Just as many trout species spawn at different times of the year, many trout species spawn in different locations. Lake trout, for instance, don't leave the lake to spawn, but instead search for an appropriate area within the lake to perform spawning, usually a sand bar or graveled shore. Anadromous trout species, like rainbow trout and the brown trout, return to the streams and tributaries in which they were born to spawn. Some smaller trout species remain in rivers they developed in, only to return upstream for spawning activities.
As spawning begins, the female trout will scout out a shallow, oxygen-rich lake or river bed to deposit its eggs into. The female will then carve out a small trench called a redd by scooping out the gravel and sand with its tail. Once the redd is complete, the female will deposit her eggs and wait for a male to fertilize them with his sperm. Males will often fight with each other using their recently developed kypes to battle for the best territory on the spawning grounds. Upon completion of spawning, the female will cover the red with loose gravel and sand as it swims away, providing the future hatchlings with shelter. Unlike salmon, trout don't die after spawning and can participate in spawning multiple times in the course of their life [source: USDA Forest Service].
During a spawning season, a single female rainbow trout can spawn 200 to 8,000 eggs. Of the eggs that are fertilized, very few will survive to become mature adults, having fallen prey to predators such as large insects, amphibians, water pollution and hungry fish, even including mature trout.
Swim over to next page to read about how an angler can fish for trout during the spawning season.