Hope For Rare Porpoises in Mexico

As the small grey dorsal fins gently slice through the calm waters of San Felipe in Mexico, the relief and elation onboard the research ship, the R/V Ocean Starr, is unmistakeable. A mere four days into a 64 day-long survey into the abundance of the critically endangered vaquita population and two have already been spotted by a team of renowned scientists. It was a promising start and provides a glimmer of hope that this rare species can be saved.

The vaquita is a small porpoise and the world’s most endangered marine mammal. Found only in the Gulf of California in Mexico, with the smallest distribution of any other mammal species, this little cetacean is under imminent threat of extinction with only an estimated 100 remaining. The main threat they face is accidental entanglement in gillnets used by fishermen to catch shrimp, as once they become trapped they are unable to surface and eventually drown. However, sadly this is not a recent issue. Fifteen years ago, Peter Evans, Sea Watch Foundation’s Director, constructed a letter on behalf of the European Cetacean Society, urging the President of Mexico to take urgent action to address the issue of incidental capture in fishing gear and save the species before it is too late. It is something that has been affecting the population for a considerable amount of time and, as a result, has caused serious damage to this isolated species.

According to acoustic data collected by research teams between the years 2011 and 2014, there was a 30% per year decline in the number of vaquitas. Last year, an international panel of scientists warned of a decrease of 100 specimens over two years and indicated that by 2018, the vaquita could vanish altogether. This shocking information prompted the Mexican government to act in order to try and secure the survival of the species and, in April 2015, the President of Mexico Peña Nieto, announced an emergency two-year ban on the use of gillnets in the area known to be frequented by these cetaceans.

On the 26th September, “The Vaquita Expedition 2015” was launched by the Mexican government in order to obtain an estimate of the number of vaquitas at the beginning of the gillnet ban. Lasting 64 days, 13 scientists on board have been using both visual and acoustic methods to document the abundance of animals in areas once dominated by nets. The visual team are using six pairs of 25x binoculars known as “big eyes” to survey the distribution of vaquitas in waters between 20 and 50 metres deep, spotting them up to six miles away. It is vital that the equipment is able to see so far away as porpoise are shy and likely to react to the ship, and therefore close observation would be difficult and the resulting abundance estimates inconclusive. Acoustically, devices called CPODs (built by Nick Tregenza from Cornwall) are being used to harmlessly detect the high frequency clicks used by the vaquitas when finding food. 134 of these devices will be deployed in a grid in shallow water where the research ship is unable to go, so as to be able to examine a wider area and build up as much information as possible. Both acoustic and visual survey methods will be used so as to provide a more complete picture and allow the scientists to build up as precise a density estimate as possible for this very rare cetacean.

So far, over the first 20 days of the survey, due to end on the 3rd December 2015, 25 vaquitas have been spotted. Whilst some of these may be the same individuals seen on multiple occasions, these are promising observations, and at least demonstrate that the near-extinct cetacean is still surviving. With only one gillnet spotted in the exclusion zone, where 700 kilometres of nets were previously used, it also shows how vital the cooperation of the fishermen is to the protection of the species and indeed the importance of the support for those who once relied upon this method of fishing. It is of course crucial to note that the levelling off of or increase in the vaquita population is unlikely to be seen over the course of just the next two years. Even without the gill-net mortality rates, the time it takes for reproduction would only see a very small population growth over this period, and so ideally this short term ban will be permanently extended in the future. Nevertheless, at a time when so many of the world’s wild animals are under pressure simply to survive, it is most certainly a welcome step forward in endangered wildlife conservation.


Image: Paula Olson, NOAAhttp://www.fisheries.noaa.gov/pr/species/mammals/porpoises/vaquita.html


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