Fish Species Composition and Physico-Chemical Properties of Manjekin Reservoir, Adamawa State, Nigeria

AJAR: http://escipub.com/american-journal-of-agricultural-research/ 1 Yunusa, M. et al, AJAR, 2019; 4:27 AJAR: http://escipub.com/american-journal-of-agricultural-research/ 2 INTRODUCTION Fisheries and aquaculture play an important role in the global food supply, food security and income generation to numerous families. More than 43.5 million people earn their living directly under this sector of the economy and most of them reside in developing countries (FAO, 2006). Fish supply in Africa is in serious short fall (FAO, 2012). Per capita fish consumption in sub-Saharan Africa is the least compared to all other parts of the world (FAO, 2014). Lakes, dams and reservoirs apart from playing the noble role of providing a relatively cheap source of animal protein, it could also provide employment opportunities and to some extent reduce ruralurban drift (FAO, 2014). Other role of lakes, dams and reservoirs is to provide support, protection and nursery to the early life cycle stages of almost all commercially and ecologically important fresh water fish (World Fish Centre, 2004). Unfortunately, economic returns from African fisheries and aquaculture are declining as a result of continual reduction in fish catches, hence, incomes and livelihoods of the small-scale fisher men are grossly affected (FAO 2012). Furthermore, the crude methods of exploitation used by most fisher men due to complete absence of established inland fisheries regulations of small dams and reservoirs in most parts of Africa is fast becoming an obstacles to increased inland fish production (Ita, 1993). The possible solution is perhaps to re-stock with hatchery breed fingerlings and well manage the existing water bodies in order to harvest more fish to meet the increasing demand. Data on fish species composition and physico-chemical properties of the reservoir and other water bodies in the study area is lacking. It is against this background that, this study was designed to investigate fish species composition and physico-chemical properties of the Manjekin reservoir. MATERIALS AND METHODS


INTRODUCTION
Fisheries and aquaculture play an important role in the global food supply, food security and income generation to numerous families. More than 43.5 million people earn their living directly under this sector of the economy and most of them reside in developing countries (FAO, 2006). Fish supply in Africa is in serious short fall (FAO, 2012). Per capita fish consumption in sub-Saharan Africa is the least compared to all other parts of the world (FAO, 2014). Lakes, dams and reservoirs apart from playing the noble role of providing a relatively cheap source of animal protein, it could also provide employment opportunities and to some extent reduce ruralurban drift (FAO, 2014). Other role of lakes, dams and reservoirs is to provide support, protection and nursery to the early life cycle stages of almost all commercially and ecologically important fresh water fish (World Fish Centre, 2004). Unfortunately, economic returns from African fisheries and aquaculture are declining as a result of continual reduction in fish catches, hence, incomes and livelihoods of the small-scale fisher men are grossly affected (FAO 2012).
Furthermore, the crude methods of exploitation used by most fisher men due to complete absence of established inland fisheries regulations of small dams and reservoirs in most parts of Africa is fast becoming an obstacles to increased inland fish production (Ita, 1993). The possible solution is perhaps to re-stock with hatchery breed fingerlings and well manage the existing water bodies in order to harvest more fish to meet the increasing demand. Data on fish species composition and physico-chemical properties of the reservoir and other water bodies in the study area is lacking. It is against this background that, this study was designed to investigate fish species composition and physico-chemical properties of the Manjekin reservoir.

