Many aquatic vertebrates other than fish feed on aquatic biota such as plants, aquatic insects, snails and other invertebrates. This group of animals is often related to the various habitat types which include the open water, vegetated shoreline, and benthic region. Within these various habitat types these animals may feed, breed and behave territorially. It is therefore logical to suppose that the presence or absence of non-fish aquatic vertebrates within a given water body would affect the dynamics of the habitat and the fisheries. For example, the faecal droppings of aquatic birds released into the water are either directly eaten as food by omnivorous fish and other aquatic animals, or may serve as fertilizer, stimulating primary productivity because they are rich in organic matter (Adams et.al., 1983). The faecal input to water bodies supporting large animal populations therefore contributes immensely to the complex food web of the aquatic system. In the study of fauna and flora of water bodies in Nigeria, most effort has been directed to the fish fauna, fishery potential and management problems, and strategies for improving inland fisheries, limnological studies on zooplankton and phytoplankton, and studies on the biology and utilization of aquatic macrophytes. There is little information on wetland wildlife, its biodiversity and contribution to the aquatic system. With the change in mandate of the Kainji Lake Research Institute (a multidisciplinary research institute) to a mono-commodity institute (NIFFR) some studies have been initiated on aquatic birds (Okaeme et.al., 1988), and their utilization, and contribution to fisheries (Okaeme et.al., 1989). In order to elucidate the various roles of wetland wildlife and its interrelationships as they affect fisheries production, this paper reviews its role in freshwater systems, and proposes some relevant research areas and strategies in the conservation and management of freshwater fisheries and non-fish resources.
There is an urgent need for such a review as information on wetland wildlife is scanty and its status in terms of population and distribution is unknown. The ever increasing population of the country, urbanization and the development of industry and infrastructure, and increasing rate of pollution of aquatic systems (Oluwande et.al., 1983) make the urgency even more obvious. These changes in habitat and water quality affect the structure and populations of aquatic animals. A review of their current status will allow the development of rational strategies for the sustainable utilization and management of the available wetland wildlife resources.
For the purpose of this discussion wetland wildlife are those vertebrate animals living, breeding and feeding in water, and those closely associated with water bodies due to their feeding, roosting behaviour and other activities associated with the aquatic environment. It includes reptiles, amphibians, mammals, and birds. They have a common feature of being good swimmers, adapted to aquatic life, piscivorous and/or feeding on organisms associated with water.
The status of the wetland wildlife resources of Nigeria is not well known. There is a checklist of aquatic birds of Nigeria (Elgood, 1982) but those of mammals, amphibians and reptiles are only extracts from lists of animals associated with National Parks and reserved areas in Nigeria (Child, 1974; Ayeni et.al., 1983; Ebin, 1983; Anon., 1986). A preliminary checklist is presented as Table 8.
There is only circumstantial evidence that creating dams across rivers in Nigeria has resulted in the loss of some species, such as fish (Lewis, 1974; Welcomme & Henderson, 1976) but this needs yet to be confirmed nationwide. It seems likely that other groups will also have suffered. Droughts often result in loss of fry and fingerlings plus other vertebrates and invertebrates in flooded areas and wetlands (Bukar & Gubio, 1985). Seasonal shoreline exposure of lakes also often results in the stranding of aquatic animals (Bidwell, 1976).
Although increasing numbers of man-made lakes, other reservoirs and fish ponds, may suggest an increase in amphibian populations, studies based on Kainji Lake National Park have generally shown a decline (Ayeni, 1983; Okaeme et.al., 1988) in the numbers of other aquatic animals over the years. Manatees used to have strong populations in the Niger and Oli rivers and below Kainji Lake and in the Upper Benue River (Woods, 1937; Beal, 1939). At present it is increasingly difficult to see crocodiles, and the manatees have not been sighted in Lake Kainji and the associated rivers since 1978. A similar observation on the decline of aquatic animals has been made by wildlife officers working on Lake Chad. Crocodiles and manatees are still being sighted in Lake Chad and other parts of the former North-eastern State.
Aquatic bird populations are also on the decline. For instance, in Lake Kainji some bird species such as glossy ibis, spurwinged goose, pintail and African darter are now difficult to see except around the widest areas of the lake near Foge Island (Okaeme, 1986, 1991: Okaeme et.al., 1988). Similar observations have been made around the Hadejia wetlands and Lake Chad and an effort to protect bird populations and their habitat is currently being made by both international agencies (e.g. International Union for the Conservation of Nature and Natural Resources) and local interest groups (e.g. Nigerian Conservation Foundation). The decline in aquatic fauna appears to be due to human population pressure and activities which include the efforts to increase crop hectarage, infrastructural developments such as dam construction, poaching and environmental pollution. While the biodiversity of aquatic fauna is not fully known their status is threatened (Table 8) due to habitat destruction, socio-cultural activities and lack of management of these animals for sustainable yields.
Today Nigeria has over 12.5 million ha of freshwaters which could yield approximately 510,000t of fish (Ita et.al., 1985). These waters also harbour many freshwater dependent vertebrates some of which depend on fish as their main source of food. There are over 200 species of fish in Nigerian inland waters, 14 species of reptiles, 7 species of mammals, 59 species of amphibians and 72 species of water-associated birds. In terms of total number of vertebrate species associated with inland waters, fish contribute 57%, and the other groups 49% of the total. This shows the importance of the latter groups for the inland water ecosystems.
