Central Alberta anglers might be surprised to hook an unusual, self-cloning fish out of the Red Deer River this summer.
Prussian carp — which can reproduce without a male of the same species — are now infesting the river and its tributaries and streams in significant numbers.
Lesley Peterson, Alberta biologist for Trout Unlimited Canada, said whoever catches this non-native fish should kill it and not release it into the river, where it can out-compete native species.
“You can take the carp home and eat them — they are safe to eat — or you can feed them to your pets, or use them as fertilizer,” said Peterson.
Alberta’s the first place in North America to have this invasive Asiatic fish in its rivers and streams in the Red Deer, Bow, South Saskatchewan and Old Man river systems. The voracious carp, first confirmed to be in provincial waters in 2006, have now invaded Saskatchewan.
The fish are hard to eradicate and are copious breeders: Peterson said females can fertilize their eggs using the sperm of other fish species.
“They are essentially cloning themselves,” she added, as all their DNA comes from the female side.
No one’s sure how Prussian carp were introduced to provincial waters.
Alberta Conservation Association biologist Mike Rodtka has a hunch someone purposely released these fish into water bodies, such as an Airdrie-area pond that Trout Unlimited stocks with rainbow trout.
“It has a lot of carp in it… It’s possible that some people are moving fish (to different water bodies) because they like to catch them,” Rodtka said.
Alternatively, Nicole Kimmel, aquatic invasive species specialist for Alberta Environment and Parks, suggests small carp could been brought in by aquarium stores as a feeder fish.
And at some point, they were released — or flushed — into a municipal water system that flows into the river.
In Red Deer, more than 880 goldfish were recently removed from the Anders storm retention pond after Alberta Environment alerted the city about its concern these fish could end up in the river.
City workers have also received reports of goldfish in other retention ponds and will be studying them.
Goldfish are so closely related to Prussian carp that it can take a close examination to tell them apart, said Brittany Schmidt, a fish biologist with the Alberta Conservation Association.
While goldfish do not reproduce by gyno-genesis, they can grow to dinner-plate proportions when unconstrained by aquarium tanks.
“Their heads remain small, but their bodies get grotesquely big (because) they will eat anything that will fit into their mouth,” Schmidt said.
The province doesn’t want more of these fish in Alberta’s waters. Kimmel said anyone who introduces a non-native species can be fined up to $100,000.
While Kimmel can’t yet gauge how much destruction carp are wielding on Alberta’s aquatic ecosystem, a 2017 University of Alberta study found less biodiversity in streams known to contain a higher number of carp.
Rodtka said, “Anytime you have a new species coming into the ecosystem, there’s lots of potential for disruption.”
He believes the answer is educating the public about the dangers of releasing any kind of non-native species into the landscape.