Assessing the Effectiveness of Whale Pingers in Mitigating Large Whale Entanglements in Gillnet Fisheries in Northern Peru

Gillnets, widely used in fisheries, are a leading cause of cetacean entanglements. In northern Peru, as the humpback whale population (Megaptera novaeangliae, stock G) actively grows, entanglements are also increasing. Mitigation strategies, e.g., pingers, have been proposed to mitigate entanglements of dolphins and possibly whales. Here, we assess the effectiveness of whale pingers (i.e., low-frequency pingers 3-20 kHz) in northern Peru's small-scale gillnet fishery, focusing on humpback whale entanglements. During the 15-month study period from September 2022 to December 2023, 115 fishing sets were observed across 22 trips by four vessels, with 49 control sets and 66 alarmed sets, resulting in the recording of 34 whale entanglements. A 52.9% reduction in whale entanglements resulted in sets using pingers compared to control sets. Catch rates of the fishery's target catch were unchanged when pingers were used. Our findings highlight the potential of pingers to reduce whale entanglement and suggest the need for continued trials and stakeholder engagement to develop sustainable entanglement mitigation strategies.