The report on the impact of climate change on Taiwan’s coastal fishery industry reveals that surface water temperatures have risen by 0.7 degrees Celsius over the past 27 years in the southwest coastal waters.
According to Lee’s research team, the marked drop in grey mullet, black pomfret and neritic squid yields can be attributed to the effects of the warming climate.
The report notes that Taiwan’s southwest coastal waters are a breeding ground for the grey mullet, which return to the area along with the southward flowing China Coastal Current in the winter season to lay eggs.
During the period between 1976 and 1985, the average annual yield of grey mullet in these waters stood at roughly 1.25 million. However, due to rising surface water temperatures and the strengthening flow of the warm Kuroshio Current, the annual yield has averaged less than 500,000 since 1990, the report says.
In addition, the reduction in the north-bound flow of water from the Yangtze River into the ocean caused by the construction of the Three Gorges Dam has had an impact on the grey mullet’s habitat and source of food at the mouth of the river, resulting in a further reduction in the fish’s numbers.
The strengthening of the Kuroshio Current and the weakening of the China Coastal Current have made it more difficult for the grey mullet to migrate back to their breeding grounds in Taiwan’s southwest coastal waters, the report claims.
It also found that gray mullet have been caught by fishermen in the stretch of coastal waters between Keelung in northern Taiwan and Yilan in the northeast in recent years. Whether this indicates the emergence of new migratory paths and breeding grounds for the fish species requires further investigation, according to the report.
Lee said that the speed of ocean changes has been much quicker than scientists had initially anticipated. He added that the question of how to ensure marine resources and human sustainability would be an important theme of future research work in this area. (SB)