Provincial conservation authorities are on alert after a fish disease recently resulted in Parks Canada closing a lake near Banff.
Parks authorities discovered whirling disease in Johnson Lake in August and closed the lake soon thereafter,prompting the Ministry of Forests, Lands and Natural Resource Operations (FLNRO) in B.C. to put out a press release calling on those who go fishing to take extra precautions to help prevent the possible spread of the deadly disease.
“The rate of spread is directly related to the ability of us to communicate effective cleaning methods to the public. Whirling disease can be transported by infected mud, disposing caught infected fish improperly, and by contaminated fishing gear. We have been communicating with the public through media and the ‘Clean, Drainand Dry’ program,” FLNRO Fish and Wildlife Branch provincial fisheries stock assessment scientist Trevor Davies told The Echo, adding that there is a heightened concern in areas such as the Upper Columbia Valley that are close to Banff, “due to simple proximity.”
Davies said “it is difficult to know where whirling disease is actually present in various systems”, but added it’s important to keep in mind that there is no risk to human health caused by the organism that causes whirling disease.
Whirling disease, according to the FLNRO press release, is caused by a parasite that burrows into the head and spine of salmonids — salmon, trout, whitefish and char — making them vulnerable to predators. It can cause the fish to swim in weird, twirling patterns (which is where the disease name comes from). The parasite can spread from one lake to another through contaminated bait, fishing gear, water and birds. Anglers and boaters can help contain whirling diseases by cleaning their boats (following B.C.’s Clean, Dry, Drain protocol) and fishing equipment before and after entering lakes or rivers, and by properly disposing of caught fish and body parts.
The fish with whirling disease in Johnson Lake are the first time the disease has been found in Canada, BanffNational Park resource conservation manager Bill Hunt told The Echo.
“It was a big deal when it (whirling disease) came up to Montana in the late 1990s. We set up a Canadian sampling program,” said Hunt. “But by 2001, when it still hadn’t spread to Canada, people kind of let their guard down and the program slowly started to fade out. A lot of people thought perhaps it was just too cold inCanada for the parasite.”
Conservation authorities in Banff are testing — with limited lab capacity — as much as they can and have so far determined that whirling disease is present not just in Johnson Lake, but also in the Bow River between Bow Falls and the Banff National Park boundary.
“We’ve started testing in Yoho and Kootenay (national parks) too. Hopefull,y we’ll know whether or not it’s theresoon. In the meantime, B.C. is putting together a sampling program,” said Hunt. “It (whirling disease) can have a devastating effect on fish populations and can have a high mortality rate.”
Some fish species appear much more susceptible than others. For instance, rainbow trout are highly susceptible while lake trout are much less so. Native cutthroat trout seems to be on higher end of the susceptibility, and“we’re concerned about that,” Hunt said.
He said it’s not yet clear how or even when whirling disease made its way into Canada.
“We may never know for sure how it got here,” he said, but added scientists may have a better idea of how longthe disease has been present in the Banff area after further sampling.
“Once it’s in area, though, it’s virtually impossible to eradicate,” said Hunt.
He said that in a typical natural scenario, where there is a population abundance of a given fish, whirling diseasewill result in a big dip in population numbers, but then resilient individuals flourish and eventually repopulatethe area, but added that the critical caveat this scenario depends on is the re-populating fish not being subjected to other population pressures — something that can’t ever be taken for granted.
Hunt said that Parks Canada is focusing heavily on education and trying to maintain isolation of key species as much as possible.
For more information, see Banff National Park’s online fact page on whirling disease athttp://www.pc.gc.ca/eng/pn-np/ab/banff/plan/aqua/lac-johnson-lake.aspx.