Redds are where trout spawn. This egg nest is made but the male and female trout, using their tails as shovels. They remove any surface algae or debris, so they can get to the cleaner gravels. Once the nest/redd is made, the male will nuzzle the side of the female until she releases her eggs. The male will now release milt over the eggs and nest. The fertilized eggs will settle into the gravel for protection, until ready to hatch as sac fry.
During this cycle of reproduction, many things can go wrong. Last year, the Hegben Dam broke and the redds of trout dried up. That year’s class was almost completely wiped out. Insects, birds, other fish, freezing, high water, and other problems will all reduce the number of fry that may hatch.
Humans also destroy Redd’s when they wade and walk into them. Some fishermen target the spawning fish and during the fight, eggs and milt are released but not over the redd. Those eggs will die. It’s best to not target spawning fish. Avoid walking in the egg nests. Keep cattle and other critters away from prime spawning gravels.
Fishpond has created a nice visual that sends this message. If you want wild trout, you need to allow them to reproduce. Brown and brook trout generally spawn in the Fall. Rainbows are Spring Spawners. Ironically, hatchery fish have been manipulated genetically to spawn during most of the year. There is a record of 17 different rainbow trout species that have been stocked in the Madison River, MT. These bows spawn in the Fall as well.
Artificial Redds have also been used to spawn trout. Fertilized eggs are placed into a plastic Vibert Box container with small openings, that will allow fry to swim away once hatched. These containers are usually marked with a sign.
Mortality is high for wild fish reproduction. Out of 1,000 eggs, maybe 3 will reach adulthood, to spawn again.
A ruined Redd means the new fish will be dead!