What is one way the tragedy of the commons could be avoided?

The answer is: People who share a common resource can organize, cooperate, and enforce responsible use of the resource.
By doing this, those people do not have to hurt each other during the competition to obtain the resource, and they also could maintain the number of the resource so it won't enter a scarcity period that often happen if one or both party over exploit that certain resource

That is true , instead try to have a sit down talk with them