Invasive Crawfish on Nose Creek

OBSERVATION

In June 2013, Guy Woods, a local aquatic specialist, discovered crawfish on Nose Creek, in Airdrie Alberta. The species he found is known as Northern crawfish, or Orconectes Virilis, and it is native to the lower Missouri and Saskatchewan River systems. There are no known native crawfish populations in Alberta, with the exception of the Beaver River system. It is not possible to say with certainty when or how these crawfish were introduce into the Nose Creek system. Reproducing females as well as several life stages of the crawfish were discovered, which confirms that they are successfully inhabiting the creek.

The crawfish discovered in Nose Creek are known to live under rocks and covered areas, where they can successfully avoid prey. This species of crawfish can reproduce rapidly, due to the large number of babies they can have all at once. In terms of diet, the crawfish are omnivores who eat invertebrates like snails and aquatic plants. The crawfish may have a significant impact of invertebrate populations, thereby impacting native fish species. Research has shown that the introduction of this species can dramatically alter ecosystems.

Given that Nose Creek is a tributary of the Bow River, which is home to a blue ribbon Brown trout and Rainbow Trout fishery, there could be serious impacts of this invasive species from an environmental, social and economic perspective.

Details regarding the discovery can be found at the following links: 1 2 3

See a video of the issue here

BACKGROUND

The Nose Creek Watershed is an urbanized creek that flows through residential and commercial areas of Calgary and vicinity, before ultimately draining into the Bow River. The map below shows that Nose Creek begins near the Town of Crossfield, Alberta and flows through the City of Airdrie and the City of Calgary before dumping into the Bow River south of Memorial Drive SE.

In 2007, local municipalities such as Calgary and Airdrie, as well as Alberta Environment, signed off on the Nose Creek Watershed Water Management Plan. The plan recognizes the stress the Nose Creek system is under due to the cumulative effects of increasing residential and commercial development, industrial growth, stormwater discharge, agricultural activity and channelization in the watershed. The plan sets out measures to improve riparian health and control the volume of runoff the enters Nose Creek during rain events. The plan can be found at: http://www.calgary.ca/uep/water/documents/water-documents/nose_creek_water_mgmt_plan.pdf?noredirect=1

Given the existing concern over the state of the Nose Creek watershed, the introduction of invasive crawfish in this ecosytstem may cause further degradation of the ecosystem and place local fish species under further strain. A Fish Survey conducted by trout unlimited in June 2010 indicates that Longnose Dace, White Suckers, Brook Stickleback, Lake Chub Longnose Suckers and Brown Trout inhabit Nose Creek. The report can be found at: www.tucanada.org/files/1/AB-025_NoseCreek_2010.pdf

Consults: Paul Christensen, Senior Habitat Biologist, Alberta Environment

I contacted Paul Christensen of Alberta Environment and parks about this issue and he indicated that he was aware of the problem when it was initially discovered in 2013. He stated that it is extremely difficult to contain these situations involving aquatic invasive species when they do arise, and that Alberta Environment fisheries staff do not take action or investigate these situations further unless there is a high probability that the situation can be contained. This does not appear to be the case with the crawfish invasion at Nose Creek. AEP focuses on educating the public about invasive species thought the 'Don't let It Loose" campaign which can be found on their website at:http://aep.alberta.ca/recreation-public-use/invasive-species/default.aspx Paul also commented that he was uncertain as to whether this is a true invasive species, or potentially a range expansion into certain areas of the south Saskatchewan River basin due to climate change. He is not aware of any research being conducted to determine the reason /pathway for how this species arrived on nose creek at this time, or any ongoing monitoring to determine if the crawfish have entered the Bow River main-stem.