About sixty-seven of the bird species of Nigeria are purely aquatic (Elgood, 1982) 76% of which are sedentary, resident and indigenous to Nigeria. Amongst the aquatic birds are the common species of herons, water fowl, fish eagle and darters, the majority of which are piscivorous. The distribution of aquatic bird families is given in Table 9.
Amongst the mammals are the marsh mongoose, civets, genets and otter, which are excellent swimmers and piscivores. Their distribution extends from Lake Chad to Lake Kainji for the other while the mongoose, civets and genets are distributed along rivers and other water bodies in the woodland savannah and forest zones.
There are two species of hippopotamus in Nigerian Parks and Game Reserves. The large cloven footed African giant Hippopotamus amphibius is found throughout the savannah areas, but confined to big rivers, lakes and similar water bodies, while the pigmy hippopotamus Choeropsis liberiensis, which is about one-tenth the size, has a limited distribution in the forest zones and is confined to the delta regions of the River Niger.
In Nigeria, the manatee inhabits large water bodies of the Sahel and is distributed throughout Nigeria to the coastal region. The population is threatened by human pressure and is now limited to large water bodies of the Plateau and a more substantial population is found in the coastal and delta regions, in particular around the Cross River and Akwa-Ibom States where this animal is worshipped. Only the species Trichechus senegalensis is indigenous to Nigeria and is well distributed in West Africa along the estuaries of the Senegal, Niger and Congo (Anon., 1976) rivers.
The main reptiles are the crocodiles and monitor lizards. In Nigeria, there are three crocodile species (Dore, 1983) the Nile crocodile (Crocodylus niloticus), long snouted (C.cataphractus) and the West African dwarf crocodile (Osteolaemus tetraspis). The Nile crocodile is the commonest with a wide distribution in rivers, lakes, creeks and mangrove swamps. The long-snouted species has more of a riverine distribution throughout the West African region while the dwarf crocodile is endemic to West African forest rivers. The commonest lizard is the Nile monitor (Varanus niloticus). It is found in rivers with stony terrain. It often drops into the water with a large splash from a basking point on top of stones and tree branches near water (Ayeni et.al., 1983). Their distribution extends to the forest zones of Nigeria but another species, Bosc's monitor lizard (Varanus exanthematicus) is found in the drier parts of the country, the Sahelian and Northern Guinea savannah to which it is limited. It has a broader head with less pattern on the skin and is hunted for its meat and leather. There are also tortoises, terrapins and snakes associated with aquatic habitats in Nigeria whose distributions, like their habitat, are more widespread during the rainy seasons.
Cursory observation reveals that frogs and toads are the most abundant amphibians and almost always associated with any available water, having a wider distribution during the rainy season. There are over sixty-seven species of frogs reported from Nigeria (Schiotz, 1963). Some snakes feed on toads and frogs and are therefore also often associated with these habitats. These include the cobras, night and puff adder and water snakes. The diversity of snakes increases towards the forest zones. A recent study of frogs and toads (Adedayo, 1988) revealed that they are abundant in Lagos, Ogun and Kwara States and that as one moves towards the coast the species diversity tends to increase.
Wildlife is important to the national economy both as a source of meat and as a basis for tourism and recreation. Although tourism and recreational interests have not attracted the desired awareness in terms of participation by the Nigerian populace, bush meat is a recognised trade at rural and urban centres. Wild animal meat is the main source of cheap protein for the majority of rural communities in Nigeria. Over 80% of the population are rural dwellers who depend on bush meat, compared with urban dwellers who depend on abattoir supplies of cow and other ruminant meat. With this cursory observation, one can therefore appreciate the significant contribution of bush meat to the national economy and in reducing the protein deficiency of rural dwellers. Among fishing communities located along riverine and coastal areas, fish and non-fish aquatic vertebrates such as crocodiles, terrapins, hippopotamus and manatee are the main source of bush meat. Charter (1970) estimated that between 1965 – 1966 a total of 617,000 tons of bush meat were consumed. The bulk of this was from mammal and reptile species associated with aquatic systems. Of the total locally produced protein which includes beef from domestic animals, poultry, fish and bush meat from wild animals, bush meat alone was contributing 19% of the total protein production (Charter, 1971). The Isoko tribe, a rural coastal community in Delta State whose water bodies are rich in crocodiles, terrapins, hippopotamus and manatees, consumes 20g of bush meat per person daily (Nicol, 1953). Considering the high population density of Delta State, the demand for meat from wild animal sources is very high. Olayide (1981) estimated that the per capita consumption of bush meat per day for the whole country was 22.02g which is the equivalent of 3.86g of animal protein per day (Ayeni, 1988). A survey of West African countries (Ajayi, 1979) revealed that the average consumption of bush meat in rural areas is between 20–90% of total animal protein intake. Thus wildlife as a source of meat contributes significantly to the national food budget of rural dwellers. These figures are either unreported or are far higher than those recorded by the Federal Office for National Statistics. The lack of information is also partly responsible for the non-recognition of this sector of the economy and the poor financial support being made for wildlife development in the annual national budget.
