The International Whaling Commission released its first-ever extinction alert Monday to warn of the potential danger facing the critically endangered vaquita porpoise.
Known to be the smallest of porpoises and all species within the order Cetacea in terms of size, the vaquita can grow up to 5 feet (1.5 meters) long. Native and unique to the northern end of the Gulf of California in northwestern Mexico, the vaquita porpoise was declared critically endangered by the International Union for Conservation of Nature’s Red List of Threatened Species in 1996. Its population has dramatically decreased from about 570 to 10 in a decade, according to the IWC.
Led by the scientific committee of the IWC, the extinct alert initiative is “a new mechanism” to “voice extinction concerns for an increasing range of cetacean species and populations,” according to a news release. “Despite nearly thirty years of repeated warnings, the vaquita hovers on the edge of extinction due to gillnet entanglement.”
Gillnets, a type of fishing net, are illegal in the area but are still used to capture the shrimp and totoaba fish that share a habitat with vaquita porpoises. The porpoises can end up in the nets as “bycatch,” even if they aren’t the intended targets.
A chance of recovery
Fishing for totoaba in the Gulf of California has been illegal since 1975. However, the practice continues as there is an especially high demand for the fish’s swim bladder in China, where it is sometimes used in traditional medicines.
The scientific committee believes the vaquita population has a chance of recovery if stronger enforcement is placed on the ban on gillnets in their habitat.
Concerns about the use of gillnets and the threats they pose to the vaquitas have been raised for years. The IWC has addressed the issue with the extinction alert now “to encourage wider recognition of the warning signs of impending extinctions, and to generate support and encouragement at every level for the actions needed now to save the vaquita,” according to the statement.
“The extinction of the vaquita is inevitable unless 100% of gillnets are substituted immediately with alternative fishing gears that protect the vaquita and the livelihoods of fishers,” the committee said in the news release. “If this doesn’t happen now, it will be too late.”
Vaquitas “have surprised us all by managing to maintain a population of only around 10 animals for about five years,” IWC spokesperson Kate Wilson said via email. “It’s this resilience that makes us think they stand a chance if the gillnets are 100% removed. A calf was seen during this year’s survey, indicating that the surviving animals are in reasonable health. But with such a small population, the gillnets will get them in the end if they are not removed.”
A resilient marine mammal
Vaquita porpoises have limited geographical range, and their home in Mexico’s Gulf of California, or the Sea of Cortez, is also known as “The Aquarium of the World” due to its variety of diverse ecosystems.
Since the appearance of their ancestors over 2.5 million years ago during the Pleistocene era, vaquita porpoises have adapted to their shallow habitat, which has a depth of 50 meters (164 feet), where they prey on fish, squid and small crustaceans. The vaquitas’ preference for this habitat makes them more vulnerable to environmental changes and disturbances.
The vaquita population has varied from a few thousand to 5,000 over the last 250,000 years, according to the National Oceanic and Atmospheric Administration. This fluctuation is rare in comparison with populations of other marine mammals.
“A prevailing view in conservation biology and population genetics is that small populations can accumulate deleterious mutations,” Kirk Lohmueller, professor in the departments of ecology and evolutionary biology and of human genetics at the University of California, Los Angeles, told CNN in 2022.
But maintaining a small population for so long has actually helped the vaquitas, which have a 21-year lifespan, reducing the risks of inbreeding because they have less genetic variation among them. The marine mammals are also less susceptible to harmful genetic mutations that might otherwise cause their offspring to die.