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Lateral view of a Male Baetis (Baetidae) (Blue-Winged Olive) Mayfly Dun from Mystery Creek #43 in New York
Blue-winged Olives
Baetis

Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.

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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By Troutnut on August 4th, 2020
Continuing my sightseeing tour of remote Idaho, I drove around a bunch of backroads and made a quick fishing stop at enticing-looking water on the Yankee Fork of the Salmon. I didn't even put waders on, just wandered out on a gravel bar in street shoes to take a few casts, aiming to keep my "at least one trout every day of the trip" streak alive on a day without any real fishing. The fishing wasn't good, but a 7-inch bull trout (quickly released unharmed) kept the streak alive.

Photos by Troutnut from the Yankee Fork Salmon River in Idaho

The Yankee Fork Salmon River in Idaho
The Yankee Fork Salmon River in Idaho
The Yankee Fork Salmon River in Idaho
I wasn't paying close attention at the time and released this fish very quickly after the picture, so I thought it was just a skinny brookie and didn't notice until looking at the photo that it's a juvenile bull trout. Good thing I was all-C&R on this trip anyway!
The Yankee Fork Salmon River in Idaho
The Yankee Fork Salmon River in Idaho

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