The “crab-divating” story of illegal species transport

Alberta is always on the lookout for aquatic invasive species (AIS), specifically the 52 species listed as prohibited on the Fisheries (Alberta) Act. Sometimes, however, we get very interesting species that have the potential to get us in hot water, if they went undetected! Over the years, we have flushed out as many invasive species as we can and this month we will be elaborating on a few Aquatic Anomalies that have tried their luck at entering Alberta waters.

What wears mittens, enjoys long walks on the beach and has eight legs? The answer is… Chinese Mitten Crabs! At less than 10 cm in size, they may not seem like a big deal but these little crustaceans pack a big pinch by wreaking havoc both on the environment and human health. Importing these crabs into Canada alive is illegal without a license but recently, people have been testing the waters.

Chinese Mitten Crab 5

Photo credit: Canadian Food Inspection Agency

On October 24th, 2018 the Canadian Border Services Association (CBSA) seized a shipment destined for a Calgary residence that was declared as “TV Lights”. This ill-marked Styrofoam box contained 21 kg of very real, very live Chinese Mitten Crabs. These greenish-brown crawlers are best known for their two claws with white tips and thick furry hair that resemble mittens. This species is native to East Asia and is considered a delicacy in Asian cuisine.

The shipment seized at the Calgary International Airport came from Hong Kong. Additionally, the importer did not have a fish import license, which is mandatory for anyone that wishes to import live fish or fish products. When CBSA finds an illegal species, they often connect with other government agencies more specialized in dealing with the species in question. In this situation, CBSA contacted both the Aquatic Invasive Species (AIS) program staff and the Canadian Food Inspection Agency (CFIA). The package was detained and the case was handed over to the CFIA, where the crabs were euthanized.

Luckily, this invasive species was detected and stopped, as Chinese Mitten Crabs can threaten aquatic ecosystems by eating fish eggs and damaging fish habitat through their burrowing activities. In Alberta, the extent of environmental threats was deemed low because the crabs were unlikely to survive, if released. However, this still left a human health concern. Chinese Mitten Crabs act as an intermediate host for the oriental lung fluke, a parasite that can be passed to humans who consume it raw.

Chinese Mitten Crab 11

Photo credit: Canadian Food Inspection Agency

The CBSA doesn’t just help in the fight against invasive species at the airport, they also collaborate with AIS program staff at land borders. In 2017, the province worked with CBSA to develop a border notification system to keep AIS staff informed when a boat passed the border outside of watercraft inspection station operating hours. Over 900 boats have been reported to date that could have otherwise been missed without this partnership. Collaboration is crucial to protect Alberta’s environment and ecosystems and we hope that you can continue to help us claw through the threat of aquatic invasive species by:

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