Here is what I believe; whales are capable of passing knowledge down through their generations, just like us. The power of their language is not yet fully understood, but I think it reasonable to assume they are able to express at least simple ideas like "Can I eat this?", "Do not eat that!" and "Those are dangerous to us." A language which can convey those ideas may be sufficient for whales to have memory of industrial scale whaling. I believe Orcas likely remember that humans are very good at killing whales, and subsequently know not to fuck with us. (They may also be able to reason this out by observing our capabilities today, even if they have forgotten what we once did.)