Stock Assessment of Oreochromis niloticus and Clarias gariepinus from River Hadejia, Jigawa State

摘要

The study aimed at assessing the fisheries potentials of Hadejia River. Data on the captured of the fishes were collected over a period of five weeks using gill nets of various mesh sizes, with the assistance of the fishermen. A total of twenty five different fish species belonging to 14 families were identified. The family Cichlidae dominated the fish fauna with 54%. The families Claridae constituted 20%, while the others were the least with only 26%. The fish caught per day was about 1,308 from six landing sites, with 14 fishermen operating averagely from each site. The study also revealed that the river was partially over-fished. Fish samples were collected weekly for five weeks period, from the sampling station using fishing gears of various mesh sizes (3, 4, 5, 6, 7, 8 centimeters), with the assistance of the fishermen. Fish samples were identify and weighed fresh, at landing sites to the nearest gram. Standard and total lengths were taken using a measuring board and also the diversity of fish recorded in this study indicates that the River has relatively high fish diversity. The number and biomass of fish caught during the study is considered high, when compared to other Nigerian Rivers. The sizes of fish recorded also indicate that the River is been over fished. It is therefore recommended that the government and other donor agencies should provide support for research and studies to collect analyze and synthesize information and harmonize existing policies, edicts and byelaws that conform to Integrated Water Resources Management (IWRM) principles, including establishing criteria for water use. The artisanal fishermen should also be encouraged to maintain the use of mesh size regulation.