The Study Area
Adamawa State is located at the area where the River Benue enters Nigeria from Cameroon Republic and is one of the six states in the North-East geopolitical zone of Nigeria. It lays between latitudes 7 0 and 11 0 North of the Equator and between longitudes 11 0 and 14 0 East of the Greenwich Meridian (Mohammed, 1999). It shares an international boundary with the Republic of Cameroon to the East and interstate boundaries with Borno to the North, Gombe to the North-West and Taraba to the South-West (Adebayo, 1999; ASMLS, 2010a), as shown in Figure Ia. According to Adebayo and Tukur (1997) (FAO, 1996).
The soils are a function of the underlying rocks, the seasonality of rainfall and the nature of the wood-land vegetation of the zone. The soils are derived from the basement complex, granite and gnesis that form the ranges of mountains. The mineral resources found in the state include iron, lead, zinc and limestone (Adebayo & Tukur, 1997).
The common relief features in the state are the Rivers Benue, Gongola, Yadzaram and Kiri Dam, Adamawa and Mandara mountains and Koma hills. The state has minimum and maximum rainfall of 750 and 1050 mm per annum and an average minimum and maximum temperature of 15 0 C and 32 0 C, respectively. The relative humidity ranges between 20 and 30% with four distinct seasons that include early dry season (EDS, October -December); late dry season (LDS, January -March); early rainy season, (ERS, April -June) and late rainy season (LRS, July -September), according to Adebayo (1999). The vegetation type is best referred to as guinea savannah (Areola, 1983;Adebayo & Tukur, 1997). The vegetation is made up of mainly grasses, aquatic weeds along river valleys and dry land weeds inter-spersed with shrubs and woody plants. Plant heights ranges from few centimeters (Short grasses) to about one meter tall (tall grasses), which form the bulk of animal feeds.
Cash crops grown in the state include cotton and groundnuts, sugarcane, cowpea, benniseed, bambara nuts and tiger nuts, while food crops include maize, yam, cassava, sweet potatoes, guinea corn, millet and rice. The communities living on the banks of rivers engage in fishing, while the Fulani and other tribes who are not resident close to rivers are pastoralists who rear livestock such as cattle, sheep, goats, donkeys, few camels, horses and poultry for subsistence (Adebayo & Tukur, 1997;Adebayo, 1999).

The Study Site
The study was carried out at Manjekin reservoir, which is located 5km along Salma Maiha road, Maiha Local Government Area of Adamawa State. The site lies roughly between latitude 13 0 -29 0 E and longitude 90 0 -100 0 N. The location has a tropical climate and savannah type of vegetation which is marked by distinct dry and rainy season. It has an average rainfall of 125-150cm and the mean temperature ranges 24 0 C-27 0 C.
The soil is generally sandy-loam with clay in Fadama areas. The common arable crops grown in the zone include Maize, Sorghum, Millet, rice, cotton, groundnut, root and tree crops. The common livestock species include cattle, donkeys, horses, camels, sheep, goat, poultry and Fish. Maiha region is bordered in the North by Mubi South LGA, in the West by Hong LGA, in the South by Song LGA and in the South-East by the Republic of Cameroon as seen in Figure IIb           for identification as described by Raji and Olaosebikan (2004). The meristic and the morphometric features of fish species caught were also determined following the method described by Thalwar and Jhingran (1991) and Olaosebikan and Raji (1998). Water samples were collected in triplicate and parameters determined include: water conductivity, P H , salinity, ammonia, hydrogen ion concentration (PH), biochemical oxygen demand (BOD), temperature, transparency, dissolved oxygen, total dissolved solid and phosphate as described by Offem et al. (2011).

Data Analysis
All the data generated were subjected to Analysis of Variance (ANOVA) to test level of significant (P>0-0.5) among sampling stations and monthly means. The (Duncan, 2006) multiple range test were employed to separate the means.

