As the sun crept above the horizon, CBS News' Don Dahler headed out in the Gulf of California with a disparate group of volunteers, veterinarians and marine biologists on a difficult -- some would say impossible -- mission to track the rarest of marine mammals: the vaquita, a species of porpoise. It's a mission two years in the making.



"This is bigger than vaquita. For conservation in general, for marine mammals, this is a big thing," said Lorenzo Rojas-Bracho who is directing the effort.

It's been an uphill battle against the odds, the cost -- now in the $5 million range -- and the elements. The challenge is amplified by the fact that there are so few of the diminutive porpoises left. Recent reports show the vaquita population has dropped from almost 600 in 1997 to just 30 today, found only in the Gulf of California.

Vaquitas are getting stuck in nets intended for tatoaba fish, which can sell for up to $10,000 on the Chinese black market. CBS News

The vaquita's rapid decline is an unintended consequence of the increasing demand for tatoaba, a type of fish that can fetch up to $10,000 each on the Chinese black market. Their swim bladder is believed to boost fertility.

"Basically the mesh size is the same size of a vaquita head, so they easily get entangled," Rojas-Bracho explained.



Thus, the desperate rush to save some for captive breeding before they're all gone. The operation requires delicate coordination. Spotter boats search the water for fins. When one or more porpoise is sighted, trained U.S. Navy dolphins act as herd dogs, moving the porpoises into position for the capture boats to net them. They're then carefully transferred onto a transport boat.



Their first stop? A specially constructed marine hospital for medical assessment. Then, a short trip to the vaquita's new home, a large retrofitted sea pen once used as a tourist aquarium that was towed there – nearly 2,000 miles from the Pacific.



Sea pen where they take the vaquitas for captive breeding CBS News

The complicated plan worked, at first. On day two of the project, they captured one for the first time ever. But that six-month-old female was just too stressed from the experience. They had to let her go.

The team took to the sea to try again, and again and again.

But all the effort and expense and frustration is also to bring the issue of illegal gillnets to the public's attention.



"If we can absolutely ensure that these underwater gillnets are not in a place where the remaining animals are, they would survive," one scientist explained. "They just need a chance."