Koi fish, which are an invasive species, have been introduced to Mashpee Pond in Massachusetts. Bottom feeders, koi can increase turbidity and reduce the amount of vegetation available to native species. "By virtue of their feeding habit they can cause siltation of the water which can affect the water quality," said Mashpee Conservation Agent Andrew McManus.
And there is really only one solution to the problem, a recreational solution for many. "Basically, it's just by fishing," said McManus. "Bow and arrow, spear fishing or just normal pole fishing. But that is really the only mechanism that you can use to try and get them out of the pond."
While some koi are incapable of producing, if the introduced fish are capable, and aren't fished out within a few years, the impact of their presence will be noticeable. The full article is available here or through the link below.