Dam's removal a boon for Formosan salmon
CNATAIPEI -- The removal of a check dam in Shei-Pa National Park in 2011 has led to a dramatic increase in the population of the critically endangered Formosan landlocked salmon, a professor said yesterday.
March 13, 2013, 12:15 am TWN
The number of salmon has grown from fewer than 500 in 2001 to 5,400 this year, said National Chung Hsing University professor Lin Hsing-juh, who embarked on a 10-year project in 2004 with 20 other scholars to monitor and research the fish.
The 15-meter by 3-meter Check Dam No. 1 of the Chichiawan Creek, one of 10 built on the river to reduce channel erosion and prevent sediment from filling a downstream reservoir, was torn down in May 2011.
Lin said the dam left the fish vulnerable to big storms.
When the creek was hit by a typhoon or flooding, the salmon would be flushed from their natural habitat in the creek's upper reaches to points downstream, the research team found.
The cold-water fish would then try to migrate back upstream but could not because of the dam, leaving them to die in the warmer water of the creek's lower reaches, Lin said.
During each major storm, one-third of the Formosan landlocked salmon in the region perished, he said.
The current salmon population has nearly reached the creek's maximum capacity of 5,800 Formosan landlocked salmon, Lin said, but he cautioned that the species still remains at risk from high-mountain vegetables, fruit and tea grown nearby on Wuling Farm.
The nitrates in the fertilizers found in washed-off soil pollute the creek and threaten the Formosan landlocked salmon's ability to breathe, he said.
The species, a holdover from the last Ice Age, needs unpolluted waters to survive and is now found only in the country's Chichiawan Creek and Kaoshan Creek in the upper reaches of the Tachia River.