人教版（2019）必修第二册Unit 2 Wildlife protection单元小测试题详情
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Finding fish is going to get harder as climate change continues to heat the world's oceans. A new study finds that warming seas over the past 80 years have reduced the sustainable catch of 80 species of fish and shellfish. The sustainable catch refers to the amount of some species that can be harvested without doing long-term damage to the health of populations.
Overfishing has made that decline worse, researchers say. Overfishing refers to catching so many fish that the size of the population falls. In some parts of the world, such as the heavily fished Sea of Japan, the decrease is as high as 35 percent. That's a loss of more than one in every three fish.
Researchers examined changes in 235 populations of fish and shellfish between 1930 and 2010. Those fish populations spread far apart across 38 ocean regions. Temperature changes varied from one ocean site to another. But on average over that time, Earth's sea-surface temperatures have risen by about half a degree Celsius.
On average, that warming had caused the sustainable catch to drop by 4.1 percent, the study found. About 8 percent of the fish and shellfish populations the team studied saw losses as a result of the ocean warming. However, about 4 percent of some populations increased. That's because certain species have thrived in warmer waters. One example is a kind of black sea fish. It lives along the northeastern U.S. coast. As warming continues, these fish will reproduce faster until they reach their limit.
About 3.2 billion people worldwide rely on seafood as a source of food. That means it's urgent for commercial fishing fleets(捕鱼船队) and regulators(监管机构) to consider how climate change is affecting the health of all of those fish in the sea.
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