107 Copyright © 2020, Indonesian Fisheries Research Journal (IFRJ) ___________________ correspondence author: e-mail: olaniyi.olopade@uniport.edu.ng DOI: http://dx.doi.org/10.15578/ifrj.26.2.2020.107-117 Available online at: http://ejournal-balitbang.kkp.go.id/index.php/ifrj e-mail:ifrj.puslitbangkan@gmail.com INDONESIAN FISHERIES RESEARCH JOURNAL Volume 26 Nomor 2 December 2020 p-ISSN: 0853-8980 e-ISSN: 2502-6569 Accreditation Number RISTEK-BRIN: 85/M/KPT/2020 Catchability …… of Fish Species Captured by Gill Net in New Calabar River, Nigeria (Olopade, O. A., et al) CATCHABILITY AND DIVERSITY OF FISH SPECIES CAPTURED BY GILL NET IN NEW CALABAR RIVER, NIGERIA Olaniyi Alaba Olopade *1 , Henry Eyina Dienye 1 , Ogheneforon Oderhohwo 1 and Nathanael Akinsafe Bamidele 2 1 Department of Fisheries, Faculty of Agriculture, University of Port Harcourt, Nigeria 2 Institute of Food Security, Environmental Resources Agricultural Research Federal University of Agriculture, Abeokuta, Nigeria Received; January 10-2020 Received in revised from July 23-2020; Accepted July 27-2020 ABSTRACT The aim of this study was to analyze fish species caught by gill nets and fish diversity of the New Calabar River. Three sampling stations were set based on the coverage situation of the river and ichthyofauna associated with gill nets were sampled twice monthly from February to July 2018. A total of 3,251 fish specimens, representing 11 orders, 15 families, and 28 species, were captured. The order Perciformes was identified as the most abundant representing five families while the remaining had one family each. The fish family Cichlidae was the most represented with seven species, and other notable families were Alestidae, Clupeidae, and Mugilidae, representing three species each. Prominent among the fish caught monthly included Liza falcipinnis, Mugil cephalus, Sarotherodon melanotheron, Sarotherodon galilaeus, Coptodon guineensis, and Sardinella maderensis. The mean catch per unit effort (CpUE) ranged from 3.15±0.2 to 4.85±0.2 kg unit -1 day -1 . Results of diversity indices revealed that Shannon-Wiener index values varied between 2.64 and 2.82, Simpson diversity ranged from 0.07 to 0.10, and Pielou’s evenness index values ranged from 0.85 to 0.95. The values obtained in this study showed that the status of fish diversity in New Calabar River was stable. Keywords: Ichthyofauna; gill nets; diversity indices; catch per unit effort; New Calabar River INTRODUCTION The fisheries sector has a vital role in the Nigerian economy, even though presently its contributions to Gross National Product (GNP) is generally very low, for example it contributed only 0.5 percent of national GDP (FAO, 2007). The annual fish production in 2015 was estimated at 1,027,000 tonnes, including marine catches, inland waters catches, and aquaculture contributed 36%, 33%, and 31%, respectively (FAO, 2007). The Nigerian fisheries sector also plays major roles as the sources of employment and food security. The country has both marine and inland waters that are rich in fisheries resources. The inland waters are very rich in fish biodiversity with about 338 freshwater fish species as recorded in Fishbase (Froese & Pauly, 2010). The inland fisheries are exploited by small-scale fishers with simple traditional and modern fishing crafts and gears. The status of the inland capture fisheries in Nigeria is largely a result of a failure of the present process of fisheries governance which poses significant threats to the management of fisheries resources (Olopade et al., 2017a). This has brought about changes in species composition, size structure, and genetic structure of stock that have implications for the fisheries. Parameters such as species composition, species richness, and abundance have been used in many studies to describe and assess fish community and diversity (Smith, 1978). One of the major ways of increasing yield from capture fisheries on a sustainable basis is by better management through enforceability of regulations. Fishing effort limitations have successfully proved in restoring abundance levels in the multi-species fisheries (Garcia & Demetropoulos, 1986). The way to place embargo on the unsustainable fishing gear is to have a good knowledge of fishing gear construction, operation, and common target species (Olopade et al., 2017b). There are a wide range of gears in use depending on the species targeted, experiences, and skills of the fishers. Gill nets are common fishing gear used by small-scale fisheries in Nigerian inland waters (Solarin et al., 2003). This gear is commonly used as it is an efficient fishing gear for pelagic fish species, offers affordable price, and requires low operating cost (Clarke & King, 1986).