We found a hatchery worker to take us on a tour of the operation. We learned that when the salmon come up river to spawn, the eggs are collected and fertilised at the hatchery and then put in giant tanks kept flushed with river water. Artificial reefs allow the the alevin (baby fish) to grow in safety until they're large enough to be released. This enhances their survival rate and consequently increases the number of wild fish returning the following year.