Eating fish - but wild-caught or cultivated?

Fish is, in principle, health food, and also good in terms of climate change. As insect eating has recently been advocated as an environmentally friendly way of actually eating meat, one needs to point out that from energetic grounds fish eating is just as good. Both insects and fish are ectothermic animals, which convert feed to meat at much higher efficiency than cows or swine, because no energy needs to be wasted to maintaining body temperature.

So, it is good to eat fish, but should it be wild-caught or cultured? The world's seas are heavily overfished. The gloomiest predictions estimate that close to half of commercially fished species become extinct within the next century. Despite the overfishing, several nations and the European Union have given large funds to the development of fishing fleets, and more effective fishing gear. At the same time the same instances have pledged to maintain the biodiversity. So, the actions are in fact opposite to promises and only serve to speed up the decrease of biodiversity. In addition to fishing causing the exctinction of species, the problem with wild-caught fish is aquatic pollution. Most pollutants are taken up and remain in the bodies of fish, because they are hydrophobic, whereby their preferred site is the body and not water. Many of the pollutants further bioaccumulate along the food chain.

So, eating wild fish is, in principle, a worse alternative than eating cultured fish. However, there are several things that make the present aquaculture practises problematic for ecologically responsible fish-eater. First, most cultured fish are carnivorous, and their feed largely consists of fish flour. So, in such a case the big fishing fleets will continue to decrease the fish diversity, now not to get food for humans, but to get resources for feed factories. The only sustainable way is to replace some of the fish flour in feed with plant product. This is a direction to which several fish feed companies have recently gone to. Second, aquaculture causes local eutrophication because of the feed and faeces, which have high amounts of nutrients. The way of prevent this would be to have aquaculture facilities separated from general aquatic environment so that all the water used could be purified. One should here point out that the cultured fish do not produce more faeces than the natural populations - the difference is that they are concentrated in much smaller areas. Third, the use of antibiotics and other drugs in aquaculture facilities is high, because parasites and diseases are much more prevalent in the dense aquaculture  populations than in the natural populations. For improvement of situation with regard to this, it would also help, if the aquaculture facilities were separated from natural wateeeeer flow. Also, the use of antibiotics should be discouraged.

In conclusion, it is possible to make aquaculture environmentally friendly, but after that is done, cultured fish will not be the cheapest food that can be found. But we should be ready to use some money to use ecologically sustainable foodstuffs.