Although the pace of wildlife conservation is slow, there have been gradual and steady developments and demarcations of parks and reserves in Nigeria. Some of the parks, such as the Yankari Game Reserve and Kainji Lake National Park, are now properly managed, while others barely exist, are poorly managed and lack infrastructure and facilities. Since the 1980s awareness of conservation efforts has improved and several government and non-government agencies have been working hard to conserve wildlife resources. Among these organizations are the Nigerian Conservation Foundation, Natural Resources Conservation Council, Wildlife Departments and units of States and Federal Ministries of Agriculture, the Ecological Society, the Forestry Association, and most recently formed, the Wildlife and Zoo Management Association and the Aquatic Sciences Association. Each of these organizations, through conferences, press briefings, scientific publications, radio-links, youth clubs and pressure groups are contributing to the frame-work strategy for conservation in Nigeria (Anon., 1986).
The present level of information on the status of non-fish aquatic animal resources in Nigeria is still scanty and limited to a few inventories of wild stocks in the National Parks. A holistic approach to their management and conservation is required and recognition that the conservation of aquatic animals, including fish, is important because of their genetic resources, biological, and food values and the socio-economic implications of their extinction. One important factor in the management of these various species, which occupy different trophic levels, is the understanding that their management requires a thorough knowledge of their role in the ecology and balance of the ecosystem. While ecology gives an understanding of how plants and animals relate to their environment, the food chain, which essentially maintains the balance, must also be understood.
A balanced population within the various trophic levels would result in a prey to predator ratio which should be in the order of 10:1. Predators must be reduced to tolerable numbers in order to have a healthy fish population. The prey population must also be in balance with the factors directly and indirectly affecting the ecology of the environment, in order to sustain a healthy and productive aquatic system. Thus in the management of an aquatic system, the animal and plant populations, and the individual numbers of each trophic level, and between the trophic levels, the habitat and their carrying capacities must be monitored before a sound management strategy can be adopted for the maintenance of a healthy aquatic system.
A scheme for the balancing of wetland wildlife resources, plants and fish in a healthy fisheries development in large water bodies must achieve sustainable yields of both fish and non-fish species. Some non-fish animals are at present managed on the premise that they all feed on fish. In most places they are therefore trapped and killed on sight in fish ponds and reservoirs, with the aim of total elimination. Fish farmers in Nigeria are frequently advised to eliminate any predator found in their facilities. There is no advice on compatible management of fish and wetland wildlife based on sound ecological understanding. There is a need for the management of such wildlife using a holistic approach rather than the current simplistic view that they have to be destroyed because they feed on fish. The advantages of their biological value needs to be explained as well as the fact that fish farmers can harvest both fish and non-fish animals without losing economically.
In Nigeria the value of wetland wildlife resources is determined by its availability and the social, economic and cultural preferences and activities of the communities where these animals are found in abundance. Their use is at non-sustainable levels just as in the utilization of any wild species. The overall consequence is overexploitation and continuous reduction in their availability. The following reviews the general uses of each resource with special reference to Nigeria where possible.
In some countries, fish-feeding birds such as cormorants, penguins and gannets are hunted in fishing communities almost to the point of extinction because they are considered as serious pests. However, most aquatic birds treated as pests are labelled as such from circumstantial evidence without in-depth studies to understand how they affect fish population structures, spatial distribution and food resources of the aquatic system. A study by the European Inland Fisheries Advisory Commission (Anon., 1988) revealed that aquatic birds interfere with the habitat of cultured fish, fish feeding and breeding activities and affect the population structure of fish. However, in natural large water bodies, the resources are sufficient and balanced so that predation does not have any deleterious effects. In Nigeria birds are regarded as predators of fish on fishing lines, in fish ponds and along the shores of large bodies of water (Okaeme, 1991). The economic consequences of this predation are not fully known.
On the positive side, some aquatic birds feed on insects or are omnivorous. It has been observed in the Lake Kainji area that the grey heron can exercise insect pest control by feeding on vermin attacking leaves of Butyrospermum, which is an important economic tree. The period of this vermin infestation fortunately corresponds with the peak influx of migrating herons to the Kainji Reservoir area. These birds therefore feed on these insects and naturally serve as agents in controlling the population explosion of this insect pest which if not controlled could destroy the fruit and oil producing ability of this economic tree. Several aquatic birds are also scavengers helping to clean the aquatic environment of dead fish and weak diseased fish therefore reducing disease incidence (Anon., 1988).
While in many countries aquatic birds are hunted for sport, in Nigeria they are predominantly regarded as a source of meat (Ajayi, 1971). Waterfowl and other large birds such as goliath heron, fish eagle and gulls (Okaeme et.al., 1988) are hunted around the River Niger and Lake Kainji. In the Lake Chad area and along the River Benue hunting is also a very popular sport amongst the local elite (Personal communication, MANR).
Aquatic birds are making an increasing contribution to the tourism industry in Nigeria and important areas presently being supported by the Nigerian Conservation Foundation are the Hadejia-Nguru Wetland Waterfowl Projects and the Yankari Game Reserve. In the Lake Kainji area, the Kainji Lake National Park currently organises lake cruises for bird watchers and at Foge Island on Lake Kainji there is a huge population of aquatic birds throughout the year. This area can serve as an important aquatic bird sanctuary waiting for development. The Chad basin is also an important area for large populations of migratory Palearctic aquatic birds which arrive each year and currently form an attraction mainly for foreigners more familiar with bird watching. However, the tourist industry could be improved with proper funding and proper organization.
While aquatic birds have an important biological role they could constitute some problems. This is usually associated with migrating flocks. These problems include littering and fouling of fishing vessels, buildings and monuments since these objects are used as perching and stopping points during migration (Okaeme et.al., 1988). Migratory flocks, can also cause aeroplane accidents and sometimes destroy cash crops particularly in irrigated farmlands (Okaeme, 1986). These pest problems are the major conflict between birds and man.
