I agree that it’s textbook tragedy of the commons. It might appear that orcas are trying to outcompete with fishing boats, but this sounds like personification or an anthropomorphism of whales.

I figured it along the lines of diminished habitat leading to attacks on a perceived invader, which just so happens to be far worse than any natural predator. It might also take additional experimentation/observation to see if some orcas are predisposed to aggressive behavior when perpetually hungry, but this seems to me quite a natural impulse to starvation. In any case, it will lead to evolutionary adaptation … or extinction.