Mystery of dead fish recurs on Lake Manitou

LAKE MANITOU – High numbers of dead whitefish, lake trout and suckers are washing up on the shores all around Lake Manitou, causing significant concerns for area residents who are worried about what the presence of these dead fish mean for the health of the lake.

“I just came from the lake there now, and there was at least another 25,” Sandfield resident Peter Hutchinson told The Expositor on Monday. “We picked up a wheelbarrow full yesterday, another 25, and there’s a lot more on the top of the water that are out a ways and haven’t drifted in yet.”

Mr. Hutchinson said he had never seen a die-off of this scale, nor had his 95-year-old father Doug Hutchinson or his 100-year-old aunt Jean McLennan. He noted that most properties he had seen on the lake lost up to two feet of shoreline due to higher water levels, which may be causing an influx of silt in the water.

“The whole (Sandfield) bay is just a milky gray colour from the silt being washed in from shore. I’m no biologist, and I don’t know whether that’s the major factor, but I believe it has a good part to play in this,” said Mr. Hutchinson.

The Ministry of Natural Resources and Forestry (MNRF) and Manitoulin Streams Improvement Association are both aware of the presence of these dead fish. Concerned residents gathered fish samples from the summer kill, froze them and transported them to both groups for possible analysis. 

MNRF issued the following statement regarding the Lake Manitou situation:

“From time to time, there are sudden die-offs in fish populations. These deaths can be caused by low oxygen levels in water, stress from spawning or changing water temperatures. We are aware of the dead fish and specimens will be collected for testing.”

The majority of reported dead fish have been whitefish and lake trout, both of which are deep-dwelling cold-water species that are sensitive to water conditions. The recent heat wave over the past couple of weeks would have had an impact on the water temperatures as well.

Mr. Hutchinson said he feared what impacts this may have on the lake’s fishery on a longer term. Confirmed reports of dead lake trout and whitefish have surfaced, with Mr. Hutchinson saying he spotted a dead ling as well. 

“What concerns me more than anything is not what I see on the top of water, it’s what is below the water,” said Mr. Hutchinson. “The whitefish and lake trout are floating in but I don’t know what’s happening below the water.” 

Members of the public are welcome to contact MNRF whenever they spot multiple dead or dying fish, especially if the fish exhibit any signs of disease. This helps the ministry to understand diseases and how they spread, improve disease management and protect fish populations.

Anyone calling to report a die-off will be asked for the kind of fish, the species, how many have been found, what condition they are in and any visible signs of illness. They are also asked for the waterbody, nearest municipality, location or landmarks of the exact spot where the fish was found and recent weather or environmental conditions.

To report a fish die-off to MNRF, call 1-800-667-1940 on weekdays from 8:30 am to 5 pm. If a caller suspects that the fish may have died due to a spill or disease, they are asked to contact the Ministry of the Environment and Climate Change’s spills action centre at 1-800-268-6060.