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Lake Manitou Area Association (LMAA)
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July 2019 Whitefish kill on Lake Manitou

  • 2019-07-11 6:35 PM
    Message # 7775972
    Anonymous member (Administrator)
    • Around the 4th of July numerous emails were received from LMAA members reporting dead Whitefish floating on the surface or next to the shore in various locations on Lake Manitou.

      Below  are two reports that update and summarize the latest information reported by two of our members.

    • Hi All,

      I noticed on the email threads that not everyone on the LMAA executive was included so I have made sure that all are included in this email.

      As a quick summary ( for those that might be unaware) I was crossing the lake on July 4th from my place in eagles nest to my parents. The lake was flat and as I crossed  I counted 10 whitefish roughly 18-22 inches in length belly up.  I found it strange so I sent out an email.  What followed were other accounts (hence the email thread) of seeing the same thing in different parts of the lake.  In all I think it is safe to say that a couple hundred whitefish were counted.

      Marian Lochead contacted the MNR and my mother forwarded her email to me which I will share below:

      I have been collecting more information on this dead fish situation. I thought I would pass it along. There continues to be some dead fish floating in Sandfield bay as of yesterday at least.  It is mostly Whitefish and from what I have seen they are usually good sized - I haven't seen any small ones, for instance.

      I called the Conservation Officer, he mentioned to me that this is also happening on other lakes on the Island including Lake Mindemoya. He provided me with a phone number within the Ministry of Natural Resources and Forestry (MNRF) to report dead fish. They have a special program - Fish Die Off Program. The Conservation Officer gave me an MNRF number in Peterborough - 1-800-667-1940. I called today and spoke to someone who asked me to fill out a questionnaire over the phone including such things as where I saw the dead fish, how many, state of the fish (bloated, decomposed...), weather etc. He said my report would be passed to the Sudbury office. He provided me with the Sudbury office phone number and suggested further reports could be made there 705-564-7823.

      I would suggest that as many people as are willing should call and make a report. It seems to me this would be one way to make our concerns heard and funnel our observations to the MNRF in a manner that seems to fit within their protocol.

      ​So I did call the numbers listed above and left a message summarizing my observations on July 4th.  Today I got a call from Wayne Selinger from the Sudbury office of the MNR responding to the message I had left.

      He told me that they have three good samples from the lake that have been sent for testing.  He expects the results to be back in the next 2-3 weeks at which time he said he would gladly share the results.  

      He suspects however that with the winter that was had, coupled with the cold spring....and then the rapid warming of the surface waters with the recent hot weather that it is a thermal issue that put the fish in a stressful state causing them to die.  Even though whitefish are a deep water fish he said that they were like feeding on mayflies on the surface.

      He suggested that we keep a look out for the following over the next couple of weeks and contact the MNR if any of the following are seen:

      1) if we continue to see fish washing up over the next couple of weeks.

      2) if other species of fish are involved in significant numbers over the same time period.

      3) If any fish are seen to have lesions  or signs of disease

      Anyway sorry for the lengthy email but everyone on the executive should be in the loop now.  If others have more to add please do!

      Sorry I can't make the AGM, I am sure it will go well.

      Michael R Costigan

    All,

    •  (‘Good Job!’ to Mike, and to all who reported their observations, got sample fish to Blue Jay Creek, etc.) 

      I also discussed the situation with Wayne Selinger (= regional biologist in Sudbury) today, and based on what is known, he I and were in concurrence that the most likely cause of the fish die-off is thermal stress from the rapid rise in water temperatures across late June to present:

      1. The vast majority of the dead fish are Whitefish; a ‘cold water’ species (like the Lake Trout are) that is intolerant of warm temperatures. They are mostly bottom-feeders in a lake’s deeper waters, but are known to take advantage of the seasonal forage opportunity presented by Mayfly (etc.) insect hatches. Those typically occur during the late June/early July in question, and mostly in shallower waters that would have been subject to rapid temperature rise.
      2. The reported locations of dead fish [Eagles Crest, Sandfield, Silver Bay and the west end of the Narrows (..assuming the ’4-marker’ shoal is the one out from Timberlane..)] demonstrate  a lake-wide impact, and therefore unlikely to have been caused  by an isolated event (‘toxic spill’, etc.).

    I have not been ‘up’ since the end of May, at which time surface temperatures were still around  11 C (= still cool enough for cold water fishes to be relatively shallow). A fair bit of June was cool/wet, retarding a more normal/gradual rise in water temperature, after which it apparently got hot, quickly.  If it was still @ 13-14 C at the onset of the quick heat-up, and got to (..guess..) 21 C in only 1-2 weeks, not only would 21 C be excessive for Whitefish, but the rapidity of the change would be a stress, by itself.  There would be an attendant decrease in oxygen levels (..roughly 11 mg/L down to 9 mg/L).  9 mg/L is still plenty, but the rapidity of the decrease (..@ 20% in 1-2 weeks) could have been an added stress.  My understanding is that fish delivered to BJCH were “normal” in appearance (..aside from “the Obvious” of being dead..), which likewise suggests that some “toxic spill” is not a factor.  MNRF is to do tests on the fish, including the possibility of a (..normally innocuous..) bacteria adding to fish’ stress from thermal/oxygen changes…..I don’t want to seem flippant or oversimplify, but it does sound like the Whitefish, “got caught with their fins in the Cookie Jar (= insect hatches)” , and unable/unwilling to react quickly enough to the rapid change in temperatures.

    Hope this helps. I won’t be available for AGM, but expect to be back up and attend Information Night, if there’s opportunity to further discuss on that occasion.

    -Rob Coulter

    (Lake Steward, one of three)


    Last modified: 2019-07-11 6:39 PM | Anonymous member (Administrator)
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