Body parts of aquatic birds are used in fishing communities as traditional medicine for ailments and protection against water disasters (Okaeme et.al., 1989). Aquatic birds are also very useful models in the study of malaria parasites, sexual behaviour, endocrinology, and for the extraction of hormones from pituitary, thyroid and sexual glands (Dorst, 1974). The use of aquatic birds as a source of raw materials has not yet attracted industrialists and pharmaceutical companies in Nigeria. However, aquatic birds such as herons and ducks have served as good models in science laboratories in several institutions of higher learning in Nigeria.
Aquatic birds are also known to transmit fish parasites and virus diseases, and human arbo-virus. These include transfer of nematode, digenean and acanthocephalan parasites, myxosporidia infections (Taylor & Lott, 1978), viral diseases (Peter & Neukirch, 1986; Anon., 1988) such as viral haemorrhagic septicemia (VHS), infectious pancreatic necrosis (IPN), spring viremia of carp (SV) and several bacterial and fungal diseases. The primary role of aquatic birds in the epidemiology of these diseases is that they serve as mechanical vehicles in the transmission of the pathogenic organisms responsible, through their faecal droppings and remains of fish kills. Those species of bird with a wide home range, in particular migratory birds, are the most susceptible to fish disease outbreaks.
Another important role of aquatic birds is as vectors of some diseases of public health significance. In fishing communities non-human blood flukes of the species Trichobilharzia occur in shoreline aquatic birds. When the cercariae of these schistosomes penetrate the human skin they cause mild to serve dermatitis known as “swimmers itch” (Meyer & Olson, 1975) and allergies, depending on the immunological response and health of the human patient. Some cestodes of aquatic birds are also known to be of zoonotic importance (Meyer, 1970), when their cysts are ingested due to consumption of fairly raw fish flesh. While the above may emphasise negative impacts, these effects are not devastating in natural systems. Rather like predators, the role of aquatic birds as disease vectors is beneficial because the parasites and pathogens are serving as a control component in moderating the population of fish and other aquatic animals such that only the fittest survive, thus permitting the propagation of individuals with most viable genetic qualities.
There are usually two groups of mammals associated with the aquatic systems of Nigeria, the semi-aquatic species adapted to living near water and deriving their food from the water, and those that live and spend the greater part of their time in the water. The latter may have webbed feet and features adapted for swimming and wallowing.
Semi-aquatic mammals may feed on aquatic plants. They cause silt turbidity in the water as they burrow into the side and bottom of a water body. This results in loss of aquatic plants, erosion and instability of the watershed (Templeton, 1984). There are no studies in Nigeria to show the role of aquatic mammals in the preservation and or disturbance of the freshwater ecology. However, it is often reported in National newspapers about the menace of hippopotamus on farmlands, and to fishing communities. These events have often necessitated the intervention of the armed forces to kill such nuisance animals (MANR, Maiduguri, MANR, New Bussa). In 1991, some rice farmlands along the shores of Lake Kainji were damaged by a hippopotamus.
Some mammals such as otter, civet, genet and mongoose feed on fish and small aquatic animals. They therefore play some role in the population dynamics of such aquatic fauna. Although their predation is frequently observed in the field in Nigeria, there is no documentary evidence or thorough investigation of the effects of predatory mammals on fish populations and fish species diversity in freshwater systems.
Bacterial diseases, particularly those caused by Pseudomonas sp., can be transmitted to fish via the droppings of aquatic mammals which contaminate the environment and increase the risk of zoonotic bacterial diseases of fish. The role of aquatic animals in the dissemination of bacterial diseases of fish has not been investigated in Nigeria.
The large mammals such as hippopotamus, manatee, otter, rodents and marsh mongoose serve as important local sources of bush meat especially during the dry season (December to April). Their meat is also an important international trade commodity because of the considerable demand for the red meat of otter, manatee and hippopotamus in rich countries such as Japan and Saudi Arabia. These animals are also hunted for other products such as their skins for leather, their cartilagenous parts, faeces, skin and hoofs as aphrodisiacs and for traditional medicine.
This is the dominant group of aquatic vertebrates other than fish in terms of their numbers and distribution, particularly the frogs and toads. They are more abundant in fish culture systems, in lakes, marshes and reservoirs, especially those rich in aquatic and littoral vegetation. They are also common in ponds where they may cause damage to fish fry and young fingerlings. While toads are not piscivorous, except for the last tadpole stage, frogs are frequently piscivorous and essentially flesh eaters.
Some frog species are edible and a delicacy to some ethnic communities in Nigeria and overseas. All the Rana species, with their very long hindlegs, are edible in Nigeria and are harvested as wild bush meat from ponds and water-logged areas in both rural and urban centres. Dried, skinned meat of toads and fresh frogs has been found useful in the feeding of catfish and poultry, either as raw materials for processed feed or whole as food for catfish. In Nigeria, it is a common practice for fish farmers to supplement the feeding of Clarias sp. and Heterobranchus bidorsalis in pond culture by feeding them frogs and toads (Pers. Comm., NIFFR Fish Aquaculturist).
