An assessment of composition and diversity of fin fish in the upper course of Otamiri river, Imo State, South-Eastern Nigeria (original) (raw)
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Benthic Fish Fauna and Physicochemical Parameters of Otamiri River, Imo State, Nigeria
The study on the fish fauna and physicochemical characteristics of Otamiri River was carried out for six months (June to August and October to December 2015). Samples were collected monthly from three sampling stations along the river. Eckman grab, scoop net, line and hook, cast net, traps and dugout canoe were used to collect the fish samples. Samples were collected from three stations, station 1 (dumpsite in the river), station 2 (dredging section) and station 3 (vegetable farming section). A total of 129 fishes belonging to 5 species, Synodontis budgetti, highest species composition (n=4) and fish abundance, 108 (83.7%), while station 1 had the least species composition (n=2) and the least fish abundance, 10 (7.8%). Temperature variation from June to December was wide at station 1 (25-28ºC), unlike station 2 (27-28ºC) and station 3 (28-29ºC). A similar trend was replicated by Dissolved Oxygen (DO). Significant correlation of S. budgetti abundance and temperature (r=0.696, p<0.05), depth of river (r=-0.615, p<0.01) and turbidity (r=0.595, p<0.01) was observed. Similarly, a significant correlation of C. nigrodigitatus abundance and temperature (r=0.473, p<0.05), C. gariepinus abundance and depth (r=-0.481, p<0.05), P. afer abundance and temperature (r=0.530, p<0.05) was observed. Fish species abundance and composition in Otamiri River was significantly affected by anthropogenic activities.
Freshwater Fish Diversity of a Tropical Rainforest River in Southeast Nigeria
Fish samples were collected at three stations twice per month from January to December 2013 with the help of local fishers using hook and line, gill net, cast net, bagnet and local traps for ecological studies of important fish species and resource management issues of Oramiri-Ukwa River, southeast Nigeria. An estimate of 25 fish species, 15 genera, 21 families and six orders were obtained. Ecological indices indicate a polydiverse community and no single species exhibited true dominance (≥ 50%). Paired group cluster analysis establishes Tilapia zilli and Hemichromis fasciatus as the focal species and identifies the associated species combinations that characterize spatial variability and account for the biodiversity resources and structure of the artisanal fishery. Other important species include Tilapia mariae>Synodontis nigrita while Polypterus senegalus>Parachanna africana and Shilbe mystus were the least in number. Monospecific and rare fish species of ecological and conservation significance identified include Ctenopoma kingsleyae, Clarias gariepinus as well as Erpetoichthys calabaricus and Pantodon buchholzi derived from interconnections with other African rivers. This study presents lower fish diversity compared to earlier reports. This difference may be linked to increased human activities and fluctuating biotic and abiotic factors of the ecosystem, among others. 1. Introduction Ichthyodiversity refers to variety of fish species depending on the context and scale; it could refer to alleles or genotypes within piscian population, to species or life forms across aqua regimes (Burton et al., 1992). Fishes are the important elements in the economy of many nations as they have been a stable item in the diet of many people. According to Ehrlich & Willson, (1991) biodiversity is essential for stabilization of ecosystem, protection of overall environmental quality for understanding intrinsic worth of all species on the earth. Freshwater biodiversity has declined faster than either terrestrial or marine biodiversity over the past 30 years (Jenkins, 2003). Biodiversity is often ambiguously misused or overused to describe population dynamics of a location or community (Lawson & Moduke, 2010). Declining river flow rates (discharge) have been a major cause of species loss and are likely to be further reduced by warming temperatures, reduced precipitation and increased water withdrawal for agriculture and other human uses (Plafkin et al., 1989). Future declines can therefore negatively affect freshwater biodiversity. Inland waters and freshwater biodiversity constitute a valuable natural resource, in economic, cultural, aesthetic, scientific and educational terms. The streams and rivers are facing number of environmental problems throughout the world largely associated with anthropogenic activities in their catchment areas (Young et al., 2004). The adverse effects of human activities have resulted in degradation of stream and reverine ecosystem which ultimately alters the structure and function of stream biota. Their conservation and management are critical to the interests of all human, nations and governments. According to Nwafili & Tianxiang (2007), artisanal fishery continues to dominate fisheries, contributing over 85% of total fish production. The inland water and coastal seas are fully exploited and the increase in fishery production is not likely. Nigerian inland water bodies are primarily utilized for fishing by fisher folks. The greater part of inland fisheries is artisanal in nature supplying families with food and income. Artisanal fishing usually is usually not a full-time activity but rather integrated with farming and other activities. The main aim of this study is to provide multi-gear and multi-species ichthyofaunal composition and spatial distribution of the Oramiri-Ukwa River in comparison with others in order to share, update information, and provide data for future analysis. This study also seeks to identify species of ecological significance in the study area and to promote discussions for the management of the fishery to avoid risk of fish stock collapse and loss of invaluable ecosystem goods. 2. Materials and Methods The Study Area was Orammiri-Ukwa River (Fig. 1) located at Azaraegbulu, Emekuku in Owerri North Local Government Area of Imo State, southeast Nigeria at approximately latitude 5 0 30 ′ N and longitude 7 0 19 ′ E. Oramiri-Ukwa is a typical rain forest River. On both sides of the main River channel are large fringes of heavily forested swamps dominated by the raffia palm. The river flows from a highland in Okigwe and joins the Mbaa River to flow through Okahia Ezihe in Isiala Mbano Local Government Area, through Opara-nadim in Mbaise to
