Red Lake , Lake Trout Population

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New clue in dwindling lake trout investigation

by Lisa Dumontier / Staff Reporter
The Northern Sun News, March 25th, 2009 issue.

The Ministry of Natural Resources (MNR) has finally uncovered a clue that could potentially address Red Lake’s dwindling trout population and ongoing problems with lake trout egg mortality at Pipestone Bay confirmed MNR Area Biologist Nadine Thebeau on March 11, 2009. Addressing local residents during a public meeting at the Campbell Curling Lounge in Balmertown, Thebeau relayed that recent sediment samples taken from Pipestone Bay have indicated a potential cause for egg mortality.

“Eggs dying in Pipestone Bay and nowhere else indicates a problem with Pipestone which is likely environmental so we’ve been doing all kinds of water quality and sediment sampling and for the longest time we were seeing nothing,” said Thebeau. “Up until now, there has been no difference in the sites where eggs are thriving and those where eggs are dying which has been very frustrating however we’ve finally gotten results that are showing something, so there is some light at the end of the tunnel.”

An ongoing saga for the Red Lake area, the declining trout population is hardly a new dilemma for Ministry of Natural Resources representatives who have been diligently working to find the root cause of the problem since a netting exercise in 2001 failed to catch lake trout under the age of eleven. When further investigation revealed that trout eggs were dying within days of being laid in the main spawning basin in Pipestone Bay, the MNR set itself up with two tasks—to establish what is causing the egg mortality and to collect eggs from Red Lake to be raised at the hatchery before being stocked back in the area—to ensure sustainability for the local trout population.

Conducting numerous tests over the course of their investigation, which frustratingly always produced normal results and left the Ministry feeling even more bewildered, the MNR finally made some headway over the course of the past year when sediment samples taken from Pipestone Bay were found positive for high levels of manganese, copper, iron and aluminum.

“We sent some sediment samples to the Ministry of Environment in Toronto and they were able to find, with the concentrated water that was within that sediment, high levels of manganese, copper, iron and aluminum and according to the scientists, the manganese was high enough to kill eggsThis is the first time our testing actually shows that something is different at Pipestone,” explained Thebeau. “Scientists have taken the sediment collected at Pipestone, put it in aquariums and replicated the Pipestone conditions with rainbow trout eggs and in the two sites from Pipestone, the eggs turned black and died but in two other sites, they survived. Being able to reproduce the scenario in the lab is a huge victory because at least we’ve been able to identify something that could be responsible for the egg mortality.”

Unwilling to rule out any potential reasons for the high mortality rate at Pipestone, the MNR isn’t putting all of its eggs (so to speak) in one basket however is—for the time being—setting its sites on manganese as the likeliest contamination culprit. According to Thebeau, while all four metals were found in the sampled sentiment, aluminum and iron levels were relatively low while manganese and copper were fairly high. Scientists are also leaning toward manganese because the eggs turned black prior to dying which is characteristic of that particular metal oxidizing.

“Pipestone is in an area that is known for its nasty rocks,” confirmed Thebeau as to where the metals might be coming from. “Just naturally those rock are high in metal concentration and unfortunately that type of rock is able to leach those metals out. So potentially, it could be just a natural cause for egg mortality. Why they would be leaching out now and not pre-1989 is still a mystery but that’s something we’re still trying to figure out.”

In addition to ongoing sediment sampling and studies to determine the true impacts of the discovered metals on egg mortality, the MNR has committed to a number of other initiatives to keep the ball rolling on rejuvenating the local trout population for the remaining six years of their current ten-year plan. According to Thebeau, studies are also in the works for next year to continue to monitor the trout population and to verify the success of the stocking program.

Area trout have been tagged on top of their dorsal fins and the MNR is asking anglers who catch tagged trout to report their tag number and location of capture to the MNR. In addition, stocked lake trout have been subject to a fin clip as per their year of stocking and those who hook a trout are asked to look for the missing fin on the fish and report its location, as well as the location of capture, to the MNR.

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