Killer Film Debut The ominous poisoning of the world''s seagoing mammals by manmade chemical pollution has been documented in Monterey Bay killer whales. It is just one of the chilling discoveries that will be broadcast nationally this weekend in a riveting National Geographic documentary.

Three years in the making, Secret Killers of Monterey Bay follows nomadic killer whales as they hunt and feed together just offshore. The film uncovers behavioral mysteries of the ocean''s top predator, a stealthy but social animal that''s challenging to study and nearly impossible to capture on film.

How the killer whales hunt larger whales in the bountiful Monterey Bay is telling. Gray whales and their calves hug the edge of the continent while migrating from Mexico to the Bering Sea. It makes them ripe targets, but the huge creatures are also in danger for another reason. Scientists released alarming reports this year about plunging gray whale populations. Secret Killers provides some clues why.

The film is full of rare footage, from killer whales feeding on a gray whale to a calf using a seabird for hunting practice. But the film also illuminates some troubling ocean trends that illustrate how ocean ecology is tightly woven.

National Geographic put one of its elite film crews on the job. Award winning natural history filmmakers Paul and Grace Atkins and their associate producer Anne Marie Hammers spent three years filming in the bay. Guiding the crew to the killer whales are Monterey-based marine biologists Nancy Black and captain Richard Ternullo.

"We discovered something very profound about the world''s oceans. It sounds cliched, but the ocean is very fragile and interconnected," says filmmaker Paul Atkins. "We discovered that the ecology of the Monterey Bay is linked to the ecology of the Bering Sea and to the changes going on in the Arctic ice there."

Beyond gathering new behavioral research, Black gets important health data, using darts to take blubber samples. As has been documented in marine mammals around the Arctic Circle, she finds that toxic chemicals like PCBs and DDT have been accumulating in these killer whales. Toxins ingested up the food chain collect in the predator at the top and can cause genetic defects in new generations. Black''s blubber sampling and analysis shows that the killer whales of the Monterey Bay have "...the highest levels of PCBs known for any marine mammals worldwide."

To see the film, tune in to MSNBC at 5pm and 8pm on Sunday, Nov. 3.

-Andrew Scutro

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