It's not that uncommon. Young adolescent goes vegetarian. Family goes nuts trying to accommodate culinary quirkiness or leans heavily on the kid to start acting normal again.

Just because someone 13 or 14 is making the decision doesn't mean it isn't heartfelt. "Starting to be aware of what was going on," Chad Halstead told his parents in Bryn Mawr 12 or 13 years ago that he was becoming a vegetarian.

At 15, he went vegan. Today, at 25, he's a deckhand on a 200-foot environmental battleship, patrolling the coast of Algeria trying to stop the illegal fishing of bluefin tuna.

"Unless something is done soon," he says via satellite phone, "it will be the next major extinct species."

Halstead's ship is called the Steve Irwin, named after the crocodile hunter who was also a dedicated conservationist. It's the lead vessel of the Sea Shepherd Conservation Society and the base of operations for Animal Planet's Whale Wars, a reality series about a group of environmentalists who go to unfathomable lengths to stop Japanese whalers from working in the Southern Ocean Whale Sanctuary.

Season three of the show premieres at 9 p.m. Friday and will run with weekly hour-long episodes leading to a two-hour finale Aug. 27.

The events it chronicles already have transpired and have been publicized by the network itself. It happens with these sorts of real-danger extreme shows because the cable outlets know that more people watch if they know major consequences await. But in this spoiler-free zone, you won't find out what occurred, except to know that nobody died. This time.

"I'm willing to die to save the whales," says Halstead, the first swabby to get airtime in tomorrow night's episode. "If I wasn't, I wouldn't be on this ship."

And what do papa John Halstead, Northeast president of McJunkin Red Man Corp., a major manufacturer of pipes, valves, and fittings, and mama Virginia Halstead think about that?

"At first, they were a little skeptical," Halstead says. "They were raised in different backgrounds. They're conservative people, but now they're super-supportive and really understand my work on the ship and the conservation movement and how important it really is now."

Not everybody does. A lot of people call the Sea Shepherd volunteers pirates. The skull and crossbones symbol is prominent on their ships and clothing. The Japanese say they are not killing whales for profit in the frigid waters near Antarctica but are conducting scientific research. They even have "RESEARCH" painted in big letters, in English, on their whaling boats.

Whale Wars shows the environmentalists and whalers battling on the high seas. The weapons on the whalers' side include water cannon and a device called an LRAD, which shoots a disorienting sonic beam. Tomorrow, the environmentalists launch a stink-bomb attack. Things will escalate as the mission goes on.

"A lot of the crew are willing to put themselves in dangerous situations to stand up for what we believe in," Halstead says. "There's no point in us being down there if we're not willing to stand our ground."

Despite a lack of pay, it's not easy joining the crew. "This past campaign, there were something like 1,000-plus applications for a ship that has 35 places," says Halstead, who brings expertise in carpentry and metalwork to his deckhand position. "I had heard that I interviewed really well. . . . Maybe my passion came through during the interview."

There must be some people just looking for a little reality-TV face time. "Yeah, I've heard that," says Halstead. "When I first applied, I didn't know about the show, but I've heard these stories from the office. . . . It's very obvious who's got the passion and who just wants to be on TV."

Halstead's passion has served him well. "I've traveled around the world, seen things I would never have been able to explore otherwise, all the while hoping to make a difference - if not for tomorrow, then for the next generation. . . . I'd much rather live this life than have a job."

John and Virginia have come to understand, Halstead says. "My mom is my favorite vegan cook in the world. On my last trip home, I got her to go vegetarian."

Jonathan Storm:

Television

Whale Wars

9 p.m. Friday on Animal Planet

Contact television critic Jonathan Storm at 215-854-5618 or jstorm@phillynews.com. Read his recent blog at http://www.philly.com/philly/blogs/storm.