Vaquita Porpoise Reproducing Despite Low Numbers and Continued Threats From Illegal Gillnets
At less than five feet long, the vaquita porpoise is the smallest living cetacean and the rarest marine mammal in the world. It also has the smallest geographical range. The little porpoise with the smiling expression and dark rings around its eyes can be found only in the northern part of Mexico’s Gulf of California, and there aren’t many left. With as few as ten individual vaquita remaining, their numbers have dropped dramatically in recent years, due to the illegal gillnets used by fishing operations within marine protected areas in the Gulf of California, according to the World Wildlife Fund.
New research indicates that, while the few vaquita that remain have been skirting extinction for years, those few that survive are reproducing and may have found ways to avoid the gillnets that threaten their species, the University of St Andrews said in a press release.
The findings of the research, “More vaquita porpoises survive than expected,” were published in the journal Endangered Species Research.
“Finding any vaquita in the area is a surprise, given the rapid declines detected in previous surveys. These survivors are the future of an endemic species of Mexico and must be protected,” said lead author of the research Dr. Lorenzo Rojas-Bracho of the National Institute of Ecology and Climate Change in Mexico, according to the press release.
Seven to 15 vaquitas were spotted in 2019, the researchers estimated, and from five to 13 individuals last year. Calves were seen both years. Earlier research had estimated that less than 20 vaquita survived in 2018, with the population decreasing by about half each year.
Scientists have said the only hope for vaquita recovery is for local fishers to stop using gillnets to catch fish and shrimp in the vaquitas’ small territory, as they can trap and drown the endangered porpoises.
The researchers said that extinction is inevitable for the vaquita without another form of livelihood for the fishers that doesn’t include the use of gillnets.
Fishing equipment that wouldn’t entangle the small porpoises does exist, but none of the alternative gear was found in recent surveys of the area, and it would require investment and enforcement to put into effect.
“Against all the odds, we still have one last chance to save the vaquita,” said research scientist at NOAA Fisheries’ Southwest Fisheries Science Center Dr. Barbara Taylor, who was co-author of the paper. “Give these animals a chance and they can survive.”
A method called “expert elicitation” was used by the research team in figuring out how many individual vaquitas were seen across various surveys in 2019 and 2021. These numbers were used to estimate the minimum size of the total population. A better estimate wasn’t possible partially due to acoustic monitors, which can provide more comprehensive data, having been damaged and stolen by illegal fishing crews.
“In the absence of direct data on the quantities of interest, expert elicitation is the next best alternative for providing quantifications that can be used for decision making,” said professor Len Thomas of the Centre for Research into Ecological and Environmental Modelling at the University of St Andrews, who, along with Cormac Booth of the University-associated SMRU Consulting, undertook the expert elicitation, the press release said.
The research team did find evidence to suggest that, during an attempt to capture some vaquita in 2017 in order to bring them into protective captivity, a few had avoided gillnets, while some had scars from earlier run-ins with the deadly nets.
“If you kill 99 percent of the animals, the one percent that is left is probably not random. Models do not necessarily account for the intelligence of vaquitas that may have learned how to escape gillnets,” said Taylor in the press release. “That could help stave off extinction of the species a little longer, but vaquita are not far from disappearing because gillnets remain the primary means of making a living in nearby towns, and even protecting the small area where vaquitas remain seems beyond enforcement abilities. Until fishers have access and training in alternatives to gillnets, vaquitas’ extinction is guaranteed.”
The way to help the vaquita is simple: let them be. Alternative equipment must be provided or another means of living found for local fishers.
“I have said several times that vaquitas are very resourceful and if we stop killing them, they will recover. Mexico has all the ‘ingredients’ for management actions to prevent this species from becoming extinct and, in the long term, to recover,” Rojas-Bracho said.