Dolphins forced to break into nets to find food by overfishing in the Mediterranean, report says

Dolphins short on prey are resorting to underhand tactics to find a meal – tearing into nets to access the fish inside.

Researchers studying interactions between dolphins and fishermen in northern Cyprus found nets were six times more prone to damage when dolphins were in the vicinity.

They concluded that the marauding marine mammals were therefore the most likely culprits.

“It seems that some dolphins may be actively seeking nets as a way to get food,” said Dr Robin Snape, an ecologist at the University of Exeter, who led the study.

Net damage is irritating for the fishermen themselves, and can cost individuals thousands of euros every year. This is particularly problematic as most operations in the region are small scale.

However, the scientists suggested the fishermen must take some share of the blame, as overfishing in the region is a likely driver for the dolphins’ unusual behaviour.

Dr Snape highlighted a “vicious cycle” that is “probably driven by falling fish stocks, which also result in low catches – meaning more nets are needed and higher costs for fishers”.

“Effective management of fish stocks is urgently needed to address the overexploitation that is causing this vicious cycle,” he said.

The results of this study were published in the journal Human Ecology.

There are currently no limits on fishing operations in northern Cyprus for licence holders.

Local fishermen have called for restricted zones and quotas in order to establish more sustainable management of the area's fisheries.

As a more short-term solution, the researchers trialled “pingers” – devices that emit sounds at frequencies intended to drive away dolphins – to reduce net damage by these marine mammals.

Not only were the pingers attached to nets ineffective, the scientists thought they may have actually worked as “dinner bells” to attract the dolphins.

More powerful acoustic deterrents could prove more successful, but they also have the potential to disturb the marine ecosystems in which they are deployed.

Besides monitoring the presence of dolphins in the region, the scientists also tried to gauge the number of dolphin fatalities resulting from interactions with people.

They estimated that at least 10 dolphins were accidentally caught in the study area each year. However, they noted that fishermen are likely to under report such incidents due to the protected status of dolphins.

Another issue highlighted by the researchers was dolphin consumption of plastic from the fishermen’s nets.

Sizeable chunks had been removed from the damaged nets observed by the scientists, and some of that net could have made its way into the dolphins’ stomachs.

Consumption of plastic by marine animals has been highlighted as one of the key reasons to tackle the global problem of plastic pollution. Everything from fish to whales have been found with guts full of plastic waste.

Little is known about the dolphins of northern Cyprus, so even small-scale losses due to conflict with humans could be having a sizeable impact on their population.