At the end of the day it will take some political will for people to realize on both sides of the Atlantic that it's a shared resource. There's an ongoing debate on whose fish they are. Are they ours when they're in our rivers, or are they ours when they're fishing off their coast? I think for the future well-being of the species people will have to come together and come to an agreement to save the fish.
One possibility that could help is there are sometimes side deals that can be made on other subjects or other species.