When Jaws blew the record for movie attendance sky high in 1975, it did more than usher in the era of the summer blockbuster. It also fueled a stampede of killer shark copy cat films, with creators who were dreaming of some sweet easy money.
Spielberg's film still holds up today, and acted as a template for blockbuster films for decades. It's actually an improvement on the Peter Benchley novel the movie was based on, and earned $7 million during its opening weekend - an enormous amount of money for the time. For the next several years the world went crazy over sharks, and needless to say, there were low rent imitators eager to shake out a few bucks with their own coattail-riding rip off films.
And there were a lot of them. In fact, I have actively sought out obscure horror and exploitation films for decades, and I still occasionally run across an old, low budget imitator of Jaws that I didn't know about. Filmmakers all over the world were gleefully churning out these water-based monster tales, sometimes using a shark (or sharks) as the baddies, and others substituting a different fish or mutated sea beast in the role of "People Eater Número Uno." There were also plenty of films that borrowed the basic formula and plot, but transferred the action onto dry land. Some of those are fun also.