A sound solution to prevent accidental dolphin catches in the Mediterranean

Dolphins are highly intelligent and playful creatures but can also be troublemakers when netted fish is in their reach. Fishers in Terracina, Italy, have frequent run-ins with dolphins which interfere with their catch, resulting in accidental captures, harm to the dolphins, and damaged nets. With the help of EU funding, fishers tested acoustic bollards – devices that emit sporadic blasts of underwater sound to keep the dolphins away. 

Dolphins in danger

The accidental bycatch of dolphins is a serious problem for both fishers and conservationists.

Artisanal fishers in the Gulf of Terracina typically use gillnets. Unfortunately, gillnet fishing attracts dolphins, which often prey on netted fish, entangling themselves and sometimes drowning in the process. 

To address this issue, La Sirena Producers’ Organisation of Terracina, in collaboration with Agrital General Cooperative Association of Italy and the Agricoltura Gestione Ittica, used EU funding to test the use of ‘acoustic bollards’. 'We decided to take action, and with the support of the small-scale fisheries cooperative, we found a way to protect both the fishermen’s livelihoods and the dolphins', explains Massimo Rampacci, lead scientist on the project.

The bollards emit sporadic blasts of underwater sound to scare away dolphins and other large predators, repelling them from vessels and preventing human-dolphin interactions at sea. This reduces accidental capture and predation, helping to save dolphins’ lives and minimising the loss of the fishers’ valuable catch.

'The European Maritime and Fisheries Fund (EMFF) was crucial in making this possible, as none of the fishermen had the extra funds to invest in gear that might not work. Most of their resources were already being used to repair damaged nets. Nevertheless, the fishermen combined their efforts and their expertise at sea, and with the support of the EMFF, we were able to put the idea to the test,' Massimo Rampacci added.

Testing the waters

The project began by surveying affected fishers to establish the scale and the characteristics of these problematic interactions. After collecting the survey data, researchers set out to compare the effectiveness of two types of bollards: the ‘DiD 01’ (Dissuasore Interattivo per Delfini-interactive dissuasion system for dolphins) and an acoustic pinger. They monitored the fishing activity of three different vessels over 20 fishing days: one equipped with the DiD 01, one with the acoustic pinger, and another with no bollard attached. 

On the unequipped vessel, damage caused by dolphins occurred on 60% of active fishing days. When dolphin interactions were confirmed, the average decrease in catch was 75%, with losses peaking at up to 90%. 

However, with the acoustic bollards in place, there were no recorded dolphin interactions, catch losses, or net breakages. 

Progressing towards a sound solution

The EMFF-supported study showed that acoustic bollards can be an effective, ecologically non-invasive deterrent. They help reduce dolphin mortality and improve working conditions and livelihoods for fishers, who earn higher profits from their catch and reduce valuable time spent repairing nets.

Both bollards proved effective, offering distinct advantages. 

• The acoustic pinger is smaller and lighter, making net maneuverability and catch hauling easier. 
• The 'DiD 01,' is sturdier but heavier, requiring buoys and a special bracket attachment. Both devices have rechargeable batteries, but the DiD 01's built-in battery requires the entire device to be charged ashore, whereas the pinger batteries are removable. 
• While the pinger has a 50m range, the DiD 01 can emit sounds up to 300m away and vary its frequency to prevent dolphins from becoming de-sensitised to the noise and rendering the bollard ineffective.

More information

The EU has adopted measures to protect cetaceans (whales, dolphins and porpoises) against hunting, capture and captivity. 

The fishing sector and Member States are investing into research and technical trials to develop and test new devices, which would allow for reduced interaction between small cetaceans and fishing vessels, fostering their co-existence in the future.

Ongoing research projects on new devices and interaction with cetaceans: PIFIL, DolphinFree, Licado, and the EU project Cetambicion.

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