Responsible Aquaculture by Minimizing Environmental Impacts on Land and Water

The United States has the best terrestrial farming technologies in the world. Unfortunately, fish farming in the US produces less than 1% of the total domestic production of terrestrial livestock. Domestic fish production is far below consumer demand, as the US faces an approximately $10 billion dollar seafood trade deficit. Fish farm expansion in the US has been largely constrained by limited water resources, site access, and regulatory limitations. These limitations, however, are now being overcome with technical innovations in fish production systems. Land-based closed-containment systems are a type of fish production system that uses water recirculation technologies to continuously filter and recycle as much as 99.8% of the water flowing through the system. Recirculating water allows for much greater control of the rearing environment, i.e., making it possible to optimize water temperature and quality to maximize fish performance. During the recycling process, these systems control and capture as much as 98-99% of fish waste solids and phosphorus, plus much of the nitrogen. The nitrogen, phosphorus, and organic matter in the biosolids (fish manure) captured in these water recirculating systems are typically flushed to a central location adjacent to the production systems where biosolids are dewatered and concentrated to at least 10% dry weight. The nutrients in this concentrated slurry can be reclaimed when applied as a soil-amendment to pasture or row crops or when used with wood chips to create compost. In addition, dissolved nutrients in the relatively small discharge from these systems can be recycled to produce high-value edible plants and herbs such as basil and varieties of lettuce, spinach, tomatoes, or other high-value produce in adjacent greenhouses. Fish farming operations employing these technologies can be located in areas convenient to major markets or with limited water resources, strict discharge regulations, or cheap electricity; e.g., rates of $0.02-0.06/kwh are available in the US. In addition, placing water recirculation systems within buildings and implementing biosecurity practices serve as effective barriers for fish pathogen introduction, eliminating the need for vaccination and improving fish welfare and farm production by minimizing disease and mortalities. The overall results are healthy fish and negligible, if any, use of antibiotics. Confidence in these technologies has risen and private investment in closed-containment systems producing premium fish is growing and may now total $50 million annually in North America.