Longtan Lake in northeastern Taiwan’s Yilan County is not only famous for its picturesque natural beauty but also renowned for its Distoechodon Tumirostris Eco Park (龍潭湖鯝魚生態園區). The Distoechodon Tumirostris Eco Park is the best place to view Distoechodon tumirostris returning to spawn upstream.
History
Distoechodon tumirostris is a cyprinid species, or ray-finned fish, in the family Xenocyprididae and genus Distoechodon. They are associated with freshwater habitats.
Distoechodon tumirostris were declared extinct by Taiwan’s Council of Agriculture in 1990. However, local villagers surprisingly found them in Longtan Lake in 1994.
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As Distoechodon tumirostris are endangered species and their spawning habit is genuinely impressive, the Longtan Community Development Association, along with residents, thus launched the Rural Regeneration Project to conserve this precious species. With funding subsidized by the Council of Agriculture’s Soil and Water Conservation Bureau, the Distoechodon Tumirostris Eco Park was established in 2013.
The uniqueness of the Distoechodon Tumirostris Eco Park
The Distoechodon Tumirostris Eco Park is located at the waterfront on the southwestern corner of Longtan Lake. It comprises a land area of about 1,200 m2 (12,917 ft2) and a water area of about 3,500 m2 (37,674 ft2).
There is a 30-meter long fish passage with wooden fish ladders in the brook flowing into the lake. In addition, a transparent plastic fishway is erected to facilitate the fish swimming upstream. The plastic fishway is 2 m (6.6 ft) in length and 10 cm (4 in) in diameter and is constructed in the stretch with steep slopes and large drops.
There are two small wooden platforms on the two sides of the brook, from where visitors can view this amazing ecological phenomenon without disturbing the fish spawning.
Characteristics of Distoechodon tumirostris
Distoechodon tumirostris is a freshwater species of fish native to Taiwan. They originally inhabited the Tamsui River system and lakes in northeastern Taiwan’s Yilan County.
This unique species of fish can be used for food. They are bony fish with a laterally compressed body shape. They are flattened from side to side with a small head and a blunt snout. Distoechodon tumirostris can grow to 15-30 cm long and weigh over 1.5 kg (3.3 lb).
Distoechodon tumirostris have a unique survival mechanism. Because they breed in the lake, their spawn is prone to be eaten by many natural predators. Thus, they developed a distinct ecological habit of swimming upstream against the stream’s current to spawn to rid themselves of natural enemies.
Distoechodon tumirostris are referred to as “hān zǐ yú” (literally means “foolish fish” 憨仔魚) by locals because the fish do not dodge when people reach their hands into the water to touch them.
This distinct species usually lives at the bottom of the lake. But they swim up to the surface to prepare for spawning when the lake water temperature is higher, around the time of the Dragon Boat Festival (on the fifth day of the fifth lunar month).
They struggle to swim upstream to spawn in a brook that flows into Longtan Lake around Xiaoman (Grain Buds 小滿), the 8th solar term of a year. It is an amazing ecological phenomenon and is believed to be the only one of its kind in the world.
Spawning typically occurs for about three days. There are 3-4 spawning aggregations per year in Longtan Lake. Each female fish can generally lay about 800-1,000 eggs. The eggs hatch in approximately 2-3 days and the newly hatched fry will work their way back to the lake.
During the spawning period, the pebbles and waterweeds in the brook are strewn with whitish round granules of the Distoechodon tumirostris spawn. However, only about one-third of the spawn successfully hatches into fry.
According to Li Zhiwen, Director General of Longtan Community Development Association, unlike salmon, Distoechodon tumirostris do not die after spawning. Instead, they return to the lake to continue this cycle and spawn multiple times throughout their lives.
Longtan Lake
Longtan Lake used to be one of the “Lanyang Twelve Scenic Wonders.” With about 20 hectares (49 acres), the lake is the largest among the five natural lakes on Lan Yang Plain.
Besides its unique Distoechodon Tumirostris Eco Park and spectacular scenery, nicely paved wooden boardwalks wind along and across the lake. Therefore, Longtan Lake is a great destination where visitors can be in close contact with nature, relax, and explore the ecological conservation of the precious Distoechodon tumirostris.
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