Hamilton

Invasive crab in Hamilton Harbour can carry parasitic lung worm

Fisheries and Oceans Canada believes the Chinese Mitten Crab found in Hamilton Harbour was released intentionally – and whoever did it wasn’t doing anyone any favours.

Chinese Mitten Crab caught in a barrier meant to keep out invasive carp

This Chinese Mitten Crab was found at The Royal Botanical Gardens Monday. It's considered an invasive species and "ten most unwanted species of the world" by Fisheries and Oceans Canada. (Royal Botanical Gardens)

Fisheries and Oceans Canada believes the Chinese Mitten Crab found in Hamilton Harbour was intentionally released – and whoever did it wasn't doing anyone any favours.

Why? Well there are three main reasons, according Aquatic Invasive Species Adviser Becky Cudmore:

  1. The invasive species sometimes carry a parasitic worm called a lung fluke that can burrow its way into lung tissue and cause chronic inflammatory lung disease.
  2. They're illegal to import or carry in Canada.
  3. The invasive species will die in fresh water, anyway.

"It could've been someone saw a crab for sale and thought they would set it free," Cudmore said. "There are segments of our population who release things for cultural, animal rights or religious reasons.

"And while we don't want to stop cultural or religious things, we do need some education. It could be very destructive to the environment."

The adult Chinese Mitten Crab was found on Monday by Royal Botanical Gardens workers in a barrier between the harbour and Cootes Paradise, the marsh that feeds into the harbour's west end.

The crabs, which are about 8 cm long, are usually found in salt water. Biologists consider them to be an invasive species because the crustaceans can reproduce rapidly, clog up fishing gear and speed up erosion by digging holes in riverbanks.

Both the Royal Botanical Gardens and Fisheries and Oceans are treating the find as a one off, and don't believe there are other crabs in the area.

The crab is very popular food item in China, but is still illegal in Canada.

"But people still really like to eat them, so they end up here," Cudmore said.

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