Diversity and Distribution of Freshwater Fishes in Oguta Lake, Southeast Nigeria
The ichthyofaunal composition of the largest natural lake in Nigeria-the Oguta Lake, was investigated from January, 2012 to December, 2013. Bimonthly random samples of fish catches of artisanal fishers employing hook and line, gill net, cast net, bagnet and local traps were analysed. A total of 1,989 fishes were sampled comprising 6 orders, 22 genera, and 32 species spread into 18 families. The Perciformes, Cichlidae and Tilapia zill were the most abundant fish order, family and species, respectively. The study reveals that species diversity was highest at station 4 (Osemotor) though no significant spatial differences were detected. The lake is of ecological significance in accommodating some threatened species like Erpetoichthys calabaricus and serving as a source of broodstock of Clarias gariepinus for aquaculture. A seriation analysis of species presence/absence matrix in the lake reveals Tilapia mariae, Synodotis schall, Mormyrus rume, Synodontis nigrita and Petrocephalus banebane are important fish species to ecosystem health of the lake. The fish abundance and diversity values in present study are lower than the findings of previous studies in the same water body, suggesting need for proper and articulated management. 1. Introduction Fisheries resources are on the decline in Nigeria due to over exploitation and inadequate management of inland waters. For sustainability of these resources, an adequate knowledge of species composition, diversity and relative abundance of the fisheries resources of the water bodies must be understood. Increased fishing pressure exerted by artisanal fishermen that are operating in this water body coupled with the downstream migration of fish in search for food, shelter and spawning, industrialization, urbanization and farming activities around the river are factors that contribute variation in fish composition and diversity in Nigeria. External factors affecting populations of freshwater species include; simple habitat loss resulting from withdrawal of water for human use such as irrigation, domestic and industrial use; impact of anthropogenic factors; impoundment, wetland drainage and flood control which cause the load of inorganic and organic pollutants in flowing waters to increase. Available evidence strongly suggests that fish abundance and diversity are in decline at the same time that human population's destructive activities are increasing. The fish supply gap in Nigeria as indicated by Adekoya and Olunuga (1999) is at least 1.0 million metric tons. As a measure to bridge the fish demand gap with its supply, Nigeria resorted to importation of fish thereby causing a considerable drain in the foreign reserve. Despite expenses on fish importation, the gap between supply and fish demand widens the more with population increase. In his contribution, Tobor (1973) advanced effective domestic production rather than fish importation in covering this gap. The contribution of artisanal fisheries is poor due to low output, poor processing mechanism, ineffective distribution and marketing of fishing products, pollution and post-harvest loss. Although freshwater ecosystems such as rivers, lakes and wetlands occupy less than 2% of the earth's total land surface, they provide a wide range of habitats for a significant proportion of the world's plant and animal species. Many are yet to be discovered, but the number of freshwater species worldwide is estimated at between 9,000 and 25,000 (Cosgrove and Rijsberman, 2000). The fish yield of most inland waters in Nigeria are generally on the decline for causes that may range from inadequate management of the fisheries to degradation of water bodies (Odo et al., 2009). Due to a general lack of data, it is difficult to access the status of the inland water biodiversity. Indeed monitoring the status and trends of freshwater biodiversity is essential to quantify impacts of human activities on freshwater systems and to improve freshwater biodiversity conservation. According to Adaka et al. (2014) environmental awareness to educate the fishers and other stakeholders on the danger of extinction of the species and the need for its conservation was necessary. Also future developments on autogenic and anthropogenic threats, and activities and harmful practices which predispose fish species extinction along the floodplain and catchment area of rivers should be subjected to environmental scrutiny to maintain the environmental health and integrity of the ecosystem. Similarly, Ude et al., (2011) stated that detailed knowledge of the function of the river system and the responses of fish species are needed for effective fisheries management planning. The aim of this study therefore is to provide ichthyofaunal composition of Oguta Lake along a spatial gradient to promote discussions for its ecological significance and management of the fishery to
Journal of Agriculture and Social Research, 2016
A twenty two weeks prelimnary study was carried out to assess the Status of the Upper Reaches of the Sombreiro River, one of the most important rivers in River state. A field survey was carried out in three sampling points in the Abua/Odual Local Govt. Area where fish samples were collected from the fishers and the Composition and Abundance assessed over the period using standard methods. Generally, the fish composition comprised of thirty seven (37) species in twenty (20) families from forty two thousand one hundred and twenty seven (42,127) individuals. However, through there was a weekly variation in composition following the seasons of the study from the dry season (weeks 1 – 14, Jan. to April) to the wet season (weeks 15 – 22, May to June). Some species were in the catch mainly in the rainy season ( H. fasciatus ) while others in the dry season ( G. decadactylus , I. africana , L. dentatus ) and some available through the period ( O. mossambicus , T. zilli , and other Cichlid. ...
