Marine problems: Aquaculture

Farming of fish, shrimp, and shellfish is often is viewed - and marketed - as a way to take pressure off wild fisheries. But some types of aquaculture are actually increasing pressure on several already threatened marine species.
 / ©: WWF
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Aerial shot of fish ponds with mangroves in the background. rel=
Aquaculture farm, Madagascar.
© Bertrand Coûteaux

Aquaculture is a huge industry, and the world's fastest growing food sector. It's worth a massive US$56 billion globally and provides one-third of the fish people consume.

When done properly, some forms of aquaculture can indeed help take pressure off wild fisheries and provide needed income to coastal communities.

However, as production rises, so too can aquaculture's impacts on the environment and wild marine species, through:

The severity of these impacts depends upon the species being farmed. Oyster and clam farms, for example, have fewer impacts than shrimp and salmon farms, which in turn have fewer impacts than tuna farms.

However, the detrimental impacts can be huge, and have even proven disastrous in some parts of the world. Impacts on local marine biodiversity can in turn cause problems for local communities that rely on marine resources for their livelihoods.

Wild Atlantic salmon in crisis

Atlantic salmon farm, Canada. / ©: WWF-Canon / WWF-Canada / Robert Rangeley
Atlantic salmon farm, Canada.
© WWF-Canon / WWF-Canada / Robert Rangeley
Wild Atlantic salmon populations have plummeted precipitously over the past three decades. And farmed salmon are putting added pressure on the remaining wild populations.
Salmon catches in the North Atlantic Ocean fell by more than 80% between 1970 and the end of the 20th century. Today catches stand at the lowest levels in known history. Wild Atlantic salmon have disappeared from much of their original range, and are hanging on by a thread in many other locations.

Over the same time period, farmed salmon production in the North Atlantic Ocean has increased 55-fold, reaching 700,000 tonnes in 2002. Threats from salmon farming are now adding to the pressure on wild salmon.

In Norway, where almost half the remaining populations of wild Atlantic salmon still survive, escaped farmed fish are invading the sea and rivers where wild salmon are struggling to survive. Norwegian wild salmon are also under threat from infestations of sealice from salmon farms. There are indications that sealice infestations could also affect wild salmon on the west coast of Canada.

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