Ecologists and other scientists have determined that the maximum sustainable yield is one half of the carrying capacity of an ecosystem. The maximum sustainable yield of a renewable resource is the maximum amount that can be harvested without compromising future availability of that resource. It is difficult to calculate and evaluate the effect of the harvest on reproduction rates because these are analyzed after a fishing season. However, because of the tragedy of the commons theory, everyone will act in their own self-interests, which is maximizing the amount of fish they catch, if they are not regulated and held responsible for their actions. Environmental policies must be passed in order to save these fish.
The United States has passed some bills to prevent or reverse the effects of overfishing. The Flexibility in Rebuilding American Fisheries Act would give more leeway to the current 10-year rebuilding period for overfished areas. The current legislation, the Magnuson-Stevens Fishery Conservation and Management Act, sets that time limit and other restrictions to prevent overfishing. The European Union has punished France, Portugal, and Spain, the biggest EU culprits in overfishing, with deeper fish quota cuts.
One of the most urgent things that need to be done is preventing Western companies from going to developing countries and overfishing in those fisheries. International cooperation is crucial for this to happen. Countries must all agree to a certain intake quota of fish and prevent their companies from exceeding that limit.
Some countries believe that bluefin tuna, once the most common and popular species in the world, should be listed under the Convention on International Trade in Endangered Species, CITES. This proposal was recently rejected by the Mediterranean countries, amongst which includes Spain. In order to allow overfished fish populations to replenish, we must give them a chance to repopulate by relieving them of the human-pressure of fishing. Once again, everyone must apply the resource conservation ethic and do what is best for the whole world.