If salmon seasons are opened at all, they are carefully monitored to minimize the number of wild fish that are caught or landed. Hatcheries produce millions of fish that are released to migrate to the ocean and back. However, hatchery fish are not as genetically robust as native populations. Hatchery fish can also have decreased resistance to diseases. In some cases hatchery fish have spawned with wild salmon, thus reducing the genetic resilience of the wild salmon population.
Dams present a significant barrier to migrating fish.
They create slack-water pools where fish expect tumbling water. In some cases, fish migrating downstream can be destroyed by spinning turbines. Reservoirs permanently flood stream habitats, and dam operations can result in streamflow conditions that are not well-suited to salmon. Salmon require certain habitats to carry out the same fundamental life functions as humans. The places in the stream and the landscape that support these basic life functions are, in fact, salmon habitat.