That statement is true
If fishing related activities are left unregulated by the government, fishers could utilize dangerous method such as using bombs that might destroy the ecosystem in the fresh water. This could make the fish population in a certain area become extinct.
Regulating fishing in freshwater would prevent such things from happening. This create positive economic impact by ensuring that the source of income would not be eliminated from the destruction of environment.
The Black Death was a huge plague spread by Rats that was very contagious, it devastated Europe and killed many people, once it was done away with new tides turned and new foot holds of power proceeded forward due to knew tech, and different method of thinking.
Korean society was strongly influenced by The Chinese model of society.