Phosphorus in Lake Diefenbaker not impacting fish

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June 12, 2013 - 1:22pm Updated: June 12, 2013 - 2:29pm
Fish walleye file photo. Wikipedia
Fish walleye file photo. Wikipedia

Despite large amounts of phosphorous being found flowing into Lake Diefenbaker, there have not been any effects found in the fish population.

The province surveys lakes in Saskatchewan on a rotating basis, and last looked at Lake Diefenbaker in 2011.

"When we do our fisheries surveys, we set a variety of mesh sizes of net to capture all sizes of fish," explained Jennifer Merkowsky, area fisheries biologist for the Saskatoon area. 

Ideally, they want to see a variety of fish end up in those nets, ranging in age and species.

"We captured 16 different large bodied fish species during the survey.  This is similar to the number of species captured in earlier surveys," Merkowsky said.

The survey also found a variety of ages of walleye, in particular, showing that the population is fairly stable.

Merkowsky explains that Lake Diefenbaker is a fairly unique body of water, where the levels fluctuate as the province makes room for spring-melt waters coming in from Alberta.  A recent study found that the Alberta water contained an alarming amount of phosphorous, which could potentially lead to the development of toxic algae.

Being that the water level fluctuates, Merkowsky says it’s difficult to compare fishing in Lake Diefenbaker to other lakes.  Species like Pike thrive in deep water, so the low water levels likely impact their reproduction.  However, the data shows species like Walleye may actually increase.

"There was a very large age class of five-year-old fish which suggests that environmental conditions during the year that the spawn took place were very successful.  So I think in a few years, we're going to see large populations of walleye coming on."

Novice anglers may find themselves frustrated fishing in that lake regardless.  Merkowksy says the size and depth of the water gives fish a lot of hiding places.

There might be some obstacles for fishing this year, Merkowsky adds, due to a large amount of winterkill.  The severe winter meant a long period of ice and snow cover, leading to winterkill situations in border waters.  However, Merkowsky says the more popular-fishing lakes look to have escaped that from happening.

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