The vaquita is the world’s most endangered small cetacean species, with a single population now estimated at only 150 individuals (1). Vaquitas are endemic to the northern Gulf of California and have the smallest known range of any cetacean (2). They are also one of the smallest cetaceans, measuring only 1.5 m and up to 55 kg at maturity (3). The vaquita’s small population size, naturally limited distribution, and low rate of increase leave the population vulnerable to the effects of disease, inbreeding, and natural processes, in addition to the threat of anthropogenic (human-related) mortality (4,5). Vaquitas are listed as a CITES Appendix I species (6), and considered Critically Endangered by the World Conservation Union (7). Vaquitas are also listed as an endangered species by the United States and Mexico.
Incidental capture in gillnets is the single greatest threat to the depleted vaquita population (4). Synthetic gillnets have been used in the Gulf of California since the 1940s, and it’s likely that the vaquita population was already in decline by the time the species was scientifically described in 1958 (2,7,8). Vaquitas are naturally rare and difficult to observe, and were poorly studied until only a few decades ago (2). The large-mesh gillnet fishery for totoaba (a large member of the sciaenid or drum family, now endangered itself ) was the greatest source of bycatch mortality for several decades (2). The fishery was closed in 1975, reopened between 1983 and 1993, and has continued to operate illegally (2,4). Today, bycatch occurs in the smaller mesh trawl and gillnet fisheries, targeting shrimp, sharks, rays, skates, curvina and mackerel, which have expanded since the closure of the totoaba fishery (2,10). Between 1993 and 1995, the bycatch rate for just one of three major ports in the region was estimated to be at least 39 animals per year, which is almost certainly greater than the population’s potential rate of increase (4,10).
The vaquita’s situation is so critical that most agencies and researchers involved in the species’ conservation prioritize immediate conservation action over additional abundance surveys or estimates of bycatch mortality (1,4,10). Area closures and acoustic alarms, the only two strategies for reducing gillnet bycatch, are not feasible options for the Gulf of California due to the high costs of implementation and enforcement (5). The closure or buyout of all gillnet fisheries is considered the most effective and immediate solution to the bycatch problem (1), though such a solution presents serious political and socioeconomic challenge (5). Fishing is a primary occupation in the northern Gulf of California, and support for economic alternatives for affected communities is considered crucial to a successful conservation plan (1,10).
Efforts to limit the number of gillnets in vaquita habitat began in the mid-nineties. The Mexican government created the Upper Gulf of California and Colorado River Delta Biosphere Reserve in 1993, and a management program was developed in 1995. In 1996, Mexico established the International Committee for the Recovery of the Vaquita, CIRVA, to create and implement a recovery plan for the vaquita. Over the last several years, the Mexican government has developed the Action Program for the Conservation of the Species Vaquita and devoted almost $20 million to its implementation (11). The program, now underway, will reduce the number of gillnets in use by buying out permits and encouraging alternative livelihoods, helping fishermen switch gears, and compensating fishermen in exchange for fishing outside important vaquita habitat (11).
References and Additional Resources:
1. Jaramillo-Legorreta, A., L. Rojas-Bracho, R.L. Brownell Jr., A.J. Read, R.R. Reeves, K. Ralls and B.L. Taylor. 2007. Saving the vaquita: Immediate action, not more data. Conservation Biology 21(6): 1653-1655
2. Rojas-Bracho, L., R.R. Reeves, and A. Jaramillo-Legorreta. 2006. Conservation of the vaquita Phocoena sinus. Mammal Rev. 36 (3): 179-216.
3. NOAA. NMFS. Office of Protected Resources. Gulf of California Harbor Porpoise / Vaquita / Cochito (Phocoena sinus).. <http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/vaquita.htm. Downloaded 21 July 2008>.
4. Rojas-Bracho, L., and B.L. Taylor. 1999. Risk factors affecting the vaquita (Phocoena sinus). Marine Mammal Science 15 (4): 974-989
5. Read, A. 2008. The looming crisis: Interactions between marine mammals and fisheries. Journal of Mammalogy 89 (3): 541-548.
6. Convention on International Trade in Endangered Species of Wild Fauna and Flora. CITES Species Database. Downloaded 21 July 2008.
7. Rojas-Bracho, L., Reeves, R.R., Jaramillo-Legorreta, A. & Taylor, B.L. 2007. Phocoena sinus. In: IUCN 2007. 2007 IUCN Red List of Threatened Species. < >. Downloaded on 21 July 2008.
8. Norris, K.S. and W.N. McFarland. 1958. A new harbor porpoise of the genus Phocoena from the Gulf of California. Journal of Mammalogy 39: 22-39
9. Contreras-Balderas, S. & Almada-Villela, P. 1996. Totoaba macdonaldi. In: IUCN 2007. 2007 IUCN Red List of Threatened Species. < >. Downloaded on 21 July 2008.
10. D’Agrosa, C., Lennert-Cody, C.E., and O. Vidal. 2000. Vaquita bycatch in Mexico’s artisinal gillnet fisheries: Driving a small population to extinction. Conservation Biology 14 (4): 1110-1119
11. Morell, V. 2008. Can the vaquita be saved? Science 321: 767