This is one of Steven Spielberg's earlier movies that proved to be more of a nightmare to make then anything else. There where 2 mechanical sharks made that where named by the film crew Bruce. However due to the fact that the sharks where used in salt water there where many mechanical problems during production.
Not only where the sharks a problem but so was the boat Orca that was used in the film started to actually sink and take on water also during production. This proved to be quite a task and the crew nicknamed the film Flaws instead of Jaws. Nonetheless Steven Speilberg did pull through.
Bruce still does exist in Universal Studios, but has been stored for many years under the hot sun and has been showing its age.
Below is a video from the film crew.