All’s not lost for the vaquita—even though its gene pool is shallow

Enlarge / The vaquita's population is small, but it may have purged most of its harmful mutations in the past. (credit: David Schneider)

With only around 10 individuals left in the world, a tiny porpoise called the vaquita is facing extinction. Somewhat surprisingly, despite the relative shallowness of its gene pool, inbreeding isn’t likely to be an issue for the porpoise. This is according to a new study by the National Marine Fisheries Service, National Oceanic and Atmospheric Administration (NOAA), University of California, San Francisco, and other groups around the globe.

The vaquita, also known as the California harbor porpoise, is the smallest cetacean and makes its home in the northern part of the Gulf of California. Over the decades, the diminutive mammals have been caught as bycatch in gillnets, and these accidental drownings have devastated their population. Ultimately, gillnets (and other random deaths) are the biggest risk the incredibly small population faces, said Jacqueline Robinson, one of the authors of the paper and postdoctoral scholar at the UCSF Institute for Human Genetics.

The reasoning goes that vaquitas have had a small population size for thousands of years and have experienced catastrophic population decline. This is a similar situation to one faced by the Channel Island Fox. “But through protection, conservation action, and captive breeding, those fox populations were able to rapidly recover and reach their pre-decline population sizes,” Robinson told Ars.