Research recently published in the journal Aquatic Conservation estimated that there were just over 2,000 individuals. “This is a very low number compared to other species of the same genus,” says marine biologist Dr. Luis Bedriñana-Romano, who led the scientific work.
The Chilean dolphin, also known as “tonina,” is the only species of cetacean endemic to our country. It is distributed between the regions of Valparaíso and Magallanes and is considered a small marine mammal (as an adult it measures around 1.6 meters;) its scientific name is Cephalorhynchus eutropia.
To date, there were only estimates of the abundance of this species in some small bays and channels of Chiloé. However, a study led by marine biologist Dr. Luis Bedriñana-Romano, postdoctoral researcher at the Center for Dynamic Research of High Latitude Marine Ecosystems (IDEAL) of the Austral University of Chile (UACh) and recently published in the scientific journal Aquatic Conservation, determined that there would be just over 2,000 animals in all of northern Patagonia, also called the Chiloense Ecoregion.
“This is a very low number compared to other species of the same genus, which reinforces the notion of vulnerability of the species,” explains Dr. Bedriñana-Romano and adds that the Blue Whale Center and the UACh have carried out surveys since the year 2009 to evaluate the distribution and abundance patterns of different cetaceans.
Although the populations of dolphins of the genus Cephalorhynchus are small, this is not necessarily related to a human effect. Unlike other species, this one tends to travel long distances in search of food. “That characteristic makes it particularly vulnerable to the degradation of its habitat. However, to know if this phenomenon is actually affecting the viability of the Chilean dolphin populations, we need monitoring programs over time, something that unfortunately we do not have in Chile,” says the researcher.
The study covered open waters, channels, bays and fjords from Puerto Montt to the Taitao Peninsula. Work was carried out in northern Patagonia, given that it is an area of great diversity of cetaceans and the main feeding and breeding place for the blue whale in the eastern south Pacific Ocean.
The research is also a pioneer in identifying the areas where the Chilean dolphin is concentrated, these being very specific areas of small bays and channels with a high influence of freshwater. Finally, the work also distinguishes sectors where the probability of encounter between these animals and the prominent aquaculture fleet is concentrated, which is focused on the eastern coast of the Big Island of Chiloé.
To carry out this study, various visual surveys were carried out. “Because Chilean dolphins are not very abundant, the amount of data available to adjust distribution and abundance models is scarce. In order to solve this problem, new statistical data integration techniques were used, which helped us have better estimates,” explains Dr. Bedriñana-Romano.
Currently, the researcher focuses on studying the status of the species in the rest of its distribution range.
To read the study, click here.