In­va­sive wa­ter species an un­wel­come guest in Red Deer River

The Drumheller Mail - - FRONT PAGE - Pa­trick Ko­lafa

The Red Deer River is a great place to be en­joyed by an­glers, swim­mer and boaters alike, but lately, it has had some vis­i­tors who are not all that wel­come.

Mail read­ers have brought re­ports of find­ing cray­fish in the river. Re­sem­bling a small lob­ster, the cray­fish are na­tive to Al­berta, but not the Red Deer River and this could be a con­cern.

“North­ern or Vir­ile Cray­fish are na­tive to Al­berta, but they are na­tive to the Beaver River Wa­ter­shed, the Bon­nyville, Cold Lake area,” ex­plains Ta­nia Rush­call, aquatic in­va­sive species bi­ol­o­gist for Al­berta En­vi­ron­ment. “That is where they are meant to be. There is nat­u­ral range ex­pan­sion, so they are mov­ing nat­u­rally through con­nected wa­ters, but they are also be­ing found in other places around the prov­ince like the Red Deer River, likely due to peo­ple mov­ing them.”

This could be peo­ple catch­ing them and us­ing them for bait or mov­ing them un­know­ingly.

“I think they are be­ing as­sisted by us,” she said.

She ex­plains that the rules for us­ing bait are that you are not sup­posed to be us­ing live bait and you are not sup­posed to us­ing bait from other wa­ter bod­ies.

“You can use some other forms of bait as long as there is not a bait ban from where you are fish­ing. Un­for­tu­nately, if they are us­ing cray­fish for bait, it sounds like they are us­ing them live and not from that wa­ter body,” she said.

She says they are not sure the kind of im­pact there is in­tro­duc­ing cray­fish into other Al­berta wa­ter­sheds, but like any non­na­tive species, there is a risk.

“Cray­fish haven’t been ex­ten­sively stud­ied so we don’t re­ally know the spe­cific eco­log­i­cal im­pact but we do know anec­do­tally these cray­fish are quite pro- lific. Their pop­u­la­tion sizes are get­ting quite large very quickly and that does pose a con­cern for us,” Rush­call said.

“Cray­fish feed on a wide range of plants, in­ver­te­brates, tad­poles, and small fish. So if they are overly abun­dant in an area ,there could be in­va­sive pre­da­tion on some of our na­tive species,” she said.

She says out­side of the Beaver River Wa­ter­shed, peo­ple are al­lowed to catch cray­fish, and of­ten they are eaten.

“You are al­lowed to catch them by an­gling, dip net, seine net, and catch­ing them by hand. These are ex­panded meth­ods as of this year in the sports fish­ing guide,” she said. “So if you want to catch them and have a cray­fish boil you are more than wel­come to.”

This is not the only an­i­mal in the wa­ter of the Red Deer River that is of con­cern. The Prus­sian Carp has gained a foothold in the river. This is a wild species of gold­fish.

“It is just Al­berta and Saskatchew­an that have these fish in North Amer­ica. They were brought here by peo­ple and were likely in­tro­duced for an­gling op­por­tu­nity or for food,” she said. “They do breed very rapidly. When we do find them, we find them in large den­si­ties.”

She says they are pro­lific be­cause they have a unique way of re­pro­duc­ing.

“They can spawn mul­ti­ple times per sea­son, and on top of that, Prus­sian Carp are able to re­pro­duce by what is called gyno­gen­e­sis. That is where the fe­male Prus­sian Carp can lay their eggs and then they can be fer­til­ized by other cyprinid or min­now species. It trig­gers cloning. The eggs will de­velop as a clone of the mother,” she said.

She says they are see­ing ef­fects of the fish in just a few years of it be­ing in­tro­duced.

“With Prus­sian Carp, one thing we are say­ing, if you catch it, kill it. We ask that you don’t put them back alive.”

sub­mit­ted

This cray­fish was found in the Red Deer River by a lo­cal. These are not na­tive to the wa­ter­shed.

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