How can China’s offshore fisheries handle climate change?
How can China’s offshore fisheries handle climate change? chinadialogue ocean
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Climate Change Threatens China’s Offshore Fish Stocks
As climate change brings warmer, more acidic waters to China, its offshore fish stocks are coming under pressure.
A number of fish populations – including the large yellow croaker, sea bream, and sandlance – are at risk, according to a study by researchers based in the US and China, and published in the Proceedings of the National Academy of Sciences (PNAS).
Ocean warming has been more pronounced in China’s offshore waters than almost anywhere else. Winter surface temperatures in the Bohai, Yellow, and East China seas, off the country’s eastern seaboard, rose by nearly 2C from 1958 to 2014 – well above the global average. And with concentrations of atmospheric CO2 rising, more of the gas is absorbed into the ocean, resulting in acidification of surface water. The trend is particularly evident in the coastal waters of southern Jiangsu, the Yangtze estuary, and Hangzhou Bay.
Rapid changes in the marine environment are already threatening species most sensitive to such changes.
The impact of climate change on China’s fisheries is alarming scientists, who say that plenty of research gaps on the issue still need addressing. Aside from the need for a high-level program to meet the challenge at a national level, coastal regions will have to come up with corresponding management approaches that suit their circumstances.
Limited Impact for Now
As the world’s largest fishing country, China’s marine catch for 2020 stood at 11.8 million tonnes, with 2.3 million coming from distant waters, according to a 2022 report by the UN Food and Agriculture Organization. However, the same year, its inland fisheries yield slipped to second in the world – behind India – due to the Yangtze fishing ban, the report stated.
The marine catch was significantly lower than the yearly average of 13.24 million tonnes during the 2010s, the report found. The underlying reason for this was the stress on coastal marine animal stocks caused by decades of overfishing.
In an effort to save the industry from collapse, the government has introduced a series of restrictions in recent years, including fishing moratoriums. However, the effects of climate change, notably warmer and more acidic seas, are piling yet more pressure on the marine ecosystem and fisheries sector.
By analyzing the impact of climate-induced seawater changes on 67 species of marine animals, the PNAS study identified some key characteristics of climate-vulnerable species. These include sensitivity to ocean acidification, subjection to overfishing, tolerance of a narrower range of temperatures, and limited migratory capacity as juveniles.
The 67 animals were split into 28 categories on various taxonomic levels (order, family, genus). Positively, the results showed that populations from only six of these categories are currently exposed to a high level of climatic risk, and that recovery potential is medium or high for those in 21 of the categories. It seems the overall impact of climate change on China’s fisheries at this stage is still fairly limited.
Impact Varies According to Animal Type
The study also found that, interestingly, species most able to withstand stress from overfishing are also the most adaptable to climate change. They generally have a high tolerance for temperature change, a broad diet, strong reproductivity, and a positive capacity for migration, making them more resilient and able to recover from population decline.
By the same token, less adaptable species are more vulnerable. The large yellow croaker, for example, is especially sensitive to ocean acidification, has a very low tolerance for environmental change, and reproduces relatively slowly.
Overexploitation of the species, which was once distributed throughout the coastal seas of eastern China, has caused wild populations to decline significantly. For Professor Tian Yongjun from the Ocean University of China’s College of Fisheries, the real impact of climate change on large yellow croaker may be even more complex and is possibly amplifying the effects of overfishing.
chinadialogueocean.net
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