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coasts and oceans > features > farmed fish gobbling up wild stocks

Farmed fish gobbling up wild stocks

Posted: 18 Feb 2003

by Emma Duncan

Although fish farming is widely believed to take pressure off wild fish, farmed fish like salmon and trout eat feed made from wild-caught fish. And without a change in industry practises, the growing number of farmed fish could eat their way through wild stocks of small pelagic fish � fish in the upper part of the ocean which are a major food source for a number of animals, including orcas, puffins, and other wild fish.

Each year, some 80 million tonnes of wild fish are caught from the world�s oceans. But not all these fish end up on our dinner plates. More than one-third is used to make fishmeal and fish oil. Even this doesn�t all go directly into food or other products: two-thirds goes to make feed for farmed fish.

Fish farms, like this one in the Faeroes::Islands, are a major consumer of fish oil::and fishmeal.::� Maren Esmark/WWF-Canon
Fish farms, like this one in the Faeroes
Islands, are a major consumer of fish oil
and fishmeal.
� Maren Esmark/WWF-Canon

Aquaculture is one of the fastest-growing food industries in the world. The growth of the fish farming sector of the industry is largely fuelled by an ever-increasing demand for high-quality fish such as salmon and trout. These are carnivorous fish that in the wild eat smaller fish, squid, and other crustaceans. When farmed, they are fed pellets made largely of fishmeal and fish oil.

Most fish oil and fishmeal is made from small, bony pelagic fish such as anchovies, pilchards, mackerel, herring, and whiting. Some species are also used for human consumption, but others, known as �industry fish�, are only used for making these products.

Huge quantities

The amount of feed needed for farmed fish is staggering. WWF has calculated that, as a conservative estimate, 4 kilograms of wild-caught fish are needed to produce 1 kilogram of farmed fish. The aquaculture industry currently consumes 70 per cent of the global production of fish oil and 34 per cent of total fishmeal. The salmon and trout fish farming sectors alone consume 53 per cent of the world�s fish oil. And if fish farming continues to grow at the current rate, then by 2010 the aquaculture industry could well be using all of the world�s fish oil and half of its fishmeal.

But small pelagic fish are a finite resource, and many stocks are already fished at � or over � their safe biological limit. A number of fisheries that supply the fish feed industry are located along the coast of Peru and Chile in the southeast Pacific Ocean. In 2001, the UN Food and Agriculture Organisation (FAO) characterised these fisheries as �fully fished�, meaning that they are fished at the maximum safe biological limit. These fish populations also fluctuate under the influence of El Ni�o events, making them particularly sensitive to overfishing. South American pilchard catches, for example, have decreased drastically from 6.5 million tonnes in 1985 to around 60,000 tonnes in 2001 as a result of El Ni�o and overfishing.

North East Atlantic fisheries, the other main source of industry fish, were characterized as fully fished in 1983, and as overfished in 1994. The species most under threat today is blue whiting (Micromesistius poutassou). These fish are harvested outside safe biological limits � the total catch of 1.8 million tonnes in 2001 was more than double the quota recommended by the International Council for the Exploration of the Sea (ICES). ICES scientists fear that if the present fishing effort continues, the stock will collapse.

All this adds up to a feed supply crisis for the fish farming industry.

Competing demands

�Demand for fish oil by the fish feed industry is predicted to exceed available resources within the next decade,� says Maren Esmark, Marine Conservation Officer at WWF-Norway, and co-author of a new report on the fish feed industry. �There is no possibility of sustainably increasing catches in any of the southeast Pacific Ocean fisheries. The situation is no better in the North East Atlantic, where many stocks are already over-exploited.�

It will also be hard to increase the percentage of the catch used for fish oil and fishmeal. Peru and Chile have large human populations and for food-security reasons, both governments advocate the use of fish for human consumption. The EU also forbids the catching of some fish for making fish oil or fishmeal.

Collapse of small pelagic fish stocks is not only a problem for fish farms. The fish species used for fishmeal and fish oil are vital for the marine ecosystem. These fish are prey for other fish, birds, and mammals. Heavy exploitation means less food for cod, haddock, and tuna � all commercially important fish � not to mention seabirds such as puffins and marine mammals such as orcas.

Many marine animals, including Atlantic::puffins (<i>Fratercula arctica</i>), also eat::small pelagic fish.::� Mich�le D�praz/WWF-Canon
Many marine animals, including Atlantic
puffins (Fratercula arctica), also eat
small pelagic fish.
� Mich�le D�praz/WWF-Canon

The irony is that fish farming is widely viewed � and marketed � as a way to take pressure off wild fish.

�Aquaculture can play an important role in providing an adequate supply of fish to consumers,� says Dr Simon Cripps, Director of WWF�s Endangered Seas Programme. �But at present, the practice of using fishmeal and fish oil derived from wild-caught fish means that instead of relieving pressure, fish farming is contributing to an increased pressure on already threatened fish stocks.�

Sustainable fisheries

Sustainable fisheries are possible. Some stocks of Atlantic herring collapsed in the 1960s and 70s but recovered after reduced catches and effective management measures were implemented. Blue whiting stocks in the North East Atlantic are under threat largely because there is no international agreement on the management of this species, and the scientific advice from ICES has not been followed. Improved management would obviously help save these stocks.

Purse seining for herring (Atlanto::scandinavian), one of the small pelagic::fish species used to make fish oil and:: fishmeal.::� Quentin Bates/WWF-Canon
Purse seining for herring (Atlanto
scandinavian), one of the small pelagic
fish species used to make fish oil and
� Quentin Bates/WWF-Canon

There are also alternatives to using wild pelagic fish for fish oil and fishmeal. Increased use of offal from fish caught for human consumption is one potential solution that, for the large part, is currently being wasted. Recent years have seen a trend towards processing fish at sea instead of on land. The result is that vast amounts of fish offal are dumped into the ocean. This offal could, however, be used by the fish feed industry.

The fish farming industry is also looking at non-fish sources of feed. One alternative is to increase the use of vegetable proteins. There are several examples where fishmeal and fish oil can be substantially replaced by alternative protein and oil sources.

But the alternatives have their own problems. Offal from fish higher up the food chain is often too contaminated by dioxins and other chemicals to be used directly. Cleaning is possible, but would raise the price of the fish oil and fishmeal. Not all farmed fish can be fed a completely vegetarian diet. In addition, the harvesting of another suggested feed alternative, krill, could seriously affect the marine ecosystem because krill is an integral part of the food chain.

Whatever solution the fish farm industry finds, it must be sustainable � and not threaten the natural environment.

"The fish farming industry needs to recognise its dependence on natural ecosystems," says Maren Esmark. "Fish used as feed by the industry might be small and not very pretty, but they are an essential part of the marine ecosystem. Farmed fish need to be produced as part of a healthy marine ecosystem, not at its expense. This is the only way that fish farming will ever be sustainable."

Emma Duncan is Managing Editor at WWF International, based in Gland, Switzerland.

Related links:

Food for Thought: the Use of Marine Resources in Fish Feed (WWF Report)

WWF Endangered Seas Programme

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