Seen One, Seen ’Em All

Here's what you need to know about Prussian carp. They're an invasive species of clones. Hundreds of thousands of mostly identical Prussian carp are now aggressively populating the Red Deer, Bow and South Saskatchewan river basins.

Prussian carp first appeared in North American waterways in about 2000 in Medicine Hat, Alta., says Mark Poesch, associate professor in the Faculty of Agricultural, Life and Environmental Sciences and principal investigator in the Fisheries and Aquatic Conservation Lab. Someone may have released the carp, lurking among aquarium or farmed fish, into the wild. Now they're here and they're making the most of it.

Each female can reproduce three times a year by hijacking other fish species' sperm, which the carp find floating in waterways. A protein in the sperm activates fertilization of the carp eggs but the offspring have zero genetic material from the stolen sperm. (Mysteriously, a fraction of Prussian carp turn out male.)

The fish, which can grow to three kilograms and 40-plus centimetres long, are also called Gibel carp. They can survive almost anywhere, even in a ditch. They plunder resources, out-competing local fish.

Australian researchers have shown they can kill the invaders with a modified herpes virus, and testing is underway to ensure the virus doesn't affect native fish. So far in Canada, we have education and monitoring. First, don't throw a carp back if you catch one. Second, Poesch and students are working with the Alberta Conservation Association to document the population distribution of the clones by taking water samples, testing for the presence of Prussian carp DNA.

There are Prussian carp recipes online. Poesch jokes that if the scientist thing goes sideways, he may start an invasive-fish-taco food truck.