More than half the world’s oceans are being fished by industrial vessels, new research reveals. The maps based on feedback from more than 70,000 vessels show commercial fishing covers a greater surface area than agriculture and will raise fresh questions about the health of oceans and sustainability of trawler fishing. The data, published in the journal Science, also shows how fishing declines sharply at weekends and celebrations like Christmas and Chinese new year. The data also helps to explain the extreme decline in some fish stocks: the UN’s Food and Agriculture Organisation (FAO) says one-third of commercial fish stocks are being caught at unsustainable levels. But the clear impact of cultural and political events on fishing also offers hope that humans can restrain overfishing, said the report’s author, David Kroodsma. “What that means is we have control as humans to decide how we’re fishing the oceans: we’re not destined to overfish, we can control it,” said Kroodsma.
Kroodsma and colleagues gathered 22bn pieces of information from satellite systems installed in the biggest fishing vessels, and some smaller ones, usually operating closer to shore. From this work from 2014 to 2016 they produced maps of where fishing activity was happening, and where it was the most intense. The blue to yellow colouring showing fishing activity covers most of the world’s oceans (see map below). Exceptions are the vast Southern Ocean, far from home and suffering extreme cold and dramatic storms; and striking black “holes” in more heavily used seas, which are either lesser-used exclusive economic zones, and “deserts” in the seas where there are too few fish and crustaceans to catch. Latest estimates have suggested the extent of fishing was even greater, but faced with such intense data and dramatic maps, the team were still stunned by how far the biggest ships roamed. “It is really surprising to look at the map and see how much fishing there is,” said Kroodsma.
The research was led by Kroodsma, research and development director for US-based charity Global Fishing Watch, part-funded by Google and supported by actor Leonardo DiCaprio. The paper is written with academics from the universities of California, Stanford and Dalhousie in Canada, plus National Geographic and Google. Among other findings is that five countries account for 85% of commercial fishing measured by hours at sea. Half of that is China; other large-scale operators include Spain, Japan, South Korea, and Taiwan – which is smaller than Switzerland, and with a population of just 23 million. On average, every person on the planet eats 20kg of fish each year, with the FAO’s estimates suggesting this makes up 6.7% to 17% of protein eaten. The figure is much higher in some developing countries, however, where people on islands and in coastal areas rely heavily on fish for their energy, up to 70% of the protein in some cases. The fish protein being measured is also caught in inland waters, and aquaculture, the controversial practice of large-scale fish farming, has expanded rapidly in recent years. The data – which without the satellite systems fitted on fishing vessels would have taken a fisheries’ expert 200 years working full-time to achieve – showed the “human face” of fishing, said Elvira Poloczanska of the research group, the Alfred Wegener Institute of Ecophysiology in Germany. “High-seas fisheries governance has the potential to reduce the risks from climate change – for example through international co-operation and the closure of high-seas areas to fishing,” she added.
Credit: Juliette Jowitt for The Guardian, 22 February 2018.