Seasonal Abundance and Species Composition of Cetacean Caught as By-Catch by Artisanal Driftnet Off the Niger Delta Nigeria

Abstract

A total of 315 dolphins were captured as by-catch, during the 575 fishing trips between 2017 and 2018, in two-landing sites (Imbikiri, Bayelsa State and Finima River State) offshore the Niger Delta Nigeria. The catches which consisted of 6 different species of cetacean , the short-beaked common dolphin ( Delphinus delphis ), the Risso’s dolphin ( Grampus griseus ), the Atlantic bottlenose dolphin ( Tursiops truncatus ), the Atlantic spotted dolphin ( Stenella frontalis ), Fraser’s dolphin ( Lagenodelphis hosei ). and the Long beak dolphin ( Delphinus Capensis ). The rainy season (April to August) recorded higher Cetacean catches than during the dry season (January, February, March, October, November and December). The short beaked dolphin ( Delphinus delphis), was the most abundant (over 56%) during dry and wet seasons while the least abundant was Risso dolphin ( Grampus griseus ) about 6% during the dry and wet seasons. The variable seasonal abundance and species composition of cetacean observed in this study could provide benchmarks for the sustainability of cetacean species abundance and variability in the Niger Delta and more so in the Gulf of Guinea.