Bivalve molluscs are motionless and feed on nutrients available in the water that surrounds them (zooplankton and phytoplankton). Due to their particular alimentation, they grow without altering significantly in size. They do not require special technological appliance to grow (they can grow on a simple rope placed in the sea), and lastly, they don’t need feeding.

This type of aquaculture is called extensive. They have been farming this way since ancient times in the majority of world and local markets for self-consumption or for trading, especially in Asia and particularly in China (where they farm 70% of the world’s total production of molluscs today).

In the Mediterranean Sea, half of aquaculture is extensive. In this area, they mainly farm mussels, oysters and clams.

Fish and Crustaceans

Breeding carnivorous or crustacean fish (worms that feed on fish, larvae...) is a different story: it is necessary to feed them. Therefore, they have to be farmed in big amounts and thus small scale harvest is not worth investing in. On the contrary, farming this type of fish is a complex activity: they require facilities (swimming pools or special cages in the sea) with a certain level of technology (the water has to be controlled for oxygen, pH, temperature, etc). Their food has to be manufactured (it needs to be consistent in flours, fish oils and cereals). A genetic selection is done in order to obtain special fish varieties that are can grow in captivity or that have certain desired characteristics. In this type of fish farms, a large amount of fish is being farmed together so the risk of diseases being spread is high and therefore, medicine such as antiparasites, vaccines or antibiotics have to be supplied. Color additives are also given to them (they normally take these from sea nutrients). This type of aquaculture is called intensive.

As this type of fish farming requires high investments, it is only viable in countries which can afford it; such as the North. In Spain, intensive aquaculture is only a tenth of the total agriculture but more than half of the overall revenue. Such fish farms are managed by large companies usually from Northern countries, however, in some cases their physical location is in Southern countries.

As we will see in the paragraphs below, fish farming does impact not only the sea itself (waste from swimming pools and sea cages causes concentration of organic matter that is superior to natural matter found in sea water, and fish that escape from the sea cages spread their disease and alter the marine genetic diversity) but also the populations of the related countries.

Is aquaculture the solution?

The FAO foresees that by 2030, aquaculture (extensive and intensive) will provide most of our fish consumption. Aquaculture is often seen as the solution to reducing fishing, and even the key to providing animal protein to the world. However, there is a major drawback in intensive aquaculture: currently the amount of fish used to make flours to feed farmed fish is a third of the total fish captured at sea, and there is no prediction that this number will be reduced. Anchoveta is the most common fish used to make fish flour and the two largest anchoveta farms are overexploited. Farms producing four out of the five most common fish used for fish flour are also overexploited.

Pro aquaculture sectors state that 90% of fish spices used for making fish flours do not have significant alternative markets for human consumption. They also affirm that, a good part of fish farms used for making fish flour are in peripheral countries, and exporting these fish provides them with valuable income. Critical sectors maintain that these types of fish do have alternatives for human consumption.

In Peru, anchoveta fishing is so disproportional (farming is five times bigger than the maximum capture allowed in years of abundance) that the five mile zone reserved for anchoveta fishing affects fishing for local consumption which has been reduced by 40% in six years. Today, a quarter of the total fish caught by traditional fishing is only crabs, which is not widely consumed and so does not provide a good income to local fishermen. The population has traditionally survived on eating anchoveta which is now difficult to catch. One out of five Peruvian children suffers malnutrition, and this could be reduced to half if 10% of the total anchoveta farming was given to local consumption.1

Peru is by far the world’s main producer of fish flour. A study carried out by the World Wide Bank in 2006, states that this economic activity causes considerable rent losses and significant environmental and social costs for the Peruvian State, and generates high external income that benefit only a minimum fraction of the industry. For example, the Peruvian state gains 5 dollars for each ton of exported flour, when the normal market price is between 600 and 1.400 dollars. Profits of only one company (the most important one in Peru) are 10 times bigger that the total income the state gets from the fishing industry.1

Chile is the world’s main salmon producer and it exports almost all of it (98%) to the United States, Europe and Japan. Twelve companies control 71% of the salmon exportation and only 6 of these companies are from Chile. For every 100 dollars gained from exporting salmon, only 4 dollars are given to wages and 40 dollars are the company’s profit. In the 90s, the region where salmon is caught went from being sixth in providing family income to being the penultimate (eleventh out of twelve). This region has some of the most serious problems in education and social vulnerability of the whole country.2

1. Brian O’Riordan: Fishmeal fishery: Golden goose or albatross? Samudra Report n. 46, International Collective in Support of Fishworkers, March 2007.
2. Ferran García: Salmones en Chile. El negocio de comerse el mar. Veterinarios sin Fronteras 2005.