Dolphins increasingly rely on trawlers for food in overfished Adriatic, say scientists

Bottlenose dolphins have always followed trawlers, but the behaviour has become more intense, the study says. Photograph: Brandon Cole Marine Photography/Alamy View image in fullscreen Bottlenose dolphins have always followed trawlers, but the behaviour has become more intense, the study says. Photograph: Brandon Cole Marine Photography/Alamy Dolphins increasingly rely on trawlers for food in overfished Adriatic, say scientists In one area 76% of fishing boats were followed, with baby dolphins learning the technique from their parents Bottlenose dolphins in the Adriatic are increasingly following trawlers to scavenge for food, with baby dolphins learning the technique from their parents, a study has found. “These days the easiest way to find [bottlenose dolphins] is to look for trawlers,” said Giovanni Bearzi, a co-author of the study and the president of Dolphin Biology and Conservation in Italy. “Many of them are followed by the dolphins that go to forage and scavenge in their wake. “When I say scavenge, I mean that they also feed on discards and unwanted organisms. Dolphins are following the trawlers because natural prey is very hard to find. Why is it hard to find? It’s overfished. “The Mediterranean Sea is one of the areas with the highest rates of fishing worldwide. The fishing pressure in the Mediterranean is twice the level considered sustainable by the FAO [UN Food and Agriculture Organization].” The scientists monitored trawlers offshore in the Adriatic for 148 days, carrying out 859 inspections across two regions and different types of trawlers. Dolphins have always followed fishing boats, but the researchers said the behaviour seemed to have increased in intensity. A study from the Adriatic in the 1990s found that 10% of trawlers were followed by dolphins, but in the recent study, in one area 76% of trawlers were followed. Many animals with depleted prey start pursuing food near humans, such as polar bears scavenging in rubbish dumps , according to the study. Trawlers could represent a simple source of food in an impoverished ecosystem. Although dolphins are highly opportunistic animals and may have learned that it is easier for them to catch fish in the wake of a trawler, this does not mean that it is advantageous. View image in fullscreen A trawler in the Mediterranean, which has one of the highest rates of fishing in the world. Photograph: Hemis/Alamy Dr Randall Reeves, one of the authors of the study and chair of the Committee of Scientific Advisors at the US 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. “Dolphins may also suffer hearing damage that results from chronic exposure to the noise of trawlers. However, finding sufficient prey away from trawlers in an overfished sea may be too difficult. It appears that for these animals, taking the risks is better t