Fish Catch
The results of the survey showed that, 13 fish species belonging to nine families were common in the reservoir. Two families namely Characidae and Claridae constituted the dominant fish families in the reservoir. Characidae constituted 34.42% (187 species) to the total number of species, followed by Claridae with 8.08% (34 species), Centropomidae 7.84% (33 species), Mormyridae 7.36% (31 species) and Bargridae 6.89% (29 species). The remaining species in that order are caracidae, cyprinidae and schilbeidae with 6.41, 4.75 and 4.51% respectively as shown in Table 1.
The results agree with Welman (1948) who reported similar findings of 181 species of fish found in Nigeria inland waters with Kaduna and Sokoto-Rima Rivers having 28 and 22 species respectively while Cross River, Ogun, and Osun Rivers having 39, 23, and 23 fish species respectively. Similarly, Ita (1993) also reported that an estimate of 230 species of fish have been recorded from the Nigerian rivers. The results also corroborate that of Boulenger (1916) who reported 976 species of African freshwater fishes belonging to 185 genera and 43 families.
The meristic features and the morphometric data of two randomly selected fish samples per species were taken and these were presented in Tables 7 and 8. They were considered to be important characters on which species identification are based. In Table 7, numerals represent the number of fin rays present on individual species, while roman figures represent the number of spines present on the fins of respective species indicated. These species have spines on their fins while the other species are spineless. The catch composition shows that Characidae and Clariidae families were the most dominant in the reservoir.
However, the results of this study with respect to catch composition disagreed with other studies conducted on some lakes in Nigeria. Analysis of catch in a study in IITA Lake, Ibadan revealed that O. niloticus and S. galilaeus were the most dominant. Similarly, studies conducted on lakes Kanji and Tatabu, both in Niger State, the cichlid species were found to be the most dominant (Fapohunda and Godstate, 2006).
The variation in this study could be due to the fact that, many carnivorous fish species were in abundance in the reservoir, which feed on the cichlids thereby reducing their population. S. galilaeus was the fourth most abundant specie in the reservoir at the time of the survey. In addition to the fish species found in the reservoir, are some other forms of aquatic fauna. Crabs were found in large quantity as well as snails. This confirmed that, natural aquatic environment inhabits variety of aquatic lives. Similarly, the results of the meristic features also support that of Gregory et al. (2009) who reported similar findings in the south eastern Nigeria. However, the results of surface water temperature had relative fluctuations, with a fairly consistent thermal regime of about 28.60 oC and the pH ranges between 6.5 and 7. But this also fell within the recommended value that supports aquatic life including fishes (Fapohunda and Godstate, 2006).

Water Parameters
The station and monthly values of the water conductivity, pH, temperature, dissolved oxygen, biochemical oxygen demand, ammonia and phosphate concentration of Manjekin reservoir are shown in the Tables  The results of dissolved oxygen content of the reservoir is within the recommended values for fish production as also reported by Olabaniya and Owoyemi (2006), that the level of dissolved oxygen should not be less than 4ppm especially for freshwater fish culture in the tropics. The results show high phosphate values which could be attributed to the large volume of the surface run-off entering the reservoir. In addition, increase in the use of herbicides, pesticides and domestic waste discharge also contributed to high level of phosphate in the reservoir. By reducing phosphate inputs in to the water bodies for instance, through proper effluent/waste treatment, the number of years required to saturate the reservoir soil with phosphate can be extended.
Fish and other aquatic organisms respond differently to varying water quality. Therefore, regular determination of water quality parameters is very important in any reservoir use for both fish production and domestic water supply. The biochemical oxygen demand content of the reservoir is also within the recommended value for fish production which corroborates the report of Vivien et al., (1986).

CONCLUSION AND RECOMMENDATIONS
The results obtained showed variations in fish species in the study area with characidae being the most dominant fish species in the reservoir. The meristic features and the morphometric data of the fish were considered important characteristics on which species identification are based.
Water quality parameters also showed variations though not outside the recommended reference values for fish production in the tropical environment. It is, therefore, concluded that despite the contamination of the reservoir with many effluents, the physico-chemical characteristics of the water is within the permissible range that could support aquatic life including fish.
It is recommended that, there is the need to evolve strong strategies that could allow effective utilization and management of the reservoir for optimum fish production. These strategies among others may include introduction of other culturable freshwater fish species into the reservoir. However, further assessment of the fish stock may be carried out to further determine any species that may have not been discovered during this study. Considering the results of the physico-chemical water parameters, remediation activities should focus on the main factors such as agrochemicals to reduce their possible effect on the level of pollution.