Offshore Aquaculture: A Needed New Frontier for Farmed Fish at Sea

Aquaculture continues to be the fastest growing food producing sector in the world and it is expected to bridge the future global supply–demand gap for aquatic food.1 However, this is a great challenge considering that a large proportion of current aquaculture for food is produced in fresh water and this resource is bound to be very scarce and even scarcer under climate change.2 Today, practically all marine production takes place by the coast or not far from it. Yet, coastal zones are becoming increasingly limiting for aquaculture. Therefore, use of open ocean sites can be a solution for future aquaculture activities. There is no single universally accepted definition of offshore aquaculture, or equivalently, open ocean aquaculture. In many cases these terms are used for any farming off the coast.3 Here, the definition proposed in a special publication by the Food and Agriculture Organization of the United Nations (fao) for offshore mariculture will be used.4 That is, farming occurring away from the coastline (> 2 km), in waters deeper than 50 m and fully or partially exposed to stronger wave and wind action. The concept opposes that of coastal aquaculture, in as far as coastal refers to nearshore sites, mainly in sheltered places and those located off the coast but in waters not deeper than 40 m and with