Analysis of Potential Effects of the Idoho-QIT Oil Spill on River-Estuarine Fisheries in Nigeria

The rupture of a 24-inch pipeline offshore of the Mobil Qua Iboe Terminal (QIT) on 12 January 1998 resulted in the release of approximately 40,000 bbls of light Nigerian crude oil. Most of the oil was dispersed by natural process and applied dispersants (299 bbls). Contact with the shoreline and estuaries of Nigeria was fortunately very limited. To determine the possible effects of the spill, a number of short and long term scientific, health related and socio-economic studies were undertaken. This report focuses on the evaluation of artisanal river-mouth fisheries using pre-spill data, data obtained during the spill and then 9-12 months later. For this analysis we reviewed catch rates, fisheries composition and fish-tissue chemistry. Catch rates in the spill zone and control areas were within the historical range of expected rainy season values. No significant differences were found in species composition values for this study and those expected for the rainy season. Regarding fisheries composition, an extensive sampling program found a rich and diverse fish population in both the spill zone and control areas, indicating no detectable effects of the spill. The analysis of metals in fish tissue found that concentrations of Cu, Pb, Cd, Zn, Hg, Ni and V below the limits recommended by FAO (1983). None of these metals are indicative of petroleum in fish tissues. Total lipids in up to 26 fish species sampled were well below the 25-ppm GESAMP standard and showed no increase in spill zone samples as compared with control samples.