Land based multi-trophic aquaculture research at the wave energy research centre

The collapse of the Atlantic cod fishery in the 1990s devastated the economies of many coastal Newfoundland communities. While many have survived through a combination of a much reduced fishery, government funding, and off shore or out of province employment, none of these are sustainable long-term solutions. Sea-based aquaculture (“fish farming” in pens) has provided stable employment in some areas, but only where there are suitable sites with protected, deep inlets with significant tidal or river current flushing. These geographic characteristics are not usually compatible with prosecuting the inshore fishery. Sites that were close to the open fishing grounds with minimal near shore currents were prized by the small boat fishers, but wind and wave protection were a secondary concern. Thus there are many towns and villages that are significant distances from ideal sea-based aquaculture sites. While shore-based aquaculture would be possible in many coastal villages, the profitability of the industry is limited by the cost of pumping water to and through the shore based infrastructure. Many existing coastal settlements do have an abundance of energy available in ocean waves. The harnessing of this energy to pump water on shore at low cost will enable the development of profitable shore based aquaculture methods that will provide sustainable long-term economic activity for these communities. Shore-based aquaculture has the additional possibility of containing and directing effluent from the production on one species to another that can use it as a feed source (e.g., fish effluent delivered to filter feeders). This effectively “biofilters” the fish production effluent while producing other marketable product (scallops and seaweed, for example) at little or no extra cost. This paper reports on a research project being conducted by College of the North Atlantic (CNA) in Lord's Cove, Newfoundland, which has the overall goal of developing a sustainable land-based aquaculture system utilizing wave energy. Development of the pump is occurring concurrently with the design, installation and commissioning of a pilot cascaded Integrated Multi-trophic Aquaculture (IMTA) facility in Lord's Cove. In this pilot farm, the effluent from the finfish (the only organisms receiving external feed input) is directed to sea urchin production tanks. From there, water flows to scallop production tanks and finally algae culture. The algae produced is fed to the urchins, who consume this and organic sediment coming from the finfish. The suspended organic particulate in the urchin effluent will nourish the sea scallops, and the algae will reduce the dissolved inorganic load before the water is returned to the ocean (Fig. 1). Until the wave pump development is complete, water for the farm is being entirely supplied by electric pumping. We are currently undergoing scale model and sea based prototype testing of the wave driven pump. As part of the design process for this pump, the wave energy resource and bathymetry at the site was measured and documented. As a result of these activities, CNA now operates the Wave Energy Research Centre (Fig. 2). This facility is now permitted for testing of wave energy absorbers and similar devices: it includes data acquisition (wave environment, weather and device performance monitoring) as well as the necessary infrastructure to support these studies and is ready to host other device developers.