The Plight of the Porpoise: Fishery Bycatch Could Cause Vaquita Extinction

Despite efforts to combat its population decline, a newly developed network of acoustic detectors has confirmed that there is an alarming 34 percent per year decline of the endangered vaquita porpoise in Mexico. A study in the journal Conservation Biology has revealed this devastating statistic.

The vaquita became endangered due to its association with the sought-after totoaba, a large fish with a swim bladder that is of great value in China. As an unintended bycatch, the vaquita's numbers have declined exponentially.

"We are witnessing the end of a species, if the illegal fishing continues," said Armando Jaramillo-Legorreta of Mexico's Department of the Environment and Natural Resources. He is also the lead author of the research describing the acoustic array and its findings. "The acoustic array is a powerful new tool that helps us see the tragic direction of this population by listening for the porpoises' voices."

A companion paper published in Conservation Letters uses both acoustic and visual surveys to reveal that as of 2015, only about 60 vaquitas remained. "The science revealing the decline was key to spurring the Government's emergency actions," shared Rafael Pacchiano, Mexico's Secretary of the Department of the Environment and Natural Resources.

The new acoustic study found that due to the resumption of illegal gillnet fishing for totoaba, the vaquita population is declining much more rapidly. Totoaba bladders are now worth up to $5,000 per kilogram, even costing as much as $100,000 on the black market in China according to information from the Environmental Investigations Agency.

The Government of Mexico has launched many campaigns to save the vaquita. They have set aside half of the small porpoise's range as a no-fishing refuge and implemented a two-year ban on all gill net fishing in the range of the species. Local fishers and related industries are even being given compensation to aid in reversing the decline of the vaquita.

"Long-term monitoring like this is usually about as newsworthy as an annual check-up," said Barbara Taylor, a NOAA Fisheries marine mammal biologist and coauthor of the new study. "In this case the monitoring exposed the shocking degree of illegal fishing that is rapidly driving the vaquita toward extinction. The science is showing us the urgency of the situation."

With numerous totoaba gill nets having been found and removed in recent months, marine experts hope for a more positive and recent abundance estimate using the acoustic monitoring that builds on last year's abundance estimate.

"This pioneering research revealed just how sharply vaquitas are declining, and how urgent the situation has become," said Cisco Werner, director of NOAA Fisheries' Southwest Fisheries Science Center. "Science may have bought the vaquita some precious time by supporting the extra protections. But we are now on the verge of losing the species altogether."