V is for Vaquita

Vaquitas have gained prominence in recent years, but not for reasons one might hope. Of the ocean's 128 marine mammals, vaquitas are the most endangered.

These small cetaceans grow to 5 feet and weigh only about 120 pounds. Dark patches surround their eyes and mouths. Vaquitas live in the shallows of Mexico's northern Gulf of California and were first discovered in 1958.

There are no more than 30 vaquitas left, according to the most recent population survey, completed in 2016—that is nearly half of the total population measured just a few years prior. It's estimated that this alarmingly low number has continued to decline.

Researchers believe about 90 percent of vaquitas have been lost since 2011. Gillnets pose the greatest threat to vaquitas that are often caught as bycatch in the illegal fishing practice.

Fishermen use gillnets to catch the endangered totoaba—a fish prized for its swim bladder, which is dried and exported to China. Much like the shark-fin trade, totoaba swim bladders are considered a delicacy and believed to have medicinal properties in some cultures.

Unfortunately, gillnets capture animals indiscriminately. When vaquitas become entangled and unable to escape, they often drown. In April 2015, Mexico announced a two-year emergency ban on gillnets throughout vaquita habitat, but enforcing that ban has proved challenging.

Some scientists have proposed capturing and moving vaquitas to a protected sea pen as a safeguard against extinction, but that is a risky and complicated operation.