What has had the greatest impact on the fishing industry in north america over the past 50 years

After some research, I'd say that the international treaties outlining proper use of international waters for fishing has had the greatest impact on the fishing industry in north America. I hope that this is the answer that you were looking for and it has helped you.

Answer after wwii, communist countries in eastern europe formed the warsaw pack, a military alliance, and comecon, an economic alliance;