Closed system aquaculture includes a wide range of technologies, each with varying levels of separation between the farmed fish and the marine environment. Technologies span from simple barriers to prevent fish escapes to systems that fully recapture and treat waste as well as recycle rearing water. The two most common types of closed containment are:

• solid walled tanks floating in water
• land-based systems such as tanks or lined ponds

For large-scale production of salmon, the systems showing the most promise for economic viability and meeting required protection of wild salmon are currently floating systems with solid walls. These systems offer a very high levels of solid waste collection and a regular exchange of the tank water with new sea water. Future refinements could include treatment of discharged water. As the technology is tested and proven, incremental improvements in waste treatment are likely.

Around the world, various types of closed tank technologies are used to grow many types of seafood on a commercial scale including:

• arctic char
• trout
• barramundi
• tilapia
• halibut
• turbot
• salmon (in freshwater closed tanks)

For a better understanding of current closed containment technologies, see our recently released, Thriving Economies, Healthy Oceans, a summary of a Global Assessment of Closed System Aquaculture. (summary pdf)

The full report, produced by the Georgia Strait Alliance and the David Suzuki Foundation on behalf of CAAR, is available at Global Assessment of Closed System Aquaculture. (80 page pdf)

Read more about examples of current closed containment technology.