About 5 minutes after the bright idea of a net struck someone, the idea of (what we commercial gill-netter fishermen would call) 'corking off' the entire river would occur.  Fishing would be fantastic for about four years...at least for the guy with the lowest position in the river...then mysteriously dry up completely.

Many years later it would be discovered that salmon return to the river in which they hatched to spawn on a four year cycle and 'society' would devise something called the 'Department of Fish and Game' who would modulate fishing effort such that the commercial and substance harvest would sustain for the lasting benefit of the entire population.