This web application uses cookies and other tracking technologies to ensure you get the best experience.
SC/69A/SM/01
Offline resourceN/A |
Request |
| Additional files | |
SC_69A_SM_01.pdf1.9 MB |
Download |
| View in browser | |
Resource ID
20060
Access
Open
Document Number
SC/69A/SM/01
Full Title
Acoustic monitoring and status of vaquita population in 2022
Author
Jaramillo Legorreta, A.M., Nieto García, E., Cárdenas Hinojosa, G. And Rojas Bracho, L.
Authors Summary
The population of vaquita has been declining since many years ago, as estimated by several works with data gathered since 1993. It is the key factor considering the species as critically endangered. By 2018 it was estimated that population was composed out of less than 20 individuals, using acoustic data to extrapolate from an estimate of abundance in 2015. Along abundance decreasing, it was also noted that distribution area was also shrinking progressively, with acoustic activity now restricted to the Zero Tolerance Area (ZTA). Given the importance of information about vaquita status, acoustic monitoring was implemented in 2022 season in the ZTA sampling during neap tide periods between April and December. The sampling protocol included a 55 sites grid, from which some sites were selected to sample along eight neap tide periods. A total of 13,964 hours of effort were applied in 42 sites and identifying 77 acoustic encounters of vaquitas in 17 of the sites. The distribution of encounters shows that the most used area is the western portion of the ZTA, with very low activity towards east. Using data of 21 of the sampling sites between October and November, that coincide with 2021, it was estimated that acoustic detection rate decreased at a rate of 11.99% (95% C.I. -38.45% to 21.13%), with 79.64% probabilities of actual decreasing. If detection rate change is a proxy of population trend, vaquita population keep decreasing. Encounters dataset allowed to calculate that, at least for periods, more than one group of vaquitas use the ZTA at the same time. The acoustic monitoring program for 2023 is already funded and will occur between July and November. Also, other survey to observe vaquitas will occur in May, with the aim to use expert elicitation techniques to estimate minimum abundance of vaquita population.
Publisher
IWC
Publication Year
2023
Abstract
2022 vaquita report