I would recommend that you look thru the WhaleNet archives, since I'm almost positive that all of these questions have been previously answered or addressed. Whales primarily communicate by sound and touch, by also do some visually, and perhaps by taste. There is lots of information on this in the library for in the past. Now-days would depend on whether you mean subsistence whaling or commercial whaling. Beached whales may die for a variety of reasons.
Animals often beach themselves when they are already dying.
Disease and old age are some reasons. Obviously, fewer whales had something to do it, as well as the advent of discovering that petroleum could replace whale oil. Good luck on the test. I think you'll find more information on these questions quite easily.