It's no secret that this movie is a blatant rip off of the "Jaws" formula, so I'm gonna get the hows out of the way right off the bat.
Locale: State forest in the West, subbing for Amity Beach, being ravaged by unusually aggressive Grizzly bear, is on brink of being closed down for the busiest holiday time of the year. Needless to say, the Superintendent is not thrilled. This is damn near plagiarism so far.
Hero: The Park Ranger (Christopher George, a low rent Roy Scheider, having all the snark and none of the class) who happens to be sick of being muscled by the bureaucrats, is bent on stopping the horrific bear killings.
Grizzled Naturalist: Although, unlike Hooper of "Jaws", he's not a rich kid with lots of high-tech toys, he's still a freakin' weirdo. This particular goofball lays around in strange woodland disguises trying to record information on the local wildlife. Hello, Richard Jaeckel.
Pilot with war stories: Andrew Prine (yes, the future nightime soap hearthrob) plays a helicopter pilot who helps in the search for the bear. He even spins an apparently ad-libbed campfireside yarn about Vietnam bloodbaths, paling in huge comparison to Robert Shaw's lengthy (and also reportedly ad-libbed) USS Indianapolis monologue in "Jaws".
No attempt at a replacement for "Farewell and Adieu, my wee Spanish Ladies"
However, the exploding rampaging creature is replaced.
The whys. To make money. "Grizzly" was the highest grossing independent film of it's year, which I believe was 1976. A surprising amount of blood for a PG-rated movie makes the movie still maintain occasional shock value, but the FX are terrible, and some of the acting is even worse.
Lots of nice scenery though. Gorgeous woodland locales. I stayed up late for this one many times. Therefore it qualifies, it's a true crap classic.
Incidentally, a sequel was made, which finished prinicipal photography, and a workprint even exists. It features a young Charlie Sheen and George Clooney, and was entitled "Grizzy II: The Concert". I wonder why it was never released with that set-up.