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Lateral view of a Female Hexagenia limbata (Ephemeridae) (Hex) Mayfly Dun from the Namekagon River in Wisconsin
Hex Mayflies
Hexagenia limbata

The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.

Dorsal view of a Ephemerella mucronata (Ephemerellidae) Mayfly Nymph from the Yakima River in Washington
This is an interesting one. Following the keys in Merritt R.W., Cummins, K.W., and Berg, M.B. (2019) and Jacobus et al. (2014), it keys clearly to Ephemerella. Jacobus et al provide a key to species, but some of the characteristics are tricky to interpret without illustrations. If I didn't make any mistakes, this one keys to Ephemerella mucronata, which has not previously been reported any closer to here than Montana and Alberta. The main character seems to fit well: "Abdominal terga with prominent, paired, subparallel, spiculate ridges." Several illustrations or descriptions of this holarctic species from the US and Europe seem to match, including the body length, tarsal claws and denticles, labial palp, and gill shapes. These sources include including Richard Allen's original description of this species in North America under the now-defunct name E. moffatae in Allen RK (1977) and the figures in this description of the species in Italy.
27" brown trout, my largest ever. It was the sub-dominant fish in its pool. After this, I hooked the bigger one, but I couldn't land it.
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Posts: 1
Trouthead on Nov 10, 2009November 10th, 2009, 2:54 am EST
I notice that there is a lot of nagitive fellings on them. my observations are that i catch a lot of big browns in the beaver ponds,
i think this is because this is the deepest water on the streams and holds large amounts of baitfish. i understand the consern on brookie streams, as it could warm the water.
Got trout?
Jmd123's profile picture
Oscoda, MI

Posts: 2474
Jmd123 on Nov 10, 2009November 10th, 2009, 5:35 am EST
I personally like beavers and their architecture, precisely for the same reason: beaver ponds hold the most, and largest, trout on small streams. I have fished several small trout streams in northern lower MI, and some pretty skinny waters get turned into major trout habitat when the critters move in and build their dams. And you can shoot the beavers and destroy their dams, and another one will just move in and build a new one - if it's an ideal location for a beaver dam, you can't keep 'em outta there.

In fact, during my Oregon days in the early 90s I saw beaver activities restoring habitat diversity in channelized streams, creating new habitat for juvenile coho salmon and sea-run cuttroats. Trout and salmon parr were THICK in the areas where the beavers had ponded the water and restored sinuosity and slack-water areas, and few to non-existent where the (straightened) channels had not been touched.

I'm sure it can happen, but I have not seen any evidence of damage to trout populations from beavers, in fact quite the opposite.

No matter how big the one you just caught is, there's always a bigger one out there somewhere...
JOHNW's profile picture
Chambersburg, PA

Posts: 452
JOHNW on Nov 10, 2009November 10th, 2009, 7:40 am EST
Wow for a second I thought that was going to a very bad place, at least for those of us in Central PA.

I think alot of the negative feelings have to do with the fact that mankind demonizes anything that isn't out there to make our lives easier and heaven forbid if said critter does it's thing without regard to Homo Sapiens. Those damn Beavers just go around usurping that land we all want to be on. ;)
I think one might be able to draw a paralell to wildfire in the Mtn. West. It is very beneficial ,some might argue essential, to the ecosystem in general but we [humans] have a bad habit of putting things of value in the way.
"old habits are hard to kill once you have gray in your beard" -Old Red Barn
NW PA - Pennsylvania's Glacial Pothole Wonderland

Posts: 398
RleeP on Nov 10, 2009November 10th, 2009, 10:07 am EST
Actually, from a Pennsylvanian perspective this beaver thing belongs on the Wisconsin contingent thread. PA was almost shed of the things (none had been seen in 15 years) when the Game Commission imported a mating pair from WI in 1915.

And the rest is history as detailed in this 1934 article from TIME Magazine..

So, it's WI that has to answer for this...:)


I think beavers can be bad or good for trout streams, depending on a lot of variables from how much canopy and bank anchorage they destroy to the thermal impacts of dams on streams. Some streams are so well infused with numerous springs that the dams make little if any thermal problem and actually can do a lot for habitat. On other streams, one dam can render a mile of creek untenable for trout. I've seen it go both ways.

I think it is also important to recognize that beaver dams can help keep the cost of wood duck flank feathers down by increasing wood duck habitat. This is not a small thing to folks who favor Catskill dries and hare's ears nymphs...:)

And needless to say, an abundance of wood duck flank feathers allows more of the onion crop to go directly to the food supply rather than having the skins used to dye mallard flank to a shade the same as wood duck...

So, like virtually everything else, this beaver thing is a mixed bag with reasons to both curse and bless.

Personally, I think they're beautiful creatures. But the older I get, the more I resent them because on small water, their dams force me to walk farther to get to the next pool..
Jmd123's profile picture
Oscoda, MI

Posts: 2474
Jmd123 on Nov 10, 2009November 10th, 2009, 10:52 am EST
Lee, I must confess that you have hit on one of the reasons I do like beaver dams - having to hike over and around them keeps the "riff-raff" out! Nothing personal, of course, but we all know that generally the fewer fisherman, the better...This kind of fishing isn't for everyone, anyway, since it's always tight waters with lots of overhang. But then again, that's what 7-foot 3-weights are for.


P.S. The beaver ponds I fish are generally on spring-fed creeks that stay cold right through August, some so cold they can't be wet-waded no matter how hot the day!
No matter how big the one you just caught is, there's always a bigger one out there somewhere...
JOHNW's profile picture
Chambersburg, PA

Posts: 452
JOHNW on Nov 13, 2009November 13th, 2009, 8:16 am EST
I was not thinking of the bucktoothed rodent variety of beaver but rather the Central PA River Monger.

"old habits are hard to kill once you have gray in your beard" -Old Red Barn

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