Stomach Content Analysis and Concentrations of Chemical Pollutants in the Clymene Dolphin (Stenella Clymene, Gray 1846) from the Coastal Waters of Ghana

Abstract

Stomach content analysis constitutes an important component of fisheries management, providing insight into fish feeding patterns and quantitative assessment of food habits. Thus, a study aimed at obtaining dietary information from stomach contents analysis of the most common by-caught dolphin species, Stenella clymene, beached from the coastal waters of Ghana, along the Gulf of Guinea was undertaken. The stomachs of 39 by-caught clymene dolphins landed at three fisheries landing beaches along the Ghanaian coast, were analyzed. A further study correlating the chemical contaminant load in tissues of Clymene dolphins to that of their preferred prey was undertaken. The stomach contents were generally composed of digested items. Fish, cephalopods and crustaceans were identified and represented a diversity of 12 species. On taxa level, fish was the most frequent (69%) and numerically the most important prey (46.57) followed by cephalopods (3.05) with crustaceans being present in trace amounts (1.55). However, both cephalopods and fish represented a more balanced share of the diet in biomass (45% and 51%) respectively. Thus, clymene dolphins off the coastal waters of Ghana appear to rely principally on both fish and cephalopods for food. Parasites also dominated the gut contents in relative abundance (48.83%). Prey items accumulated chemical contaminants at relatively the same concentrations (50%) as the blubber, liver and muscle of the clymene dolphins, confirming that food is the main source of exposure to contaminant load for marine mammals. With regards to quantitative analysis of prey species of cetaceans, this study of diet in clymene dolphins is the first recorded in this area.