Tourism Threatens Dolphins in Balearic Islands

Factors like climate change and habitat loss are often the source of declining species populations, but in the case of bottlenose dolphins in the Balearic Islands, a rise in tourism, along with fishing and sea transport, is threatening their wellbeing, new research shows.

The common bottlenose dolphin (Tursiops truncatus) is one of the most common cetaceans in the Mediterranean Ocean. But for one small population living close to humans in coastal waters off the Pityusic Islands, their numbers are suffering. The subpopulation of this species has decreased by 30 percent in the last 60 years, now numbering at a mere 517 individuals. This group was subsequently declared "vulnerable" by the International Union for Conservation of Nature (IUCN).

"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," lead researcher Joan Gonzalvo at the University of Barcelona said in a statement.

The Balearic Islands have over 400 handcrafted boats, more than 60 trawlers, three longline fishing boats and 11 seiners, so the likelihood of running into dolphins is high. These marine mammals frequently get entangled and trapped in fishing nets, with fishers reportedly causing 30 to 60 dolphin deaths a year in the area.

Aside from fishing, sea traffic between the Iberian Peninsula and the Balearic Islands is of increasing concern. Dolphins risk colliding with boats full of tourists, not to mention the noise disturbance affects the behavior of these animals.

So why do these dolphins stick around? Well, researchers say that this species is stubborn (or loyal) to their habitat and so refuse to leave, while also having relatively limited mobility across the archipelago. This forces them to stay in an area where overfishing, habitat degradation, tourist boat disturbance and an ever-growing fishing industry are a threat.

"Conservation measures are needed beyond those already in place," Gonzalvo concluded.

The findings are described in the Journal of the Marine Biological Association of the United Kingdom.

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