The vaquita porpoise, the world’s smallest cetacean, teeters on the brink of extinction, with fewer than 10 individuals remaining in their sole habitat in Mexico’s Gulf of California. UCLA biologists and their colleagues discovered that despite the critically endangered species’ dwindling numbers, the vaquitas are relatively healthy genetically and could survive if illegal gillnet fishing is stopped. The researchers found that the vaquita is not plagued by genetic issues, such as harmful mutations, which often affect other species with similarly diminished gene pools. Instead, illegal fishing poses the most significant threat to their survival. The researchers analyzed the genomes of 20 vaquitas that lived between 1985 and 2017, conducting computational simulations to predict the species’ extinction risk over the next 50 years.

The study concluded that if gillnet fishing ceases immediately, the vaquita has a high chance of recovery, even with inbreeding. The vaquita’s genetic diversity is not so low that it threatens their health and persistence; it merely reflects their natural rarity. Vaquitas have survived for tens of thousands of years with low genetic diversity, gradually purging harmful recessive gene variants that could negatively impact their health under inbreeding conditions. This resilience sets them apart from other species facing similar population crashes. However, saving the species remains a challenge due to tensions between conservationists and locals, and difficulties in enforcing gillnet fishing bans by the Mexican government.

The researchers hope their genomic analysis and novel simulation approach will guide conservation efforts for other endangered species, but the fate of the vaquita porpoise ultimately depends on the cessation of illegal gillnet fishing and the implementation of effective conservation measures. The loss of the vaquita would represent a tragic loss of unique diversity within the Gulf of California, robbing the ecosystem of an important predator adapted to this distinctive environment. The vaquita’s plight serves as a stark reminder of the need to protect endangered species and their habitats, as their extinction would have far-reaching consequences for the ecosystems they inhabit.

For our podcast Not a Dolphin, we chatted with Dr. Barbara Tylor, a scientist with NOAA’s Southwest Fisheries Science Center. Dr. Taylor has been involved with the vaquita conservation cause for decades.

These naturally small populations that have lived with being small for many, many generations, they’re actually less vulnerable. So of all the things that I lose sleep over about vaquita. The one thing I don’t lose sleep over is their genetic situation because, um, apparently they’ve been doing just fine at these low levels for at least 200,000 years.
Dr. Barbara Taylor

Listen to Ep. 6 of Not a Dolphin