16 MARCH 2016 • WORLD AQUACULTURE • WWW.WAS.ORG quality feed ingredient and food item (Rombenso et al. 2014). Harvest, Final Product and Consumer Market. Generally, after 12 months of grow-out, cobia reach market size with an average weight of 4-5 kg. Faster growth rates have been reported in Taiwan and Indonesia (Liao and Leaño 2007) but achieving 4-5 kg harvest weight within 12 months is satisfactory, assuming an average water temperature of 25 C during the year and a minimum water temperature of 18 C. During the 2014 production cycle, approximately 3.5 t of cobia were harvested, which was completely absorbed by fine-dining restaurants, particularly Japanese cuisine, in Rio de Janeiro, with retailers consuming an average of 100150 kg of fresh, on-ice cobia per week. Although production was relatively small, the results from this single, small-scale pilot initiative are valuable to promote the activity, demonstrate the suitability of this species to local culture conditions and gauge market acceptance of the final product. As cobia has no established market in Brazil, especially in the southeast region where wild catches are rare, it was encouraging that cobia was readily accepted by restaurants and seafood markets in Rio de Janeiro. Because the consumer market is located only three hours from the farm, it is feasible to deliver very fresh fish for consumption on the same day as the harvest. There is an apparent increasing demand for local, high-quality, fresh seafood products driven by the limited regional supply of farmed fish. Farmed cobia has therefore been able to fill a niche market as a healthy (omega-3 rich) specialty seafood and has achieved a high selling price of US$ 18-20/kg of whole gutted fish. For marine finfish, it is rare to have a business that can obtain such a high value for a product, although prices are expected to decrease in the future as mariculture production and supply increases. Alternative Approach At the current facility, marine finfish culture is not the only focus, but forms the heart of a unique approach, combining IMTA and linking mariculture and tourism for ecologically sustainable mariculture. The IMTA Approach. The IMTA system consists of mussels Perna perna, scallops Nodipecten nodosus, and seaweed Kappaphycus alvarezii, which use organic matter and nutrients originating from cobia cage culture. The IMTA concept is based on recycling available nutrients from uneaten food and feces released by fish into food for lower trophic groups. Bivalve mollusks extract particulate organic wastes and seaweeds assimilate dissolved inorganic nutrients (Chopin and Bastarache 2004, Fang and Zhang 2015). In this balanced trophic design, it is intended that nutrients in the environment surrounding fish cages will be removed by these organisms. Currently the program is still in the experimental stage of evaluating the optimal positioning of each culture organism to minimize the environmental footprint and maximize the growth of each system component. The IMTA approach fits well with the local environmental and socio-ecological context, which includes favorable mariculture characteristics, high biodiversity, tropical weather, minimal environmental pollution from industrial sources and involvement of the local community. Currently, tourism is the main economic activity in the region, which is not the most attractive or economically beneficial activity for local communities. Local inhabitants have a direct connection with the ocean and, in the past, most were involved in wild capture fisheries. In this context, mariculture provides a promising livelihood opportunity to keep working locally on an activity that produces seafood, thereby contributing to improved food security, and also helps to preserve the environment. The efficiency of the IMTA system is expected to increase with the addition of sea cucumbers as a new component. Sea cucumbers have been successfully co-cultured with scallops and abalone in China (Fang and Zhang 2015), seaweed in Zanzibar (Beltran-Gutierrez et al. 2014) and finfish in Southeast Asia (Mills et al. 2012). Sea cucumbers have a number of attractive aquaculture characteristics, including a high market value and increasing demand, relatively fast growth (achieving market size in 1-2 years), and relatively simple husbandry technology (Robinson 2013). In addition, sea cucumbers offer several benefits as a benthic IMTA component. They mainly feed on organic matter in the sediment and thereby reduce the environmental impacts of other organisms by consuming uneaten food and feces and recycling nutrients to primary producers (Robinson 2013). For these reasons, sea cucumbers have been identified as the best extractive candidate species for IMTA (Orr 2012). Recently placed macroalgae Kapphaphycus alvarezzi. The indigenous sea cucumber Isostichopus badionotus is a high-value species in the region.
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