To Save the Vaquita Porpoise, Conservationists Entreat Mexico to Keep Gillnets Out of the Northern Gulf of California

The country must enforce its ban on gillnet fishing in the area to save the world’s most endangered marine mammal, experts warn. Only around 10 of the porpoises are thought to remain.

Demonstrators with The Animal Welfare Institute hold a rally to save the vaquita, the world's smallest and most endangered porpoise, outside the Mexican Embassy in Washington, D.C., on July 5, 2018. Credit: Saul Loeb/AFP via Getty Images
Demonstrators with The Animal Welfare Institute hold a rally to save the vaquita, the world's smallest and most endangered porpoise, outside the Mexican Embassy in Washington, D.C., on July 5, 2018. Credit: Saul Loeb/AFP via Getty Images

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In San Felipe, a fishing town on the northeast edge of Baja California, the use and transportation of gillnets have been banned by the Mexican government since 2017 as a measure to protect the rare vaquita porpoise. 

The nets, however, are hard to miss. On land, local fishermen clean shrimp out of the gillnets with impunity, and at sea, the gillnets are dragged behind pangas, the small, white boats that freckle the surface of the Gulf of California, also known as the Sea of Cortez.

A small cetacean with endearing black patches around its eyes and mouth, the vaquita porpoise is the most endangered marine mammal in the world. Historically, this charismatic creature has persisted only in small populations at the northern end of the Gulf of California, where it meets the Colorado River Delta in Mexico. 

Over the last 25 years, estimates of the population size have dropped from 600 to only about 10  as the porpoises got entangled in the illegal gillnets. The nets are designed with holes large enough for a fish to get its head through but not its body, so that it becomes ensnared by its gills while trying to escape.

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While the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) prohibits the international trade of both the vaquita porpoise and totoaba fish, experts say both species are threatened with extinction because the Mexican government has failed to enforce the treaty and its own laws designed to protect them.

“There is a single cause of the vaquita’s decline: Mexico’s failure to stop illegal fishing with gillnets for totoaba and other species,” D.J. Schubert, a wildlife biologist for the Animal Welfare Institute, said in November during the 19th annual meeting of the convention in the Panamanian capital. 

Now, some conservationists are worried that the remaining 10 or so vaquita porpoises may not survive the next totoaba mating season, which begins in mid-December and lasts through May. The big fish become targets of fishermen’s gillnets as they migrate into the Gulf of California, which threatens the stocky porpoises as well. 

Monitoring Mexico’s Lack of Enforcement

Early this year, CITES scientists traveled to San Felipe to investigate whether Mexico had complied with previous recommendations to enforce the gillnet ban. While the mission noted efforts by Mexico to follow up, it concluded that more surveillance was imperative. 

In March, the Mexican navy clearly demarcated a zero-tolerance area in the vaquita marine sanctuary where all fishing and motorcraft are prohibited. But the scientists found that the navy, which has been charged with enforcing the ban on totoaba poaching since 1975, did not inspect boats entering the sea from a well-known but unauthorized launch site nearby. Fishermen in the area are required to use an authorized launch site where navy officials inspect boats for gillnets, but they can easily circumvent those regulations. 

In one hour, the scientists observed 15 boats departing from the unauthorized launch, uninspected and unregulated. CITES’ mission ran from late May through early June, well before the peak of fishing season in the Gulf of California, meaning that even more boats may be heading out uninspected in the coming months. On Dec. 1, 29 vessels were observed within the zero-tolerance area by the Sea Shepard Conservation Society.

Vaquita Porpoises All But Extinct

The fishermen also know that under navy policy, there will be effectively no consequences for refusing to remove gillnets when they are caught using them. “Enforcement is needed, but there’s this nonconfrontation policy in place,” said Barbara Taylor, a retired National Oceanic and Atmospheric Administration (NOAA) researcher who has worked with the vaquita since 1997. “They’re just completely outgunned, quite frankly.” 

Andrew Read, a marine biologist at the Duke University Marine Laboratory, contends that the Mexican government’s decision to avoid confrontation is a mistake. “You’ve got poachers who are engaging in illegal activity, harvesting an endangered fish, driving another endangered species to extinction,” he said. 

