Thousands of goldfish threaten a whole lake ecosystem

Officials in the US are seeking information on the person(s) responsible for releasing goldfish into a Colorado lake.

The alien goldfish have multiplied so successfully that what may have started out as four or five unwanted pets released a couple of years ago into Teller Lake #5 in Boulder, has become a population of 4,000 or more.


Fish that are being threatened by the goldfish include channel catfish, bluegills and sunfish.

Wildlife officials say they have two options: draining the lake and rebuilding the natural fish stock from scratch, or electrofishing the lake to collect the goldfish, which would then be sent to a raptor rehabilitation centre for food.

"Most people don't realise the far-reaching effects of introducing exotic species to the environment," said Ken Kehmeier, senior aquatic biologist for Colorado Parks and Wildlife (CPW).


Also of concern is the "bucket brigade" — anglers who choose to dump sport fish of their choosing into Colorado waters. While some non-native fish are stocked at times, aquatic biologists only do so after a rigorous biological assessment to determine what can be stocked and where for a balanced ecosystem.

