Mexico recently launched a comprehensive survey for the vaquita, the endangered porpoise that is native only to a small part of the northern Gulf of California. This is the world's most endangered marine mammal, and one was recently sighted. These porpoises are threatened mainly by gillnet fishing and the pursuit of a fish called the totoaba, according to a release.

The survey, led by the Mexican Ministry of the Environment and Natural Resources, will span roughly 100 miles by 50 miles, the species' distribution area. NOAA Fisheries will also be involved for field work, analytical expertise and support on logistics to a scientific team from Mexico, the U.S., Germany and the United Kingdom, the release said.

It will be a two-part survey: a team will do a visual study from a ship, looking through high-powered binoculars for vaquita up to five kilometers in the distance; secondly, a team will set out an expanded grid of "acoustic buoys" in water; these will listen for vaquitas echolocating to track down food. Taken together, the two information sources will tell more about where and how many vaquita exist in that range, according to a release.

"The results will provide a baseline with which to assess the conservation strategies implemented by the Government of Mexico," said Rafael Pacchiano, Mexico's Minister of the Environment and Natural Resources, in the release.

The survey will run for two months, until early December, and take place on board a 175-foot research vessel, Ocean Starr.

Vaquitas's last survey by ship was in 2008 and determined that the population then was around 250 animals, a big drop from about 600 in 1997. The vaquita is retiring and often difficult to find at sea.

Already, scientists are aware that the vaquita population is below 100; the porpoises are caught in gillnets for fish and shrimp and the totoaba, which has swim bladders that sell for high prices in China. The Mexican government in April declared a two-year ban on gillnets in the porpoise's habitat and more enforcement of illegal fishing of totoaba.

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