The vaquita, the world’s smallest porpoise, is going extinct because it drowns in illegal fishing nets set for another endangered species, the totoaba fish. As of 2024, only an estimated 6 to 8 individual vaquitas remain in their sole habitat in Mexico’s Upper Gulf of California. The cause is remarkably specific: nearly all vaquita deaths trace back to a single threat, and that threat is driven by a black market thousands of miles away in China.
Gillnets and the Totoaba Trade
Vaquitas are air-breathing mammals. When they swim into a gillnet, a wall of nearly invisible mesh suspended in the water column, they become tangled and cannot reach the surface. They drown. These nets are not set to catch vaquitas. They target the totoaba, a large fish whose swim bladder is one of the most valuable animal products on Earth. Totoaba swim bladder can sell for up to $80,000 per kilogram in Chinese markets, making it worth more than gold or cocaine by weight. The organ is used as a luxury food, an expensive gift, and even a speculative investment.
The totoaba is itself critically endangered, and fishing for it has been illegal in Mexico since 1975. But the staggering prices drive a persistent poaching industry. Local fishermen in the towns of San Felipe and El Golfo de Santa Clara set gillnets under cover of darkness, and the vaquita, which lives in the same shallow, murky waters, gets caught as collateral damage. This accidental capture, called bycatch, is the sole meaningful driver of the vaquita’s collapse.
A Population in Freefall
The speed of the decline has been staggering. Acoustic monitoring, which uses underwater microphones to detect the clicking sounds vaquitas make, documented an average population decline of 45% per year through 2018. The animals’ range shrank alongside their numbers, contracting to a small patch of ocean now designated the Zero Tolerance Area, or ZTA.
More recent monitoring suggests the rate of decline has slowed, dropping from that 45% annual loss to roughly 14% between 2021 and 2023. Researchers also detected vaquita sounds outside the ZTA in 2024, which was considered encouraging because it suggests the remaining animals haven’t been completely cornered into one tiny area. But even a slower decline in a population this small is precarious. A 2024 census placed the population at 6 to 8 individuals, down from an estimate of 8 to 13 the year before.
Why Enforcement Hasn’t Been Enough
Mexico banned gillnets in the vaquita’s habitat in 2014 and has implemented progressively stricter protections since. Conservation vessels, including ships operated by the organization Sea Shepherd, patrol the ZTA to find and remove illegal nets. In a single fishing season (2019 to 2020), Sea Shepherd removed 106 recently set nets by the end of February alone. And enforcement has had some effect: the 2022 to 2023 fishing season saw a 90% decrease in gillnetting within the ZTA.
The problem is that even occasional net-setting in such a tiny population can be fatal. With fewer than 10 animals left, losing even one individual to bycatch is a significant blow. And the economic incentive to poach totoaba remains overwhelming. A single totoaba swim bladder can represent months or years of income for a local fisherman, creating a situation where the financial reward far outweighs the risk of getting caught.
Failed Alternatives for Local Fishermen
Over the past two decades, the Mexican government has tried multiple strategies to reduce fishing pressure. These include buyout programs that paid fishermen to surrender their nets and pursue alternative livelihoods, compensation programs for not fishing inside the vaquita’s range, and efforts to develop vaquita-safe fishing gear that could still catch commercially valuable species like shrimp.
The results have been disappointing. Testing of alternative fishing gear did not produce yields that local fishermen found commercially acceptable. Compensation programs turned fishing communities into “clients” of government payouts, creating dependency without fundamentally changing the economic calculus. Meanwhile, the totoaba trade continued to offer life-changing sums to anyone willing to take the risk. The core problem remains unsolved: no legal fishing method has matched the income that illegal totoaba poaching provides.
Why Such a Small Population Can’t Bounce Back Easily
Even if every gillnet disappeared tomorrow, the vaquita would face a long road to recovery. Vaquitas reproduce slowly. Females don’t reach sexual maturity until at least three years of age, and evidence suggests they give birth no more than once every two years. With so few individuals left, even under perfect conditions the population would take decades to rebuild.
A captive breeding attempt in 2017 was abandoned after a captured vaquita died from stress. Researchers observed vaquitas in groups of one to three on eight days during that field season, but the animals proved too sensitive to handling. The species will have to recover in the wild or not at all.
Genetics Offer a Surprising Bright Spot
One common assumption about critically small populations is that inbreeding will doom them regardless of other factors. Closely related animals mating with each other typically produces offspring with more genetic defects and lower fitness. But genome sequencing of 20 vaquitas revealed something unusual: the species has always been rare, and that long history of small population size actually worked in its favor genetically.
Because vaquitas have lived in small numbers for thousands of years, harmful genetic variants were gradually weeded out over many generations. Their inbreeding load, a measure of how much damage would result from related individuals mating, is far lower than the typical mammal’s. The remaining individuals appear healthy and are actively reproducing. Genomic simulations published in the journal Science concluded that the vaquita is not doomed by its genetics and can recover if bycatch is eliminated.
This finding reframes the entire crisis. The vaquita’s extinction is not an inevitable consequence of being a small, genetically compromised population. It is being driven by a single, preventable cause. The species has the biological capacity to survive, but only if the nets stop killing them first.