The vaquita (Phocoena sinus) is a critically endangered species of porpoise found only in a small part of the Upper Gulf of California, Mexico. Less than 100 of these animals are thought to be alive today, and an international team of scientists are currently leading an expedition to obtain a precise abundance estimate of this species. One of Azura’s Associate Scientists, Melody Baran, has joined the expert team of marine mammalogists on this quest to find and count the vaquita. She shares the following blog article which includes inside information about this spectacular Vaquita Expedition 2015.
Day 31 from the ‘Log from the Sea of Cortez’
-by Melody Baran
Vaquitas, in addition to being extremely rare, have proven to be quite difficult to find. They are very small (among the smallest of all cetaceans), less than 4 – 5 feet in length and weighing an average of about 100 pounds. Their surfacings are quick and are easily concealed by almost any amount of swell or even slightly rough sea state. They are also difficult to see because they show very little surface active behavior, and they are seen in very small numbers. They most often occur as singles, pairs, or sometimes three individuals, whereas leaping groups of dolphins that number in the dozens or hundreds are much easier to spot even at a distance of several miles.
The end of Leg 1 of Vaquita Expedition 2015 finds us with a total of 19 sightings of vaquita, several of which have consisted of two (and in one case three) vaquitas. The final number of sightings, of course, will not be known for quite some time as the second half of the survey will not be completed until December 3. After that point, the data that are collected will be rigorously analyzed to estimate vaquita density and abundance. Some of our team members were able to get great photographs of a couple of vaquita which have already been shared and even tweeted by President Peña Nieto.
A beautiful and persistent part of our scenery as we survey is a very distinctive geological formation known as Rocas Consag or Consag Rocks. This isolated peak (and surrounding rocks) of igneous, or volcanic, rock stands about 286 feet above the water and is located about 17 miles ENE (east north east) of San Felipe, Mexico. Interestingly, all vaquita sightings, even including those in past surveys, have been in view of Rocas Consag. The tides in this part of the Gulf of California are extreme (up to about 30 feet). These tides mix and circulate the sediments in the delta region of where the Colorado River used to enter the Gulf, making it a productive and biologically rich, yet murky, area. The Gulf of California is a semi-enclosed ocean basin that has relatively high salinity because it has a high net evaporation rate, high heat retention, and minimal fresh water inflow.
Our survey takes place in the far northwestern waters of the uppermost Gulf of California, which is also relatively shallow (most of our time is spent in waters less than 200 feet deep). We’ve even seen a group of killer whales in the relatively shallow northern part of the Gulf of California. There has also been a humpback whale, several more fin whales, Bryde’s whales, bottlenose dolphins, and long-beaked common dolphins. Non-mammal sightings include a juvenile (10-foot long) whale shark, a couple of juvenile hammerhead sharks, and a few sea turtles (loggerhead and green sea turtles).
Additional updated information can be found at the Southwest Fisheries Science Center website: https://swfsc.noaa.gov/MMTD-Vaquita2015/
For those avid avian experts who are curious about the feathered, we’ve generated a cruise Bird List: