|dc.description.abstract||An experiment was conducted utilizing a highly intensive fish production system in the Black Belt region of western Alabama. Three main objectives were addressed in this study. The first was based primarily on channel and hybrid catfish production and performance capabilities. The second objective dealt with detailed water chemistry and nutrient budgeting, while the third and final objective involved an economic analysis to determine the feasibility and commercial possibilities of the system.
The goal of this project was to improve the profitably of commercial catfish aquaculture by demonstrating methods to enhance feed efficiency and survivorship. A commercial size In-pond Raceway System (IPRS) was constructed in 2007 and installed in a 2.43-ha, traditional, earthen pond on a 170-ha catfish farm in Dallas County, Alabama. The IPRS consisted of six, individual raceways that share common walls. Each raceway has the capacity of water exchange every 4.9 minutes (≈12X/hr). Mean water velocity was determined to be 0.026 m/sec - equivalent to a flow rate of 8,853 l/min/raceway.
Individual raceways were stocked with 12,000 to 30,000 channel and hybrid catfish with average weights of 59.1 to 418.2 g, respectively. A total of 49,913 kg of catfish was harvested throughout an 8-month production season. An additional 6,365 kg of paddlefish and tilapia were harvested at the end of the study. The feed conversion ratio (FCR) for catfish ranged from 1.16 – 2.11 and mean survival was 83.7%. Catfish growth rates ranged from 1.1 to 2.2 g/fish/day. The results signify a high potential for efficient production of catfish along with other co-cultured species.
Water, nitrogen, phosphorous, chemical oxygen demand (organic matter), and dissolved oxygen (DO) budgets were estimated over the fish production season for the IPRS. Even with the addition supply of water from rainfall and runoff, 70 cm of well water were applied to the pond to offset evaporation and seepage. For each 1.49 kg of feed fed to the fish, there was one kilogram of weight gain. However, 51.7 g of nitrogen, 13.4 g of phosphorous, and 0.41 kg of chemical oxygen demand (COD) were released into the environment. The catfish harvested accounted for 33.9 % of nitrogen, 13.1 % of phosphorous, and 28.3 % of organic matter (COD) that was applied as feed. Large amounts of nitrogen and organic matter were lost from the system, although there was significant accumulation in pond mud. Organic matter was consumed in respiration while nitrogen was lost through denitrification and ammonia volatilization. Phosphorous was harvested in fish and absorbed in pond mud. Diffusion and mechanical aeration assured proper DO levels for fish production because the total respiration exceeded the levels produced by photosynthesis.
The economic analysis provides evidence that the IPRS may be more efficient for producing food-sized catfish as compared to traditional farming methods. The IPRS was more efficient at producing catfish as compared to the whole farm in 2008 and about as efficient as the average 4-year performance of the whole farm over the course of the study. Continual food fish production while utilizing the additional production from co-cultured species would be the most feasible for the IPRS. The cost of production for food fish was $1.565/kg with a total cost of production of $1.904/kg. With the addition of co-cultured fish (paddlefish and tilapia), the overall cost of production and total cost is reduced to $1.388/kg and 1.689/kg, respectively. The electrical efficiency of the IPRS with and without the co-cultured species is 0.639 and 0.535 kg of fish produced per kW•h used, respectively.||en