Records of Fraser\'s dolphin Lagenodelphis hosei Fraser 1956 from the Gulf of Guinea and Angola

Abstract

Although Fraser's dolphins Lagenodelphis hosei are considered to inhabit deep tropical waters worldwide, their occurrence in the tropical eastern Atlantic Ocean from the Gulf of Guinea southwards to Angola is only represented by two specimen records from Ghana. During cetacean surveys carried out concurrently with geophysical seismic surveys off Nigeria in 2004 and off Angola in 2007 and 2008, a pod of 150 probable Fraser's dolphins was videoed 130 km south of Nigeria and schools of 120 and 60 animals were photographed 170 km and 140 km respectively off the coast of Angola. All records occurred in deep water (>1 000 m). Cetacean bycatch was monitored at six artisanal Ghanaian fishing ports between 1998 and 2000. Four Fraser's dolphin specimens comprising one adult, one juvenile and two calves were photographed at two ports. Drift gillnets were identified as the probable cause of mortality for at least two specimens. Two sightings of Fraser's dolphins off Angola provide the first at-sea records for the Gulf of Guinea region and, together with bycaught specimens, confirm new southern and eastern distribution limits for the species within the Atlantic Ocean. Further information is required on the status of Fraser's dolphins and the potential impact of fisheries bycatch on this species within the Gulf of Guinea.

Keywords: Angola; Fraser's dolphin; Ghana; Lagenodelphis hosei; Nigeria

African Journal of Marine Science 2008, 30(2): 241–246