Large koi fish dumped in McKenzie River near Eugene

PORTLAND, Ore. (KOIN) -- A large koi fish was spotted and removed from the McKenzie River near Eugene after a report to the Oregon Invasive Species Hotline on Wednesday.

The Oregon Department of Fish and Wildlife says the koi was likely intentionally dumped. This is sparking concerns about its potential impact, as they are a non-native species that could irreversibly disrupt the environment.

According to ODFW, koi can reproduce rapidly, lay up to 500,000 eggs and survive harsh winters. They also compete with native fish for food, as well as disturb the plants that keep the riverbed free of silt.

ODFW also warns that once invasive species are introduced, they are nearly impossible to eradicate.

“Introduced, non-native fish can spread deadly diseases to wild fish populations,” said Jeff Ziller, an ODFW fish biologist. “There are plenty of examples in other states and countries where koi have damaged or changed aquatic ecosystems so extensively that vast amounts of public resources have been allocated to eradicate them, largely unsuccessfully."

As a result, ODFW is urging people not to dump unwanted fish or aquarium contents into waterways and to report sightings of invasive species to 1-866-INVADER.