Location: Warmwater Aquaculture Research Unit2013 Annual Report
1a. Objectives (from AD-416):
The overall objective of this project is to improve the profitability of channel catfish by improving farm-level production efficiency. This will be accomplished by addressing key production inefficiencies over a broad range of issues (nutrition, production system design, and product quality) affecting production in all post-hatchery production phases (fingerling production, foodfish production, and post-harvest). Over the next 5 years, we will accomplish the following objectives: Objective 1: Explore alternative feed ingredients to reduce production costs of catfish. Objective 2: Improve culture methods for fry and fingerling production. Objective 3: Develop new and improve existing production strategies for large catfish. Objective 4: Determine the relationship between pre-harvest, harvest, and post-harvest practices and product quality.
1b. Approach (from AD-416):
Catfish aquaculture was a profitable and rapidly growing industry in the southeastern United States prior to 2003. Since that time, profitability has declined due primarily to competition from imports and increased feed prices. Although these macroeconomic issues are difficult to address, new technologies can improve farm production efficiency and help restore profitability. This project addresses key production inefficiencies in fish nutrition, production system design, and product quality. Objective 1 will address the rising cost of catfish feed by finding suitable replacements for traditional feed ingredients that have recently increased dramatically in price. Objective 2 will evaluate the use of natural feeds and different stocking densities on growth and survival of catfish fry, with the goal of reducing feed costs and improving growth of fish from fry to fingerling stage. Objective 3 will evaluate ways to reduce feed-input costs by providing food-sized catfish with forage fish as a secondary source of food. A second subobjective proposes to alter pond design to overcome production limitations related to loading limitations of traditional earthen ponds. Objective 4 will address the large number of fish rejected for processing due to product-quality issues. Fish rejected for processing has become an important inefficiency for foodfish producers. The benefits of this project will be development of techniques to enhance economic performance, improve global competitiveness, and allow domestic aquaculture to reduce dependence on imports to meet the U.S. demand for seafood.
3. Progress Report:
During Fiscal Year 2013, a pond study was conducted to examine the use of hydrolyzed feather meal as a replacement for soybean meal in diets for pond-raised channel catfish. Four 28%-protein diets were evaluated that contained 0, 5, 10, or 15% hydrolyzed feather meal. No significant differences were observed for weight gain, feed conversion ratio, and survival among fish fed various levels of hydrolyzed feather meal. There were also no significant differences in net yield of fish fed diets containing 0, 5, and 10% hydrolyzed feather meal, but net yield of fish fed a diet containing 15% hydrolyzed feather meal was significantly lower than that of fish fed the control diet. Fish on diets containing 5% hydrolyzed feather meal and above were fed significantly less feed than fish fed the control diet. Results showed that with supplemental lysine hydrolyzed feather meal may be used at 5% of the diet without marked impact on performance of pond-raised catfish. However, fish fed diets containing hydrolyzed feather meal at 5% and above had reduced carcass and fillet yield. Studies on stocking different ages of fry have been completed. Stocking hatchery-fed fry resulted in 41.6% survival, stocking swim-up fry resulted in 7.1% survival, and stocking sac fry resulted in 4.5% survival. The final recommendation is to continue feeding fry in the hatchery before stocking to improve survival rates. Following stocking in nursery ponds, fry were shown to thrive without commercially processed feed for 6 weeks by feeding on naturally occurring zooplankton. This work showed that implementing a regimented fertilization program to optimize zooplankton levels can provide a sufficient source of food for fry during the first 4-6 weeks of fingerling production. Reducing or eliminating fry feedings during the initial stages of fingerling production can reduce feed costs by at least $236/acre. Adding threadfin shad to catfish ponds did not improve catfish growth but reduced algae-caused off-flavor in summer and caused fishy flavors in the winter. Presence of fathead minnows had no effect. In a second forage fish study, no differences were detected among treatments. Lack of forage fish effect was attributed to wild-spawning of catfish, confounding treatment effects. Hybrid catfish stocked at 37,000 fish/hectare (ha) in a 1.8-ha split pond grew to an average size of 0.73 kg in 210 days, for a gross yield of 23,600 kg/ha. Although total production was high, average fish size showed a density-dependant reduction compared to fish stocked at lower rates. The recommended stocking density is 24,700 fish/ha for fastest fish growth.
1. Use of alternative feed ingredients to reduce production costs of catfish. The prices of soybean meal, the most commonly used traditional protein source in channel catfish diets, have increased dramatically in recent years. Using less-expensive alternative feedstuffs to partially replace soybean meal would reduce feed cost. Scientists at Mississippi State University (MSU) at Stoneville, MS, investigated the use of hydrolyzed feather meal as a partial replacement for soybean meal in diets for pond-raised channel catfish. Results demonstrate that hydrolyzed feather meal may replace about 20% soybean meal in catfish feeds without marked impact on fish growth performance when prices are favorable. However, caution should be taken when using hydrolyzed feather meal because it reduces carcass and fillet yield.
2. Development of improved culture methods for fry and fingerling production. Survival of fingerling catfish in nursery ponds is highly variable and averages between 50-60% on most commercial operations. While disease is an important variable, fingerling survival is often poor in the absence of disease. Scientist from Mississippi State Univeristy (MSU) conducted pond studies to evaluate hatchery practices on growth and survival of catfish fingerlings. Channel catfish fry were transferred from the hatchery to nursery ponds at different developmental stages to reflect current industry practices. Fry were stocked before being fed a commercial fry diet (before or at the time of yolk sac absorption) or 4-7 days after being fed a commercial fry diet. Stocking fry in the early developmental stages resulted in poor survival. Since nursery ponds contained adequate zooplankton populations that serve as a food source, poor survival of early stocked fry was likely related to predation by aquatic insects. To increase fingerling survival fry should not be stocked in nursery ponds until they are fully developed and readily accept commercial diets. There are no differences in fish production between fry nursery ponds that are fed commercial diets and ponds that rely on natural productivity for the first 6 weeks. Total kg of feed fed was significantly reduced in the delayed feed treatment, averaging 26 kg/pond less feed fed. If proper fertilization practices are implemented, large numbers of desirable zooplankton for catfish fry culture are attained, and these zooplankton are able to sustain catfish fry stocked up to 250,000/ha. Therefore, no commercial diets are required during the first 6 wk of culture, saving over $95.55/ha in initial feed costs.
Mischke, C.C., Griffin, M.J., Greenway, T.E., Wise, D. 2013. Effects of mosquitofish, gambusia affinis, on channel catfish, Ictalurus puncatatus, production ponds. Journal of the World Aquaculture Society. 44:288-292.