Rare porpoise population of nine faces extinction from illegal fishing nets
of the world’s smallest and most endangered porpoises could be extinct within a year, scientists at the University of St Andrews have warned.
Numbers of the rare vaquita porpoise, which only lives in the upper Gulf of California in Mexico, may now have dropped to less than ten according to research published today in Royal Society Open Science.
Estimates had put the worldwide population at just 30 in 2016, but despite the Mexican government banning the gillnet, which causes the porpoises to be killed as a bycatch, illegal fishing has continued.
Ten dead vaquita have been found since then, with all deaths, where the cause could be determined, as a result of drowning in gillnets.
The researchers’ best estimate is that there were nine animals remaining at the end of the last acoustic survey in August 2018.
The vaquita has also suffered from the demand in China for the swim bladder of the totoaba, an endangered fish that lives in its habitat.
Illegal fishing for and trafficking in this fish have led to serious population losses for the vaquita and totoaba alike.
In 2017, most gillnets were banned in the upper gulf, with the refuge area being increased by 750 square kilometres a year later.
Professor Len Thomas, director of the university’s centre for research into ecological and environmental modelling, was on an international expert panel of ecological statisticians analysing the data.
“The ongoing presence of illegal gillnets despite the emergency ban continues to drive the vaquita towards extinction. Immediate manone agement action is required if the species is to be saved,” Prof Thomas said.
Researchers studied recordings of vaquita echolocation clicks, made via a large grid of acoustic sensors spread out in the mammals’ habitat, to estimate species decline.
Their studies showed alarming declines in numbers – by 98.6 per cent since the current monitoring study began in 2011, and by nearly 50 per cent annually since the 2016 study.