The Mexican government has convicted eight cartel members associated with totoaba trafficking of illegal possession of the fish since 2018, according to Lorenzo Rojas-Bracho, a scientist who left Mexico’s National Commission of Protected Natural Areas after studying the vaquita for 25 years. “And that’s completely absurd because we know there’s way more criminals than eight.” Among those convicted was a cartel leader commonly referred to in the news media as the “El Chapo” of totoaba.

Rojas-Bracho added that the totoaba is not the only fishing target costing the vaquitas their lives: Most of the vaquita recovered for scientific study over the course of his career were found in shrimp gillnets. “The navy will not enforce what they don’t believe in,” he said. “For them, shrimp gillnets are not a problem for vaquita.” 

For years, the Mexican government looked beyond the gillnets and blamed other factors for the vaquitas’ rapid decline. The Mexican fisheries authorities and other influential stakeholders argued that the damming of the Colorado River in the U.S. was the main threat to the species. They contended that it drastically reduced the flow of nutrients reaching the Gulf of California, causing both the vaquita and the totoaba to die out. 

Rojas-Bracho counters, “Trying to blame it on the Colorado River is a political decision: Say ‘It’s the gringos who are responsible for the [decline of] the vaquita, not Mexico.’” Research that he published in 2006 showed that the reduced flow of the Colorado River was not a risk factor because nutrient productivity in the vaquitas’ habitat remained high.

Concrete Blocks and Futile Warnings

This year, however, the Mexican government has moved toward accepting gillnets as the sole threat to the vaquita, the CITES scientists and other experts note.

In October, the navy announced the completion of a project to locate 193 concrete blocks with steel-rod hooks extending upward in the water column around the zero-tolerance area. In the project’s environmental impact statement, each rod is described as being bent inward at the tip to catch and tear the gillnets of any poachers encroaching on the zone. 

Read, of the Duke Marine Laboratory, said he worried that the blocks were spaced too far apart: “The question is whether or not those concrete blocks will really deter poachers.”  He said he was not concerned about the environmental impact of the concrete itself, although the cement manufacturing industry is producing a growing amount of carbon emissions. 

The environmental impact statement requires the navy to monitor the zero-tolerance area over the next six years, both to keep fishermen out and to remove any abandoned nets that remain on the hooks.

The navy recently established a partnership with Sea Shepherd Conservation Society, a nonprofit that monitors the vaquita refuge from two of its ships. Sea Shepherd was effective in removing many nets from the area until 2019, when attacks by groups of fishermen led the navy to ask the ships to leave the area, according to the Cetacean Specialist Group.

Around the same time, fishermen rioted against the navy. “The fishermen are not afraid of the navy,” said Alex Olivera, a marine biologist at the University of Baja California Sur who visited San Felipe this year. “They know that they can beat the navy in a confrontation.”

One positive result of the collaboration between Sea Shepherd and the navy has been the removal of abandoned gillnets, known as ghost gear, from the refuge, said Valeria Towns, a biologist at the Universidad Nacional Autónoma de México. She added that a group of local women from San Felipe was working to spread awareness that the fishermen’s nets will now snag and break if they try to enter the zero-tolerance area. 

Pesca ABC, a grassroots organization consisting of fishermen committed to their community and the sustainability of the region, is contributing to the effort. According to the group’s 2021 annual report, Mexico’s National Commission of Protected Natural Areas provided funds to remove nets that had been abandoned by poachers fleeing enforcement authorities. 

But so far, experts say that the response from Mexico’s government has fallen short both on the water and on land. According to Taylor, the retired NOAA researcher, every vaquita recovery report since 1997 has said that the only way to save the porpoise is to provide an alternative source of income for local people. “If the fishermen have no other way to make a living other than using gillnets, why would an agreement between Sea Shepherd and the navy make a difference?” she said. 

Pesca ABC also works with scientists to place acoustic monitoring devices underwater to keep track of vaquita populations and develops alternative fishing gear that would not harm the porpoises. The Mexican government originally planned to develop vaquita-safe fishing gear as part of its conservation work but never manufactured any.

