Flukes of resilience: new sightings of Atlantic humpback dolphin Sousa teuszii (Kükenthal, 1892), but bycaught bottlenose dolphins Tursiops truncatus (Montagu, 1821) in Benin

Koen Van Waerebeek, Sévérin Tchibozo, Hong-Yu Lai, Zacharie Sohou, Josea Dossou-Bodjrenou

The updated number of confirmed Atlantic humpback dolphin Sousa teuszii case records for Benin’s coast (period 2013-2025) amounts to six, including five sightings and one live-stranding. If no re-sightings occurred, maximally 22 individuals were involved. However, the two 2025 sightings may have been the same pod. Group size was small (mean= 4.57; SD= 2.37; median= 5; range= 1–7; n= 6) compared to other monitored S. teuszii populations (Guinea, Senegal). The combination of scientific shore-based visual survey effort with incidentally recorded observations is starting to yield useful information. However, citizen reports must be carefully verified. The low cost of shore-based survey effort, compared to cost-intensive boat-based surveys, besides problematic logistics associated with the use of local canoes, represents a practical alternative in a resource-poor Global South reality. Implementation in other range states is greatly recommended.
Unexpectedly, the Cameroon dolphin population of S. teuszii in the Bight of Benin is showing signs of resilience in the face of anthropogenic threats. However, long-term sustainability is in question, whether the evidently small population will be able to cope with mounting fisheries pressure and potential hidden directed takes. Concern for the status of coastal common bottlenose dolphin Tursiops truncatus in Benin is underscored. No free-ranging individuals were observed nearshore in 25 yrs, while at least two, and possibly three, individuals were registered killed in small-scale fisheries since 2023. Population structure, whether offshore or inshore morphs are involved, remains unstudied. Limiting fishing effort, especially beach-seining in suspected primary habitats and in Benin’s two existing MPAs (Bouche du Roy and Donaten), could positively support conservation. Gentrification of beach front areas around Cotonou, which currently promotes low-impact beach tourism while locally reducing artisanal fisheries operations, could help provide a safer nearshore environment for coastal dolphins.