Fish Biodiversity Studies in Some Selected Major Rivers in Oban and Okwangwo Divisions of Cross River National Park, Cross River State, Nigeria.

सार

The Nigeria National Park Service is expected to have on record all the biodiversity resources in each of its Parksincluding aquatic resources particularly fisheries, butavailable literatures showed thatno fish biodiversity study had beendone inside Cross River National Park but outsideits border. This study was conducted to bridge this gap by evaluating species composition, diversity, abundance, distribution of fish species and also evaluate some surface water physico-chemical parameters within the Park.Fish and Surface watersampleswere collected from 10 sampling stations along with five major rivers each in Oban and Okwangwo Divisions. Data were obtained in July - September and in February, March and April of the yearand analyzed using standard methods. A total of 2, 795 fish-catches recorded in Oban (1,684) and Okwangwo (1,111) belonging to 25 families, 48 genera and 114 species.The physico-chemical conditions inthe study stations were within the tolerable ranges for temperature (26-31^OC), Dissolved Oxygen (6.5-9.0 mg L-¹), and pH (6.8-7.5). The abundance indexforBagridae, Characidae, Cyprimidae and Cichlidae were21.57, 19.59, 19.54 and 15.59% respectively. The dominantspecies were Chrysichthys nigrodigitatus, Alestes dentex,Labeo cubie and Oreochromis niloticus. Shannon Diversity Indextest was4.272 and 4.233, Margalef at 14.81 and 15.54, evenness at0.65 and 0.63and Simpson’s Dominanceat 0.98 and 0.98 for Oban and Okwangwo respectively. However,diversity of fishes in Oban division is significantly higher (P 0.05) than in Okwangwo and the Kolmogorov-Smirnov testrevealed significant difference (P 0.05) in the diversity of fishes in the two areas. The rich fish diversity confirms that the Cross River National Park is an important site for the conservation of fish species.