance traits and metabolic responses of the channel x blue hybrid catfish (Ictalurus punctatus female, Jubilee strain x I. furcatus male, D&B strain) in response to chronic nightly hypoxia were evaluated in this 197-d study. Sixteen 0.25-acre earthen ponds were stocked with 6,141 hybrid catfish/acre (0.104 lb/fish) and managed to maintain the minimum dissolved oxygen concentration at approximately 12%, 24%, 36%, or 48% of saturation during the warmer months when aeration was necessary. Growth and yield of channel x blue hybrid catfish was significantly related to minimum nightly dissolved oxygen concentration. The cumulative effect of nocturnal dissolved oxygen concentration and the duration of exposure to hypoxia (termed dissolved oxygen-minutes) may be a more biologically meaningful independent variable for regression analysis than minimum nightly dissolved oxygen concentration. Gross and net yield and mean individual weight increased curvilinearly as dissolved oxygen-minutes increased (Fig. 1). Chronic nightly hypoxia affected daily feed consumption and channel x blue hybrid catfish in the higher dissolved oxygen treatments grew faster because they consumed a greater percentage of their body weight at each feeding (Fig. 2). Feed consumption increased linearly in response to dissolved oxygen-minutes during the peak production period (June-August), but curvilinearly over the entire study. Body compositional indices largely were unaffected by chronic nightly hypoxia. Lipid was the primary depot affected by hypoxia and lipid indices increased with increasing dissolved oxygen concentration. Citrate synthase activity was 14.6% higher in the highest compared to the lowest dissolved oxygen treatment and a strong inverse relationship between citrate synthase activity and fish body mass was observed in the highest dissolved oxygen concentration treatment. Results of this study suggest that pond dissolved oxygen concentration should be maintained at 48% saturation during the peak production period (water temperatures above 25 deg C) and at 36% saturation during the rest of the growing season.