It’s not unusual to spot a trout species in a Calgary river but you might not expect to find a lobster-like crustacean. In the last 10 to 20 years however, the marbled crayfish — a crustacean not native to the Bow River — has begun spreading to rivers and lakes throughout Alberta. It’s a problem that Nicole Kimmel, aquatic invasive species specialist for Alberta Environment and Parks, is trying to tackle. Historically, the crustaceans are normally found in between Wainwright and Ryley in the Beaver River watershed south of Edmonton, Kimmel told The Calgary Eyeopener. But now they’ve been showing up in water bodies anywhere from the Edmonton area, down to Calgary and Medicine Hat, as well as in the Milk River region. It’s not likely that the critters are crawling between rivers and lakes, though they can move on land for short periods, Kimmel said. Instead, the province suspects the movements of the crayfish might be aided by humans either for bait use or they are potentially being brought back home and discarded in local waters.
‘Freak accident’ leads to quick reproduction
“Once they’re introduced to a breeding pair, they can breed pretty fast,” Kimmel said — the creatures can produce 200 to 400 eggs in a reproduction cycle. Kimmel calls the marbled crayfish a kind of “freak accident” of two crayfish species that may have been imported from Florida into Germany in the ’90s and were able to mate. Through that mating, the crayfish kept an additional set of chromosomes that allowed them to reproduce asexually, meaning all the females could lay unfertilized eggs which develop into genetically identical offspring. In essence, a self-cloning crayfish was born. To attempt to control their spread, Alberta has banned the crayfish province-wide unless it’s kept as a pet. Most pet stores have stopped carrying the specimens, but it’s still possible to find them sold online by individuals. Ducks have been munching on them, along with some humans, but Kimmel says its important to make sure the ones used for consumption are coming from clean water sources. Kimmel says the province has partnered with Mark Poesch, Associate Professor in Agricultural Life and Environmental Sciences at the University of Alberta, to understand what the effects are on the habitats the creatures are invading. “We highly suspect that they’re probably impacting food webs where they’re being moved around,” she said.
Other crayfish creeping into Canadian waters
The marbled crayfish aren’t the only species of their kind causing concerns — there’s an extensive list of crayfish-type creatures being found in Canadian waters, Kimmel explained. For example, B.C. is worried about red swamp crayfish and in Manitoba there are concerns about crusty crayfish. Meanwhile Saskatchewan, along with Alberta, has ramped up its legislation around marbled crayfish. If you spot a crayfish, Kimmel says to report it to the province along with the location it was found. “We’re very much interested in knowing the location that you’re finding them as well as if you can snap a picture of what they look like,” Kimmel said. “We don’t want any of those other invasive ones that other jurisdictions are worried about.” The province isn’t actively getting rid of the crayfish right now until there’s a better understanding of where the crayfish are located and what can be done for eradication.
