The fishery potential of the minor lake (Nabisojjo) - Luwero District

Luwero district before the creation of Nakasongola District had a share of south-western portion of Lake Kyoga. After loosing the portion of the lake, they want to resort the minor lake (Nabisojjo) for supply of fish at least to the population around this lake. The plans were to start commercial fishing. The lake is 45 km from Luwero town adjacent 10 the road going to Ngoma town. River Nabisojjo, a tribulary of river Mayanja flows through the lake on its way to river Kafu. The main objective of the scientific field study on Lake Nabisojjo was therefore to generate information on the status of the lake fishery and recommend to the local authorities the next line of action.

Fishery resources: their exploitation, management and conservation in Africa

The beginning of the 20th century saw the discovery of Africa's vast natural resources. Not only did explorers "discover" lakes, rivers, forests and mountains but scientists and naturalists also "discovered what at that time were called new species of plants, fish and other animals. Thus scientific names were tagged to various species using the famed binomial nomenclature and immortalising the names of some of the people who first described those species. Africa of course abounds with thousands of different floral and faunal varieties and the early colonial scientists found the African environment lucrative fron the point of discovery of new species. This paper therefore attempts to descrihe the role science could only in the development and exploitation of one of Africa's renewable resources namely fisheries. This paper has attempted to expose the value of fish in human nutrition, provision of employment and uplifting of social and economic standards. The fishery resources of Africa are extensive and in the main not fully exploited. These resources like other natural resources are exhaustible although renewable. Efforts to exploit these resources must be encouraged but scientific planning and management of the resource is called for.

The need for a trawl fishery on Lake Victoria

The idea of mechanised fishing on Lake Victoria is not new. Trawling experiments have been carried out in the past by the East African Freshwater Fisheries Research Organisation (EAFFRO), the Lake Victoria Fisheries Service and the Uganda Fisheries Department. In 1950 it was recognised by EAFFRO that commercial possibilities existed in the exploitation of Haplochromis by this gear. However, it was not until 1966 that, by a happy collaboration of the Uganda Fisheries Department and EAFFRO, the vessel 'Darter' was converted into a stern trawler and serious and successful experimentation into trawl fishing commenced. Darter has continued to undertake trawling work ever since and this work was augmented by the arrival in 1967 of the Lake Victoria Fisheries Research Project's vessel 'Ibis'.

Training aspects for a trawling fishery

Trawling experiments carried out by the United Nations Development Programme Project and the Uganda Department of Fisheries, strongly suggest that the trawling method of fishing, if introduced on Lake Victoria, would bring about a tremendous increase in fish production from the lake. It is recognised, however, that before trawling is introduced, its economic, social, technical, biological and manpower implications must be carefully analysed. I now propose to discuss the training aspects of a trawl fishery on Lake Victoria.

The present-day fishery of the Uganda waters of Lake Victoria

The Uganda waters of Lake Victoria comprise an area of 28,500 square kilometres with a shore line of 2,380 kilometres extending from the Uganda/Tanzania border in the west to the Uganda/Kenya border in the east. A large part of the Uganda waters of the lake is less than 60 metres deep, waters deeper than 60 metres being on the eastern side of the lake. Thus the Uganda part of the lake is tilted towards the east. A number of rivers drain into the lake from the north and the River Nile flows out of the lake towards the Mediterranean Sea. The Ssese, Kome, Buvuma and Busoga Islands form a very distinctive feature of the lake. These are perhaps the remaining high hills which survived the drowning of the northern valleys during the formation of the lake. In fact, in T. P. O'Brien's book 'The Prehistoric Uganda Protectorate (1939)', Solmon gives a critical summary of the work on the formation of Lake Victoria and shows that the northern part of the lake has numerous drowned valleys, a feature which provides varying habitats for particular species of fish and which may have an effect on the species composition reflected in the catches in different areas along the northern shore of the lake. It is interesting to note that although Lake Victoria as a whole has a number of rivers draining into it, Halbfass (1923) calculated and found that 76 per cent of the water entering the lake is precipitation on the lake surface.

A discussion of possible management methods to revive the Labeo victorianus fishery of Lake Victoria, with special reference to the Nzoia river, Kenya

Labeo victorianus Boulenger, the "ningu", is commercially the most important migratory fish of Lake Victoria, as well as being one of the most abundant of all species landed. Annual catch records of the Fisheries Departments of Uganda, Kenya and Tanzania show that a high yielding seasonal, floating gill net fishery is based on the concentration of sexually mature fish at the river mouths at the time of migration during the bi-annual floods. Migrating fish used also to be caught in high numbers at "kek" barrier traps across the river, as at Hainga on the Nzoia river. Since the heavy exploitation at the river mouth which occurred with the introduction of nylon gill nets in 1956.

The potential for clupeid fishery in Lake Kainji, Nigeria

The potential for a clupcid fishery in Lake Kainji has been examined using both experimental fishing samples and the results obtained from those of the commercial fishermen. A total annual production of 1,400 tons has been estimated. In money terms, this amounls to N198.800 (£99,400) per annum. This production has been sustained by the abundant zooplankton food available the year round on the lake. Recommendations for the effective methods of cropping clupeids were made, bearing in mind the need to maintain the fishery on a sustained yield basis. The place of c1upeids in the ecology of the lake was examined and on the basis of the evidence available it was recommended that Pellonula afzeluisi could be exploited on a large commercial scale without any adverse effects on the fishery in the lake.

