Someone decides they want a better fishing experience so they dump live yellow perch into the waters of a nearby Alberta lake. The fish eventually do grow big and become plentiful but there can be serious ramifications. And in the end that fishing experience isn’t much of anything.
Even though against the law, illegal stocking happens quite a bit, said John Tchir, Alberta Environment and Sustainable Resource Development resource manager for the Red Deer/North Saskatchewan region.
Tchir, who is based in Rocky Mountain House and was senior fisheries biologist for the Rocky area before a promotion, said Crimson Lake has been illegally and deliberately stocked with yellow perch. These lake is in the Rocky area.
Years ago, Crimson Lake was stocked with trout by the province. But the small, shallow, warm lake turned out to be a poor fishery, as the fish were dying off from lack of oxygen (winter kill). Eventually it became a lake without sport fish and instead became a recreational lake, Tchir said.
“It’s an extremely popular water ski, jet ski, boating lake. It’s quite a small lake, so you can imagine there’s not much room if you would want to go for a quality angling experience, then you’ve got conflict with the user group that’s already there.”
The Fish and Wildlife division of ESRD never saw to restock Crimson Lake because of the potential for conflict and the low probability of a good fishery taking off because the lake is so shallow — two to three metres throughout.
Then someone put yellow perch in the lake. Only the provincial government can stock public waters. No one has been charged.
Tchir said people do illegal stocking because “they believe it’s going to improve their fishing opportunities without thinking about the long-term implications, or effects on other user groups for that matter.”
Last summer ESRD became aware that people were catching yellow perch at Crimson Lake. Word got out so that this past winter quite a few anglers were taking advantage of the little tiny lake, Tchir said.
There is always concern that someone will put perch in a stocked trout water body, which has occurred, he said.
“What happens essentially is the perch have no predators in these situations and the population expands at a really fast rate. They typically out-compete the trout that are stocked there, so the growth rate of the trout and the condition of the trout goes down.
“If the density of the perch gets high enough, basically ESRD will stop stocking that water body because the return on investment goes way down in terms of the quality of the fishery that’s produced for trout.”
Based on the size of the perch, which are native to Alberta, Crimson Lake was probably illegally stocked six to eight years ago, said Tchir.
“Illegally stocked fish perchery are usually only good for a few years in terms of producing fairly big fish.”
After a relatively short period of time, because there’s no predation and anglers are keeping the bigger perch, only high densities of very small perch remain where there used to be an opportunity for a stocked trout fishery, he said.
There can also be serious problems caused by illegal stocking.
“In terms of genetics, but also by moving the fish, you’re also moving whatever parasites come along with those fish. … there are implications for the eco-system, as well as creating a fishery in some cases that is in conflict with other uses of a water body.
“You’re also potentially moving aquatic invasive species … that are really bad for our fisheries, like prussian carp, or other aquatic invasive species, including some of the plants.”
Tchir predicts Crimson Lake will eventually see winter kill.
“Even if it doesn’t, we’ll see high-density population dominated by very small fish. That’s the fate of almost every illegal perch stocking essentially where you don’t have a predator.”