The world’s most endangered marine mammal, the vaquita porpoise, is still hanging on in the waters off Mexico’s northwest coast — and, against all odds, it’s reproducing.

Classified by the International Union for Conservation of Nature and the U.S. National Oceanic and Atmospheric Administration as the world’s rarest marine mammal, the vaquita is found only in a small section of Mexico’s Gulf of California.

Aerial footage taken during a joint expedition between Sea Shepherd Conservation Society and Mexican authorities shows a rare and hopeful sight: an adult vaquita swimming alongside a calf.

Scientists and officials said the expedition recorded between seven and ten vaquitas — slightly more than the previous year’s estimate of six to eight — suggesting the population may have stabilized after years of decline.

From the deck of the Sea Shepherd vessel, observers peered through large binoculars, scanning the calm waters of the northern Gulf of California for any trace of the elusive porpoise.

"It’s a miracle, these survivors that are here," said vaquita researcher Barbara Taylor.

"To see them and find them and get to see them, you know, the mothers and calves swimming in the northern Gulf of California. But seeing all the places that they are no longer in the Gulf is a sad thing," said Taylor.

The team’s work combines science, surveillance, and community cooperation in an area long threatened by illegal fishing nets.

Over the years, entanglement in gillnets used to catch totoaba — a fish prized for its swim bladder — has decimated the vaquita population, now estimated at fewer than a dozen.

Local fishermen say they’re learning to see the effort not as a punishment, but as a necessity.

For researchers like Taylor, saving the vaquita is about more than biology.

"Conservation is not about, is not entirely about doing science with the animals,” she said. "It’s mainly about changing human behavior."

As Sea Shepherd ships continue patrolling these protected waters, every new sighting fuels the fragile hope that the world’s rarest porpoise may yet endure.