Corpses of battered porpoises are turning up on beaches along the San Francisco Bay. The culprit, experts say, is the bottlenose dolphin. "I've lived here 15 years, and I've never seen anything like that," says one biologist who witnessed a porpoise killing while jogging on the beach. "They would chase the porpoise, and it looked like they were sandwiching it between them, then they would throw it up in the air. The porpoise just couldn't get away from them."
Researchers have documented such attacks around the world since 1991, and on the Pacific Coast for a few years, but Bay Area "porpicides" are becoming far more frequent. Some experts blame the recent influx of porpoises there. The newcomers likely run into young, male, sexually frustrated dolphin gangs who take out their anger on the smaller creatures. "We are just seeing dolphins more realistically," one porpicide expert tells the San Francisco Chronicle. "Like most species they have rules in their society and sometimes they act aggressively too."