Everything humans do will somehow take a toll on the environment. So unless we all go kill ourselves, we're going to affect our environment one way or another. We can instead be responsible and make sure we don't strain a specific resource, and be educated consumers (it might just happen). So a solution would be to find alternative fishes and balance it out, cut out other fish oil uses.
That being said the article stated that fish oil is only one of the many things contributing to this. I think we could cut out lipstick before we cut out treating mental illnesses.