There's a little sleepy seaside burg debating whether to add a new cannery. Life is slow there, and the fishing is dying. It turns out that the reason the salmon are disappearing is that the owners of the cannery company have been doing some DNA experiments on salmon. They accidentally released genetically altered salmon into the ocean, and those altered salmon were eaten by predator fish. This special diet turns the predator fish into - you guessed it - Humanoids From The Deep. (Add echo chamber in your mind).
Now what do you think the loony humans do? Hint: remember that the monsters have been living on genetically altered salmon, and then they have nothing else to eat but the real salmon. The humans go ahead and hold the 93rd annual Salmon Festival! It's like advertising a tourist attraction for salmon-eating monsters. Then there is a silly subplot, added after the fact by the filmmakers. The monsters are super-evolved and need to propagate their species. They don't seem to have any females in their race. They are also humanoid (Well, sort of. They appear to be as human as Vic Morrow, but just barely). They therefore need to kill human males and mate with human females.
First they come upon a girl and her boyfriend camping on the beach. He is a ventriloquist, for no apparent reason. They maul the twerp, and the dummy's eyes continue to follow the action, even after the ventriloquist is dead. This apparently supernatural phenomenon is never explained. (Hey, it's a Corman movie). The monsters proceed to rape her. Later, another girl's boyfriend is feeling her up in the water, and this makes the humanoids really horny, so they kill another twerp, and rape another girl. In the movie's final scene, she is giving birth, and ...... I think you can probably figure it out.
The movie's climax comes at the Salmon Festival, a carnival where humans and humanoids alike meet to share a few memories. The humanoids show that, while they are not smarter than average humans, they are quite a bit smarter than carny folk, and smell a lot better as well. Dental care is about even.
The monsters rip off the bra of the Salmon Queen before chasing her through the midway. Before tracking down the Salmon Queen, however, the monsters stop to ride some of the midway rides (say, they are genetically advanced), and of course slaughter the humans on the rides. Then the monsters stop for some cotton candy. Not by salmon alone does man live. Then they head over to the midway to play some carny games. One of the monsters is really hacked off that he can't knock down the bowling pins and win an Eeyore for the Salmon Queen, especially since he has seen some other monsters with Eeyore's and even one with a Tigger! He really gets steamed when he realizes that those other monsters were audience plants, allowed to win by the carny barkers in order to sucker in the players. Of course, when he finds this out, he rips the carny geek limb from limb and resumes chasing the Salmon Queen, intending to take her by force if he cannot woo her with presents.
But, by jingo, we humans are not defenseless, you know. Our salmon queens can take care of themselves, thank you very much. This gal squares off and dukes it out with the big guy. The human spirit endures. So if you evil superintelligent movie humanoids are out there reading this review, listen up. You'll never take us. If you think you can just come here and rape our women, Mr. Johnny Monster, you've got another think coming. We've got mighty tough Salmon Queens and Van Damme and Bruce Willis, and no movie monster or asteroid is going to crush this race, nosireebob.
Review by Scoopy from the Internet Movie Database.