Passive acoustic monitoring of the decline of Mexico's critically endangered vaquita |
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| Authors: | Armando Jaramillo‐Legorreta Gustavo Cardenas‐Hinojosa Edwyna Nieto‐Garcia Lorenzo Rojas‐Bracho Jay Ver Hoef Jeffrey Moore Nicholas Tregenza Jay Barlow Tim Gerrodette Len Thomas Barbara Taylor |
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| Affiliation: | 1. Instituto Nacional de Ecología y Cambio Climático/SEMARNAT, Coordinación de Investigación y Conservación de Mamíferos Marinos, Ensenada, B.C, México;2. Departamento de Biología de la Conservación, Centro de Investigación Científica y Educación Superior de Ensenada, Ensenada, Baja California, México;3. Alaska Fisheries Science Center, NOAA Fisheries, National Marine Mammal Laboratory, Seattle, WA, U.S.A.;4. Southwest Fisheries Science Center, NOAA Fisheries, Protected Resources Division, La Jolla, CA, U.S.A.;5. Chelonia Limited, The Barkhouse, Mousehole, U.K.;6. University of St Andrews, Centre for Research into Ecological and Environmental Modelling, The Observatory, Buchanan Gardens, U.K. |
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| Abstract: | The vaquita (Phocoena sinus) is the world's most endangered marine mammal with approximately 245 individuals remaining in 2008. This species of porpoise is endemic to the northern Gulf of California, Mexico, and historically the population has declined because of unsustainable bycatch in gillnets. An illegal gillnet fishery for an endangered fish, the totoaba (Totoaba macdonaldi), has recently resurged throughout the vaquita's range. The secretive but lucrative wildlife trade with China for totoaba swim bladders has probably increased vaquita bycatch mortality by an unknown amount. Precise population monitoring by visual surveys is difficult because vaquitas are inherently hard to see and have now become so rare that sighting rates are very low. However, their echolocation clicks can be identified readily on specialized acoustic detectors. Acoustic detections on an array of 46 moored detectors indicated vaquita acoustic activity declined by 80% between 2011 and 2015 in the central part of the species’ range. Statistical models estimated an annual rate of decline of 34% (95% Bayesian credible interval –48% to –21%). Based on results from 2011 to 2014, the government of Mexico enacted and is enforcing an emergency 2‐year ban on gillnets throughout the species’ range to prevent extinction, at a cost of US$74 million to compensate fishers. Developing precise acoustic monitoring methods proved critical to exposing the severity of vaquitas’ decline and emphasizes the need for continual monitoring to effectively manage critically endangered species. |
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| Keywords: | extinction Phocoena sinus population decline statistical modeling declive poblacional extinció n modelado estadí stico Phocoena sinus |
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