Evaluating humpback whale (Megaptera novaeangliae) behavioral responses to whale pingers in breeding grounds of northern Peru

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Abstract

This study evaluated the behavioral responses of humpback whales (Megaptera novaeangliae) to whale pingers (3-20 kHz) in northern Peru during the 2022 breeding season. Land-based observations were conducted from the "La Mesa" rock cliff at 33 m above sea level in the district of Los Organos (4°10'S, 81°8.27'W). Monitoring consisted of observing the behavior of whales that passed within a radius of 1,000 m of a fixed sea-based pinger station. Surface time, breathing frequency, dive time, and movement patterns were analyzed across 104 individual whale trajectories under two treatments, 'pinger on' and 'pinger off.' Results showed a significant reduction in surface time when the pinger was on (from 41 to 32 s, P = 0.004), particularly among mother-calf groups, which comprised 71% (n = 34) of the observed groups within the pinger radius. However, no significant differences were found in breathing frequency, dive time, or directness and deviation indexes. These findings suggest that while humpback whales detected and responded to pinger signals through reduced surface time, they maintained their movement patterns. The study provides insights for developing entanglement mitigation strategies in Peru's artisanal fisheries, where gillnet interactions pose sizeable risks to both whales and local fishing communities. Further research is recommended to more accurately assess its effectiveness in reducing interactions between whales and fishing activities while preserving their critical behaviors in reproductive areas.

Galán, A., Guidino, C., Francia-Quiroz, J., Alfaro-Shigueto, J., & Mangel, J. (2025). Evaluating humpback whale (Megaptera novaeangliae) behavioral responses to whale pingers in breeding grounds of northern Peru. Latin American Journal of Aquatic Research, 53(3), 439-449. doi:http://dx.doi.org/10.3856/vol53-issue3-fulltext-3379

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