Fishermen, TaiPower seek to save aquatic ecosystem at Sun Moon Lake

This article was published by the Taiwan Headlines on September 22, 2006. It reports that in recent years, the aquatic ecosystem at central Taiwan's Sun Moon Lake has been damaged by the introduction of foreign freshwater fish and shellfish, such as mussels and a type of fish known as glass sweepers. The glass sweepers have consumed a large number of eggs laid by the local sharpbelly fish. Meanwhile, the number of freshwater mussels has increased to the point that they are damaging the facilities of a hydroelectric plant located at the lake.

To counter these problems, local government officials, fishermen and workers at Taiwan Power's Takuan electricity plant recently released over 70,000 small fish from seven species, into the Sun Moon Lake. The aim is to balance the ecosystem in the lake and get the lake's freshwater mussel population under control.

Since 1988, the electricity plant has been releasing small fish into the Sun Moon Lake every year. Workers at the plant carry out discussions with local fishermen associations on which species of fish should be used to populate the lake. In 2006, of the 71,500 small fish released, the snakehead fish comprised the largest number, amounting to 21,000. Meanwhile, a total of 18,000 president fish were released, as well as 16,500 bighead carp. Finally, 8,000 small local carp and black carp each were released into the lake.

According to this article, a large number of mussels, which are not native to the lake, have been clogging pipes from which the plant sucks in water in order to generate electricity. In particular, the Danshui mussel and several other types have an extraordinary ability to affix themselves to things; they also have a special fishy smell. In addition to clogging the electricity plant's pipes, the mussels also affix themselves to screening gates. For example, in 1994, the number of the mussels had expanded to such a degree that they literally forced the collapse of the electricity plant's screening gates. The electricity plant then decided that it had to do something about the mussels and began releasing fish into the lake that would prey on them.

Initially, the electricity plant only released snakehead fish in the hope that they would eat the offensive mussels. As time went by, workers discovered that local carp also ate mussels. Better, they found that bighead carp ate mussels in their planktonic larval stage. Indeed, over the past several years, in order to improve the Sun Moon Lake's aquatic environment and to benefit local fishermen, the electricity plant has been consulting with the area's fishermen associations and releasing several other types of fish into the lake.

As for the increasing number of glass sweepers, which people have raised and then discarded into the lake, local fishermen have yet to find a natural predator for them. The glass sweepers reproduce rapidly, and they love to eat the president fish and fish larvae. As a result, the president fish is on the verge of extinction in the Sun Moon Lake.