Humanoids from the Deep

Anglers from the fishing village of Noyo, California catch what appears to be a monster. The young son of one of the anglers falls into the water and something unseen drags him under the surface. Another angler prepares a flare gun but he slips and accidentally fires it into the deck, which bursts into flames and explodes. The murderous, sex-hungry mutations are apparently the result of Canco's experiments with a growth hormone they had earlier administered to salmon.