December 15, 2014

Image Caption: Conflicts with fishers cause 30 to 60 dolphin deaths a year in the area. Credit: Joan Gonzalvo

Provided by SINC Team, FECYT Spanish Foundation for Science and Technology

The rise in tourism, fishing and sea transport between the Iberian Peninsula and the Balearic Islands is compromising the wellbeing of a small population of common bottlenose dolphins living in coastal waters off the Pityusic Islands. This is the conclusion of a study led by the University of Barcelona (Spain), which has, for the first time, counted these mammals in summer and spring, which are crucial seasons for them.

Despite being one of the most common cetaceans in the Mediterranean Ocean, the common bottlenose dolphin (Tursiops truncates) resides in areas close to human beings, and is thus subject to continual conflicts so much so that in 2006, the International Union for Conservation of Nature (IUCN) declared the subpopulation of this species in the Mediterranean vulnerable after it had decreased by 30% in the preceding 60 years.

As Joan Gonzalvo, a scientist at the University of Barcelonas (UB) Institute for Research on Biodiversity, explains to SINC: Anthropogenic activities such as fishing, coastal development, tourism and maritime transport, especially in summer, are some of the threats faced by dolphins in the Balearic Islands.

Gonzalvo is the main author of a study that evaluated the abundance of these cetaceans over three years, as well as movement patterns between the islands and their group dynamic. The results, published in the Journal of the Marine Biological Association of the United Kingdom, estimates that there are 517 dolphins inhabiting this area of the Mediterranean.

The Pityusic Islands are considered a refuge for marine species, especially this population of bottlenose dolphins probably one of the largest in Spain. However, the study demonstrates that the total number of these sea mammals is smaller than previously thought. It may not be more than a few hundred, the researcher says.

The team drew up a series of dolphin distribution maps based on sightings between 2002 and 2004. Most sightings were in summer and spring, when the dolphins could have been avoiding coastal waters due to the growing number of boats and ships and greater human presence, Gonzalvo reasons.

Danger point

The rest is here:

Tourism Poses A Threat To Dolphins In The Balearic Islands