“Our preference is not to work with the government,” said Enrique Sanjurjo-Rivera, the executive director of Pesca ABC. “We have a lot of reasons to believe, but not enough reasons to prove or demonstrate, corruption and problems of management in the government.” 

Last year, Pesca ABC tested multiple gillnet alternatives, including small trawl nets for shrimp and hook-and-line techniques for fish. In a presentation at CITES, Towns presented preliminary findings from interviews with 600 fishermen and their wives that found 69 percent were willing to use alternative gear as long as it guaranteed the same value for them as gillnets. 

A Most Resilient Species 

Despite inefficient protection measures, the vaquita is seen as a resilient species. The current estimate of 10 porpoises is greater than experts had expected. The rapid rate of population decline has decreased in recent years despite an increase in gillnet fishing within the last area where vaquitas remain.

Between 1997 and 2015, the estimated number of vaquitas declined by 92 percent. In 2018, scientists estimated that the population was shrinking by 47 percent per year and would likely soon die out. Yet a survey in 2021 estimated that five to 13 individuals had survived, prompting the scientists to theorize that the adult vaquitas may have learned how to avoid entanglement in gillnets. 

“The vaquitas are somehow managing to live in this really scary environment for them,” said Taylor. “The last time we went out to do research, we had a hard time following vaquitas because there were so many gillnets inside the zero-tolerance area.” The remaining individuals, including mothers with their young calves, are identified by scars in their dorsal fins caused by those gillnets.

Recent research has shown that the vaquita would be capable of making a comeback, but only if the nets are removed from their habitat. A team of experts was convened to analyze the genomes of vaquita to determine whether genetic factors would get in the way of their recovery. 

The fear that a population made up of only 10 individuals would not be able to recover arises from the likelihood of inbreeding. In most groups that experience a bottleneck, or a rapid decline in population, the subsequent necessary inbreeding would expose recessive genetic disorders or traits that could threaten the survival of the species. The offspring are more likely to receive matching lethal or harmful copies of a gene, which in turn damages the health of the entire population and can lead to extinction.

Chris Kyriazis, a genomics researcher at the University of California, Los Angeles and author of the study, said that through scientific modeling, his lab found that if illegal fishing ceased entirely, there was a very high probability of recovery; only 6 percent of the simulations of that scenario ended with the vaquitas’ going extinct. But even moderate mortality related to unintentional bycatch of the vaquitas would result in a high likelihood of extinction, the study showed. 

“The models gave a more optimistic picture than I had expected,” said Jacqueline Robinson, an evolutionary geneticist at the University of California, San Francisco and a lead author of the study. “I was very pleasantly surprised when we looked at the outcomes of these simulations and saw how much of an impact gillnet mortality was having.”

It was not the first time that Robinson had examined a population that had very quickly declined by more than 90 percent. In the 1990s, four populations of Channel Island foxes in California declined by more than 90 percent because of new predators and disease. They later rebounded under human management in the fastest recovery of any mammal listed under the federal Endangered Species Act. 

Robinson analyzed the genomes of these populations, which are the dwarfed descendants of mainland gray foxes and have inhabited the Channel Islands for more than 9,000 years. She found that the long-term isolation and small population sizes over thousands of generations had protected the foxes from the classic effects of inbreeding depression. They had persisted in small populations for so long that the lethal and other harmful versions of those genes had already disappeared. 

Researchers at NOAA thought that the plight of the vaquitas bore striking similarities to that of the island foxes. While the vaquitas don’t live on an island, they were isolated within the upper Gulf of California for tens of thousands of years. In fact, the porpoises have the lowest genome-wide diversity of any species documented to date. They had survived as a population of only a few thousand individuals for thousands of generations.

Over time, the vaquita’s long-term small population size eliminated many of the species’ lethal alleles, or harmful copies of genes in their DNA, according to Phillip Morin, a research molecular geneticist at NOAA. “So as the population declines, some of those get lost and very few [harmful alleles] remain in the few remaining individuals,” he said. “So the chances of getting inbreeding depression are greatly reduced.”

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But human management, which helped save the island foxes, is not a viable option for the recovery of the vaquita because none of these porpoises has ever survived in captivity. In 2017, 90 marine mammal specialists from around the world traveled to the Gulf of California to attempt to capture a vaquita and take it into human care to prevent the extinction of the species. 

