ODFW release – SALEM, Ore. – ODFW has recently received several calls regarding the release of koi into Cottage Grove Reservoir. Please call Oregon State Police at (800) 442-0776 if you have information about illegal invasive species releases. The ODFW Springfield office received the first report on May 30, 2024, but there are rumors that koi may have been released up to 4 years ago. One angler estimated seeing 300 koi in a day. If you catch koi in Cottage Grove Reservoir, please do not release them back into the reservoir alive ODFW conducted an extensive boat electro-fishing survey in 2018 and no koi were encountered at that time. Koi are colorful variants of carp originally bred in Central Europe and Asia and are sold around the world as ornamental aquatic pets. Koi can live up to 25 years, reproduce rapidly, and can survive very cold winters. An 8-10 inch koi can produce 5,000 – 10,000, eggs and the largest koi can lay 500,000 eggs. They are omnivores with a voracious appetite, consuming fish and amphibian eggs, aquatic insects, and competing with native fish for food. Koi also stir up sediment while uprooting and consuming aquatic plants which can reduce forage and cover for waterfowl and other animals. Introduced fish can also spread deadly diseases to wild fish populations. There are many 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. Once non-native species are introduced to a waterbody, they are nearly impossible to remove. Help spread the word to never dump unwanted fish or aquarium contents in or near waterways, streams, ponds, lakes, or stormwater drains. It can have serious ecological consequences and can ruin recreational opportunities for future generations of Oregonians.
