Brown trout are found in many parts of the US and around the world and typically spawn during the fall (exact details below).
Knowing about their spawning habits helps anglers work out what times to target trout and when to leave them alone to reproduce.
In this article, we describe the brown trout spawning process, when it occurs, and where it occurs.
What Time of Year Do Brown Trout Spawn?
Brown trout in the US tend to spawn between September and December, depending on the location and how wet and cold the year has been.
To get the right conditions for brown trout to spawn, you need the water temperature to be between 43 and 53 degrees Fahrenheit (5-12 degrees Celcius).
That’s because the trout eggs and the juvenile trout need lots of dissolved oxygen in the water, and the colder the water, the more dissolved oxygen it contains.
Water temperatures that are too high or too low can kill off the eggs, meaning fall is the safest bet for brown trout to spawn.
In the southern hemisphere – Argentina, Chile, New Zealand, and Australia – spawning seasons for brown trout occur in April, May, and June, which is fall in this part of the world.
Factors That Affect Brown Trout Spawning
Temperature
Having that water temperature between 43 and 53 degrees Fahrenheit (5-12 degrees Celcius) is probably the most important factor in triggering spawning runs of brown trout.
Stream Flow
Brown trout need a decent water flow to spawn. An increase in water flow after a rainy period will often trigger a spawning run. The higher flow allows the trout to feel safe as they move upstream to their spawning areas. Ideally, the flow should be high enough to cover spawning areas in 1-3 feet of water.
River Bottom
Trout need a section of the river with loose gravel to form their redds and bury their eggs. Trout will key in on these areas.
Oxygen Levels
The higher the oxygen levels in the water, the more conducive it is to successful spawning for brown trout. The colder the water, the more oxygen it holds, hence why trout down spawn successfully above the temperature window mentioned earlier.
Where Do Brown Trout Spawn?
Brown trout, like most trout species, choose shallow gravel sections of a river bed with a strong current to spawn. This ensures the eggs can be buried in the gravel and still get plenty of oxygenated water flowing by.
Brown trout are not afraid to travel several miles upstream in the river or its tributaries to find the right areas in which to spawn.
What Is a Redd, and What’s It Look Like?
A redd is a nest made of gravel where female brown trout can deposit their eggs, and the males fertilize them. Spawning trout construct redds in shallow, gravelly sections of the river with reasonably fast flow. You can see the redds in the gravel beds as they appear cleaner as the individual grains of gravel have been turned over by the trout in constructing the redd.
It is important when fishing for spawning trout to avoid stepping on or disturbing the redds as this will damage the brown trout’s eggs and threaten the success of the spawn.
Can Brown Trout Spawn in Lakes
Yes, they can, but spawning in lakes has a much higher mortality rate than in rivers, largely because of the lack of flow of oxygenated water at the right temperature. So trout in lakes will usually try to seek out a stream flowing into the lake to spawn. Lakes with few or no streams flowing in have virtually zero natural recruitment, and this sometimes sees those fish present in the lake grow to trophy size! Of course, there will be relatively few of them!
How Do Brown Trout Spawn
The spawning process for brown trout sees the females dig holes in the gravel with their tails to build a nest or redd. When the redd is complete, she will release her eggs into it, and the male will release his milt to fertilize the eggs. They will then bury the eggs by swishing gravel over the top of the redd.
The eggs hatch into alevins in a few months’ time, depending on the water temperatures.
When Do Brook Trout and Other Species Spawn
Brook trout tend to spawn a little later than brown trout, typically commencing their spawning in September.
Should I Fish For Spawning Trout?
Trout tend to be very vulnerable when they are spawning. For starters, they have come up into very shallow water, and they are distracted by reproducing and don’t have their usual wariness.
Some people believe it is unethical to fish for spawning trout, while other people have no problem with it at all.
Opponents of fishing for spawning trout make a couple of arguments: that it is too easy or unsporting and that it prevents trout from reproducing to maintain healthy stocks.
It is a complex argument as in some smaller river systems, it is arguably beneficial to have less natural recruitment to increase the average size of the trout in the river.
But it is also preferable to avoid having to stock fish in a river or lake and instead maintain a wild trout population.
Proponents of fishing for spawning trout say that there are enough to go around, and it is a good way to introduce children or beginners to trout fishing.
As always, the most important thing is complying with all local rules and regulations. There are often specific laws in various states on fishing for spawning fish.
How Do I Fish For Spawning Brown Trout
Assuming you are legally allowed to fish for spawning brown trout in your area, then the main method of targeting these fish is with a fly or lure that emulates trout eggs.
Spawning brown trout will feed on loose eggs dislodged from redds during the spawning season.
Fly fishing is a great method for this period. Small round bright orange flies drifted past a spawning trout will often elicit a strike. I often fish a dual fly rig with a nymph tied off the back of the Glo Bug fly.
Spawning season allows you to target some very large brown trout with some giant hook-jawed males and powerful hens that you wouldn’t otherwise see present in very skinny water!
Another way to fish the spawning run is to target rainbow trout and other trout species that aren’t spawning at the same time but do like to follow the spawning browns so they can eat any brown trout eggs that get dislodged.
Brown Trout Spawning FAQs
Will Brown Trout Die After Spawning?
No, brown trout can spawn multiple times in their lives. After they spawn they will soon head back downstream to their usual section of the river (or drop back into the lake if they have come up into a headwater stream to spawn).
Post-spawn brown trout have usually lost a lot of condition on the journey upriver and through the spawning process itself, so often feed well. Fishing with streamer fly patterns to post-spawn browns is a great way to target them.
When Do Brown Trout Spawn in Montana?
Brown trout usually commence spawning in Montana streams in late October or early November, but it does, of course, depend on water flow levels and water temperatures. A cold front with rain during the fall will bring on spawning.
When Do Brown Trout Spawn in Colorado?
Brown trout in Colorado commence their spawn as early as September and as late as November, depending on local conditions. Cool water temperatures and a rise in river levels will get brown trout focused on spawning.
When Do Brown Trout Spawn in Wyoming?
Late September to early November is the typical spawning window for brown trout in Wyoming streams, with the exact spawning period depending on local conditions in terms of water temperature and stream flow.
When Do Brown Trout Spawn in Michigan?
Brown trout spawning runs in Michigan streams start in early fall, typically in September or October. The exact timing of spawning runs is governed by water temperatures, and stream flows with cool water and rising river levels are likely to trigger the spawn.
