Was There Any Question As To HOW Sean Died?

Sean's death had a big impact at the beginning of the film but was there any doubt that Sean was killed by a shark? It seems obvious but I was wondering if the film was trying to set it up so that Ellen Brody was the only one who believed that Sean was killed by a shark. That does not seem fully established but if it was known that Sean was killed by a great white, it seems that the town would be in full panic mode considering the events of the first two movies. Granted, Mike takes Ellen away to the Bahamas for Christmas but I always wondered if the town was freaking out about that or if it wasn't really a big concern since it was winter and no one would be in the water. After the events in The Revenge, Ellen would have gone back and told them that the shark was gone but after THREE blood thirsty sharks, I would think Ellen would always be terrified of another one popping up.

I still hate the one line in the movie where Hoagie refers to the shark as the same one that killed Martin and Sean. Martin was not killed by a shark but died from the "fear" of it. The one who killed Sean had nothing to do with that. Maybe Martin should have died under mysterious circumstances a month or so before implying that this shark actually killed him.