September 17, 2018, by Tim Radford
Fish can flourish with good management – and a suitable environment. Image: By NOAA (public domain), via Wikimedia Commons
There may indeed be abundant fish in the sea – but only if nations confront overfishing and limit global warming.
LONDON, 17 September, 2018 – US and Japanese scientists have worked out how to encourage more abundant fish populations, deliver more food for human consumption and make more profits for the world’s fishermen and women.
The answer is simple. First, the seagoing nations must introduce effective fisheries management practices.
And second, they must limit global warming to the 2°C already agreed by 195 nations in Paris in 2015.
If these two things happen, then in principle global fishing could be sustainable, and oceans could be highly productive for decades to come. In theory global profits could rise by $14bn a year and the global catch by 217 million tonnes a year.
But, the scientists warn, inaction on either option would mean even more dramatic losses of fish, lower incomes for those working in fishing, and shrinking supplies of protein for an ever-hungrier world.
“If we can adopt sustainable fishing policies and keep global warming at no more than 2°C, we can still realise significant benefits to fisheries”
Right now, the global harvest is 80 million tonnes a year and fish provide 20% of the animal protein for around 3 billion people.
The world’s oceans are warming, and well-established fishing grounds have begun to change as valuable fish migrate to cooler habitats. Researchers have warned that stormier weather promised by climate change could make fishing more dangerous.
The dangerous mix of warmer oceans and greater pressure on fishing grounds could damage the health of the oceans.
But researchers report in the journal Science Advances that they tested possible future outcomes for 915 fish stocks around the world – these constitute up to 67% of present global catch – under alternative scenarios for fisheries management and for climate change.
They thought about the impact of a changing climate on fishes’ productivity and range, under climate regimes in which temperatures rose by no more than 1°C (the world has already warmed by 1°C in the past century) to the 4°C predicted under the notorious business-as-usual scenario, in which nations just go on burning fossil fuels at ever greater rates, to load ever more greenhouse gases into the atmosphere.
“The results from this study are surprisingly positive – if we can adopt sustainable fishing policies and keep global warming at no more than 2°C, we can still realise significant benefits to fisheries across the globe,” said Merrick Burden, senior economist with the Environmental Defense Fund oceans programme and one of the authors.
“But these benefits require action, and this study serves as a wake-up call to governments that they must change the way that fishing takes place or risk losing a crucial opportunity to secure our food supply for generations to come.”
Even if nations co-operate, and save the oceans, there will be losers. Profits in tropical waters will dwindle; equatorial nations – many of them dependent on seafood – will be hardest hit.
Winners and losers
Nearly all species will experience changes in productivity; half of all the species examined will shift their grounds and migrate across national offshore boundaries.
“Even with the right management changes, there will be winners and losers, and we have to tackle this head-on,” said Steven Gaines, dean of the University of California Santa Barbara’s school of environmental science, who led the research.
“Success will require not only emissions reductions but also multilateral cooperation and real changes in fisheries management.
“With our growing global population and the increasing needs for healthy sources of protein, these changes will be critical for meeting the United Nations Sustainable Development Goals.” – Climate News Network
Tim Radford, a founding editor of Climate News Network, worked for The Guardian for 32 years, for most of that time as science editor. He has been covering climate change since 1988.