Half of the fish consumed in the Netherlands comes from aquaculture. Aquaculture looks like the answer to overfishing, but farmed fish is not always more sustainable than wild-caught fish. The farming of fish can also create environmental problems. The effects on the environment depend on the chosen farming system and fish species. The assessments are based on an average situation in a country. There are often individual companies that have better practices. We stimulate wholesalers to search for these companies. There is also farmed fish with the Aquaculture Stewardship Council (ASC) certification. These fish are guaranteed responsibly farmed.
Effects on the Environment
A farming system can have an open connection to the environment, with e.g. a sea or river. This causes the following problems:
-Pollution of the surface water with faeces, medicines and chemicals
-Spread of diseases and parasites by infection of wild animals.
-Crossbreeding of escaped farmed fish and wild fish. The genetic characteristics of farmed fish are focused on growth-characteristics.
A closed farming system, that does not have an open connection to the environment, does not have these negative effects.
Carnivore or herbivore
The amount of fish feed, fish meal and fish oil to farm a kilogram of fish differs with species. Species like salmon, turbot and eel need a lot of fish meal and fish oil. The less fish oil and fish meal a fish needs, the more sustainable the fish is. To make fish oil and fish meal, wild-caught fish is needed. This can lead to overfishing. For example, to produce 1 kilogram of salmon an average of 2 kilogram of wild fish is needed.
Juvenile fish from the sea or not
Most species can reproduce in captivity. The farming of eel, tuna and mussels however depend on wild-caught juvenile fish or shellfish (seed). By taking these out of the sea and grow them for consumption, the problems of overfishing of endangered species or harmful catching methods won’t go away.