Quote: Originally Posted by CDNBear
It would seem to be ahead of BC.
Quote: Originally Posted by bill barilkoNot welcome in Canada: Preventing a Northern Snakehead invasion
Old News and already banned in Canada-as always Saskabushewan is decades behind the rest of the country.
The Northern Snakehead might enjoy life in Canada, but it would not be welcome here.�This fish, native to eastern Asia, has invaded parts of the United States, where it threatens to disrupt ecosystems and native fish species unaccustomed to its presence.�Scientists at Fisheries and Oceans Canada (DFO) want to stop the snakehead from establishing a base in Canadian waters – and building a strong defence is the key to success.
The risk posed by snakeheads is very real. Several of the 36 species have a long history of invasions, and are very hardy. They can even live out of the water for a time – to pursue their prey or find a new home if the former one dries up.�They survive winter under the ice of northern lakes; some have even recovered from being frozen!�The Northern Snakehead, in particular, thrives on conditions that are similar to many Canadian waters. It is a voracious predator, and it grows rapidly to an adult length of 1.5 metres or more.�
The Northern Snakehead could be an aggressive invader if it escaped to the wild in Canada. Credit: United States Geological Survey
In their native waters, some snakehead species are fished for food or used for aquaculture.�Many are exported to other countries where they may be sold live in food markets and pet shops.�Scientists believe that the Northern Snakeheads found in lakes in some US cities may have originated from food markets. Some may have been released to the wild in an ill-advised attempt at fish stocking or because they were no longer wanted as pets.�
Since Canadian lakes are equally vulnerable, DFO is investigating the species to find ways to block its path.�In 2005 Becky Cudmore and Nick Mandrak of DFO's Centre of Expertise for Aquatic Risk Assessment in Burlington, Ontario undertook a study to assess the risks. DFO wanted to know which of the snakehead species might be successful invaders. Which species might find suitable food and habitat in a new territory?�Would the climate be favourable, the water temperature suitable, the prey attractive?
When a new species reaches an ecosystem where it does not occur naturally, many cannot adapt to new surroundings and fail to spread; some disappear entirely.�Others, however, can become aggressive aliens in ecosystems that lack the natural checks and balances to control their numbers.�These invaders can decimate native plants or animals through predation or competition for food and living space.�What remains of the ecosystem can often be quite different, and less productive, than before the arrival of the invader.�
Most snakehead species are native to warmer regions and thus unlikely to thrive in Canadian waters or survive our cold winters.�But some, the Northern Snakehead in particular, occur naturally in colder waters.�This species had the potential to become an aggressive alien, and became the focus of the researchers' attention.�
The risk assessment looked at several factors: how likely were snakeheads to come to Canada and become established? How bad would the impacts be? And might they bring along a disease, parasite or other fellow traveller?
The Northern Snakehead is the most popular of all the snakehead species to be used for food. The scientists concluded that, as the species could be available in the live food and pet trades, it could escape into the wild in Canada.�If this were to happen, the snakeheads were quite likely to survive, reproduce and spread to other areas.�Serious impacts on ecosystems would also be likely, as the snakehead could prey aggressively on many native fishes and compete with others for food.�The study could not readily determine the risks of snakeheads bringing stowaway diseases or parasites; very little is known of these �hitchhikers.'�But the issue is certainly a cause for concern.
Results of environmental modelling indicate areas in Canada of high suitability (red) for northern snakehead. Credit: From Herborg, L-M., N.E. Mandrak, B. Cudmore and H.J. MacIssac. 2007. Comparative distribution and invasion risk of snakehead and Asian carp species in North America. Can. J. Fish. Aquat. Sci. 64: 1723-1735.
For Becky Cudmore, the conclusion is all too clear. We must, "protect Canadian ecosystems before the species arrives. We can put up roadblocks by determining how they could get here. Prevention is key."
To build effective roadblocks, Canadian scientists needed to learn a lot about a species that is not familiar in Canada.�Researchers focused on the snakehead's environmental tolerances.�What water temperatures did they prefer � what seasonal variations could they tolerate� and so on. Cudmore and her colleagues used computer models to study environmental conditions in the Northern Snakehead's native ranges and identified what they need to survive.�Where the snakehead's home conditions match those in a Canadian aquatic ecosystem, scientists will need to monitor the ecosystem closely.�The Northern Snakehead is not likely a threat in extreme northern Canada, for example, because the environment isn't suitable for the species there.�But "it would love the Great Lakes," says Cudmore, and Vancouver Island would also be at risk for a snakehead invasion.�Selling live snakeheads is now prohibited by law in Ontario, but British Columbia has no such ban.�
The threat should not be taken lightly.�On a recent trip to British Columbia, DFO scientists were able to purchase a live Northern Snakehead at a local food store, confirming rumours that the species was readily obtainable.
Identifying suitable snakehead habitat in Canada, and points of entry where the species could be introduced, helps managers focus on areas where prevention can be most effective.�In British Columbia, with its highly suitable environment and the availability of Northern Snakehead in trade, we need to be extra vigilant says Cudmore.
Armed with knowledge of the risks, DFO and its partners in other federal and provincial agencies can work to control the threat.�This knowledge can give scientists and fisheries managers an edge.�It allows them to take preventive measures before the species gets a toehold here, and keep an unwelcome invader out of the country.