The Black Tide, which usually flows from the Philippines to the Japanese archipelago, bringing warm tropical currents northward via the corridor along Taiwan's east coast, has deviated some 100 nautical miles further east of Taiwan this year, according to the Fisheries Research Institute under the Cabinet-level Council of Agriculture.

Researchers at the institute believe that the rare deviation could have resulted from global warming and El Nino conditions.

Singang port in the eastern county of Taitung, one of the major fishing areas in Taiwan, reported marlin and sword fish catches totaling only about 2,500 kg per day this season, compared to a daily average of 4,000 kg in past years, said Tsai Fu-rung, chairman of the Singang Fishermen's Association.

"The value of the catch has also declined to some NT$88 million (US$2.7 million) a year from the previous NT$120 million per year, " Tsai said.

Fishermen from the northeastern fishing port of Suao said that each year they have had to go further and further afield because the fishing grounds off the coast are shrinking.

"In addition to drastic climate changes, increasingly depleted fish stocks have also led to an annual decline in our catch, " said Lin Yueh-ying, chairwoman of the Suao Fishermen's Association.

The fishermen's association in Hengchun in Taiwan's southernmost county of Pingtung said its boats have caught only about 2,500 fishes of southern bluefin tuna fish this season, which is the smallest catch in 10 years.

Southern bluefin tuna, also known as toro in Japanese, is a high-priced fish that is used mainly to make sashimi.

(By Deborah Kuo)