Some frogs, such as the leopard frog are beautifully coloured and they have been found useful in aquaria and zoological gardens to attract tourists. In the developed countries of Japan and Brazil, but not yet in Nigeria, ornamental frog museums and aquaria are now becoming part of the garden and beautiful attributes of important buildings. The small bodied frog Phrynobatrachus sp. (about 2cm long), numerous in wetland areas at the end of the dry season, has great potential as an aquarium specimen because of its small size and attractive skin colouration.
Among this group of animals are those that feed on fish and those that feed on the fish predators, including snakes. While crocodiles and terrapins are among the first group and spend most of their time in water, the tortoises, monitor lizards and snakes spend a greater part of their time on land near water. They all, however, contribute to the biological function of the aquatic community. Crocodiles, terrapins and monitor lizards feed on fish while snakes feed on frogs, toads, lizards and small rodents that inhabit water bodies. Active predation therefore contributes to the stabilization of the animal communities.
Crocodiles and monitor lizards are hunted extensively, even to the point of extinction, for their meat and skins which are important foreign exchange earners. The high demand for crocodile skins, meat and body parts for traditional medicine certainly have contributed to the observed decline in their populations in Nigeria. During the late 1960s most large bodies of water in Nigeria harboured crocodiles but now both crocodiles and monitor lizards are listed as threatened species in Nigeria (Ebin, 1983; Anon., 1986). Crocodile culture, either to increase protein production or as a source of income from trade in the skins, and for conservation purposes, successfuly tried in various tropical countries, has also been initiated in Nigeria. The Enugu Crocodile Pilot Project (using a 32 × 20m fish pond) was the first attempt to rear crocodiles at the Enugu Zoological garden in 1982 (Dore, 1983). Although the project is still in existence, the mortality of the crocodiles is high.
Reptile watching is a very important tourist attraction in zoos and parks. Nigeria is blessed with several colourful species of snakes and so has a good resource for developing this sector of the tourist industry and tortoises are also kept in Nigerian households in aquaria. There is also potential for the production of venom and anti-venom as an important undeveloped bio-medical industry in Nigeria.
Game Reserves and National Parks (Fig. 2) are important reservoirs for wetland wildlife. These designated areas are the remaining strong-holds where such animals have large populations, breed under natural conditions and represent a large reserve of genetic resources. Some parks, because of their suitable habitat and ecology, now serve as major sanctuaries for aquatic birds, crocodiles and manatees (Table 10).
Gashaka/Gumti Game Reserve:
Located in the north-east of Nigeria this is the largest Game Reserve in the country. It has an area of 6670km2 and extends to Cameroon. It has a variety of habitats such as Guinea savanna, montane and forest habitat. It is rich in animal life, such as crocodiles, manatees and amphibians.
Pan Dam Wildlife Park:
Located in Plateau State, Pan Dam Wildlife Park is famous for its wildlife and enjoys the patronage of Plateau State Government as a tourism show piece (Ebin, 1983). It has an area of 225km2, with grasslands interspersed with patches of high forest. It also has Pan Lake which is about 150 metres wide and 3.5km long. Pan Lake is a sanctuary for manatee, red river hog, crocodile and hippopotamus and a variety of fish species.
Kwale Game Reserve:
It is situated in the low coastal zone of Delta State, characterized by rain-forest vegetation and deltaic swamps. It is rich in reptiles and water associated animals, particularly red river hog, sitatunga and a variety of brackish, marine and freshwater fish species.
Ologbo-Emu-Uro Game Reserve:
It has similar features to Kwale Game Reserve but is much more swampy and has similar flora and fauna. It is located in Edo State.
Buturiya (Wetland) Game Reserve:
Buturiya is a game sanctuary located 40km from Hadejia. It is an important wintering-ground for migrant birds from the Palearctic regions of Europe, north-western coast of Africa and Asia. Buturiya wetland is very rich and a sanctuary for the pelican, knob-billed goose, grey hornbill and white faced duck. It is also rich in crocodiles, monitor lizards and amphibians.
Lake Chad Game Reserve:
Lake Chad is an important game sanctuary for birds, mammals, reptiles and fish. Because of its location in the Sahelian region, and its role as an important water resource, it is a wintering ground for Palearctic migrating birds. Apart from the lake the game reserve includes an area of 388.5 km2 of sahelian vegetation type. Lake Chad is rich in clawless otter, sitatunga, crocodile, hippopotamus, manatee, spur-winged goose, white face duck, pelican, pintail duck and black duck, among others.
Kainji Lake National Park:
This very large park was the first established National Park. It has a total area of 5340 km2 and has two main sectors, the Kainji Lake Sector (3970 km2) and Zunguruma Sector (1370 km2). The park is rich in wild animals with over three hundred and ninety species of birds, seventy-five of which are aquatic, four species of Chelonia (turtles), Squamata (lizards), with an abundance of Nile monitors and Bosc's monitor lizards as well as two species of crocodile (Crocodylus niloticus), and (C. cataphractus), over twelve species of amphibians including two species of toads, sixty-two species of mammals, which include those associated with aquatic systems such as the hippopotamus, manatee and claw-less otter. The manatee is presently under human threat.
Figure 2. Major Parks and Game Reserves of Nigeria
These wetlands have been identified as an important port of call for both Palearctic and Afro-tropical water birds and they have attracted international funding for their conservation. The wetlands are expected to be incorporated into the new Chad Basin National Park. Studies on these wetlands have provided information on fuel wood utilization, the socio-cultural activities of the communities bordering the wetland areas, fisheries economics, agricultural activities and, in particular, small-scale irrigation and the use of technologies for dry season irrigation. The Hadejia-Nguru wetlands are a most important sanctuary for waterfowl and ducks but information on other aquatic resources is still limited.
