When visiting anglers ask Mike Boatwright where the action is on the Yampa River, he doesn't have to say much. Boatwright swings the flat panel computer screen on the counter at Straightline Outdoor Sports into view and lets the picture do the talking.
The screen shot is a close-up of a fly rod and fly line, both coated with tiny mayflies - more specifically, tricorythides, trikes or tricos, for short.
Anglers who are willing to walk up and down the Yampa River Core Trail in Steamboat Springs this week are apt to locate clouds of the tiny insects, particularly in the mornings. And when they do, they could be in for some of the most interesting and changeable action of the late summer.
"When you see the insects 10 feet above the river, that means they're about to die (and fall onto the surface of the water)," Boatwright said. "They have just a four- to five-hour life span to hatch, mate and die. They're dying all the time."
Jonah Drescher of Steamboat Flyfisher said the daily trico hatch, which started earlier than usual this summer, can begin as early as 8 a.m. Expect a lull in activity by mid-afternoon.
Because of their tiny size (hook sizes 20 to 22), the fact that trout sometimes slurp them in remarkably shallow water, and the constant recycling of their life span, fishing the tricos can be daunting for intermediate fly fishers.
Steamboat fishing guides say there are strategies that will make it easier to fish this August hatch.
"It's a really good hatch, and it can be very technical to fish," said Colin Taylor of Bucking Rainbow Outfitters.
He suggests anglers avoid the stretches of river where the trico hatch is most prolific in favor of stretches where there aren't quite so many insects. It can be difficult to compete with the natural insects where the water is literally carpeted with tricos, he said. The fish won't be quite as selective where there are fewer of the insects to feed on.
Taylor also advocates letting a dry fly sink just beneath the surface in order to tap into somewhat less discriminating fish.
"A drowned trico really is the way to go," Taylor said. "Eighty percent of the feeding that takes place is under the water." He recommends a plastic bead head pattern that sinks - but not too much.
Because the flies are so tiny, Taylor suggests placing a small foam pinch-on strike indicator about 16 inches above the fly. Any twitch of the indicator should alert the angler to a strike from a fish.
Drescher likes to use a second, slightly larger dry fly when fishing adult trico patterns. A size 16 parachute Adams tied on above the trico will not only key the angler's vision to the location of the tiny trico pattern, but also can attract fish and sometimes even trigger a strike.
Trout often work the trico hatch in water so shallow that their dorsal fins protrude from the water. Anglers need to resort to longer casts in these instances.
"Longer casts always help," Drescher said. "If you can cast 20 feet instead of 10 feet, that's good."
The good news on the Yampa is that the fish are accustomed to human disruptions - if you put a fish down, he probably won't stay down long before resuming feeding.
Drescher said he has encountered success by barely dragging a trico emerger pattern through the water.
Tiny flies suggest fine tippets, but Drescher said the trout in the Yampa aren't leader shy, and there's no need to drop down to a wispy 7x tippet. For fishing the trico hatch in the town section of the Yampa, 6X is more than adequate, and anglers who aren't experienced at playing substantial trout on fine tippet will often do fine with 5X.
The Yampa is flowing at 143 cubic feet per second on Aug. 18, 5 cfs greater than its historical mean, and tourism has quieted this week before the big Labor Day finale. That makes this a good week to sneak out at mid-morning and fish a hatch that will soon give way to autumn.