This Small Business Innovation Research (SBIR) Phase I project will determine whether integrated multi-trophic aquaculture (IMTA) can be imported from off-shore salmon farms where the concept is being pioneered into on-land recirculating aquaculture systems (RAS). RAS Corporation, and the University of Maine's Center for Cooperative Aquaculture Research are already employing a tank of black sea bass (Centropristis striata) plumbed directly to raceways containing sand and deposit-feeding polychaetes (Nereis virens) to demonstrate that the worms will consume virtually all of the particulate fecal waste and unconsumed feed, thereby eliminating intermediate filtration equipment while generating a valuable by-product. Phase I proposes to add an algae bioreactor downstream in order to culture microalgae that will cleanse CO2, nitrates and phosphates from the flow while adding back oxygen. Excess plant cells will be extracted by flowing them through adjacent impoundments, containing filter feeding oysters (Crassostrea virginica), hence a second by-product. A computer model system will be developed to maintain the balance of the four trophic levels. Success will result in having IMTA-RAS software that projects how many kilos of baitworms, microalgae and oysters can be grown from the waste of a certain load of fish, determining the optimum carrying capacity of each trophic level.
The broader impact/commercial potential of this project will make on-land and indoor fish production less costly, more profitable and organic in character, thus more sustainable. Expansion of offshore cage culture of finfish is limited by natural conditions, environmental constraints and competing uses for space while RAS technologies are poised for greater enhancements. The two most common criticisms of aquaculture are: (1) it generates waste; and, (2) the fishmeal in fish feed is derived from wild-caught forage fish. This project will demonstrate that wastes are valuable resources, which, if used internally, can yield two by-products; baitworms and oysters if grown in concert with microalgae. This is achieved by substituting biological versus mechanical methods for water treatment. While recreational and commercial fishermen represent a large market for baitworms, it has also been demonstrated that polychaetes make excellent fish feed, hence a potential substitute for fish meal and oil. After trial extraction of halibut waste to feed sandworms, CCAR concluded that 10 mt of fish harvest would yield 1.0 mt of worm harvest (Brown, 2011).
. The correct management of waste is a challenge to all of agribusiness and aquaculture is no exception. Achieving zero waste is not only possible; it is an ethical and moral obligation. Since its inception, Acadia Harvest, Inc. was determined to achieve this goal by treating fish fecal and feed waste as not a pollutant but a resource. The company’s final Phase I report considered three main factors: intent, method and results. The intent was to fully utilize both solid and dissolved waste in a way that would generate byproduct crops, specifically sandworms and oysters, the former valuable as recreational bait and the latter a step towards the day when land-based production of marketable shellfish becomes industrial in scale. The method used is simple. The particulate waste was directed to sandbeds of deposit-feeding sandworms while dissolved nitrate and CO2 is flowed to nourish microalgae that in turn are food for filter-feeding shellfish. The result: in the final weeks, the system operated with 100% recirculation, thus zero-waste discharge. All four trophic levels – fish, sandworms, algae and shellfish - share the same recirculating seawater containing a mixture of nutrients and energy that is in effect a man-made ecosystem. By the end of the trial, the balance achieved was so effective that near-100% of the waste was utilized with zero discharge. This not only satisfies optimum environmental guidelines, but suggests that marine aquaculture can be conducted anywhere inland, hence opening up opportunities for protein production not previously considered feasible. Next, the company plans to expand the feasibility study into a pilot plant that emulates a full scale aquafarm, so that after two years of practical experience with maintaining the eco-balance while harvesting, restocking and introducing other normal husbandry requirements, it will be possible to finance, install and operate a commercial version that initially will be ten times larger. The experimental work is carried out at the University of Maine’s Center for Cooperative Aquaculture in Franklin, ME while the full aquafarm will be located on the company’s waterfront site in the new Acadia Aquaculture Park, Corea, Maine. A successful merger of the several innovations on a commercial scale in Corea is likely to yield a model for the US finfish and shellfish industries.
