Shark Swarm (2008)

Corporate real estate tycoon Hamilton Lux sets his sights on developing the quaint seaside town of Full Moon Bay into a prime getaway for the wealthy, but runs into some unexpected problems. Lifelong fisherman Daniel Wilder owns property exactly where Lux wants to build high-priced condos, and isn't planning to sell. Lux secretly laces the local waters with a toxin deadly to marine life, decimating the fishing industry in an attempt to starve Daniel out. Alas the chemical react differently on the area's sharks, drastically increasing their aggressive tendencies and transforming them into engines of pure destruction moving in coordinated swarms. Without fish to feed on, shark attacks on humans rapidly increase. Lux uses media contacts to paint the attacks as random incidents. Daniel, his marine biologist brother and a concerned E.P.A. agent must expose Lux's plan and rid the area of the chemically-altered sharks before the town's entire population is devoured by hungry sharks.