Review of recirculation aquaculture system technologies and their commercial application

Abstract

Recirculation aquaculture systems (RAS) are designed to minimise water consumption, control culture conditions and allow waste streams to be fully managed. They can also provide some degree of biosecurity through measures to isolate the stock from the external environment. RAS technology has steadily developed over the past 30 years and is widely used for broodstock management, in hatcheries and increasingly for salmon smolt production. By comparison, the progress of RAS for grow-out to market size products has been more restricted and there is a substantial track record of company failures both in the UK, Europe and internationally. The reasons for this are varied, but include challenges of economic viability and operating systems at commercial scales. This review considers the current status of RAS technology and its commercial application with particular reference to its potential impact on Scottish aquaculture. With increased reliability and efficiency new opportunities are open to the Scottish industry to both enhance salmon production and diversify to other species. On the other hand, the greater flexibility in locating RAS farms could present a threat to some salmon production in Scotland where production can move closer to key centres of consumption – either in the UK or abroad. After all, one of the environmental advantages of RAS is to enable production in areas unsuited to other forms of aquaculture and where promotion of sustainability is a key element. Consequently, farming close to markets, thereby reducing food miles, may have benefits for both the retailer and consumer. However, what proportion of caged salmon production might eventually be substituted by land based RAS is debateable. This may depend on the economic advantage to some current salmon export markets farming salmon in their own country using RAS technology developed in Europe or North America.