Fish and Shellfish Technologies, 2009

Non-Technical Summary: Seafood remains the only mainstream protein source in the American diet that is still hunted in the wild, and the commercial oceangoing fisheries are experiencing the consequences of decades of overfishing, habitat destruction, coastal construction, and pollution. As the wild supply is decreasing, domestic demand for seafood is continuing to increase. Given these factors, it is clear that ocean-caught fish will not meet this rising demand. Many ocean species already face threats of extinction, and conservation efforts are further limiting an already dwindling harvest. Aquacultured seafood products, largely imported from the developing world, currently fill the supply gap. In 2006, the U.S. seafood trade deficit topped $9.2 billion - the largest deficit for any agricultural commodity. Over 80% of our seafood is imported with over 40% coming from China. The U.S. cannot depend on these imports; the producing countries will need their seafood to feed their own growing populations. At the same time, many regions of the U.S. have seen a decline of traditional farming, mining, and manufacturing industries. In rural portions of Virginia and West Virginia many people who were once employed in the textile, furniture, mining, and tobacco industries remain underemployed due to the disappearance of these jobs, and are seeking new ways to support their families. Controlled environment aquaculture, conducted indoors using recirculating systems, can restore resources, preserve and create jobs, and offer a new source of income for rural areas nationwide where traditional agriculture, furniture, textile, industrial manufacturing, or mining economics no longer support families and rural life-styles. However, indoor, recirculating aquaculture is still a fledgling industry that faces many challenges technical challenges to assure its economic viability and survival. The culture of animals is complex, especially in a water environment. Therefore, it is important to understand how to optimize animal husbandry, mitigate wastes, and improve feed management. This research project is designed to address questions related to these areas. <P> Approach: To evaluate the long term negative effects of elevated levels of nitrate on Pacific White shrimp and determine safe levels for culture, shrimp will be reared in aquaria maintained with 4 levels of nitrate (0, 200, 450, and 900 mg/L). Water quality and shrimp health will be monitored. Statistical analyses will be performed using SAS v9.1 for Windows. To determine the value and marketability of offal (fish waste) from tilapia fillet processing, market-sized tilapia will be processed for skinless fillets and the offal will be evaluated as a feed (fresh offal, fish silage, compound feeds) and as compost (composted fish offal). Findings will be published in popular trade magazines for industry. The feasibility of generating a formulated diet for intensive raceway production of shrimp using bioflocs generated from biological treatment of tilapia effluent will be investigated. Treatability studies will be conducted using pilot-scale sequencing batch reactors to process wastes from a recirculating tilapia farm. Carbon will be added to the process to promote heterotrophic biological treatment while attempting to increase crude protein and total fat levels. Digestibility trials will be conducted in 20 L opaque tanks using recirculating aquaculture systems with seawater renewal. Four juvenile shrimp will be stocked per tank, and 6 tanks will be used per experimental diet. Feed and appropriate ingredients will be analyzed for calorie, carbohydrate, crude fat, crude fiber, crude protein, and total ash content. Apparent digestion coefficients will be determined for the nutritional components. Statistical analysis will be performed using SAS v9.1.3 for Windows. Because the carbon added to the sequencing batch reactor wastewater treatment process represents a significant input cost, the ability of sequencing batch reactors to process tilapia waste water without carbon supplementation will be determined. In addition,the nutritional value of bioflocs produced without carbon supplementation will be investigated to determine the value of these bioflocs as an ingredient in formulated shrimp feed. Nutritional tests of the non-carbon-supplemented biofloc will be conducted in the same manner that the biofloc produced with carbon supplementation will be tested. Two Oncorhynchus species of fish grown in recirculating aquaculture systems will be studied to determine expected shelf life. The fish will be processed in two market forms: headed and gutted, and filleted. Shelf life for each form will be evaluated. The fish will be slaughtered and stored at 1 and 4 C for 0, 4, 6, 8, 12, and 15 days or until spoilage occurs. On day 0, samples of each form will be frozen to use as a control for sensory analysis. On each sampling day, samples will be analyzed for aerobic and anaerobic plate count, color and texture. On all sampling days except day zero, sensory analysis (odor and appearance) will be conducted to compare stored fish to a sample that was frozen on day 0 and thawed the day of the sensory evaluation. The experiment will be replicated three times. Statistical analysis of the data will be performed using SAS v9.1.3 for Windows.