Rediscovery of Cameroon Dolphin, the Gulf of Guinea Population of Sousa teuszii (Kükenthal, 1892)

Isidore Ayissi,Koen Van Waerebeek,Gabriel Hoinsoudé Segniagbeto

doi:10.1155/2014/819827

Abstract

Since the 1892 discovery of the Atlantic humpback dolphin Sousa teuszii (Delphinidae), a species endemic to coastal western Africa, from a skull collected in Cameroon, not a single record has been documented from the country or neighbouring countries. Increasing concern about the continued existence of the Gulf of Guinea population of S. teuszii or “Cameroon dolphin” prompted an exploratory survey in May 2011. Shore-based effort, on foot (30.52 km; 784 min), yielded no observations. Small boat-based surveys (259.1 km; 1008 min) resulted in a single documented sighting of ca. 10 (8–12) Cameroon dolphins in shallow water off an open sandy shore near Bouandjo in Cameroon's South Region. The combination of a low encounter rate of 3.86 individuals (100 km)−1 suggesting low abundance and evidence of both fisheries-caused mortality and of habitat encroachment raises concerns about the Cameroon dolphin's long-term conservation prospect. Our results add to indications concerning several other S. teuszii populations that the IUCN status designation of the species as “Vulnerable” may understate its threat level.

Highlights

We describe coastal survey effort implemented in Cameroon in an attempt to relocate the “Cameroon dolphin,” that is, the Gulf of Guinea population of the Atlantic humpback dolphin Sousa teuszii (Kukenthal, 1892) [1]
The single sighting translating into a boat-based encounter rate of 0.386 sightings (100 km)−1 or 3.86 individuals (100 km)−1 suggests that the present abundance of S. teuszii in Cameroon may be very low
After almost 120 years without humpback dolphin records in Cameroon, documentation of the unique Bouandjo sighting in 2011 and a single specimen captured at Campo in 2012 evidenced the continuing occurrence of Cameroon dolphins in the country

Summary

Introduction

We describe coastal survey effort implemented in Cameroon in an attempt to relocate the “Cameroon dolphin,” that is, the Gulf of Guinea population of the Atlantic humpback dolphin Sousa teuszii (Kukenthal, 1892) [1]. This population has been “lost” to science since 1892 when German zoologist Willy Kukenthal described the new dolphin species Sotalia teuszii, later reassigned to the genus Sousa. A second specimen was collected in 1925 in Senegal, it remained unrecognised till 1965 [2]. After its discovery, was not reported again from Cameroon between 1892 and 2011, its historical link with the country faded and the species became known as the Atlantic humpback dolphin [6, 8]

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Conclusion