It seemed a good idea at the time. About thirty years ago the problem of the algal build up in sewage treatment plants of the USA was solved introducing the Asian carp, that feeds on them. But since then the fish managed to enter the Mississippi River, proliferated and now ti is making its way toward North America's Great Lakes.
The carp can reach over a metre of length. It is displacing all other fish along the way, altering and reducing the biodiversity along the way. And now the city of Chicago is facing the problem of how to stop the carp from invading Lake Michigan.
One suggestion is to block the access, which would cost about $18 bn. A cheaper option would be to fish them to extinction, transforming it in food. One specialist fish shop in the city already sells carp burger. Add some lemon zest and some pepper… But is there enough demand for carp fillets?
The problem is there, and must be solved soon.