If you want to throw streamer flies, you can leave the big meat box in the closet. Right now is the best time for little streamers. There is an overabundance of small fish in the river now from this year’s spawning cycle. Anglers willing to do the math can now make a strong case for fishing small streamer flies.
Colorado Parks and Wildlife (CPW) establishes closures for spring spawning activity in certain bodies of water from March 15 through May 15. With this data, anglers can do the math. Small variables like water temperature can increase the gestation period before eggs hatch in Alevin. But from laying the eggs to hatching takes about 60 days.
Alevin are the first stage of development of the rainbow trout, in which the egg sac is still attached to the belly of the young fish. Once the egg sac is absorbed, the small trout is in the brood stage. Almost an inch long, the fry swim around the bed. Flood will start to move them as they develop.
Considered fry to three inches or longer, the small fish will begin to develop Parr markings. Parr marks are the distinctive spots that color small rainbow trout. During development, the parr marks are lost as they mature into fingerlings.
The period from a newly hatched rainbow trout or alevin to juvenile is the window we are currently in. There really aren’t nearly as many juveniles or yearling trout as there are juveniles. Fry learn to swim and fast currents take the little Parr-tagged minnows on an uncontrollable ride. The many small trout that enter the food chain are, so to speak, a pseudo-brood.
Fast-swimming brown trout make light meals of the highly targetable and highly visible morsels battling in turbulent currents. Competing against an adult monster hook-toothed brown trout is a losing game for baby rainbows.
So the window is open for the new rainbow round to run the gauntlet into summer. Anglers looking to cast streamers should convert their knowledge of rainbow trout development into smart fly selection decisions.
The small rainbows range from 1″-3″. Their sides have very visible spots running the length of the fish. They don’t swim very well so they seem to fight. Present your flies to mimic fighting for a realistic presentation.
Gary Lafontaine was a great fly fisherman, teacher and person. His writing and videos taught anglers a world and instilled a thirst for fly fishing that I have not quenched in over thirty years of fly fishing. He believed that a struggling, weak, injured baitfish could not swim with strength. When float fishing, he consciously threw towards the bank and patched downstream. The downstream repair would pull the streamer with the current, much like a wounded or easily eaten baitfish would swim.
It’s always a good idea to try another catch attempt when throwing streamers. This presentation can be killer as the falling currents still keep the water in the fairly high category but are definitely going down. Trout have seen many small fry being blown into the river. Ambush points, rocky obstacles, and woody debris form the opportunistic attack positions that predators seek.
Fish the small streamer flies on a short leader. Small flies don’t need much weight to sink them, but a sinking headline will pull the fly down with an enticing drop. The change in depth a few meters from shore is good water for fishing.
The Streamer targets obstacles with bright but striped markings to mimic Parr markings and can spawn some healthy enemies. Brook trout are ready to feed and the little rainbowfish are just the big protein bite they’re used to in the river.
Now is not the time for your bushy, limber streamers. A tiny, white bow tie with a glue gun egg pouch is a unique streamer for this time of year. But any small streamer that swims enticingly can mimic the rainbow trout’s early developmental stages. Break out the little ones, you won’t regret it.
Michael Salomone moved to the Eagle River Valley in 1992. He started fly fishing professionally in 2002. His freelance writing has been published in magazines and websites including Southwest Fly Fishing, Fly Rod & Reel, Eastern Fly Fishing, On the Fly, FlyLords, Pointing Dog Journal, Upland Almanac, Echo Website, Vail Valley Anglers and more. He lives with his wife Lori on the banks of the Eagle River; two daughters, Emily and Ella; and a couple of yellow labrador retrievers.