Documenting the imminent extinction of the vaquita

On 16 March 2017, Len and I gave a CREEM seminar on the current status of the vaquita porpoise. The abstract of the seminar is shown below.

My part of the seminar was about being out on the last two visual surveys (2008 and 2015) but also included some of the issues encountered and a mention of the great work that the sea shepherds are doing in the region. More pictures of the 2015 survey are here.

Abstract:

The vaquita is a small porpoise endemic to the Gulf of California, Mexico. It is subject to bycatch in gillnets set by local artisanal fishermen – most recently an illegal fishery for an endangered fish, the totoaba. Despite many attempts to reduce bycatch and protect vaquita, there has been a long-term decline in population size. Here, we report on two recent surveys of population size and trend, both led by Mexican and American scientists: (1) a combined visual line transect and passive acoustic survey that took place throughout known vaquita range in 2015 and (2) an acoustic monitoring programme that has been running in the core vaquita habitat since 2011. These are both complicated by the low population size; also, in the former case by the vaquita’s elusive nature and in the latter by loss of recorders. Our talk will focus on implementation of the line transect survey, and on analysis and results from both surveys. Results are shocking: we estimate an ongoing decline of around 40% per year (posterior mean 39%; CRI 26%-52%), with only around 30 vaquita (posterior mean 33, 95%CRI 8-96) remaining as of autumn 2016. As a result, planning is now underway to try to catch the last remaining vaquita and preserve the species in captivity.