Vaquita news update!

The "Vaquita" or Gulf of California Porpoise is the most endangered marine mammal in the world; and in my other life I have been involved in an international project to analyse acoustic line transect data to improve automatic click detectors within the PAMGUARD framework to be better able to assess the current status of the Vaquita population.  In November this year myself and Dr. Douglas Gillespie from the Sea Mammal Research Unit at the University of St. Andrews,  along with colleagues from Mexico and United States will be presenting the following paper at the 162nd meeting of the Acoustical Society of America in San Diego, California.
 

Towed hydrophone surveys for monitoring trends in the abundance and distribution of the critically endangered Gulf of California porpoise, “Vaquita”.

René Swift1, Shannon Rankin2, Tim Gerrodette2, Barbara Taylor2, Douglas Gillespie, Jonathan Gordon1, Lorenzo Rojas-Bracho4, Armando Jaramillo-Legorreta4.

1. Sea Mammal Research Unit, Scottish Oceans Institute, University of St. Andrews, St. Andrews, Fife, KY16 8LB. U.K. 2. Southwest Fisheries Science Centre, 3333 N. Torrey Pines Court, La Jolla, CA 92037, U.S.A. 3. Instituto Nacional de Ecologia / CICESE, KM 107 Carretera Ensenada-Tijuana, Ensenada, B.C. 22860, Mexico.

The vaquita (Phocoena sinus) is a critically endangered small cetacean found only in the upper Gulf of California, where fisheries bycatch remains an acute threat. Cost, shallow heavily fished areas and the vaquita’s extreme avoidance of noisy motorised vessels argue against using large vessels typically used for visual line transect surveys. Towed hydrophone surveys, using RainbowClick semi-automatic detection software, were carried out from a 24' sailing trimaran in autumn 2008. Ultrasonic (~130kHz) vaquita echolocation clicks were reliably detected and tracked using classification parameters developed for harbour porpoise. Transects were sailed on 49% of days, and 31 groups were detected within the vaquita’s known range and in areas not easily surveyed using traditional methods. Although very high levels of ambient noise presented challenges for acoustic monitoring, perpendicular distances were calculated to 30 groups giving an estimated strip half-width of 198m. The detection algorithm has since been implemented in PAMGUARD software and significantly improved using survey data. Shallow, heavily fished areas remain difficult for estimating and monitoring trends in abundance. Towed arrays proved effective for the former and may remain the only alternative for the latter. Precision is likely to remain low for the quick detection of small rates of increase.

For more information about the desert porpoise (Vaquita) visit the following sites:

• http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/vaquita.htm
• http://vaquita.tv/
• http://www.vivavaquita.org/

For more information about PAMGAURD visit:

• http://www.pamguard.org/home.shtml