It turns out that the dolphins in the Mediterranean that are struggling to find enough fish have resorted to stealing the catch of fishermen hunting the same prey.
While we’re used to hearing about human-wildlife conflict on land, there are increasing reports of such cases occurring out at sea. Researchers have now looked into the relationship between dolphins and fishermen in the waters off northern Cyprus and found that when the cetaceans are present, nets are six times more likely to be damaged. The paper is published in the journal Human Ecology.
“It seems that some dolphins may be actively seeking nets as a way to get food,” explains lead author Robin Snape, of the Centre for Ecology and Conservation at the University of Exeter, in a statement. “This is probably driven by falling fish stocks, which also result in low catches – meaning more nets are needed and higher costs for fishers.”
The majority of fishermen in the region are small scale and set nets roughly 1.2 meters (4 feet) tall on the seafloor to catch fish. The researchers found that in about 28 percent of fisheries, common bottlenose dolphins have learned that these nets offer up an easy meal, particularly where over-fishing is driving the fish stocks down.
The marine mammals often tear the nets to get at the prey. This is not only dangerous to the dolphins – the team believe that around 10 are caught by accident each year, although they admit this is likely an underestimate – but also costly to the fishermen, who have to shell out thousands of euros every year to fix their nets.
The team think that there is a “vicious cycle” occurring in these waters. The overexploitation of the fish stocks means the dolphins have less food to eat and that the fishermen have to lay more nets, perpetuating the situation.
While investigating the impact that fishermen are having on dolphins in the region, and vice versa, the team also attempted to limit the stealing of the fishermen’s catch and destruction of the nets using acoustic “pingers”. Unfortunately, this did not exactly have the desired result. Rather than keep the marine mammals away, it instead acted in effect as a “dinner gong” to the dolphins, alerting them to where they can get their next free meal.
The solution that would help both parties here is more effective management of the fisheries in the region. The fishermen want restricted zones that will not only help provide nurseries for commercially important species of fish but also help the dolphins too.