Study reveals world is losing fish to eat as oceans warm up



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Fish populations are dwindling as the oceans warm, threatening an essential source of food and income for millions of people around the world, according to a new study released Thursday.

The study found that the amount of Seafood that humans could sustainably harvest from a wide range of species decreased by 4.1% from 1930 to 2010, a victim of climate change caused by humans.

"This 4% drop seems small, but it was 1.4 million tonnes of fish from 1930 to 2010," said Chris Free, lead author of the study, which appears in the journal Science.

Scientists have warned that global warming will put pressure on global food supplies in the coming decades. But new discoveries – separating the effects of water warming from other factors, such as overfishing – suggest that climate change is already having a serious impact on seafood.

Overall, the number of fish declined during the eight decades studied.

Researchers focused on sustainable catches, using a measure developed by the UN that quantifies the amount of food that can be harvested repeatedly from a base population of fish. "Fishing is like a bank account and we try to live with interest," said Dr. Pinsky.

Several previous studies had predicted that climate change would reduce the number of marine fish in the future, but new research looked at historical data to determine that declines had already begun.

"This is one of those innovative studies that will be cited over and over again," said Trevor Branch, associate professor at the School of Aquatic and Fisheries Sciences at the University of Washington, who did not participate in the study. study. "Most of what I've seen before in terms of the impact of climate change has been speculative:" We think that's what will happen in the future. "It's different."

The researchers used a dataset of 235 fish populations in 38 ecological regions of the world. The detailed data told them not only where the fish were, but also how they reacted to environmental effects such as changes in water temperature.

The team compared these data with records showing that ocean temperature has changed over time, broken down by region. These regional analyzes were important because some parts of the ocean warmed up faster than others.

"We then matched the populations to which the populations responded positively, negatively and not at all," said Dr. Pinsky.

The data revealed other trends. Fish populations in the coldest parts of their range tend to perform better than those in warmer areas – for these fish, the extra heat was too much. This was particularly troubling for researchers because the data they used was less detailed in the tropics. Fish losses in these areas may have been higher than in the areas studied, Dr. Pinsky said.

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