This study was done by the American Fisheries Society. The research showed that 60 out of 100 trout don’t make it past the first week. This is because many creatures such as fish eagles, blue herons, and even raccoons feast on freshly stocked trout.
Stocked trout usually grow up in fish farms where they receive an ample supply of food, which they don’t need to put in effort to attain. They also don’t have the survival skills needed to ward off predators and find good hiding spots.
Once a water body is stocked with trout, the trout generally stay put for a while before they start moving. Since how long trout live depends on the moving state itself, this reduces their survival chances due to their prolonged inactivity which causes predatory animals to attack.
Though stocked trout can essentially spawn, they are often hindered due to various different factors and external conditions. One of the prime examples is that people catch them before they get a chance to spawn.
Stocked trout are usually hatched in incubators in laboratory conditions. The way they are bred artificially dictates their sterile states, making it very hard for them to reproduce. Despite being healthy, stocked trout don’t face the urge to mate.