Limnological research in Nigeria: some perspectives

A brief review on limnological research in Nigeria is given: the status of the research in the country and perspectives for future development are illustrated

Incidence of mayfly (Povilla sp.) infestation of wooden infrastructures of artisanal fishers in the lagoon and marine fisheries locations of Ogun State, Nigeria

A diagnostic survey of the incidence of mayfly (Povilla sp.) infestation of wooden infrastructures of the artisanal fishers in ten (10) lagoons and marine fishing villages of Ogun States (Nigeria) was carried out through the application of structured questionnaire and participatory Rural Appraisal interviews. The demographic, infrastructural and socioeconomic characteristics of the ten fishing villages sampled were derived and analyzed. The infestation which occurs all year round is found to be most prevalent (70%) in the wet season, increasing proportionally with salinity from 56% (brackish water); to 63% (marine water). The life-span of Povilla sp. is reduced from 55% to 62% (freshwater); 41% (brackish water) and 38% (marine water). Annual financial loss of N10,000.00 per fisher or N80,000,000.00 to the 8000 artisanal fishers affected in Ogun State is discussed. It is recommended that fishers should preferably use non-wood crafts and infrastructures while adopting appropriate management strategies for containing the existing infestation

Fisheries development in Nigeria with special reference to Cross River State

The paper appraises fisheries development in Nigeria with specific reference to Cross River State and the problems militating against increased fish production. The potential for developing the industry to supplement the low level of animal protein consumption in Nigeria is discussed as well as the import of a vibrant fishery industry to contribute to the employment and international trade. The need to legislate on fisheries activities while enforcing the existing laws for sustainable exploitation of the fisheries resources is elaborated. Similarly, the need to maximize the proceeds from Nigeria's Exclusive Economic Zone (EEZ) by protecting the operations of this economic sector and other unauthorized fishing practices is elucidated. In view of the present situation where most of the country's water bodies have been over-fished, more attention and emphasis should be placed on aquaculture development. The paper also proffers recommendations to boost fish production in capture and culture fisheries

Preliminary study of the aquatic macrophytes of selected fish ponds and reservoirs in Makurdi, Benue State, Nigeria

A five months survey was conducted to identify the aquatic macrophytes in fishponds and reservoirs in Makurdi (Benue State, Nigeria) between August and December 1999. A total of 3-prominent aquatic macrophytes were identified: Ipomoea aquatica, Nymphae lotus and Echinochloa pyramidalis at two-study sites (site 1, receives organic manure effluent from a cattle ranch, site 2, receives inorganic fertilizer through application). Ipomoea aquatica were found restricted to site l, while Nymphae lotus and Echinochloa pyramidalis were found associated with site 2. Analysis of the results indicates high level of ammonia-nitrogen at site 1 compared to site 2. Mineral analysis of the plant tissues indicate high level of iron in Ipomoea aquatica and Nymphae lotus. Mineral concentration were found to be significantly higher (P,L, 0.05) in Ipomoea aquatica and Nymphae lotus when compared with concentration in Echinochloa pyramidalis

Lead accumulation by hammerhead shark, Sphyrna couardi (C.) off Lagos coast, Nigeria

Levels of concentration of lead in the hammerhead shark, Sphyrna couardi, off the Lagos Coast of Nigeria were investigated. The standard length of the specimens examined ranged from 31.4cm to 47.2cm while the weights ranged from 451.5 to 1,667g. The lead concentration ranged from 0.11 degree kg/G to 0.38 degree kg/G. The mean lead concentration was 0.56 degree kg/G (dry weight). The gill has the highest lead concentration. There was no linear correlation between the length and weight and the amount of lead concentrated

Parasites and non-fish predators of tilapia with particular reference to the sustainable management of fisheries of Lake Kainji Nigeria

The fisheries of Lake Kainji, Nigeria, experienced a boom year following impoundment, then decline post impoundment and now is in a period of stabilisation of the fish resources. Several reasons have been advanced on factors responsible for these changes, but two outstanding factors are those of nutritional status and fishing methods of the lake. Two important fish families however continue to dominate the lake fisheries in daily fisherman catches: Clupeidae and Cichlidae (tilapias). Recent studies have also shown that the dominance of the tilapias and clupeids is an important factor in the understanding of the stability of fisheries of Lake Kainji. One area which has remained undiscussed concerns the parasites and non-fish predators of tilapias which can affect the population dynamics of tilapias. This paper examines therefore some aspects of the fisheries of Lake Kainji and the potential roles that parasites and non-fish predators of tilapias can contribute in developing strategies for consideration in the sustainable management of the fisheries

Absorption of food in the black-jaw tilapia, Sarotherodon melanotheron (Ruppell) from a small tropical man-made lake in Ibadan, Nigeria

The carbohydrate, protein and lipid contents of the food ingested and their absorption in the intestine of Sarotherodon melanotheron inhabiting Awba lake in Ibadan, Nigeria, were investigated. Total carbohydrates of the ingested food ranged from 39.33 to 55.38% (mean = 48.70% while total protein and total lipid ranged from 10.10 to 17.13% (mean = 12.91%) and 7.79 to 8.96% (mean = 8.28%) dry weight, respectively. Calculated total percentages absorbed were 54.86-62.01 (mean 58.07) carbohydrates 47.33-54.06 (mean = 50.43) protein and 43.27-52.23% (mean 46.56) lipid. Absorption of protein and carbohydrate occurred mostly in the fore-gut (the first one-third of the intestine), while lipid was mostly absorbed in the mid-gut (the second one-third of the intestine). Dietary carbohydrate, protein and lipid contents of the food as well as the absorptive capacity of the intestine for these components of the food varied with size of fish

