Another “Long Hot Summer” Likely to Stress Northern Michigan Trout Fisheries

July 16, 2012

Fisheries

Regardless of the causes or circumstances, we are in the midst of yet another “unseasonably” warm summer which is again placing stress on many of our northern Michigan cold-water systems.  In the coming days, we will be asking several of our contributors to weigh in on their take on the situation and perhaps offer possible long term solutions for a problem which does not appear to be going away any time soon.

One such contributor is Tom Buhr who, through his engagement in the Au Sable Big Water Preservation Association (http://www.asbwpa.org) was aware of the sustainability challenges facing some of these systems even before the issue became fashionable.  He and the ASBWPA are advocates for the “70 degree Pledge” http://www.70degreepledge.org/.

While we may be limited as to what we can do to reverse the water temperature trends, there may be strains of trout which are more suitable to these conditions.  One such possible solution Tom has written about in the past is the Sturgeon River strain of brown trout.  His story follows:

Sturgeon River Brown Trout Could Be The Answer To Tailwater Blues – by Thomas Buhr (A version of this article appeared in RIVERWATCH 62)

It’s not a bird.

   It’s not a plane.

   It’s just a strain of brown trout.

   But what it could do would be super!

The DNR Fisheries experiment with the Sturgeon River strain of brown trout in two of the State’s most popular tailwaters is showing signs of success.  Well, at least in one case.  The idea is to find a strain of brown trout that can handle the warm water associated with river sections flowing out of top-draw dams.

The stretches below dams on the Au Sable (Mio) and Manistee (Hodenpyl) have long been popular spots to fish for trophy brown trout.  Unfortunately, being tailwater these reaches also suffer from overheating in the summer months.  High water temperatures can devastate salmonid populations, especially if fishers mistakenly practice catch-and-release when there is little chance of a trout surviving it.    

The summer of 2011 was another buzz kill for any coldwater system that lacks enough factors to ensure reasonable diurnal temperature swings.  Trout can handle short periods of high water temperatures.  It is sustained heat that wears on them.

The Big Waters experienced 96 consecutive hours above 75 degrees at Mio Dam including 48 of those above 77 in July of 2011.  (A report on water temperature below Mio for the 2011 season can be obtained at http://www.asbwpa.org).  Six weeks of unremitting warm water lowered oxygen levels, blew out the hatches, and wore on fish more suited to 60 degrees.

The latest DNR report indicated that many trout were lost, but there is a bit of a silver lining.  The numbers were ugly, a 57% decline in brown trout over 2010 estimates.  For rainbow trout it was apocalyptic, an 83% decline to a rock bottom figure of two ‘bows per acre. 

Now the silver lining, returns two years into the great Sturgeon River versus Wild Rose planting experiment show that the former is surviving at a better rate, 167% in 2010 and 400% in 2011.  This suggests that Sturgeon River strain brown trout may be able to handle the Big Water’s biggest bane, high water temperatures.

There’s even anecdotal evidence from credible sources of historically high numbers of 13″ to 17″ brown trout caught – the true mid-teen fish, including during the white fly hatch and fall streamer blitz.  The problem below Mio for a decade has been the lack of trout between 10 and 20 inches.  There had to be some because how else did the 20-inch plus monsters get there?  But there were not very many.

Late in 2011 “teenagers” were very common.  What does that mean for 2012?  Well, let’s not get ahead of ourselves yet, but these teen-wonders have survived two tough summers and one winter.

It has been difficult to analyze the results on the Hodenpyl stretch because so few trout were captured for survey in 2011.  The year before, however, the Sturgeon River strain survived at an 800% rate in comparison to Wild Rose.  Let’s not forget that 2010 was a hot one too.

There are three more years left in the Sturgeon River/Wild Rose study.

A popular game in fly shops, drift boats, and stream-banks is poor mouthing DNR Fisheries Division.  Any idiot can do it.  I’ve heard more than my share of folks spout on and on about the shortcomings of Fisheries in managing our coldwater resources.  I’m no cheerleader but the results of this study coupled with the new Gear Restrictions show me a Division that is making some pretty good calls lately – Respect Due!

We will never have all the pieces to the puzzle for tailwaters, trophies and high mortality.  The top draw dam makes it a paradox, capable of making scores of 20 inchers or decimating entire year classes.  Too many fishers, especially some in the industry, squawk nonsense, but numbers never lie and so far things look promising in this instance.

About Northern Michigan Conservation Network

The mission of the Northern Michigan Conservation Network is to "connect conservation-minded hunters, anglers, and outdoor enthusiasts to those issues affecting Michigan's forests, waters, and wildlife."

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