The remaining 10 vaquitas have enough genetic diversity to restore their species, but only if there is a dramatic reduction in illegal fishing operations in the Gulf of California.

life


May 5, 2022

Wakita caught as by-catch in Baja California

Flip Nicklin / Minden Pictures / Naturepl.com

There are only 10 wakits left in the world, but genetic analysis shows that small guinea pigs are not necessarily doomed to extinction – as long as they stop getting caught in fishing nets, ie.

As the smallest marine mammals on the planet, wakites are particularly vulnerable to entanglement in gillnets used in illegal fishing operations in the Gulf of Mexico, where they live. One and a half meter long guinea pigs were not known to science until the 1950s. Since then, they have become one of the most endangered animals in the world.

Marine biologists estimate that even among its most populous, the Wakites have never numbered more than a few thousand individuals. By the 1990s, only hundreds remained. Naturally, the small size of the Vaquitas population reduces their genetic diversity, which researchers fear could lead to offspring that are less healthy than their parents.

“It has been said in people’s minds that low genetic diversity is a bad thing,” he said Jacqueline Robinson at the University of California, San Francisco. “But our research shows that the reality is more nuanced than that.”

To find out if the few remaining wakites can rebuild their populations, Robinson and her colleagues analyzed 20 wakite genomes. Genomic samples were collected mainly from dead animals between 1985 and 2017. Because the samples were collected close in time from an evolutionary point of view, Robinson says they are probably “extremely similar” to those of the surviving wakites.

The researchers then used a computer model to simulate future wakit populations in different scenarios. They found that when vaquita deaths dropped by 80 percent, the species became extinct in more than half of the simulations. But when by-catch deaths stopped altogether, the species recovered in more than 90 percent of the simulations.

“I was pleasantly surprised that the model showed that vaquitas have a good rebound capacity if they are adequately protected,” says Robinson. “I did not expect [the results] to be so optimistic. “

While the model found moderate effects of inbreeding, Robinson said that “they are very moderate and have much less impact than other factors, such as the amount of pressure on the gillnet for fishing.”

Alejandro Olivera The Center for Biological Diversity in Mexico agrees that the results are “very good news.” Now that there is evidence that the small size of the vakitas population is not a certain death sentence, Olivera says the work could boost even tighter protections for marine mammals. “Now this is a difficult science, there is no denying it.”

The results give Robinson some hope, but not without a break. “There’s a chance the Wakites will survive,” she said, “but it just depends on human actions and decisions.”

Reference in the magazine: science, DOI: 10.1126 / science.abm1742

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