Ichthyo-faunal composition and diversity of middle reaches of Sombreiro River, Rivers State, Nigeria

An investigation was conducted to determine the fish species/family composition and diversity of the middle reaches of Sombreiro River, Rivers State, Nigeria. A twenty-four week survey was conducted. Fish samples randomly collected twice weekly, from three sample sites along the river. Fish composition and diversity were assessed using standard methods. Results revealed a composition of 31 species in 20 families from 40,509 fish catch. Diversity revealed the family Carangidae exhibited the highest diversity (12.9%, four species) and outstandingly thirteen families (Scombridae and others) exhibited the lowest diversities (3.23% -one species each). Statistical analysis revealed significant difference in species diversity between the experimental weeks and the highest diversity in week 1 (2.7996±0.1), and significantly different from other weeks (P <0.05). Thus, the Sombreiro River has a high composition of fish species/families, with a high diversity of fish families. However, majority of the families have very low species diversity, and diversity varied significantly within the period. These variations in diversity are most likely as a result of fishing pressure and environmental pollution from human activities. It is recommended that further research be carried out to elucidate this low diversity issue in order to proffer management/conservation strategies if and when necessary.Keywords: Fish, species composition, species diversity, Sombreiro Rive