Though measuring only 20 centimeters long and with numbers of less than 100, the Taiwan trout has been receiving considerable attention as of late. In the past two years, the Council of Agriculture has spent NT$10 million (US$250,000) on the fish's behalf. Biologists have commissioned the construction of research stations at its breeding grounds in upper Taichia Creek and have studied its native ecology. Plans have been drawn up for raising the fish, even to the point of hiring retired army personnel to aid with security. During the building of the research station, officials and scholars of all stripes came to "supervise" the construction.
Over 150 different kinds of fish swim in Taiwan's rivers and lakes. What makes the Taiwan trout so special?
"In principle," says Tseng Ch'ing hsien of the National Taiwan Science Education Centre, "there should be no trout in Taiwan." Trout belong to moderate temperature regions, swimming in water of 16℃. In the semi-tropical climate of Taiwan, only in waters 1500 meters above sea level can such temperatures be found.
The first formal finding of this quirk in nature came in 1935, in a paper by the Japanese chemist Oshima. He reported that in 1917 a quirk technician, making a survey of fresh-water fish in the mountains of Ilan County, encountered a policeman who told him that local aborigines frequently caught trout. The technician at first discounted the report, but later wrote of his finding to Oshima, then studying at Stanford University with the noted ichthyologist Jordan. The men paid little heed, but Oshima proceeded to come to Taiwan. He caught a specimen and sent it to Jordan for a thorough investigation, which disclosed that the fish was indeed a trout. Oshima continued his research and published a comparison between trout as found in Japan and Taiwan. This small fish thus became the first rare animal from Taiwan to achieve international prominence.
Taiwan trout used to resemble like species in moderate climes in that they returned home from the sea to spawn. Females would return to their original birthplace, lay their eggs, and then die. Males on the other hand, would go back to the sea once again. Newly-hatched fish would remain in their native waters to grow for a spell, and then swim out to the sea, continuing the life cycle.
How do the fish remember the way back to their native stream? "Some say that every stream has its own individual scent. Others say fish have a sense of direction, preventing them from becoming lost. Still another opinion claims fish rely on the earth's magnetic force to guide their way home. But there is no real definite answer," concludes Tseng Ch'ing-hsien.
During the Ice Age, Taiwan trout were plentiful. Later, the earth's crust shifted, and the present topography of Taiwan began to take shape. The temperature rose, and peaceful, level rivers became quick-flowing streams spanning different elevations. Only the upper reaches of Tachia Creek retained its original, level topography and lower temperatures, making it suitable for the Taiwan trout. Later, construction of a dam prevented the passage of the fish to the sea, turning it into a fresh-water trout.
In his research, Oshima noted the presence of red stripes on the fish's sides, and some people today still mistake the Taiwan trout for a relative of the Japanese salmon. Nevertheless, such red-striped specimens are a minority. After spawning season, their color usually turns a shade of yellow, resembling the fresh-water variety found in Japan. Fresh-water trout can be found in Manchuria, South Korea, Japan, and Tachia Creek, serving as living evidence of Taiwan's former attachment to the Asian continent.
A further look at Oshima's research shows that compared with other trout, the Taiwan trout tends to have fewer spots on its back, with fewer ribs in its fins. The color of its side spots are quite clear, and the combination of these features make the fish unique to Taiwan.
Overfishing substantially cut the number of Taiwan trout. A staple of the diet of local aborigines, the fish has been unable to sustain its former population in the face of advances in fishing techniques. One hopes that its current special treatment can allow it to recover some of its previous abundance.
