“Hey, Koz, can you back the boat up?”
“Did you snag again?”
“No, I saw something, we need to check it out.”
“is it a dead body?”(thinking it was a trout/hoping it was a merganser)
“No, I think I saw some suspect algal growth.”

Didymo- Didymosphenia geminata aka ‘Rock Snot’ has a certain wet wool feel.


Didymo. There is a certain mossy wet wool billowy look to it. I’ve seen it, at least an algae very similar. We quickly grabbed a sample and I slipped my Nancy P out of its ziploc package and we placed the potential algae in the cooler for further inspection. It was serendipitous to have Sam Day in the stern of the boat. He works for the Tribe as a fisheries specialist and has a keen eye for these unwanted invasive species. Later he would look at the sample under a microscope and inform EGLE/DNR, MITU and other interested parties.

About a week later Sam texted me with some funny looking squirmy microscope photos and he saddened me with bad news.  It was confirmed. We have Didymo, aka ‘Rock Snot’ in the upper Manistee River. Which leads me to believe it is more widespread than we know. We need to be more vigilant with boat & wader cleaning. This doesn’t just jump from watershed to watershed- it needs a host, someone to transport it in a host environment. What do we do now?

I know myself and most of my fishing friends do a diligent job of cleaning their boots/waders and the local DIY car wash gets a good chunk of my guide tip money every week cleaning off the Adipose, but apparently we need to do more. Perhaps more signage at popular put-ins and take outs. I wouldn’t be surprised that a large population of recreational river users don’t even know how to spell  ‘invasive species’ much less know the potential devastating impact this can have on a watershed and the livelihood of many anglers/guides. We need to inform the average river user how to properly clean and disinfect boats/gear before they carry this to more places. Do yourself a favor and go to nearest Farm & Fleet store and buy some Virkon S, it is made for animal health and disinfection, specifically designed to kill 64 strains of virus, 34 strain of bacteria and 5 fungi. It comes in tablet form, you can throw your boots & waders in a large tub, fill with water and drop a tablet in, soak for 1/2 hour, pull out and dry.

This can have a large impact on already stressed rivers across the state. We have seen record low water levels and some pretty warm seasonal temperatures. The new algae will occupy niches where there is relatively low flow and attach itself to solid surfaces. It goes dormant in winter, but will return in spring and we will be monitoring along with many others. The algae can choke out other native plants and algae that would otherwise be in these locations and indirectly have the greatest impact on macroinvertebrate populations. I hope we can contain this.