— Fish constitute more than half of the total number of all the aquatic vertebrates in the world; thus, a study was carried out for six months from January-June, 2016 to investigate the physico-chemical parameters, composition, abundance and diversity of ichthyofauna present in some sections of Omambala, Ezu and Ahommiri Rivers in Anambra state, Nigeria. Water samples were collected for physico-chemical analysis and fish samples were also collected with the assistance of artisanal fishermen using different types of traditional fishing gears namely-gill nets, cast nets, hook and line, local traps (baited) and bag nets to evaluate fish species composition and abundance. The result of the physico-chemical analysis showed uniform values for temperature (25±0.16 o C-30±0.48 o C), dissolved oxygen (3.65±0.78-5.65±0.11mg/l) and biochemical oxygen demand (13±0.03-16±0.08mg/l) which favoured the distribution of fishes present in different sections of the three Rivers. A total catch of 11,031 fishes were recorded from the three Rivers which comprised 11 orders, 29 families, 43 genera and 69 species. Umuoba-Anam section had 9691 catches, Ebenebe section (702) and Awa section (638). Monthly composition showed highest in March (1,909) and June (2,294) for dry and rainy seasons respectively. Seasonal composition showed highest during the rainy season with a total number of 5922 fishes while 5109 fishes was recorded for the dry season. The diversity indices of the three Rivers indicated diverse communities with ten common species variety and Shannon Weiner (H') diversity index of 2.755-3.682. Tilapia zilli (22.2%) was the most common and abundant species followed by Clarias anguillaris (21.4%), Malapterus electricus (18.9%), Heterobranchus bidorsalis (15.4%), Xenomystis nigri (14.6%), Heterotis niloticus (13.0%), Auchenoglanis monkei (11.0%), Tilapia dageti (10.2%), Hepsetus odoe (8.1%) and Bagrus filamentosus (7.2%). The study revealed that taxa richness and species diversity increase with increased water level and uniform physico-chemical changes. Further survey of fish species diversity and abundance should be carried out continuously for a longer period on a larger scale for a thorough assessment of the water bodies and their fishery potentials.
Fish species composition of a tropical lentic freshwater ecosystem (Umudike Water Reservoir, Umuahia, Nigeria) belonging to the National Root Crops Research Institute (NRCRI) was investigated from July 2004 to December 2004. The fishes were sampled twice every week using cast nets, traditional baskets traps (drum type), and hook-and-line of various sizes. A total of 896 fish approximately 500 kilogramme by weight were sampled. The sampled fish species belonged to fifteen (15) families, twenty-four (24) genera and thirty-two (32) species. Family cichlidae topped the list in number and weight with 665 (74.2%) fishes and 400, 900 g (82.8%) respectively; while the families Anabantidae and Hepsetidae had the least number, 7 (0.8%) each; 1,400 g (0.8%) and 1,500 g (0.3%) respectively. There was significant difference among the different species composition. The reservoir, with the fish species composition could be utilized for fisheries.
The fish yields of most Nigeria inland waters are generally on the decline for causes that may range from inadequate management of the fisheries to degradation of the water bodies. Sustainable exploitation requires knowledge of the ichthyofaunal composition in the water bodies. We did a survey of fish species in Anambra river basin for 22 months. Fish samples were collected using four different gears –hook and line of size 13, caste nets, gill nets, and cages of mesh sizes of 50mm, 75mm, and 100mm each. We recorded 52 fish species belonging to 17 families: 171, 236, and 169 individuals at Ogurugu, Otuocha, and Nsugbe stations respectively. Two families, Characidae, 19.5 %, and Mochokidae, 11.8%, constituted the dominant fish families in the river. The dominant fish species were Citherinus citherius, 9.02%, and Alestes nurse, 7.1%. Other fish species with significant abundance were Synodontis clarias 6.9%, Macrolepidotus curvier 5.7%, Labeo coubie 5.4%, Distichodus rostrtus 4.9%, and...