Article prepared by Lorenzo Rojas-Bracho and Barbara Taylor, Chief Scientists of Expedicion Internacional Vaquita Marina 2015.
The Government of Mexico has commissioned a new survey to find out how many vaquitas remain at the start of the emergency 2-year gillnet ban. The survey was launched by the Secretary of the Environment and Natural Resources Rafael Pacchiano Alamán and a host of dignitaries. Miraculously, vaquitas appeared and were seen by the Secretary and several other dignitaries as if they knew to appear for those who had the power to save them.
After 20 days of our 64-day survey on R/V Ocean Starr in the northern Gulf of California, 25 vaquitas have been spotted though some may have been seen multiple times. We are hopeful of obtaining a useful, updated estimate of population size when the survey is completed. At this stage, we can at least report that vaquitas, unlike baijis when we surveyed the Yangtze River in 2006, are still present, and in habitat that appears healthy and free of gillnets.
The Mexican Government’s emergency ban on gillnets throughout the vaquita’s range is the first large-scale ban on artisanal gillnetting in the world (as reported on this website in mid-January 2015). The ban was accompanied by a compensation package for fishermen and others in the region who rely on the fishing industry for their livelihood. In hard economic times, the Mexican Government is investing $37 million (US) per year in saving this endemic species. President Peña Nieto rolled out the emergency strategy, which also includes a new Navy enforcement program, in April in San Felipe, one of the two small fishing villages affected by the ban.
The main method of documenting trends has been and continues to be an innovative scientific method that uses acoustic detectors to monitor vaquitas (details available here in English, and in Spanish). These detectors provide over 3,000 days of continuous listening each year. The acoustic monitoring program indicated a 30%/year decline between 2011 and 2014 and it was this finding that prompted the emergency actions (details here).
The present survey, like previous ones, has been a collaborative effort between Mexico and the US. The survey design involved the world’s top experts to get the most precise estimate possible (more details summarised at Survey Design and in this detailed Report). In waters where more than 700 kilometers of net usually would have been set each day during the start of shrimp season, only a single gillnet has been observed thus far.
The survey involves both a visual team working on a ship in waters more than 20 m deep and the passive acoustic detectors in shallower waters. There is an area of overlap that will be used to calibrate the visual with the acoustic methods. To make the abundance estimate as precise as possible, we are using the same ship that was used to obtain the previous two abundance estimates for vaquitas, one in 1997 and the other in 2008. The visual team uses 6 high-power binoculars to spot the small porpoises that are only visible in very calm seas. The acoustic effort involves 135 detectors placed in a grid. Both the visual and the acoustic teams will work from 26 September through 3 December 2015. Results including the new abundance estimate are expected in the spring of 2016.