The world is losing fish to eat like hot oceans, study finds


Fish stocks are declining as the oceans heat up, placing a major food and income source at risk for millions of people around the world, according to new research published on Thursday.

The study found that the amount of Seafood that humans could sustainably harvest of a wide range of species declined 4.1 percent from 1930 to 2010, a victim of man-made climate change.

"This 4 percent decline looks small, but it's 1.4 million metric tons of fish from 1930 to 2010," said Chris Free, lead author of the study, published in the journal Science.

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

In general, more fish populations have declined than they did over the eight decades of the study.

The researchers focused on sustainable catches, using a measure developed by the United Nations that quantifies the amount of food that can be harvested repeatedly from a fish base population. "Fisheries are like a bank account and we are trying to live on in the interest," said Dr. Pinsky.

Several previous studies predicted that climate change would lead to fewer oceanic fish in the future, but the new research looked at historical data to determine that the falls had already begun.

"This will be one of those innovative studies that are cited repeatedly," said Trevor Branch, an associate professor at the University of Washington School of Aquatic and Fisheries Science who was not involved in the study. "Most of what I've seen before in terms of the impacts of climate change has been speculative in terms of: We think this is what will happen in the future. This is different. "

The researchers used a dataset of 235 fish populations located in 38 ecological regions around the globe. The detailed data told not only where the fish were, but also how they responded to environmental effects, such as changing the water temperature.

The team compared these data with records that showed how ocean temperatures changed over time, broken down by the various regions. These regional analyzes were important because some parts of the ocean warmed up faster than others.

"So we connect those to whom the populations responded positively, negatively and who did not respond at all," Dr. Pinsky said.

The data revealed some other trends. Fish populations in the cooler parts of their areas tended to outperform those in warmer areas – for those fish, the extra heat was too much. This was especially troubling to the researchers, because the data they used was less detailed in the tropics. Fish losses in these regions may have been higher than in the regions where the study was concentrated, Dr. Pinsky said.


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