This is why polluting the Ocean (or at least what ever Ted Turner thinks we're doing with it) is a good idea.

More pollution > More dead Dolphins > Less chance that they evolve into another intelligent species > No competition against Humanity.

Or, we could take the other route and purpose-engineer a virus to wipe them out without having to destroy the fishing industry.

Either way: Fuck Dolphins! The sooner the squeaky rape-fish goes extinct, the better!