Multitrophic Integration for Sustainable Marine Aquaculture

The seafood industry is at a crossroads: while capture fisheries are stagnating in volume and decreasing in profitability, they are also falling short of world demand, as the annual consumption of seafood has been rising, doubling over the last three decades. As this trend is expected to persist, the importance of aquaculture, as the solution for providing the difference between the demand and the biomass available, could increase. The majority of aquaculture production still originates from extensive and semi-intensive systems; however, the rapid development of intensive marine fed aquaculture (e.g., carnivorous finfish and shrimp) throughout the world, even though it represents only 11%, is associated with concerns about the environmental, economic, and social impacts these often monospecific practices can have. To continue to grow, the aquaculture sector needs to develop innovative, responsible, sustainable, and profitable practices. This article examines some of the different options available to face these challenges (geographical expansion, intensification of the existing sites, diversification, social acceptance) and recognizes that changes in attitudes are needed and innovative practices have to be developed for further advancement. One of these options is integrated multitrophic aquaculture (IMTA), which combines the cultivation of fed aquaculture species (e.g., finfish) with inorganic extractive aquaculture species (e.g., seaweed) and organic extractive aquaculture species (e.g., shellfish) for a balanced ecosystem management approach. Through IMTA, some of the food and energy considered lost in fed monoculture operations are recaptured and converted into crops of commercial value (extractive plants and animals), while biomitigation takes place. Several examples of IMTA systems in different parts of the world are described to illustrate the concept. For IMTA to develop from the experimental scale to sustainable commercial food production systems, appropriate regulatory and policy frameworks, and financial incentive tools, which recognize the economic value and environmental benefits of biomitigation services by biofilters, need to be put in place.