Taylor, Rojas-Bracho and Read were among the scientists who journeyed to San Felipe. In the choppy waters of the Upper Gulf of California, they constructed a holding pen similar to those used to bring harbor porpoises into captivity. 

Unfortunately, the adult female that was captured and placed in the ocean holding pen died of stress. The official cause of death, capture myopathy, has been observed in other cetaceans. When the experts saw that she was in distress, they tried to release her back into the ocean, but it was too late.

“It was shattering to have failed and to have lost the adult female that died as a result of the capture events,” Read said. “That was probably the saddest I’ve ever been in my professional life.” 

Breeding the Totoaba in Captivity

While wild totoaba populations remain endangered, companies such as Earth Ocean Farms have been approved to breed the fish in captivity. The sale of meat from these captive-bred fish has been legal throughout Mexico, and in March CITES approved international sales. 

Some of the young totoaba fish from the captive-bred population are released into the Gulf of California every year, but there is no evidence yet that this work has helped the wild population recover. 

The totoaba is valuable for its swim bladder, a gas-filled organ that helps bony fish control buoyancy. The bladders are thought to have medicinal properties in Chinese markets and are trafficked out of Mexico via several cartels to be sold at exorbitant prices, according to Earth League International. The swim bladders are often referred to as “aquatic cocaine” and can be sold for more per ounce than gold. 

The swim bladders of the totoaba bred in captivity for their meat are required to be destroyed to discourage such trafficking. As of Nov. 13, representatives from Mexico reported at the CITES conference in Panama City that the bladders produced from the captive-bred population were in a warehouse waiting to be pulverized and mixed with other fishmeal. 

Some conservationists fear that the aquaculture of captive-raised totoaba will nonetheless spur demand for illegally sourced and traded swim bladders. Schubert, the wildlife biologist from the Animal Welfare Institute, for example, welcomes the pulverizing effort but feels that it is far from foolproof.

“Pulverizing the swim bladders, in my mind, is not synonymous with destroying the swim bladders,” he added. “We know from the illicit trade in rhino horn that there can be value in the powder that is produced by the pulverization process.”

On Nov. 24, representatives from Mexico, the U.S. and China agreed to updated terms to ensure stricter regulation of the totoaba fishery and protection of the remaining vaquita porpoises. Mexico pledged to empower the navy to carry out seizures of unauthorized vessels and fishing gear. 

Some conservation groups argue that the only way to ensure that Mexico takes effective enforcement action against the totoaba trade is through sanctions that would embargo all wildlife products from the country. About 40 percent of all Mexican fishery exports flow to the U.S. market. On Dec. 14, the Center for Biological Diversity, the Animal Welfare Institute and the Natural Resources Defense Council (NRDC) sued the U.S. Department of the Interior in the United States Court of International Trade to seek an import ban. 

The groups argue that the federal Department of the Interior ignored a petition submitted in 2014 by the Center for Biological Diversity seeking sanctions for Mexico under a U.S. law called the Pelly Amendment, which authorizes the U.S. president to impose bans on imports of threatened wildlife. 

“While the United States has delayed for eight years, the vaquita population has plummeted from 97 to 10,” said Zak Smith, a senior attorney at the NRDC. “It’s time for the United States to use this ultimate tool—broad sanctions—to compel Mexico to save the vaquita.”

Andrea Crosta, the executive director of Earth League International, said the reason that decades of vaquita conservation have failed is that law enforcement agents target the “small fish,” either poachers or illegal fishermen. “They keep focusing on what happens at sea and they almost completely disregard the trafficking part,” he added. “I don’t see any hope for the vaquita or totoaba if they don’t start working also on that.”

The criminal networks responsible for trafficking swim bladders from the Gulf of Mexico to China and Hong Kong also traffic in shark fin, sea cucumber and seahorse, according to an  Environmental Crime Convergence report from Earth League International and the John Jay College of Criminal Justice. 

Whether from illegal gillnets or global trafficking, no animal under CITES’ protection has been completely wiped out due to international trade since the convention was signed 50 years ago. “If vaquita go extinct,” said Taylor, “it’s a massive failure.”