In 2022–2024, we visually surveyed, both slow walking and stationary, the coastal areas near 50 fish landing sites along Benin’s shoreline, undertook a few experimental sorties in small canoe and interviewed 251 locals, mostly artisanal fishermen, seeking information on cetaceans. A total of 120 km was covered for an effective search duration of 83 hrs. The study was especially focused on two coastal cetacean species, the Atlantic humpback dolphin Sousa teuszii (Kükenthal) and the (inshore ecotype) common bottlenose dolphin Tursiops truncatus (Montagu). Although neither species was directly observed during dedicated field research, two sightings of S. teuszii and an unusual entanglement in large plastic debris were reported by members of the public. Furthermore, a new lethal bycatch was photographed in SE Nigeria by a Beninese fisher. Strandings of 10 large whales were documented in the period 2009–2023, including humpback whales Megaptera novaeangliae (Borowski) (n= 5), sperm whales Physeter macrocephalus Linnaeus (n= 3) and unidentified species (n= 2). Eight sightings of live humpback whales, one with a small calf, were reported in July–October 2022. Video recorded by a fisherman provided the first likely evidence of melon-headed whale Peponocephala electra (Gray) for Benin. A live-stranded Gray’s pantropical spotted dolphin Stenella a. attenuata (Gray) was also a first record. The beach and small-boat surveys, as well as fishermen’s perceptions indicate that nearshore occurrence of dolphins in Benin varies from ‘occasional’ to ‘rare’. Entanglement in fishing gear, particularly in ubiquitous beach seines and set and drift gillnets appear to be the main cause of mortality of inshore dolphins, while large plastic debris is newly identified as potentially lethal. The conservation status of inshore T. truncatus, not encountered in Benin for 24 years, may be as dire as that of S. teuszii. Citizen science is playing an increasingly important role in marine mammal information collection in the Gulf of Guinea and western Africa.
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