In Nigeria, aquatic resources administration has been very much limited to water management (Mustafa, 1989), the main goal being the management of water to satisfy socio-economic needs and natural phenomena. The major requirement is the provision of a potable water supply for domestic use. However, other needs include agricultural and industrial use, hydro-electric power generation, water-ways, transportation, and the recreational use of water. To cope with these various water management strategies government has formed several agencies and this has often resulted in duplication and complication of functions, resulting in no single consistent policy guidelines for the management of water bodies. The management of water resources in Nigeria is undertaken by the following agencies:
River Basin Development Authorities are responsible for river basins and their development.
Federal and State Water Corporations are responsible for potable drinking water and its supply to the populace.
Federal Inland Water Ways, a division of the Federal Ministry of Works and Transport, is responsible for transportation on water.
National Electric Power Authority, a parastatal agency of the Federal Ministry of Mines and Power, is responsible for hydro-power generation.
Chad Basin Commission is responsible for the intergovernmental administration of water bodies extending beyond the Nigerian borders.
Water Resources Institute, a parastatal agency of the Ministry of Agriculture and Water Resources, with responsibilities for training of technical manpower and research on surface and ground water monitoring, flood control and water utilization.
The Federal and State Ministries of Health are responsible for monitoring the maintenance of hygiene standards for drinking water.
The Directorate of Food, Roads and Rural Infrastructure (DIFFR) is responsible for rural development schemes including domestic water needs.
The Livestock Water Development Unit is a division of the Ministry of Agriculture with responsibility for the development of rural water supplies for farmers and their animals.
Federal Environmental Protection Agency-responsible for monitoring pollution of water bodies and other functions for both livestock utilization and rural communities.
The Federal and State Meteorological Departments responsible for monitoring weather and climatic changes.
There are other ad hocagencies which are responsible for water management but, as stated earlier, their functions frequently overlap which may interfere with the implementation of their responsibilities.
The management of fisheries has been carried out through agencies and guidelines formulated, as part of the nation's agricultural policy, for the harvesting of fishery resources. These efforts have so far neglected the non-fish vertebrate resources. Agencies with responsibilities for fishery management include:
Federal and State Departments of Fisheries, as divisions of the Ministry of Agriculture, responsible for monitoring and control of fishery resources of Nigeria, fishery laws and their implementation.
Research Institutes of Oceanography and Marine Research, and the National Institute for Freshwater Fisheries Research, responsible for research into fisheries and other aquatic resources.
Federal Environmental Protection Agency (FEPA) responsible for monitoring pollution and the safety of aquatic resources.
National Resources Conservation Council, under the presidency, responsible for monitoring and conservation of natural resources including water and aquatic resources.
Aquatic resources have been recognised as part of the agricultural policy aimed at meeting the demand for food in Nigeria. The food demand, growing at a rate of 3.5% (World Bank, 1987 -cited by Ayeni, 1991), is high and there is therefore a widening gap between domestic food supply and the total food requirement. Government has therefore developed an agricultural policy covering all sectors of agricultural production with the aim of achieving self-sustaining growth in agriculture and attaining self-sufficiency in food production. The areas of aquatic resources strategies so far developed are set out below.
The strategies and main objectives of fishery development are to:
encourage the production and harvesting of fish from deep-sea trawling, freshwater and marine sources and the development of aquaculture.
provide incentives and fishery inputs, and regular training of fishery staff and fish farmers,
create and develop fishery cooperatives and organizations as a means of reaching the grass-roots and making government economic development opportunities available to the general public,
develop technologies to accelerate fish production and reduce fish losses through spoilage,
promulgate and enforce fisheries regulations and laws to prevent depletion and overexploitation of fish resources.
Implementation of these strategies is slow (Satia, 1990) because no national fishery laws have been promulgated. However, some state governments e.g. Niger, Kwara, Ondo, Kebbi and Sokoto States have edicts regulating fishing. Development and training in non-fish aquatic resources management is lacking as only fish and shellfish are considered.
The strategies and main objectives of water resources development are:
comprehensive development of both underground and surface water resources for multi-purpose use,
development and maintenance of dams, dykes, boreholes, irrigation, drainage and other systems to improve food production and human needs,
to control pollution of water bodies and food, erosion and any other processes that may be detrimental to water,
training of personnel in water management.
The strategies for water resources development are contained within the policy on agriculture but there is the need to have a national policy involving socio-economic development, water management laws, health, industrial development, shipping and water resources management, other than fish.
Water pollution falls under the control of the Federal Environmental Protection Agency (FEPA). The main objectives and strategies are:
the provision of adequate quality and quantity of water acceptable to meet domestic, industrial, agricultural and recreational needs,
to consider the impact of water resources development on the environment, and to develop quality criteria for different water uses.
These strategies are concentrated more on water and environmental pollution and are often in conflict with other agencies. However, there should be no reason for conflict with other agencies if FEPA concerns itself with the formulation of quality criteria and ensuring these policies are implemented.
The main implementing agency of natural resources conservation is the Natural Resources Conservation Council, the main strategies of which are to:
co-ordinate the means of conservation of natural resources of Nigeria,
formulate a national policy on natural resources conservation,
fund and monitor the activities of programmes and projects on natural resources conservation.
