Aquaculture

Abstract

The farming of aquatic plants and animals is known as aquaculture. The production of fish, crustaceans and shellfish by aquaculture has become the fastest-growing animal food sector in the world. Today, aquaculture supplies an estimated 43% of all fish that is consumed by humans globally.

Species that dominate world aquaculture are those at the lower end of the food chain, that is, aquatic plants, shellfish, herbivorous fish (plant-eating) and omnivorous fish (eating both plants and animals). However, marine aquaculture of carnivorous (animal eating) species is also increasing, most notably salmon and shrimp and, more recently, other marine finfish.

The growth of commercial aquaculture has brought with it more intensified methods of production. In some instances, particularly for carnivorous species, intensive methods of aquaculture have created serious environmental problems. There have also been human rights abuses associated with commercial aquaculture in a number of countries. The environmental and negative human rights impacts associated with intensive methods of aquaculture production are discussed in this chapter, using the examples of salmon farming and shrimp farming.

Of further concern is the growing dependence of aquaculture on fishmeal, fish oil or low value fish as feed. Many of the so-called ‘industrial fisheries’ that are used to supply fish for reduction to fishmeal and fish oil are unsustainable. In addition, the production of carnivorous species by aquaculture requires more wild-caught fish as feed, by weight, than the overall output of the farmed fish. Hence there is a net loss of fish protein in the farming of carnivorous species. In cases where the wild-caught fish used as feed can also be consumed by humans, the issue of food security is raised.

Much work has been done on trying to replace fish-based feeds with plant-based feeds. For some herbivorous and omnivorous fish, it has been possible to replace completely any fishmeal in the diet with plant-based feedstuffs, without impacting on fish growth. Therefore, cultivating such species in this way suggests a more sustainable future path for aquaculture so long as the plant feedstuffs are derived from sustainable sources. However, for carnivorous finfish, it has not been possible so far to replace fishmeal and fish oil completely in the diet.

In order for aquaculture operations to move towards sustainable production, the industry needs to recognise and address the full spectrum of environmental and societal impacts caused by its operations. Essentially, this means that it will no longer be acceptable for the industry to place burdens of production (such as the disposal of waste) onto the wider environment. In turn, this implies moving towards closed production systems. A series of recommendations by Greenpeace are given towards promoting aquaculture that is both sustainable and fair.