Eugene L. Torrans

Effect of Oxygen Management on Culture Performance of Channel Catfish in Earthen Ponds

Abstract Aeration allows for higher feeding rates and increased production of channel catfish Ictalurus punctatus in intensive and semi-intensive aquaculture systems. However, the effect of specific dissolved oxygen (DO) concentrations on various production parameters remains unknown. The purpose of this 2-year study was to determine the effect of daily minimum DO concentration on channel catfish production. Six 0.1-ha ponds were each equipped with three 0.37-kW (0.5-hp) aerators and one 0.37-kW circulator. Dissolved oxygen concentrations were monitored and recorded with a commercial oxygen monitor that also controlled aeration. During both years, aeration in the high-oxygen treatment was initiated when the DO concentration dropped below 5.0 mg/L (mean, 64% saturation from May to September); aeration in the low-oxygen treatment was initiated when the DO concentration dropped below 2.5 mg/L (32% saturation; 2001) or 1.5 mg/L (19% saturation; 2002). The minimum DO concentrations resulting from this aeration...

Production Responses of Channel Catfish to Minimum Daily Dissolved Oxygen Concentrations in Earthen Ponds

Abstract This study determined the effects of the minimum daily dissolved oxygen (DO) concentration on the production parameters of channel catfish Ictalurus punctatus in earthen ponds. Fifteen 1-acre ponds (five ponds per treatment) were managed as high-oxygen (minimum DO concentrations averaging 4.37 ppm or 54% air saturation from June through September), medium-oxygen (minimum DO concentrations averaging 2.68 ppm or 33.2% air saturation), or low-oxygen treatments (minimum DO concentrations averaging 2.32 ppm or 28.7% air saturation) using one 5-hp electric paddlewheel aerator per pond. Fish in the high-, medium-, and low-oxygen treatment ponds were fed a mean total of 14,008, 13,212, and 12,607 lb/acre of 28%-protein floating feed, respectively. Net production paralleled the total amount of feed fed, averaging 5,772, 5,278, and 5,113 lb/acre in the high-, medium-, and low-oxygen treatments, respectively. Individual fish weight at harvest also showed a similar trend, averaging 1.37, 1.33, and 1.30 lb in...

Influences of Cyclic, High Temperatures on Juvenile Channel Catfish Growth and Feeding

Abstract Effects of high summer temperatures on Channel Catfish Ictalurus punctatus are poorly understood, particularly for thermal regimes that mimic pond aquaculture conditions. Therefore, this study examined the effects of three cycling upper-range temperature regimes (23–27°C, 27–31°C, and 31–35°C) characteristic of aquaculture environments in the Mississippi Delta. Feed conversion ratio, feed consumption, specific growth rate, activity levels, survival, and overall growth in terms of wet weight and TL were measured in fingerling channel catfish over an 8-week period in a flow-through, multiple-tank system. Specific growth rate, feed consumption, TL, and wet weight of fish increased significantly in the 27–31°C treatment in contrast to the 23–27°C and 31–35°C treatments. Feed conversion ratio was lowest in the 27–31°C treatment, whereas activity levels were highest in the 31–35°C treatment. Survival significantly decreased for catfish in the warmest treatment compared with catfish in the coolest treat...

The sock-saver: A small trailer for providing liquid oxygen to remote sites on commercial channel catfish farms

Abstract A small, single-axle trailer was designed and built to hold three 50-gal liquid oxygen Dewar flask tanks. The unit is small enough to be moved around a commercial channel catfish Ictalurus punctatus farm with a pickup truck or small tractor. It is being used successfully to provide supplemental oxygen at remote on-farm locations to channel catfish that are being held in a sock (net cage or live car) at high density before sale. The total materials cost of the complete sock-saver with trailer, Dewar tanks, pressure/flow regulators, and diffusers was

Design and Testing of a Closed, Stirring Respirometer for Measuring Oxygen Consumption of Channel Catfish Eggs

8,333.16. It is simple to operate, durable, and virtually maintenance free. Because no electrical or mechanical power source is required, it can be set up anywhere. The small “footprint” of the trailer does not interfere with the other equipment normally used when loading fish from a sock. Individual flow regulators allow use of one, several, or all eight diffusers as needed. The diffusers and hoses are self-weighted and tangle-free and do not interfe...

Comparison of Phytoplankton Communities in Catfish Split-Pond Aquaculture Systems with Conventional Ponds

Abstract A closed, stirring respirometer was designed to agitate small egg mass samples of channel catfish Ictalurus punctatus while measuring oxygen consumption by the eggs. Egg mass samples ranging in size from 15 to 46 g were placed on a screen platform above a magnetic stir bar in the respirometer; the degree of agitation was controlled with a magnetic stir plate. Dissolved oxygen (DO) concentration and temperature were measured with a luminescent DO sensor and meter. The respirometer was used to determine routine metabolic rate and limiting oxygen concentration (the presumed hypometabolic transition zone) on egg mass samples from 10 different spawns at 0 to 5 d postfertilization. Routine metabolic rate increased from 4.8 ± 1.3 (0 d postfertilization) to 174.0 ± 7.8 mg O2·kg−1·h−1 (5 d postfertilization). The limiting oxygen concentration increased similarly up to 87.0% ± 2.7% (maximum individual value = 95.9%) air saturation by 5 d postfertilization. The respirometer described could not be used for s...

Growth and Feed Conversion Ratio of Pond-Raised Hybrid Catfish Harvested at Different Sizes

AbstractThere has been a growing interest and use of variations of partitioned aquaculture systems (PAS) in recent years by the southeastern U.S. catfish farming industry. Split-pond systems, one type of PAS, are designed to better manage fish waste byproducts (e.g., ammonia) and dissolved oxygen levels than the conventional earthen ponds that have been used by farmers for many decades. Recent studies have focused on design, water flow rates, and other management areas of catfish split-ponds, but so far there has not been a focused examination of phytoplankton community composition and biomass in these split-ponds. In the current study, pond water samples were collected from split-ponds at a research facility in western Mississippi and at a commercial fish farm in western Alabama approximately every 3 weeks during the fish grow-out period (May to November). Water samples were analyzed for chlorophyll a concentration (phytoplankton biomass) of several major phytoplankton divisions and for types of phytopla...