the north face rucksacks Invaders from the north
Anglers, environmentalists and scientists who are wary of an invasive species of crayfish that has been introduced to Airdrie Nose Creek are urging people to keep them contained.
It turns out northern crayfish, also known as Orconectes virilis, have been lurking in the waterway since the mid 2000s.
Originally native only to the Beaver River watershed in the northern prairie provinces, the species has been naturally marching westward in rivers and streams due to some newly favourable habitat. But a biologist who studied the invertebrates said the ones in Nose Creek were definitely introduced by humans.
seems much more of introduction via curiosity, so people may have found them elsewhere and thought they were neat and brought them home, or just brought them back and threw them in the closest water body, said Bronwyn Williams, who studied the spread of the species for her PhD at the University of Alberta.
She said many of the first reports of this species were from popular fishing areas in Southern Alberta, leading her to believe bait bucket dumping is another likely method of introduction.
Orconectes virilis lives around and under rocks on the creek bed where it can avoid predators, and it often thrives under bridges and on overgrown banks.
All it takes is one careless fisherman or curious child to transfer one inseminated female into a waterway like Nose Creek and start a population that could alter the ecosystem.
can have lots, and lots, and lots of babies all at once. These guys can have a couple to several hundred babies in a row, said Williams. the research suggests that these crayfish can really change those ecosystems dramatically. Sancartier, a spokesperson for Alberta Environment and Sustainable Resource Development (AESRB), said if anybody sees someone dumping fish into a waterway they should call local fish and wildlife officials or the report a poacher hotline at 1.800.644.3800.
is illegal to take crayfish from one system and put them in another water body, but that is what appears to have happen. If someone caught doing that, they can be charged, she said.
The crayfish are omnivores who eat just about anything. Snails and aquatic plants are high up on the menu, but they also eat damaged, decaying and dying organisms, which could be good for the ecosystem overall.
Local fisherman Guy Woods said he concerned because small invertebrates like snails, worms and insects are at risk, which could mean trouble for fly fishermen if all of a sudden their catch has nothing to eat.
can expect to see these changes occur, in fact they probably are occurring, said Williams. anticipate that if we look closely we will start to see shifts in what we think of as natural or native in Nose Creek, but I wouldn anticipate a massive destruction or that this will be something horrible. is unique that we don have raccoons or otters to prey on the crayfish, she said. However, many birds could take to a new crayfish diet.
times you see a very rapid increase in the density of the crayfishes and then they self regulate, said Williams. crash. They achieve a density that they can withstand and then maybe we do have some potential predators that do pick up on this new food source. only takes a minute to catch a few crayfish in Nose Creek if one looks in the right places, but she said that not necessarily something to worry about.
wouldn consider that an abnormally high density. There have been situations where I been walking across the creek bed and you can hear the crunching of the crayfish under the rock. They can get a lot higher let me put it that way, said Williams.
The focus of Williams research reveals an intriguing fact about the northern crayfish that is unique to Nose Creek. By looking at genetic markers on the samples she took, she discovered that there were at least two separate introductions.
The variance in the gene pool in Nose Creek shows Airdrie crayfish are actually a hybrid of two distinct groups. Some belong to a group making its way upstream from the natural habitat in Beaver River up North, while some are part of a genetically distinct group only found South of the Medicine Hat area.
This mixing of the two populations only occurs where they meet on the South Saskatchewan River, and in Nose Creek.
Creek is the only true isolated population where we see this evidence of more than one source, said Williams.
Airdronians better get used to the idea. Now that the species are in the creek it is nearly impossible to get rid of them, but Williams said nobody should panic.
is going to be here to stay, it may change things a little bit, but that new equilibrium will be achieved, she said.
Most of all she stressed that people not aid the Northern Crayfish in expanding any further.
are really cool organisms, but keep them in place. Nobody worry, they be fine, but there is that concern of what will this actually do to the ecosystem and what they will eat, said Williams.
If people are careful with the city new residents, the species can be contained to Nose Creek. Calgary Bow River is cold enough that there little chance of it spreading significantly into that waterway, because the female won lay her eggs in water colder than nine or 10 degrees Celcius.