When Do Brown Trout Spawn & Should You Fish When Brown Trout Spawn

If you are reading this then you probably have a healthy addiction to catching brown trout with a fly rod. There is no better trout species to catch, in my eyes, than brown trout as they are the wisest and the most beautiful of them all, which makes landing one just that bit more exciting.

But, as much as we love catching brown trout, there are times when we shouldn’t fish for them in order to protect them, and one of these times is during spawning season.

When brown trout spawn, they are creating the next generation of fish for us to target in the years to come. The last thing any of us fly anglers want is for there to be less brown trout in our rivers which is why it is important to know when brown trout spawn so we can leave them alone.

Join me as I answer the question when do brown trout spawn in detail so that you can do your bit and leave these beautiful fish in peace while they have their young.

When do Brown Trout Spawn?

Brown trout are found all over the world from New Zealand to Argentina, the USA, Europe and more. They don’t all spawn at the same time, their choice to spawn comes down to one thing, water temperature.

Generally speaking, in the northern hemisphere, brown trout spawn between October and December, and in the southern hemisphere between April and August.

What Affects the Success of Brown Trout Spawning?

There are quite a lot of different factors that affect how successful brown trout spawning can be.

The main one is temperature which we will discuss in more detail below, along with all the other factors you as an angler should be aware of.

Why does Temperature Play Such a Vital Role?

As I already mentioned, brown trout spawn in temperatures between 5°C and 10°C but their eggs have the best chance of surviving in temperatures between 7°C and 8°C.

Why is this?

It is all about how much oxygen is available in the water.

A study has shown that in water temperatures above 13°C, almost 100% of brown trout eggs die and this is because warmer water has less oxygen in it than colder water.

The eggs and resultant trout fry require a good amount of oxygen to grow and survive, and in water temperatures of 13°C, there is simply not enough.

The study also showed that in water temperatures of 4°C and below, 25-30% more brown trout eggs or fry died compared to ones in waters between 7°C and 8°C.

This is because it takes the eggs much longer to hatch, creating a higher risk of them floating away and being eaten. The fry that do manage to hatch in colder waters are also much smaller and therefore are less able to swim and find food.

What Else Affects the Oxygen Content of the Water?

The other factor that affects how much oxygen is in the water is flow. The flow of a stream or river constantly washes the eggs with oxygen as they grow for 4-6 weeks before hatching.

This stage is incredibly important as the eggs are slowly becoming small fish and without oxygen, this process cannot happen effectively.

Where do Brown Trout Spawn?

Brown trout spawn in streams or rivers in areas where their eggs and coming fry have the best chance of survival.

The spawning male and female will look for a gravely area with a lot of current. Gravel is an ideal bottom for the eggs to attach themselves to securely and the current provides enough oxygen for them too.

Once the adult brown trout have found a good area, they create a nest, or redd. The redd is made up of gravel that is carefully cleaned and arranged in an oval shape. Once the redd is built, the female lays her eggs and the male fertilizes them.

After fertilization, the parents hover above their redd for 4-6 weeks in order to protect it until the eggs hatch into small fry.

Do Brown Trout Spawn in Lakes?

A brown trout’s need to spawn is in their DNA and they will spawn wherever they are whether it is a lake, river or stream.

Brown trout in lakes will instinctively look for an inlet or outlet in the lake where there is enough current for their eggs. But, not all lakes have an inlet or an outlet, so what do they do?

In this case, the trout will find the best possible place they can to lay their eggs on the bottom of the lake. Unfortunately, the water temperatures at the bottom of lakes are usually too warm and the lack of current means they are not very oxygenated either.

What does this mean?

This means that eggs that are hatched in lakes usually do not survive. A few eggs might be lucky and make it to hatching but the majority will not have enough oxygen to hatch.

How Often do Brown Trout Spawn?

Brown trout spawn just once a year like most salmonid and trout species. They do not continuously spawn or spawn more than once in a year when the water temperature is correct.

This ties in nicely with the rhythms of nature as the spawning window of water temperatures drop to between 5-10°C only happens once a year, during the colder months.

How Many Eggs do Brown Trout Lay?

The number of eggs a brown trout lays depends on the size of the female brown trout laying them. A female brown trout will produce on average 900 eggs per one pound of body weight.

This means a 3lb brown trout will lay around 2700 eggs, a 10lb brown trout will lay 9000 eggs, and a 20lbs brown trout 18000 eggs.

This is an excellent example of natural selection as the bigger brown trout, with likely better genetics since they have survived to be so large, will have more offspring than smaller brown trout.

Do Brown Trout Die After Spawning?

No, unlike some salmon species, such as Atlantic salmon, brown trout do not die after spawning. They continue with normal life having spawned and do so again the following year.

