What are redds? When is trout spawning season? How should we approach angling during this time of year? Neil answers your questions and provides insight into ethical angling during the spawning season below:

For today's catch and release fly fishing, the spawning season is an ethically-challenged and opinionated time of year. My goal is to provide you with insight into where, when, and how brown trout tend to spawn, and potential ways to ethically fish in these waterways. As responsible anglers, we should educate ourselves as to the spawning process, thereby allowing us to make educated decisions regarding angling and wading into sensitive spawning areas.

By now, many areas have had nighttime air temperatures dip into the 30's or 40's, while daytime temps still may reach the mid 60's if we're lucky. The key here is water temperature, which normally will be between 44 and 54 degrees for optimal spawning conditions. For most Pennsylvania trout streams, this occurs in late October through early December.

First we'll cover the spawning season, and then explore fishing considerations.

Once spawning activity is occurring, you will see the females depositing her eggs across the spawning redd. At the same time, the male will release his milt to ensure the eggs are fertilized. After this occurs, the eggs will be covered up by the female trout with a small amount of gravel for protection – allowing the eggs to develop into alevins. 

This process requires highly oxygenated water, and usually lasts 60 to 80 days. The alevins will live on the redds and use the yolk they are born with for nutrition. This process usually lasts 14-30 days, at which time the yolk has been consumed and the alevins become fry.

As fry develop, they need to wander from the redd, searching out light and small aquatic insects to eat. The fry are vulnerable at this stage of life to predation by birds, and other fish. Habitat is essential for survival, as the fry will hide among the rocks and other cover for survival.

The fry will continue to develop and begin eating other small fish and continue to grow. They are called "Parr" for the first year of their lives. During this phase of life, Parr tend to have distinctive markings on their sides called "Parr Marks." These marks assist in camouflage, helping the juvenile trout to survive and continue to mature. These marks tend to fade away at a year's time, leading to a small adult trout.

Another note to consider would be pre-spawn aggressive feeding behavior. If you notice trout are chasing your streamer, but not paired up with a potential mate, there is likely a chance this fish is in pre-spawn stages. With no visually apparent redds, I'd say "fish away!" However, if you are in knee deep or shallow water with clean gravel and pairs of trout, and they're chasing your streamer – you're fishing the spawning redd. You may want to reconsider trying to catch these trout in their vulnerable stage of life. 

Similarly, nymphing through a run with visible redds would be playing to a trout's weaknesses. They are just picking things up and moving them off the redds to ensure the best potential for eggs to be left undisturbed.

Our actions on the stream during this time can be harmful or detrimental to spawning success just by wading around, so caution must be taken. By kicking up sediment, we can cover a freshly cleaned redd, and reduce the chance the eggs mature into alevins. If we wade across or into a spawning redd, we could crush the eggs or alevins, thereby affecting the efforts of spawning trout.