By Zach Lazzari
Spring is an exciting time of year for trout anglers. The ice is disappearing from local rivers and Blue Wing Olive hatches draw trout to the surface before the snowmelt blows everything out. This spring season is also spawning season for rainbow trout and they frequently occupy gravel areas where they dig beds or redds and reproduce. This process is critical to the sustainability of wild trout populations and suitable fishing etiquette is equally important.
Timing of the Spawn
The exact timing varies slightly based on the river system. In tailwater fisheries where the water temperatures see little variance below the dam, the spawn can even cycle out of season at random. In most cases however, rainbow trout spawn in the spring or late spring. Runoff often hits a few weeks after the spawn is complete.
Timing of the rainbow spawn often depends on geographical location. At lower elevations, like near our Mystic Headquarters in Denver and along the Colorado Front Range, rainbows will frequently spawn in February and March. Higher in the same river systems, temperatures are much colder and the rainbow trout will spawn in March and April. Depending on where you live, the spawn may occur between February and May with a few regions pushing the outer limits of this timeframe.
How to Identify Redds
Rainbow trout frequently spawn on pea size gravel although they will dig redds on slightly larger substrate. Being a spring spawner, the rivers flows are likely to fluctuate and they often choose locations that are covered with water at low and high flows. The heads of riffles are popular spawning areas but they will also utilize flat water and the inside of a bend for spawning territory.
The redd itself is identifiable by either first spotting the fish gathered or by the cleaned section of gravel. When building a redd, the females fan their tails over the gravel to create the nesting zone. This area stands out visually because the rocks and substrate are cleaned and tidy when compared to the remainder of the river bottom. A female on the redd is not uncommon and other males will sit downstream, jostling for position to spawn or eat free-floating eggs.
Rainbows are Spawning, What Now?
Rainbows have a habit of spawning in the same areas we naturally wade. This requires special attention from anglers during this spawning season. If you see fish suddenly scattering about or an obvious redd, step back and choose a different route. Continue this practice after the redds are abandoned to ensure the spawn reaches full cycle without disturbance.
Spawning fish does not require that you cease fishing however. Simply do not fish areas where the redds are present. Leave those spawning fish alone and move to another spot up or down river. Fishing egg patterns during this time period is a common practice and you can catch rainbows, browns and cutthroats using this approach.
To really avoid pressuring fish that are spawning or preparing to spawn, fish a big streamer to only target brown trout and other fish that are dedicated to eating a big calorie meal. Or, solely focus on targeting trout that are visibly feeding on the surface. Avoid the shallow water and riffles where fish are actively spawning and you can still have a great day on the water.
False Spawn and Questionable Tactics
In lake systems, rainbow trout will continue spawning or attempting to spawn. In lakes with inlets and outlets, fish can successfully spawn. Avoid fishing the mouth areas during the spawning season and definitely do not fish in the actual streams where the spawn occurs.
Lakes without inlets or outlets are stocked with rainbow trout and they will attempt to spawn in shallow, gravel filled areas. These fish are not capable of actually reproducing in this manner and that makes the event a false spawn. Targeting these fish is not uncommon and it falls in a grey area on the ethics front. Ideally, you will work outside of the obvious redds. In a put and take fishery however, keeping a few trout opens the door to using any legal technique and fishing near redds is not uncommon. This decision is one made by each individual angler in lakes where a false spawn occurs each spring.
Zach Lazzari is a fly fishing guide and an outdoor writer based in Montana. Zach has fished and guided in Alaska, Colorado and Patagonia. Zach is also the blogger behind The Busted Oarlock.