What is the difference between closed and open aquaculture systems

Aquaculture systems are very diverse in their design and function. The three most basic categories of culture systems are open, semiclosed and closed systems. Open system culture generally refers to fish farming in natural water bodies such as oceans, bays, estuaries, coastal lagoons, lakes, or rivers. Semiclosed systems are those in which the culture water makes one pass through the system and is discharged.

Systems of this nature are referred to as flow-through or once-through systems. The raceway falls into this category. Closed aquaculture systems are primarily used for freshwater species with silver perch, barramundi, yabbies and marron amongst the most common marketable species in Australia. Blacklip and greenlip abalone are the main marine species produced in closed systems, and are experiencing rapid growth due to demand from Asian markets.

Closed system aquaculture is considered one of the more environmentally benign methods of rearing aquatic species. Fishmeal pellets comprising small schooling fish species may be added to feed carnivorous aquaculture species, and is a concern as it places continued demand on wild fish stocks. However, there is negligible interference with waterways as a result of tight control over waste water and the prevention of fish escape.

Want more? Check out the Fishing Techniques page to learn how wild fish stocks are harvested. Open Aquaculture Systems: Sea-cage active feeding Open sea-cage aquaculture refers to the rearing of aquatic species, within enclosures in natural waterways.

Open Aquaculture Systems: Sticks, ropes, racks and cages passive feeding The culture of numerous shellfish species is carried out in systems open to natural waterways. Semi-closed Aquaculture Systems Semi-closed aquaculture refers to the land-based production of a species, in which water is exchanged between the farm and a natural waterway.

Closed Aquaculture Systems Closed system aquaculture refers to the land-based rearing of aquatic species in raceways, tanks and ponds. Our goal is to achieve both financially viable aquaculture and healthy local ecosystems. Closed system aquaculture is already providing better ways to farm fish. This involves barrier technologies that ensure no contact between wild and farmed fish, thus eliminating the most negative impacts of fish farming and significantly reducing others. Around the world, CSA is producing fish and profits without degrading the rich abundance of oceans, lakes and streams.

Closed system aquaculture provides a better way to farm fish as the global demand for seafood increases and ecological constraints put limits on wild fish supplies. Here is a summary of common aquaculture methods. Salmon are typically farmed this way. Open-net pens allow free exchange of waste, chemicals, parasites and disease.

There is also the potential for farmed fish to escape. Farms can also attract predators, such as marine mammals, that can get tangled in fish farm nets and drown. Ponds: Ponds are semi or fully-enclosed bodies of water. Tilapia and shrimp are typically farmed this way. They can also cause devastating habitat damage. For example, shrimp ponds are a leading cause of mangrove destruction.

There are three main eco-certifications for farmed seafood products, including those produced using these high-risk methods.

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