Author
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Torrans, Eugene |
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Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/30/2005 Publication Date: 7/1/2005 Citation: Torrans, E.L. 2005. Effect of Oxygen Management on Culture Performance of Channel Catfish Ictalurus punctatus in Earthen Ponds. North American Journal of Aquaculture. 67:275-288. Interpretive Summary: Channel catfish were produced in ¼-acre ponds in which the dissolved oxygen (DO) concentration was controlled using an automated oxygen monitor which also initiated aeration. When the DO concentration was maintained at or above 2.3 mg/L, feed consumption was reduced by 6% (compared to a high oxygen control treatment in which the DO concentration was maintained at or above 4.3 mg/L), but growth and net fish production were not significantly affected. However, when the DO concentration was allowed to fall as low as 1.3 mg/L (the lowest monthly average), feed consumption was reduced by 45%, average fish weight by 31% and net fish production by 54% compared to a high oxygen control treatment. Feed conversion was not significantly affected at any DO concentration tested. The results of this two-year study indicate that maintaining the DO concentration above 2.3 mg/L will allow for near-optimum growth and production of channel catfish while minimizing aeration costs. Technical Abstract: Increased aeration allows for higher feeding rates and increased fish production. However, the effect of dissolved oxygen (DO) concentrations on various production parameters remains unknown. The purpose of this two-year study was to determine the effect of daily minimum DO concentrations on food consumption, food conversion, growth and production of channel catfish grown in ponds. Each of six 0.1-ha ponds were equipped with three 0.37-kW (½-hp) aerators and one 0.37-kW circulator. Dissolved oxygen concentrations and temperatures were continuously monitored and recorded with a commercial oxygen monitor which also controlled aeration. Aeration was initiated in the high-oxygen treatment both years when the DO concentration dropped below 5.0 mg/L (mean 64% saturation from May through September); aeration was initiated in the low-oxygen treatment when the DO concentration dropped below 2.5 mg/L (32% saturation; 2001) or 1.5 mg/L (19% saturation; 2002). Fish were fed a commercial floating feed daily to apparent satiation. Compared to the control, delaying aeration until the DO concentration dropped below 2.5 mg/L reduced feed consumption by 6%. Other production parameters were not significantly different. Compared to the control, delaying aeration until the DO concentration dropped below 1.5 mg/L reduced food consumption (45% less), average fish weight (31% less), and net production (54% less). Even at the high feeding rates of 2002 (maximum of 680 kg/ha/day; 44,066 kg/ha total in one pond), other water quality variables were acceptable. Neither FCR nor survival was significantly different between treatments either year. There was little benefit in maintaining the minimum DO concentration above 2.5 mg/L in channel catfish production ponds. However, the reduced feed consumption and growth resulting from maintaining minimum DO concentrations lower than this may extend the culture period for food fish production. While these results cannot be extrapolated directly to large commercial ponds, it appears that feeding rates and resulting production may be increased above current commercial levels with increased aeration. |
