An invasive Asian carp species has been found just 9 miles away from Lake Michigan!

The term “Asian carp” is used for a number of species, but what they all got in common is that they are originally from Asia (or at least partially from Asia), belong to the family Cyprinidae, and are considered an invasive species in the United States. These fish tend to be able to do great damage to local ponds, lakes or rivers if they were to be released, and some lakes have already had their entire ecosystem ruined by one of these species.

Just a few days ago a commercial fisherman found an Asian carp in Calumet River, just 9 miles away from Lake Michigan; the largest freshwater lake in the entire world. The fish he found was a 71 centimeter long silver carp (Hypophthalmichthys molitrix)! This is terrible news for this aquatic system, and if there are more fish of the same species present, they might breed and make lots of fry. A single pair of silver carp can lay over 500,000 eggs during a single breeding, and the population of the fish will have an exponential growth.

A pair of juvenile silver carps (Hypophthalmichthys molitrix). Image by Mirko Barthel, posted with the Creative Commons Attribution-Share Alike 3.0 Unported license.

What is really troublesome is that the silver carp has a huge capability to destroy the ecosystem in Lake Michigan if it were to reach it. It will prey on ciscos (Coregonus sp.), bloaters (Coregonus hoyi), and yellow perch (Perca flavescens), and have no natural predators. The lake trout and walleye will not be directly predated by the silver carp, but they will lose their source of food, and most likely decrease dramatically in numbers.

Lake Michigan. Image by Ken Lund, posted with the Creative Commons Attribution-Share Alike 2.0 Generic license.

What happens now?

If these carps were to reach Lake Michigan we could face an extremely large ecological disaster, but luckily there are a few programs in action to prevent this. There are already electric dispersal barriers put in place to stop these invasive species from getting up from the rivers nearby, but the newly found silver carp was actually located above this barrier, either proving that it is not 100 % effective, or it had to have been released above the barrier.

After the fish was found a forced 14 days mandatory search began, and the results from this will determine if more actions are needed. A single fish of this species is not dangerous, but if they find more during this time they will have to deal with it somehow. Completely getting rid of an entire fish species from an aquatic ecosystem is also extremely difficult, because they can’t really drain the entire river just to make sure there are not invasive fish left.

Despite this huge threat to the Great Lakes’ ecosystem, the Trump administration seems intent to cut over 97 % of the budget that is in part used as a preventive action in stopping the invasive species to reach the Great Lakes. This could make this threat a lot more real in the future, but this incident might hopefully help them to change their minds.