Vaquita Bycatch in Mexico's Artisanal Gillnet Fisheries: Driving a Small Population to Extinction

• Published in: Conservation biology 2000-08, Vol.14 (4), p.1110-1119
• Main Authors: D'agrosa, Caterina, Lennert-Cody, Cleridy E., Vidal, Omar
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Bycatch; Conservation biology; Conservation, protection and management of environment and wildlife; Fisheries; Fisheries science; Fishers; Fundamental and applied biological sciences. Psychology; Gill nets; Gulfs; Mexico; Mortality; Parks, reserves, wildlife conservation. Endangered species: population survey and restocking; Phocoena sinus; Population estimates; Sinuses
• ISSN: 0888-8892; 1523-1739
• DOI: 10.1046/j.1523-1739.2000.98191.x

The world's most endangered marine cetacean, the vaquita (Phocoena sinus), continues to be caught in small-mesh gillnet fisheries throughout much of its range. We monitored fishing effort and incidental vaquita mortality in the upper Gulf of California, Mexico, from January 1993 to January 1995 to study the magnitude and causes of the incidental take. Of those factors studied, including net mesh size, soaktime, and geographic area, none contributed significantly to the incidental mortality rate of the vaquita, implying that the principal cause of mortality is fishing with gillnets per se. The total estimated incidental mortality caused by the fleet of El Golfo de Santa Clara was 39 vaquitas per year (95% CI = 14, 93), over 17% of the most recent estimate of population size. El Golfo de Santa Clara is one of three main ports that support gillnet fisheries throughout the range of the vaquita. Preliminary results indicate that fishing effort for San Felipe, Baja California, is comparable to that of El Golfo de Santa Clara, suggesting that this estimate of incidental mortality of vaquitas represents a minimum. We strongly recommend a complete and permanent ban on gillnets in the area. Alternative or supplemental mitigation strategies include (1) a maximum annual allowable mortality limit of vaquitas; (2) mandatory observer coverage of all boats fishing within the Upper Gulf of California and Colorado River Delta Biosphere Reserve; (3) extension of the Upper Gulf of California and Colorado River Delta Biosphere Reserve to encompass all known vaquita habitat; (4) rigorous enforcement of new and existing regulations; and (5) development of alternative sources of income for gillnet fishers.