The elusive vaquita porpoise has the unfortunate distinction of being the rarest marine animal on the planet – and sadly, a new study estimates that there could be fewer than 19 of them left in the wild.
Scientists have been tracking the vaquita’s activity since 2011 to estimate their population numbers, using sightings and their clicks to make their calculations. The scientists are able to track the cetaceans because they use clicks to echolocate and communicate on an almost constant basis, the number of clicks collected by the team’s underwater sensors over a 62-day period (June 19 to August 19) can be used to work out year-on-year fluctuations in population numbers.
From The Marine Mammal Center:
The tiny vaquita porpoise (Phocoena sinus) is found only in the shallow waters of the northern Gulf of California, Mexico. It is the most endangered of the 128 marine mammals alive in the world today. The Comité Internacional para la Recuperación de la Vaquita (International Committee for the Recovery of the Vaquita), an international team of scientists established by the government of Mexico and known by its Spanish acronym CIRVA, estimated about 200 vaquitas remaining in 2012.
By 2014, CIRVA estimated that about half of them had been killed in gillnets, leaving fewer than 100 individuals. Of these, fewer than 25 were likely to be reproductively mature females. A report prepared by CIRVA in March 2019 presented an even more dire estimate, finding no more than 22 vaquitas during the summer of 2018. This represents a decline of more than 95% since 1997.
“Based on the uncertainty inherent in the models, the number could be as few as six,” said Prof Len Thomas, a statistician at the University of St Andrews and an author on the study.
According to the study, published in the Royal Society Open Science, the average number of clicks detected each day fell by 62.3 percent from 2016 to 2017 and a further 70.1 percent from 2017 to 2018. What’s more, the researchers say there is 99 percent certainty that vaquita numbers have declined 98.6 percent since tracking began in 2011.
The study backs up previous reports that highlights dramatic population decline – even if the exact numbers vary, there is no denying that their numbers are dwindling. In 2014, it was announced that vaquita numbers had dropped below 100 for the first time. By 2017, there were thought to be just 30 of the porpoises left. That figure fell to 12 in 2018 and a report earlier this year found there were only 10 vaquitas remaining.
The critically endangered species get caught and drowned as a bycatch in gillnets. These nets are vertically suspended in water and the spacing of the mesh is supposed to allow only fish of certain size to be caught, but in practice marine mammals and sea turtles can quickly become entangled and drown.
From The Marine Mammal Center:
The Vaquita and The Marine Mammal Center
The Marine Mammal Center is working with an international collaboration of conservation scientists, animal care specialists and marine mammal veterinarians to save the vaquita through efforts like gillnet removal. The Center is also helping raise awareness about the vaquita and the threats to its survival, supporting development of alternative fishing gear, and providing administrative support for initiatives such as population surveys. In addition, the Center provides technical support and training in the investigation of mortality events in the Gulf of California.