I would like to discuss the spawn of the brown trout which should be still in progress in the Great Smoky Mountains National Park. I was astonished to learn from NC Biologist that brook trout will not stray far from where they were born, sometime staying in the very same pool. Brown trout unlike brook trout will travel great distances upstream to spawn often repeating the trip each year.
To make the spawning trip, they must be in excellent shape because they will travel upstream in strong current and often jump considerable heights up waterfalls. I have seen trout in Alaska jumping as far as three to four feet attempting to navigate the falls.
To spawn the temperature must be right, the current and water depth must be correct and the stream must have a gravel bottom. The gravel bottom with sand and small pebbles is important and this is one reason why silt is such a detriment to trout reproducing naturally.
The female brown will use her tail to swish the gravel and small pebbles to form a bed, called a redd, in which to lay her eggs. When satisfied with the redd, she will cut a trench or small area where will lay her eggs. At this time, the male brown trout will deposit his sperm called milt, which appears to be milky or cloudy, on the eggs and the immediate area.
After the eggs are fertilized, she will cover them carefully with the gravel (remember that I said gravel is important). The gravel will permit the water to flow thru the nest and it will keep the eggs from floating away as well as offering protection from predators. Sometimes, she will repeat this process within the same redd. As a result of the spawning process, one or two thousand eggs will be deposited and fertilized.
During the entire process, the male is very territorial and aggressive in protecting the female as well as the spawn. As you might guess this is a very stressful time for the brown trout both male and female. Many trout are lost in the process, whether by the female not laying all her eggs, or by anglers catching either the male or the females.
The entire window for the spawning process usually encompasses approximatey 4 weeks during which time, the trout are very vulnerable. It is quite easy to catch an aggressive brown trout at this time. Some biologist as well as some anglers do not feel that fishing for the spawning brown trout presents a significant hazard to the species. However, for me I plan to let them replenish the species without worry.