Brook Trout Spawning : Everything You Need To Know

If you are an avid angler, or just interested in freshwater fishing, you probably have heard about brook trout. These fish are interesting and have some pretty neat information if you dig a little bit deeper. Here is a closer look into brook trout and their spawning habits.

Before we go any further, it is important to realize that brook trout are not actually trout. They are in fact, members of the char genus, which is part of the salmon family. These fish are native to the eastern portion of North America, as well as Canada. These fish are found in freshwater rivers and streams and are known to be fighters, as well as for their distinctive colors.

The spawning behavior of the brook trout is perhaps the most important aspect of its life. It is crucial for their survival as a species. During peak spawning, the brook trout will exhibit certain behaviors that are distinct for males and females and they have certain environmental conditions that need to be met as well.

Brook Trout Spawning-Everything You Need To Know

Brook Trout Spawning-Everything You Need To Know

What are the environmental requirements for brook trout to spawn?

Brook trout spawning behavior is directly influenced by fluctuations in water temperature. When the warm summer water starts to give way to cooling fall water, the brook trout begin their annual spawning.

Once the water temperature drops to between 40-49° F, brook trout spawning season starts in earnest. If for some reason water temperatures rise above 55° F during the spawning season, there is the strong possibility that there will be a negative effect on the success of the next generation of fish.

Any sudden rise in water temperature that lasts more than a few weeks will cause brook trout to delay spawning. The issue here is that it will cause the fry to be born much later in the springtime.

These fry will then struggle to gain enough in size and weight in order to survive their first winter. In addition, later hatched trout are far less likely to be mature enough to spawn their first year.

At what age is a brook trout ready to spawn?

Brook trout are considered to be fast developing fish. Trout that are born in the early spring can be ready to spawn in that same year. Female trout develop quicker than male fish. This means that female brook trout are sexually mature and ready to spawn in their first year. Some males may reach sexual maturity and can be ready to spawn in that first year of life too. However, the general consensus is that female brook trout are ready to spawn in the first year and all males should be ready to spawn by their second year.

What is the life cycle of an egg?

Brook trout enter their spawning season in early September and it can run through October depending on water temperatures.

The egg incubation period is from 95-100 days. This is also influenced by water temperature.

After about 100 days, the eggs will begin to hatch and the fry will start to emerge. This usually happens sometime between February and March. The earlier the fry hatch, the easier it will be for them during their first winter. No male fry born in April will be ready to spawn during their first year. As the spawn begins, males will try to force the females into shallow water that have gravel bottoms. If the female is willing, she will then select a good site and start building a redd.

A redd is a salmon form of a nest. These nests resemble little mounds of gravel.

As the female is building the redd, the male trout will begin its courtship activity. This involves the male brook trout darting and quivering next to the working female. He may also swim up against her and touch her with his fins.

During the spawn, the female will lay hundreds of eggs and the male will fertilize them. After the spawn, the female brook trout covers the eggs by sweeping pebbles near the downstream portion of the redd. This action helps to build a wall which will protect the eggs from being swept downstream. After she finishes her first redd, the female may move upstream and start making a new redd.

Physical changes of spawning brook trout

Male brook trout undergo changes in physical appearance during spawning. The lower portion of the body will turn deep orange or even a bright red. Even more noticeable in males is the development of the trademark kype jaw. All male brook trout’s lower jaws will develop this hook shape. Some will be mild while, while older males have very defined hooks.

Other interesting facts

  • The total number of eggs a female brook trout can lay depends greatly on both the size and fitness of the female. Larger, healthier females will lay more eggs than younger ones.
  • During their first years of life, female brook trout will only lay 100 eggs. As the female matures and her body grows, it is possible that she could lay between 400-600 eggs for fertilization.
  • The brook trout eggs are slightly denser than water. This enables them to sink to the bottom and be able to resist being moved by currents. Stronger currents or rainbow trout rooting through the redd mounds can cause the eggs to be carried away.
  • Newly hatched brook trout fry are very vulnerable to predators in their early days. The fry will immediately seek out shelter and look to hide in submerged vegetation, submerged timber, large rocks, or in the shallow water closest to the shoreline.
  • The brook trout fry will eat zooplankton and tiny insects. Once they grow large enough, they will start to head out to deeper water start eating larger prey.
  • Brook trout will swim about a mile in order to spawn.


Brook trout make for some interesting fishing. This member of the salmon family is native to the eastern United States and Canada. Under the right conditions, these fish are known to spawn plentifully. Be sure to check local regulations in regards to you being able to “take” them during spawning season.

Tom Chandler

"When your hands hit the floor, they get cut up. When mine hit the floor, they slide with ease"

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