You already know quite a bit about the Brook Trout. Let's take a closer look at the life cycle of this fascinating fish.
Brook Trout lay their eggs in the gravel beds at the bottom of cold water streams. Here the eggs develop. After the eggs hatch they become alevin which look like little fish but are still attached to the yolk sac which continues to provide them with food. These little alevin still live in the gravel beds at the bottom of the streams.
After the food in the yolk sac is gone the little fish are called fry and they leave the gravel beds where they were born. They begin to find their own food. They eat almost any microscopic animal they can get in their mouths. With this food they begin to grow and as they grow they can eat larger and larger foods.
When the young Brook Trout are a few inches long they develop dark bands on their sides. These bands are called parr marks and the young Brook Trout are now called parr.
The parr continue to feed and as they grow they are able to take larger food. At this point most of the food is insect larvae such as mayfly and stonefly larvae.
At the same time as the young fish search for food they must be careful that they do not become the food of some other animal. Other fish, even older Brook Trout, feed on the small fry and parr. They also have to watch out for herons, mergansers, kingfishers and river otters.
As the parr grow they gradually lose the parr marks and are now juveniles. The juveniles in turn become adults. And when the adults return to the gravel beds to lay their own eggs the cycle is complete.
Not very many of the eggs laid in the gravel make it past all of the dangers and become adults which lay their own eggs. Of the hundreds or thousands of eggs a female lays during her life only a few will make it to the parr stage, and of those only two, on the average, will become adults that spawn on their own.