Seventh successful field survey in the Saloum Delta Senegal!

Seventh successful field survey in the Saloum Delta Senegal!

From May 4th to the 21st, CCAHD partner, the African Aquatic Conservation Fund (AACF) hosted the seventh successful boat-based field survey in the Saloum Delta, Senegal. Surveys have been conducted annually since the joint AACF-CCAHD project began in July 2021, with two surveys conducted in February and October, 2025. 

This year’s survey included 148 hours of time on the boat, covering a total distance of 1,941 kms, of which 92 hours and 1,078 kms were spent ‘on effort’ searching for dolphins.  In total, the team documented 36 sightings of Atlantic humpback dolphins, of which 33 were made ‘on effort’, and 3 were made while speeding to and from starting points of transects – one of the highest encounter rates documented on the Saloum surveys to date.  Over 32,000 photos were taken, and a high proportion of observed dolphin groups included calves – a sign that the population in the Saloum is reproducing.  

This year the team was thrilled to welcome Leveto Mendez from Guinea-Bissau’s Instituto da Biodiversidade e das Áreas Protegidas (IBAP – Institute of Biodiversity and Protected Areas), who joined the fieldwork from May 12-21.  As the Adjunct Director of a Marine Protected Area in the Bijagos Archipelago, which is thought to also host a significant population of Atlantic humpback dolphins, Leveto was able to get hands-on experience with the CCAHD boat-based survey and photo-identification protocols, as well as exchange experience and expertise with the AACF-CCAHD team and managers and staff from MPAs in the Saloum Delta. The AACF team always invites participation from MPA staff in their surveys, and this year two MPA Directors and one staff member participated, providing an excellent opportunity for exchange.

In addition to documenting the dolphins’ distribution and building on the long-term photo-identification catalogue, the team took water parameter measurements throughout the study area, and recorded dolphin clicks and vocalizations during encounters, with an aim towards building up a catalogue of ‘voucher recordings’ that can be used to develop ‘classifiers’ that will allow AI to detect and classify different marine mammal vocalisations recorded by remote/anchored recording devices (see this project description for more detail).

Overall, this year’s survey was a huge success, and the AACF-CCAHD team are enormously grateful to the donors and collaborators who made this work possible, including Fundacion Loro Parque and the HX Foundation who provided funding, and the University of St. Andrews that provided a hydrophone and recording equipment as well as technical support for the acoustic work.

The team also documented active fishing effort, which will allow modelling of bycatch risk. Although many vessels loaded with nets were observed in transit during the surveys, these nets were never observed in the inshore waters of the delta where dolphin observations were recorded.  Most gillnet fishing seems to take place further offshore, while traps and occasional beach seining were more frequently observed in the Delta.