The poachers quickly fled, but the conservationists, from their own boat, used the drone to track them, relaying coordinates and headings to the Mexican Navy. Once the latter took over the chase, the Sea Shepherd crew investigated the scene of the crime. In the poachers’ left-behind nets (which snag the gills, spines, or other body protrusions of a fish, causing it to become entangled) they found a variety of creatures, including four live crownose rays and two dead hammerhead sharks.

A hammerhead shark caught up in the nets.
A hammerhead shark caught up in the nets.
Image: Sea Shepherd

The poachers were after something more valuable: totoaba. Native to the Gulf of California, the totoaba can grow to six feet long and live up to 25 years. Chinese medicine prizes a tubular organ that regulates the fish’s buoyancy; the bladder, of sorts, is thought to help promote fertility. That one body part can fetch as much as $645,000 in black markets, as Quartz reported earlier.

To catch totoaba, poachers use gillnets that kill many other species. In the process they’ve driven the vaquita—a shy, snub-nosed porpoise native to the Gulf of California—to near-extinction. All nets are dangerous to vaquita, but especially ones used to catch totoaba, due to the mesh size. Vaquita get entangled in the nets and drown. Today it’s the most endangered marine mammal in the world, with the population suspected to be only a few dozen individuals.

To save the vaquita, in April 2015 Mexico enacted a two-year ban on the use of gillnets in a large portion of the northern Gulf of California, where the porpoise lives.

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