Why was Trump talking about sharks at a campaign event?

"It must be because of M.I.T., my relationship with M.I.T., very smart. I say, 'What would happen if the boat sank from its weight and you're in the boat and you have this tremendously powerful battery, and the battery is now underwater, and there's a shark that's approximately 10 yards over there?" Trump said. "By the way, lot of shark attacks lately. Did you notice that?"

In land locked NEVADA.