The original salmon populations were destroyed by pollution and development.
The downward spiral of the salmon population is troubling for several reasons.
Under the banner of environment, he is involved in efforts to improve the salmon population.
The latest record of a salmon population in the river dates from 1744.
They are then released into rivers, often in an attempt to increase the salmon population.
The 10,000 fish killed this week are more than the river's entire salmon population in some years.
As a result, the salmon population increased to about 500 in 2005.
Human activities have heavily damaged salmon populations across their range.
But some scientists say the wild salmon population is less than 1 percent of what it was back then.
Special action is required to save the wild salmon population.