ASSESSMENT OF AGRICULTURAL RUNOFF (OCCURRENCE OF CHLORPYRIFOS) ON Clarias gariepinus IN KOMADUGU YOBE RIVER, NIGERIA.

This study assessed the occurrence and spatial variation of Chlorpyrifos contamination in water and Clarias gariepinus along three sampling locations (Usur, Mashayar-Bade, and Zango) of Komadugu Yobe River in Gashua. The research was prompted by the increasing agricultural runoff in the region and growing concerns over declining fish stocks and public health risks. Water and fish samples were analyzed using High-Performance Liquid Chromatography (HPLC) at the Yobe State University laboratory following standard procedures. The results revealed that all sampling sites contained detectable concentrations of Chlorpyrifos in both water and fish tissues. Water samples recorded concentrations ranging from 121.70 to 136.20 µg/L, while fish tissues contained 61.06 to 84.26 µg/kg. These values significantly exceeded the WHO permissible limits of 1 µg/L for water and 10 µg/kg for fish, indicating severe contamination. A significant difference exists between sampling sites (p ˂ 0.05). Highest water contamination occurred in Usur and Mashayar-Bade, whilst highest fish contamination occurred in Zango. The presence of Chlorpyrifos in water and edible fish tissues raises serious ecological and public health concerns. The study recommends stricter pesticide regulation, improved farming practices, and continuous environmental monitoring.