Tuna catches have fallen by 80 per cent in the past 20 years.

The amount of fish in the world's oceans is dwindling fast because of unsustainable fishing practices. This has led to an increasing reliance on fish farming, which many object to because it has caused widespread destruction of coastal ecosystems and pollution.

But fish farming will continue to expand, argues John Marra in this article in Nature. He says opposition to the industry is futile; what is important is ensuring that fish farming is made sustainable.

Marra says that key issues for the marine research agenda should be to identify which fish species can be bred sustainably in captivity, where fish farms should be situated, and how fish farms should be constructed.

Farming fish in offshore enclosures instead of coastal ponds would, for instance, reduce pollution and the impact on coastal ecosystems, but could cost much more. Research can help identify the most sustainable and practical options, he says.

Ultimately, countries will need to stop competing for limited fish stocks and start thinking about ways to protect those that remain, says Marra. 

Link to full article in Nature