These strategies are all-embracing with regard to natural resources and could improve the present status of non-fish aquatic resources. What is needed therefore, is documentation of the available resources, their present status, utilization and a national policy on sustaining these resources.
As mentioned above there is at present no policy on the management of non-fish, water-dependent aquatic vertebrate fauna. The following approach is suggested in order to achieve its sustainability under rational management and exploitation conditions.
Non-fish aquatic fauna in their natural environment could be harvested (based on their biological value) at a rational, sustainable level. To achieve this requires better information on the diversity of species, their population densities and annual yield curves. Sustainable management also requires that harvesting corresponds to the available biomass and year-classes. Such management cannot yet be adopted because the relevant information and necessary regulations are lacking.
Another rational approach is the creation of sanctuaries to protect wildlife from overexploitation and to reduce the threat of extinction. This requires the identification of habitats where animal populations are still abundant and relatively undisturbed. The area should be acquired and protected, with all legal backing. The crocodile, manatee, otter, edible frogs (Rana sp.) and birds, in order of importance, require sanctuaries. Sanctuaries should be protected from all disturbances excluding scientific investigations. Suggestions for the location of such sanctuaries, covering the different ecological zones of the country are summarized in Table 11.
Captive management, including propagation, of wild crocodiles and some other large animals has considerable potential in Nigeria, and should be seriously considered in the nearest future. Such management would remove some pressure from the wild stocks and prevent their overexploitation.
Preservation of fauna has been a major concern of ecologists and many laudable strategies have been adopted but its implementation has often failed because of the inability of ecologists to translate ecological requirements into economic realities. Most projects have remained unfunded. While obvious effects such as dwindling animal populations, extinction of species due to illegal trading of animals and their products, and socio-economic conflicts associated with poaching, are well documented ecological studies have often failed to attract funding because the formulation and appraisal of such programmes do not often contain economic appraisal of a sort to attract international funding. The following groups of animals have realistic prospects with rational management and propagation.
Crocodile is one of the animals listed under the Convention on International Trade in Endangered Species of wild flora and fauna (CITES). In a number of countries, such as India and Indonesia (Bustard, 1974), Papua New Guinea (Bolton, 1978), Ethiopia (Bolton, 1986) and Zimbabwe, crocodiles have been managed through FAO assisted programmes, their population increased and the mass production of this species has improved the economic well-being of the rural people. Proper management of crocodiles leads to the development of commercial crocodile farms, crocodile leather trade, crocodile meat and a tanning industry. In Nigeria, crocodile can be reared for meat because the meat is highly accepted with a large southern meat market and a high demand for skins in the north. The most suitable species for propagation is the Nile crocodile. It is widly distributed, adaptable and reaches a size of up to six metres in a few years if properly managed.
Manatee and otter
Both these animals attract tourists worldwide but the manatee is a more popular and a better known species and therefore an important animal for game viewers and for the location of the hotel industry. Rational exploitation of these animals for meat and for increasing their population can be achieved by allowing them to grow in designated protected areas of the country. Manatee is a threatened species in Nigeria and there is need for a gradual build-up of its stocks. It has been identified as an excellent aquatic weed controller in areas where aquatic weeds are considered a nuisance. Such results have been obtained in North, Central and South America and the Caribbean. Some of the preferred species of aquatic plants are Ceratophyllum, Ipomoea, Panicum, Nymphaea, and Azolla. These plants are a nuisance in the lagoons and estuaries of the coastal waters of Nigeria. There are good indications that manatee in some areas could control these weeds.
Frogs (Rana sp.)
The economic importance of frogs as a source of meat in rural communities has not been assessed but in some areas of Nigeria frog meat is considered a delicacy. There are usually large numbers of frogs at the beginning of the rainy season. With the present high cost of livestock meat and fish, edible frogs could become an important part of the diet in some parts of the country. Because of their ready availability, and ease of trapping they have potential for rapid propagation.
In view of the limited research, constraints and the lack of recognition of water-dependent vertebrates (other than fish) as an integral and important part of wildlife management, there is a need for the development of this resource. It should therefore be incorporated into the main stream of agricultural and aquatic resources management objectives and policies. By definition, fishery resources should include all aquatic plants and animals, both edible and non-edible (Dill, 1990). The best use of fishery resources requires consideration of other segments of the aquatic food chain. Non-fish aquatic vertebrates also contribute to the socio-economic development of the country. In order to achieve their sustainability for the purpose of establishing a reliable source of food, the following research, management, administrative and legislative activities are recommended.
A national survey of the non-fish water-dependent vertebrate fauna, their distribution, population and stability.
Studies of the predator/prey relationships of such fauna and their potential application to the management of fisheries in small reservoirs and small scale commercial fish and integrated farms.
Investigation of the acceptability and economic utilization of such fauna. Identification of species with potential for further development.
Investigation of the socio-economic implication of crocodile, frog and toad populations as meat and as a source of raw-materials.
Studies of the biology of species suitable for controlled farming.
Studies on the impact of dams, radio-active chemicals, and thermal changes associated with power generation on the wildlife.
Establishment of an aquatic resources management council whose role would be to guide the rational sustainable utilization of aquatic wildlife.
Studies of fishery resources conservation and improvement to formulate guidelines for the protection of natural habitats against major disturbances caused by damming, channalization, water uptake and diversion etc.
Increasing awareness of needs for nature protection and exforcement of the existing laws and regulations for conservation of aquatic wildlife.