But, they are more at risk during spawning season as they use a lot of energy in order to spawn and guard their redd instead of feeding as heavily as usual.

This means that if you do happen to catch a spawning brown trout, you should take as much care as possible to ensure its safe and healthy release.

When do Brown Trout Spawn in Each State?

Below, you will find a table showing you when brown trout spawn in each US state. You’ll notice that it can change from one state to another depending on when the water temperature becomes correct.

Generally, it is October to December for most states.

Should You Fish for Brown Trout when They are Spawning?

Whether you should fish for brown trout during spawning season is an ethical and moral question for you to answer as an angler.

In my opinion, all anglers should leave brown trout alone while they are spawning so the fish are given the chance to create the next generation. Spawning season doesn’t last that long and you can tie some flies or target other species while the browns are doing their thing.

That being said, a good time to fish for brown trout is just before the spawning season known as pre-spawn. This is when brown trout are very aggressive as they are trying to gain weight before expending a lot of energy when they spawn.

The pre-spawn period is often the best time to catch trophy brown trout too, as they lose some of their wisdom in return for piling on the pounds and will be fooled more easily.

Can You Legally Fish for Brown Trout During Spawning Season?

Whether you can or should fish for brown trout during spawning season are very different questions. Should is a moral question we have just answered while can is dependent on the regulations of the fisheries.

In almost all rivers and streams in Europe, fishing for brown trout is closed from October to March to protect the fish while they spawn and their eggs hatch.

In the US and Canada it is a little different. Some fisheries close their fishing while others make it catch & release only.

This means you can fish for spawning brown trout in some places, but it is best to leave them alone and focus on the rainbows and cutthroat trout that are not spawning.

What Should You do if You Hook a Spawning Brown Trout?

When fishing for other species like grayling, rainbow, and cutthroat trout during brown trout spawning season, you might catch a spawning brown trout by mistake. This happens, and it is not your fault if you are not intentionally targeting them.

So, what should you do?

If you do hook a spawning brown trout, you need to do all you can to ensure it survives and this involves a few things.

Firstly, try to reduce the fight time to as little as possible so the fish is not incredibly tired at the end. You should also avoid air exposure at all costs which means not taking them out of the water, not even for a photo.

Once you have removed the hook, give the fish as much time to recover as possible. This means holding it gently underwater in the current and letting it get its strength back by flushing water through its gills. It will wriggle and shake when it is ready to go back to its redd.

How to Avoid Stepping on or Disturbing a Redd

Another great way of protecting the brown trout species is by ensuring you don’t disturb a redd. This is very important for anglers who have other species they can fish for in a river while brown trout are spawning.

The first step is being able to identify a redd. A redd will have two adult brown trout hovering over it and be an oval shape of gravel, in a gravely area. Be sure to keep your eyes peeled for these in a river and if you do see one, get out of the water and walk around it.

Some fisheries GPS mark redds so that anglers can avoid them, others put a colored stick on the river bank in line with a redd. If you see these, be sure to get out of the river and walk around the stick before continuing to wade.

The last thing any angler wants is to kick a few thousand eggs of their favorite species down river to their demise, so be careful when fishing in spawning season.

FAQs

Do sea trout spawn the same way as brown trout?

Sea trout are sea-run brown trout meaning they were born in a river as a brown trout and chose to go to sea to feed instead of staying in the river.

Sea trout spawn very similarly to brown trout as they migrate up rivers until they find a good gravel bottom with lots of current. When they find this spot, they wait there until the water temperature drops to between 5°C and 10°C, then lay their eggs.

This means that sea trout behave like salmon, as they return to the river they were born into to spawn, but once they are in the river, spawn like a brown trout. They do not die after spawning and will return to the sea once their fry are large enough to survive on their own.

What are good fishing tactics for other species during brown trout spawning season?

I have already mentioned not fishing for brown trout during their spawning season, but fishing for other species in the same river is fair game.

During spawning season, rainbow trout and cutthroat trout will sit below the brown trout redds feeding on any small fry or eggs that get washed down in the current. This is an opportunity you should take advantage of.

Fish with egg flies and hot spot streamer flies as these are deadly. The rainbows/cutthroats will happily sip your egg fly off the surface as it drifts past. Hot spot streamers have a bright patch on them somewhere, head or tail, which can be mistaken for an egg, or as a fry too.

Fish these patterns on a normal 5 weight setup with a floating line and a long 12ft leader and you should have a lot of success.

Winding Up

I hope you enjoyed it and now know everything you need to know around the question, when do brown trout spawn.

It is very important to leave brown trout alone while they are spawning so they have the chance to have as many fry as possible. But, you can always use it to your advantage and catch those rainbows and cutthroats feeding on the eggs and fry.

Please share the article with your fishing buddies and leave us any comments and questions below, we would love to hear from you!