Are reservations necessary in late June?

No just got to get there early. Its august where you may need them

I recommend it. If the weather is not good or you do not see a whale, they accommodate for another trip out.

Although you don't need too, it will secure your spots when you actually want to go!

From what I have seen, it is not necessary, but you may end up taking an unnecessary chance when it only takes a call or online visit. However, with construction still going on, I am sure you will have no problem. I managed it in early fall with no issues. I just had to arrive in time.