Trending Science: Climate change is causing fish to disappear

Fish are a major source of food and income for millions of people worldwide. Climate change is here to impact both negatively.

According to findings published in the journal ‘Science’ climate change is endangering fish around the world reducing populations by up to 35 % in coastal regions near China and Japan. Ocean warming has led to a 4 % global decline in sustainable catches. This is the largest amount of fish that can be caught without depleting stocks long term.

“That 4 percent decline sounds small but it’s 1.4 million metric tons of fish from 1930 to 2010” lead researcher Dr Chris Free a quantitative ecologist at the University of California Santa Barbara told ‘The New York Times’. “Fish provide a vital source of protein for over half of the global population and some 56 million people worldwide are supported in some way by marine fisheries.” He added: “The ecosystems in East Asia have seen some of the largest decline in fisheries productivity. And that region is home to some of the largest growing human populations and populations that are highly dependent on seafood.”

Scientists from Rutgers University in the United States used data from 235 fish populations located in 38 ecological regions around the globe. This represents roughly one third of the reported global catch. They examined how the availability of fish for food has changed from 1930 to 2010. The greatest losses in fisheries productivity are seen in the Sea of Japan, North Sea, Iberian Coastal, Kuroshio Current and Celtic-Biscay Shelf ecoregions. Hardest hit are East China Sea and Japan’s Kuroshio Current, where stocks plunged by 15 % to 35 % over the 80-year period.

Are fish in hot water? Blame soaring ocean temperatures

“We were stunned to find that fisheries around the world have already responded to ocean warming” study co-author Malin Pinsky a Rutgers University ecologist told ‘USA Today’. “These aren’t hypothetical changes sometime in the future.”

East Asia supports the fastest-growing populations and has very big seafood demands. Shrinking fish stocks in these regions are troubling because as stocks continue to plummet, East Asian countries could start importing fish from other parts of the world. This will drive up prices. Overfishing also intensifies climate change effects. Removing the largest fish diminishes a population’s reproductive capacity and makes it more vulnerable to global warming over time.

Research shows that not all fish suffered from ocean warming. In fact, some species have benefited from warming waters. There were gains among fish populations in the Labrador-Newfoundland region, the Baltic Sea, the Indian Ocean and the north-east US shelf.

“We hope that this highlights the importance of accounting for the fact that climate change is driving shifts in productivity,” Dr Free told ‘The New York Times’. “Fishery managers need to come up with new innovative ways of accounting for those shifts. That includes reducing catch limits in warm negative years, but it can also include increasing catch limits in cooler positive years. Having regulations that are adaptive to climate change is going to be really important for maximizing food potential.”

Speaking to ‘USA Today’, he gave more proposals: “We recommend that fisheries managers eliminate overfishing, rebuild fisheries and account for climate change in fisheries management decisions.”