Title: Assessment of dolphin bycatch in artisanal drift gillnet fisheries off the Niger Delta, Nigeria.

This work provides the first data on landed bycatch of dolphin in the Niger Delta Nigeria from artisanal drift net longline and dug out Ghana canoes. The project originates from a survey on dolphin bycatch in artisanal fisheries in Lagos, Ondo, Bayelas, River and Akwa Ibom states. From these, two states and eight captains were selected in the two communities responsible for 50-75% of dolphin catches. A total of 315 dolphins were captured, during the 575 fishing trips. This was recorded from January 2017 to 2018, at the two-landing sites at Imbikiri, Bayelsa State and Finima, River State. The drift net longlines caught 26 different species, with a total of 38,037 individuals or more. Mitochondrial DNA (mtDNA) of 20 samples was analysed for species identification to ascertain the diversity of the dolphin bycatch species found in the Niger Delta of Nigeria. Short-beaked common dolphin represented 60% of the DNA samples. Fraser’s dolphin represented 20% of the DNA samples. The Atlantic spotted dolphin represented and Risso’s dolphin each accounted for 10% of the DNA samples. Of the 315 dolphins that were photo identified, the Atlantic spotted dolphin represented 57%, the short-beaked common dolphin 43%, the common bottlenose dolphin 10%, and the Fraser’s dolphin 8%. Unidentified dolphins represented 6% of the catches. Comparing the 20 samples analysed out of 315 photos identified, we determined that morphological identification of dolphin species was not accurate. The average number of dolphins per set of nets in each month for two years, per captain, July, August 2017 the highest catch of dolphin 51 and 30 on average per set is (0.6 and 0.4), with no catch of dolphin in September and October. Likewise, no catch was observed in September and October 2018. The maximum catch was July, March 27 and 20 giving the average (0.3 and 0.3). The total set of nets was 1,518 and the total bycatch of dolphin is 315, for the average of the two years, average of 0.20. This study has shown the amount and species composition of dolphin bycatch in the drift net longline fishery in the Niger Delta. It also provides information on the value of this fishery and will enable policy makers and regulators together with other stake holders, such as International NGOs to find way to tackle this problem.