No, Tuna are too big for dolphins to eat, indeed Dolphins and Tuna frequently share the same prey, the dolphins coral bait fish into a bait ball which is then preyed upon by a number of large marine predators.
... they chew on another dolphins tail... they eat a dolphinor... if their pod is starving, they pick on the weak dolphinsAll of the Dolphin Species, Common, Dusky, Spotted and Purpoises (Larger...