Mexico banned totoaba fishing in 1993, but it was only in 2015 — when vaquita numbers dwindled to about 100 — that the government also banned most gill nets, including those used for catching shrimp and other kinds of fish. The gill nets catch the totoaba, and also trap the vaquitas.
Fishermen are still allowed to use a different type of net, intended for catching corvina fish, that is not supposed to pose a threat to the vaquitas. But because the corvina and totoaba fishing seasons overlap, fishermen can hide the totoaba nets beneath the corvina nets on their boats, said Lorenzo Rojas-Bracho, the director of Vaquita CPR. “You can use a corvina as a cover-up, and that’s what happened,” he said.
Most of the region’s fishermen, who have been out of work since the ban, poach totoaba swim bladders, which fetch $3,000 to $10,000 per kilogram, said Andrea Crosta, the director of a group that investigates the totoaba trade. An equivalent catch of shrimp might earn a fisherman $200 at best.
“If you’re out here on the water, you’re not risking jail time to catch shrimp,” said Dave Bader, a spokesman for Vaquita CPR.
After the death of the captured vaquita, the scientists agreed to shut down the program. “The evidence today is vaquita are not good candidates for being protected in this way,” Dr. Smith said. “It’s heartbreaking.”
The scientists had hoped to keep the animals in captivity temporarily, and possibly even breed them, until gill nets were eliminated from their habitat. While any wild animal is expected to experience some stress when captured, the group had hoped the vaquita could cope with being handled. (Last month, the scientists released a vaquita calf they had pulled from the waters when they determined it was too young to be separated from its mother.)
Other conservationists had been critical of the plan. “I was telling them that this was going to happen, you’re going to stress out the animals,” said Paul Watson, the…