Trout reproductive cycle inside a hatchery
Trout reproduce through the spawning process at around 2 years of age.
Spawning takes place in shallow areas of streams and inlets where the gravel can be worked by the female to build a redd- nest- using her tail.
As the redd is completed she and a male will release the eggs and milt into the nest and fertilisation occurs. Then the female will cover the red with the gravel she originally removed. The adult trout both the leave, while the female will continue to spawn until all the eggs 400-3000 stored in her body cavity have been released.
In the wild of course the young trout are exposed to natural dangers.
From the hatchery prospective the eggs and milt are readily removed from the adult trout through the process stripping which is simply rubbing the trouts body and both when combined are only fertilised when water is added. The eggs can be handled during this time.
Throughout the early life temperature and water quality are an essential part. As the trout develop they now soften as they progress to the eyed stage, this is when eyespots appear.
Trout then develop as Sac Fry or Alevins,-free swimming embryos with a yolk sac which they consume- advancing through to swim up with fins so they can swim and find their own food. This takes a about a month.
Of course the trout survival rate is significantly higher in the hatchery than the wild and it follows that this contributes to the trouts sustainability as a sport fishing opportunity and delightful dinner.