Chinese mitten crab mysteriously appears in Canada

Scientists are puzzled over how a Chinese mitten crab showed up in Canada. Photo: Fisheries and Oceans Canada
Scientists are puzzled over how a Chinese mitten crab showed up in Canada. Photo: Fisheries and Oceans Canada

A live Chinese mitten crab, listed as one of the 100 worst invasive species on Earth, was captured Monday at the Cootes Paradise Fishway, a structure designed to capture invasive Asian carp.

The bizarre discovery is a mystery to scientists at the Royal Botanical Gardens at Cootes Paradise, as they are at a loss to explain how it got there, the Hamilton Spectator reported.

Cootes Paradise is the largest wetland at the western end of Lake Ontario on the west side of Hamilton Harbour in Ontario, Canada. The fishway is the Great Lakes’ first two-way fishway and carp barrier designed to keep non-native carp out of the wetland.

One theory about the mysterious appearance of the Chinese mitten crab was that it was accidentally transported there via the ballast water in a ship. But Becky Cudmore of Fisheries and Oceans Canada dismissed that possibility as unlikely because of strict monitoring and the fact the Chinese mitten crab was an adult.

However, Hugh MacIsaac, an invasive species expert from the University of Windsor, told The Hamilton Spectator that the crab, as larva, could have been carried by a ship into the freshwater lakes where it was released and grew to its adult size, as the crab can live in freshwater and saltwater at various stages of its life.

But Cudmore believes the only reasonable explanation is that the crab was smuggled into Canada and deliberately released by someone, possibly for religious reasons, she told The Spectator.

Cudmore said that some believe that if you release “a very highly valued organism, a long-lived organism or hardy organism into the wild … it provides points for your karma afterlife.”

A Chinese mitten crab next to a $2 Canadian coin for perspective. Photo: Fisheries and Oceans Canada
A Chinese mitten crab next to a $2 Canadian coin for perspective. Photo: Fisheries and Oceans Canada

Inexplicably, there have been 24 Chinese mitten crabs recorded in the Great Lakes between 1965 and 2007. This one was the first since 2007 and the first ever found in Hamilton Harbour.

“I was absolutely amazed how big the crab was and the fact that it was living in freshwater,” Tys Theysmeyer, head of natural lands at the RBG, told the Hamilton Spectator.

Chinese mitten crabs, featuring furry, mittenlike claws, is a burrowing crab that has caused major problems for Europe.

As reported by the Spectator, the World Conservation Union says that the Chinese mitten crab “modifies habitats by causing erosion due to it intensive burrowing activity and costs fisheries and aquaculture several hundreds of thousands of dollars per year by consuming bait and trapped fish as well as by damaging gear.”

As destructive as it is, the Chinese mitten crab is not a major concern to Canada.

“This species poses no threat to the Great Lakes waterways,” Kevin Hill, a spokesman for Fisheries and Oceans Canada, told GrindTV in an email. “[The] Chinese mitten crab requires saltwater in order to reproduce and therefore it would be impossible for the species to establish a population in the Great Lakes Basin.”

Hill also told GrindTV that the crab was positively identified and later destroyed by Fisheries and Oceans Canada.

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