Assessment of post-harvest losses in Nigeria fishery: the Kainji Lake model

The paper provides a description of a methodology used for quantitative assessment of post harvest losses in the Kainji Lake Fishery (Nigeria). The sample population was made up of 314 fisherfolk, 115 processors, 125 fish buyers and 111 fish sellers. For the determination of handling losses, 24,839 fishes weighing 2,389.31 kg belonging to 43 species were examined of which 10% by number and 9% by weight deteriorated at checking and 4% by number and 3% by weight at landing. Processing losses recorded 22% by number and 16% by weight deteriorated prior to and during smoking with the traditional 'Banda' kiln. During marketing, 16% of fish sold had deteriorated and 6% by weight of fish bought also deteriorated, mainly due to insect infestation during storage. Based on the 1995 yield estimate for Kainji Lake fishery, approximately 1000 tons of fish estimated at 80 million Naira were lost during handling alone. This figure would be much higher if the level of losses during processing and marketing are included. This assessment technique is recommended for use in obtaining quantifiable data on post harvest losses from other water bodies in Nigeria

Twenty years of fisheries development in Nigeria

The paper traced the historical development of fisheries development in Nigeria. The paper was further discussed under the following sub-headings:- Ten years development plan 1945-1954, First National Development Plan 1962-1968, Second National Development Plan 1970-1974, Third and fourth National Development Plans. Several of the government programmes rolled out to enhance fisheries development are discussed, such as National accelerated fish production programme, operation feed the nation, the Green Revolution and structural adjustment Era. The paper confirmed that the past twenty years have witnessed phenomenal growth in Fisheries Development in Nigeria. However, decline has been noticed in the area of local fish production. This, has been due to a number of factors some of which are: prohibitive price of spare parts and fishing inputs, the increasing price of automatic gas oil.

Enhancing potential fish catch in Nigeria's inland waters

The paper enumerated the following ways of improving fisheries:- Effective implementation of the inland fisheries Decree of 1992, stocking and introduction of new species in to small and medium size reservoirs, enhancement of fish catch through increased artisanal fisheries development, fish hatchery development in strategic zones for increased fingerling production to stock reservoirs and natural water bodies, extensive culture development in flood ponds, and encouragement of commercial aquaculture under private entrepreneurship. The paper further elaborate on the strategies for effective implementation of the above guidelines with the hope of offering solution to problems hindering production in Nigeria

Preliminary report of fishing at the Alawariwa beels, Ogun State, Nigeria

The Alawariwa beels located in the flood plains of the Ogun River, off Ibafo in Owode/Obafemi Local Government Area of Ogun State number 16 with an approximate total surface area of 28.0 hectares. The beels are conveniently exploited between January and April annually when the dry season and riverine contraction make this possible. The daily landing showed that the fish enclosure is truly a natural fisheries reserve as well as a medium of biodiversity. Fish catch per unit effort is reasonable especially for the more abundant fish species. The beel is sufficiently productive and worthy of the fishing efforts of the fishing efforts of eight fishers undertaking the daily assignment. Beel fishing is therefore economically advisable for fishers having access to such valuable communal or individual natural wetland resources

The effect of traditional handling, processing and storage methods on the quality of dried fish in small scale fisheries in Nigeria

Most of the fish marketed throughout Nigeria are in either smoked or dried form. The technological requirement for other forms of preservation like chilling and freezing cannot be afforded by the small scale fisher folk. Considerable quantities of fish processed for distant consumer markets are lost at handling, processing, storage and marketing stages. Significant losses occur through infestation by mites, insects, fungal infestation and fragmentation during transportation. This paper attempts to describe the effect of these losses on fish quality and suggests methods of protecting fish from agents of deterioration

Review paper on the production trials of rice-cum fish culture - a transferable concept into Niger State, Nigeria

This paper reviews the production trials of rice-cum-fish culture. Rice and various fish species using rotation and concurrent methods of cultivation are used. The farming system is mostly practiced and researched in to in Southeast Asian countries. It addresses the problems of high external inputs, sustainable aquaculture, poverty and nutrition in the rural population, insect pests, use of insecticides, weeds control and under-utilization of agricultural lands. The production trials yields are summarized and a summary of annual income per hectare from rice and fish have been given. The yield however depends to a large extent on the species stocked, culture period, fertility of the soil and water, degree of supplemental feeding and culturing methods. The production results are discussed. Niger state is blessed with abundant wetlands/rice fields suitable for the practice. However, ecological differences from country to country and region to region, research and development trials are necessary to ensure a successful adoption of the technology to farmers in the State

The reproduction of Oreochromis niloticus (Linnaeus) in Opa reservoir, Ile-Ife, Nigeria

Oreochromis niloticus is one of the commercial fish species in Opa reservoir. It bred throughout the period of study in the reservoir. The fish species is a maternal mouth brooder with the female specimens carrying eggs and alevins in their mouths. The sex ratio of O. niloticus was 1:1 and the maximum fecundity recorded was 1810 eggs. The fecundity increased as the fish length increased. The relatively high fecundity of the fish species in the reservoir is an indication of the suitability of the small reservoir in contributing to fish production

Homestead fish pond and the environment in Nigeria

Homestead fish culture is a recent innovation for mass production of fish at backyard in Nigeria. The processes of pond construction often have resulted in soil disturbances, vegetation losses, and creation of new aquatic environment. The paper discusses homestead ponds in Nigeria, their potential impact on the environment which includes erosion, over flooding, pest and disease, accident risk, undesired fossil fuel production, vegetation destruction and fish genetic conservation, strategies for environmental management in relation to pond construction are suggested