To implement the above will require adequate funding, training of specialists in a number of disciplines and assistance, both governmental and international.
The subject of aquatic plant and wetland wildlife management is a relatively new area for development in Nigeria. The present publication aims to create the necessary awareness of the subject, and to draw the interest of government and international organisations. The matter is rather urgent because wetland wildlife resources are especially threatened throughout Nigeria by overexploitation. There is a need for research and the development of management strategies for sustainable utilization of these valuable resources, and their protection as a genetic pool. It is therefore recommended that the following strategies be adopted as first steps towards developing this sector.
Creating awareness of this new sector by including it in the fisheries/agricultural sector for policy formulation and budgeting.
Proper funding of a wetland wildlife resources sub-sector with the formation of a National Committee for the managment of these resources. The Committee shall be responsible for the implementation of the objectives.
Training of specialists in taxonomy, population dynamics, management and husbandry of wetland wildlife resources. This requires the assistance of non-governmental agencies and international organizations.
A National Workshop on wetland wildlife resources to be organised by the National Committee in order to draw up national strategies on the conservation and utilization of such resources.
Inclusion of wetland wildlife resources in the strategies for conservation, and creation of the necessary awareness through conferences and seminars.
Table 1. Limnological characteristics of some reservoirs and rivers of Nigeria.
|Total Dissolved Solids|
|Free carbon dioxide|
|Kainji Res.||33.0–84.0||33.1–68.8||6.3–8.4||0.0–10.04||0.0–25.2||18.0–54.6||1.9±1.3||2.7±6||-||0.5±0.4||22.7±12.2||Adeniji (1978)|
|Asa Res.||79–100||50.4–70.0||7.2–7.6||5.4–5.9||-||-||-||-||-||-||-||NIFFR* (1990)|
|Jebba Res.||44–250||-||6.2–7.7||2.68–7.1||-||1.0–3.0||0.0–2.0||-||-||0.0–6.5||0.02–60||Adeniji (1991)|
|IITA Res.||250–260||-||7.1–7.2||0.84–2.0||4.9–6.9||170–230||5.75||-||430–470||0.007–0.009||12.5–15.0||Adeniji (1979)|
|Bakolori Res.||58–70||47–58||7.2–7.4||5.8–6.6||-||-||-||-||-||-||-||Adeniji (1980)|
|Tiga Res.||-||-||6.9–7.6||0.3–7.8||-||-||-||-||-||-||-||Adeniji & Ita (1977)|
|R. Niger||62.8–66.2||-||7.32||Saturated||-||-||0.13||2.41||54.8–58.2||-||22.49||White (1965)|
|R. Kaduna||46–48||32.2–33.6||6.4–7.2||3.7–7.2||-||22.8–30.6||0.006–0.033||2.3–2.5||-||0.1–0.15||50.6–52.6||NIFFR (1990)|
|R. Eku||30–100||-||6.9–7.2||4.6–9.6||-||-||0.11–0.42||-||-||0.5–2.0||-||KLRI** (1986)|
* National Institute of Freshwater Fisheries Research, New Bussa, Nigeria
** Kainji Lake Research Institute (predecessor of the above)
Table 2. Aquatic plants of Nigeria
(based on Welman, 1948; White, 1965; Imevbore, 1971; Obot, 1987)
|Family/species||No. of species|
|1.6||Sagittaria (Lophotocarpus) guayanensis|
|12.1||Utricularia reflexa (=charoïdea)|
|12.2||U. gibba subsp. exoleta|
|12.3||U. inflexa var. inflexa|
|12.4||U. reflexa (=platyptera)|
|12.7||U. inflexa var. inflexa (=thonningii)|
|12.8||U. benjaminiana (=villosula)|
|18.1||Jussiaea repens var. diffusa (=Ludwigia stolonifera)|
Table 3. Aquatic plant zonation
|No.||Species||Marginal flora zone||Floating plant zone||Submerged plant zone|
|5||Anubias barteri var. glabra (=lanceolata)||+|
|37||Jussiaea repens var. diffusa||+|
Table 4. Occurrences of some freshwater aquatic plants in selected water bodies of Nigeria.
|No.||Species||Lake Kainji||Jebba Lake||Bagauda Lake||Tiga Lake||Ruwa Kenyah||Asejire Dam||Ebub-Ochani River (Port-Harcourt)||Cross River Floodplains|
|5||Anubias barteri var. glabra||-||-||-||-||-||-||+||+|
|37||Jussiaea repens var. diffusa||+||+||+||+||-||-||-||-|
Table 5. Aquatic macrophyte productivity.
|Species||Productivity or standing crop||Crude protein content %||Remark||Source|
|Ceratophyllum demersum||ND||21.7||Acceptable to livestock||F.A.O. 1979, p10.|
|Pistia stratiotes||2068 kg/ha||12.0||Suitable for pollution control||F.A.O. 1979, p10.|
|Echinochloa stagnina||161,000 t/ha (L. Kainji, whole lake)||8.8||Acceptable to livestock||Obot, 1984.|
|Eichhornia crassipes||ND||1.1||Acceptable to livestock||F.A.O. 1979, p13.|
|Ludwigia decurrens||ND||19.1||Acceptable to livestock||F.A.O. 1979, p11.|
|Sorghum arundinaceum||446 g/m2||7.5||Acceptable to livestock||Obot et. al., 1991.|