The most comprehensive genetic estimate of the world’s rarest marine mammal, Wacquita, offers a glimmer of hope that this small tropical porpoise, from the Gulf of California in Mexico, may not be extinct even though its population has dwindled to 10.
According to genetic data from 20 Vacuitas researchers on Thursday, although the species has minimal genetic variation – differences in DNA between different individuals – the number of potentially harmful mutations that threaten its survival through reproduction is very small.
Vacuita, first described by scientists in 1958 and now considered extinct, is the smallest cetacean, including whales, dolphins and porpoises, reaching about 5 feet (1.5 m) long and 120 pounds (54 kg). Its torpedo-shaped body is gray at the top and white at the bottom with a dark circle around the eyes.
Researchers’ calculations to estimate the risk of extinction have shown that wakvitas, which have lost more than 99 percent of their population since the beginning of the 20th century due to human activity, are more likely to recover if fishing gillnets are completely removed from their habitat. Guillotines, large nets hanging in the water, are used to catch fish and shrimp, but kill many vultures that get trapped and drown.
“Our key research suggests that wakvita is not at risk of extinction through genetics, as some have speculated,” said Christopher Kiriazis, a doctoral student at UCLA Ecology and Evolutionary Biology, co-author of the study. Published In the journal Science. “These discoveries are important because they give hope to an endangered species, and many are now giving up.”
Guillotine hunting is an endangered species of fish known as totoba. Totoba swim bladders, said to be fertility enhancers, are valuable in China.
“Dried Totoba swimming bladders are traded on the black market in China for traditional medicinal purposes and fetch more than cocaine,” said Philip Mory, a research geneticist and research geneticist at the U.S. National Oceanic and Atmospheric Administration’s Southwest Fisheries Science Center. .
The Vakvitas, despite their small numbers, are still actively reproducing, living in the northern Gulf of California, known as the Cortage Sea between the mainland of Mexico and the Baja Peninsula.
“Guillotine fishing is banned in the Wakwita habitat, but the ban has not been enforced and wakwitas continue to perish in nets,” said Jacqueline Robinson, co-lead author of the study, postdoctoral research at the University of California, San Francisco Institute for Humans. Genetics.
The first census, conducted in 1997, had approximately 570 vacuoles. Since then the population has shrunk by almost 50 percent annually.
Researchers estimated the genetic health of a species that evolved from its closest relatives about 2.5 million years ago by examining samples from 20 individuals obtained between 1985 and 2017, mostly archived from the deceased Vacuitas. One concern with such a small population is that unavoidable intercourse between people in close contact increases mutations that are detrimental to the survival of the species.
Genetic data indicate that hundreds of thousands of years before the crash caused by human activity, the Wakvita population was already very small – about 5,000 people – and that low genetic variation was a natural feature of the species.
It also showed that fertility in waxvitas was very low and that very few harmful regressive mutations could lead to congenital malformations during breeding – which could impede the survival of the species – less than the estimate of 11 other cetacean species, including the blue whale.
A Cetacean species already appears to have become extinct by humans in recent decades: the Baiji, or Chinese river dolphin.
“Because of its shy nature, very little is known about Vacuita,” Robinson said. “This species is in danger of becoming extinct before we fully realize what we are missing out on and will not replace it once it is gone.”
© Thomson Reuters 2022