Predicting interactions of sperm and killer whales with longline fisheries in the Southern Ocean : a spatiotemporal modelling approach for conflict mitigation in the Crozet and Kerguelen Archipelagos

2026

Article référencé dans le Web of Science WOS:001729810800003

Mollier Margaux, Guinet C., Péron C., Massiot-Granier F., Gasco N., Chazeau C., Derville Solène, Wilson E., Corney S., Robert V., Mazé-Lambrechts C., Tixier Paul

Biodiversity and Conservation, 2026, 35 (4), p. 118 [34 p.] ISSN 0960-3115

Toothed whale depredation of fish caught on fishing gear raises socioeconomic and conservation concerns. It can lead to substantial losses for fishers and impacts on depredating species, but effective solutions remain limited. In this study, we implemented a spatiotemporal modelling approach to predict depredation occurrence and intensity, based on natural distribution of predators involved and fishing practices, to support mitigation strategies. Using 11 years of data from the Patagonian toothfish (Dissostichus eleginoides) longline fisheries operating around Crozet and Kerguelen islands, and generalized additive models (GAMs), we assessed the environmental and operational factors influencing catch depredation by sperm whales (Physeter macrocephalus) and two killer whale (Orcinus orca) ecotypes: Crozet and Type-D. All models indicated strong seasonal patterns in depredation, particularly for sperm whales, whose presence decreased in winter and was primarily driven by high abundance of large toothfish. Crozet-type killer whales were associated with shallow, low-slope areas near the continental shelf, whereas Type-D killer whales were more frequent in deeper waters and near seamounts, suggesting a more offshore distribution. Longer soak times and line lengths increased killer whale depredation, likely by increasing catch accessibility. Crucially, vessels that moved more than 70 km after a depredation event significantly reduced the likelihood of further interactions with both predator species. The results indicate spatial overlap between fishing grounds and whale-preferred habitats, but highlight clear depredation hotspots within that overlap. Avoiding these areas provides fishers and managers with easy-to-implement, cost-effective options for mitigating depredation while maintaining the socio-economic viability of the activity.

Sciences fondamentales / Techniques d'analyse et de recherche [020] ; Sciences du milieu [021] ; Ressources halieutiques [040] ; Etudes, transformation, conservation du milieu naturel [082]

OCEAN ANTARCTIQUE ; CROZET ; KERGUELEN

Fonds IRD [F B010096932]

fdi:010096932