it depends on which size Jaws we're talking about...the 25 footer in the original movie or the massive 35 footer in Jaws 3-D.
Interesting fact. The Sharks in the Jaws movies are all related. The shark in Jaws 2 is supposed to be the mate of the shark in the first one. The shark in Revenge is supposed to be the child of the first two...according to the novelizations.
In the novelization of Jaws 2 and Jaws 4: The Revenge - which, belonging to minor differences, are in continuity with the book of Benchley, ignoring the events of Jaws 3 - explains that sharks are all related to each other: the shark's first book would have impregnated one of the second book, and that of the third book would be their son. This particular is not mentioned in the film. It then suggests that the reason why attack the family of Martin Brody would be tied to a voodoo curse hurled by a shaman enemy Brody. This detail does not appear in the film, however, in the film version of the story is a phrase uttered by Michael Brody that references this subplot of the book: "Come on, sharks do not commit murder. Tell me you do not believe in what voodoo. "