Fishery resource assessment and monitoring in the development and control of fisheries in the Lake Volta

Gill-netting and rotenoning have been used for assessing and monitoring fish stock abundance in Volta Lake. The lake and the main gear types used on it have been described. Before a gill-net sampling plan was set up, a preliminary survey was undertaken which largely determined the final form of the plan. An investigation as to whether or not the lake was being overfished concluded that it was being underfished. Commercial and experimental catch data analyses disclosed that the adults of the small species were being little utilized. Commercial sized species were also not being harvested according to their apparent proportion in the population. Production is presently fluctuating between approximately 37,000 and 40,000 tonnes. A high correlation between commercial and experimental catch was realized. Developments which have followed in the wake of stock assessment and monitoring studies include: introduction of monofilament nylon net, development of a special scoop net to permit mass harvest of clupeids after they have been attracted to light, and the design of a larger canoe which would help to extend the fishery into open water. New regulation and management policies will have to be formulated in the light of new findings before a rational exploitation of all the species can be achieved.

A note on fishery development on the Kafue Floodplain

The annual fish catch from the Kafue floodplain varies between 2,000 and 11,000 tons with a median of 5,500 tons valued at about K 500,000. It is believed that over 1,500 persons fish full time in the area. Fishermen's earnings can vary from a ew ngwee per day to a period in June 1970 when in one day four owners of drawnets in the Maala area, after hauling 13 times, caught 395 kg of fish valued at K 43.45 (i.e. about K 10 each per day). (I Kwacha=IOO Ngwee=US $1.40 Fresh fish is bought by traders with five to ten ton trucks more commonly in the upstream Namwala sector than in the central and downstream sectors of the floodplain (where consignments tend to weigh less than 125 kg). Over 25 tons (fresh weight equivalent) may pass through a fish market such as Busangu each month. Dried fish is destined for a greater range of towns than fresh fish.

Report of the catch assessment survey: fishery survey of Kyoga Lakes August 1990 - March 1991

This report presents the information obtained during catch assessment surveys made by the ADP Fishery Survey of Lake Kyoga and Lake Kwania between August 1990 and July 1991. It supersedes previous interim reports on these surveys. The Kyoga lakes had not been surveyed in a long time. Information on the state of the stocks was largely confined conclusions drawn from data collected along the southern shore of L.Kyoga proper. The effect of harmful/illegal gear types on the stocks was not documented. Part I provides a description of the survey. Part II comprises a review of the fishing strategies. Parts III and IV present the principal results obtained on L.Kyoga and L.Kwania. Part V presents a discussion of the main conclusions.

The commercial fishery of Lake George, Uganda (East Africa)

A shallow, highly productive, tropical lake is descrihed with a brief history of its commercial fishery. Three separate assessments of the present (1967-1970) yield are compared, with an apparent confirmation of the values derived from Fishery Department statistics over a period of 20 years. The seasonal change in the catch is noted with, an apparent anomaly shown by ohservations of canoe landings. Long-term trends during the period 1950-1969 are considered with a brief discussion of possible future trends in the fishery.

A preliminary report on the spiny lobster fishery of Zanzibar

The object of this account is to report the preliminary progress made in the investigation of the size characteristics of the lobsters in the commercial catch.

Fishery resources and some economic aspects of four fishing villages on Lakes George and Edward in the Queen Elizabeth National Park, Uganda

The fishery resources of Lake George and Ugandan waters of Lake Edward are described. The main fish species currently observed in the commercial catches were determined and the reasons of changes in species composition of the catches. that occurred in the recent years, are explained. The fishing activity and some economic and nutritional aspects of four fishing villages, selected among the ten present within the Queen Elizabeth National Park boundaries, are analyzed, In the end some suggestions are given for management of the fishery resources of these lakes.

Fishery methods and fish diversity in the Kilombero River in south-eastern Tanzania

Assessment of common fishery methods and of fish diversity was undertaken in two fishing camps on the Kilombero River in south-eastern Tanzania in surveys towards the end of the dry season, 1994. Fishermen identified 23 different types of fish that they caught on a regular basis. Only 19 species of fish, belonging to 17 genera and 11 families were, however, identified according to Linnean taxonomy. Hooks, nets, traps and spears were used to catch fish. Fish were either sold fresh. or preserved for storage and long-distance tranport by smoking or frying. based un frequency distributions of the numbers of fish landed over a 4 day period at one of the camps, a Shannon-diversity index of 1.95 was calculted. The fork (or total) length of 480 fish and the weight of 413 fish were measured and length frequency distributions as well as length-weight relationships determined for the six most common species. It is concluded that local fishing methods applied in the Kilombero River allow for sustainable fish production.

The role of man on the changing fishery potentials of Lakes Victoria and Kyoga

The traditional lucrative fisheries of Lakes Victoria and Kyoga were based on similar multispecies itchthyofaunas. Man's activities on and around these lakes have both directly and indirectly assisted to modify the natural trends and components of the commercial fisheries. The exotic L.niloticus and O.niloticus together with the native R. argentea form the major component of current commercial landings. The total catches are higher but it is not yet clear whether the increase would endure given the fragility of predator/prey systems. The trophodynamics are still modifying and it is not certain how ecosystem function would be influenced. It is, therefore, prudent and desirable to undertake appropriate research investigations in order to guide the multiobjective activities of man on these lakes.