Source: Central News Agency

Taipei, Sept. 4 (CNA) Taiwan has received data from a yellowfin tuna that it tagged and released into the ocean in 2008 in a study of the fish's migration habits, a researcher said Friday.
The tuna, one of 786 that were hatched and released by Taiwan's premier fisheries institute, was caught by Japanese fishermen April 28 in waters off the Amami Islands, located between Okinawa Island and Kyushu, southern Japan, the institute reported.

The fishermen sent the tag from the fish to the Japan Fisheries Agency, which passed on the data to the Taiwan Coastal and Offshore Resources Research Center of the Fisheries Research Institute under the Council of Agriculture, according to the center's director Wu Lung-ching.

The data, which is vital in the research of yellowfins' movement in the waters around Taiwan and their migratory habits, showed that the tuna had traveled the longest distance ever recorded for yellowfins released from Taiwan hatcheries, Wu said.

He said the yellowfins each weighed around 2 kilograms and were 35 centimeters long when they were released on Oct. 25, 2008 in waters southeast of Lamay Island, a coral islet that lies 15 km west of Tungkang in Pingtung County, southern Taiwan.

But surprisingly, the fish that was caught was still the same size after six months, he said. The institute is trying to come up with an explanation for this bizarre finding, he added.

Wu said it is important to know the migratory path of yellowfins in the waters off southwestern Taiwan in order to promote conservation of the species, which is one of the most popular seafoods in the world.

Researchers are trying to determine whether the yellowfin tunas swim from Penghu Islands off southwest Taiwan northward to Japan along the Taiwan Strait, or if they swim to the east coast of Taiwan then follow the Black Tide to Japan, Wu said.

The research could help the institute to devise plans to prevent over-fishing of yellowfins in waters around Taiwan, he said.

In addition, the results of the research will be shared with the international community to develop integrated conservation of marine resources, he added.

According to Wu, some 1,000 tons of yellowfin tuna are caught in Taiwan waters each year, which is a tiny percentage of the 800,000 tons taken worldwide annually.

Yellowfins are widely distributed in tropical and sub-tropical waters of the Atlantic, Pacific and Indian Ocean. Yellowfins are also found in Canadian waters along the edge of the Gulf Stream and Georges Bank, the Scotian Shelf and the Grand Banks.

Commercially harvested yellowfins range from 30 to 170 cm in length and weigh up to 100 kg.

The fish has a dark blue-to-black colored back, with silvery sides and bright yellow fins.

(By Elizabeth Hsu)