Trout Reproduction

Notice the area of stream bottom that appears to be "cleaned off". This area is known as a redd.
Notice the area of stream bottom that appears to be “cleaned off”. This area is known as a redd.

In my blog post last week “Featured Fly- Eggs Explained”, I mentioned that egg patterns are a staple in my fly box through the fall due to trout reproduction. The vibrant colors that are especially visible on trout during the fall are also a result of trout reproduction.

In our streams, you could find trout actively reproducing, also referred to as spawning, anytime from August to December. Rainbows tend to spawn in the early months from August to October, while browns tend to spawn from October to December.

Trout can travel as far as miles to spawning areas (that they want to return annually). To start the reproduction process, the females will turn on their side and dig with their tail to build a nest, which is called a redd (pictured above).

A redd is usually built on pebble-sized gravel bottom sections of moving water that will provide ample oxygen. Females will “clean” these sections of stream off with their tail to dig a divot for eggs to be laid in.

After the redd is built, the dominant male will fertilize the eggs once they have been laid. Once the male has fertilized the eggs, the female will then use the same digging motion as before to cover and protect the eggs until they hatch. After the eggs have been covered, the male will stay close by to “protect the nest” from other fish and predators that would be happy to take advantage of an easy meal.

Redds will vary in size depending on how large of fish are spawning. In an area that is ideal for spawning, it is not uncommon to find multiple redds.  It is very important to watch where you are walking this time of year to avoid disturbing fish that are actively spawning, as well as trampling over eggs that have been laid.

Trout reproduction is an amazing process that can currently be witnessed in our water here in Pennsylvania. I would encourage anglers to take advantage of witnessing this process that can only be seen during the fall months.

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