ADRIATIC SEA — A study published in the journal Frontiers reports that 76% of trawlers in some areas of the Adriatic Sea are now followed by bottlenose dolphins scavenging for food. The researchers attribute this reliance on fishing vessels to the depletion of the dolphins' natural prey due to overfishing.

Giovanni Bearzi, a co-author of the study and president of Dolphin Biology and Conservation in Italy, said, "These days the easiest way to find [bottlenose dolphins] is to look for trawlers." Bearzi added, "Many of them are followed by the dolphins that go to forage and scavenge in their wake." He explained, "When I say scavenge, I mean that they also feed on discards and unwanted organisms." Bearzi stated, "Dolphins are following the trawlers because natural prey is very hard to find." A study conducted in the Adriatic during the 1990s found that 10% of trawlers were followed by dolphins.

Scientists monitored trawlers offshore in the Adriatic Sea for 148 days. This monitoring included 859 inspections across two regions and different types of trawlers.

Dr. Randall Reeves, another author of the study and chair of the Committee of Scientific Advisors at the U.S. Marine Mammal Commission, said, "It is known that bottlenose dolphins are occasionally injured or killed by trawl gear, and that foraging behind trawlers can affect dolphins' diet, social organisation and communication." Reeves added, "Dolphins may also suffer hearing damage that results from chronic exposure to the noise of trawlers." Regarding the trade-off, Reeves said, "However, finding sufficient prey away from trawlers in an overfished sea may be too difficult." He concluded, "It appears that for these animals, taking the risks is better than going hungry."

Bearzi noted that young dolphins learn this behavior from their mothers. "The baby dolphins follow the trawlers with their mothers, watch the adults foraging and learn that kind of behaviour," Bearzi said. He added, "It is transmitted culturally." Bearzi also stated, "The Mediterranean Sea is one of the areas with the highest rates of fishing worldwide." He said, "The fishing pressure in the Mediterranean is twice the level considered sustainable by the FAO [UN Food and Agriculture Organization]."