The exploitation of small pelagic fishes of the great lakes of Africa with reference to the mukene (Rastrineobola argentea) fishery of the northern waters of Lake Victoria

Small pelagic fish species have ultimately become important on most of the Great Lakes of Africa, especially after the depletion of the larger, initially preferred fish species. In Lake Victoria, the small pelagic cyprinid Rastrineobola argentea is now the only abundant native species supporting a fast growing light fishery. In Pilkington Bay, off Lingira Island the artisanal light fishery is well established and in the last two years this bay has witnessed a sharp increase in the fishing effort. This has been followed by a modification of fishing method and a reduction in the mesh size of nets used. R. argentea now caught from this bay consist of mainly juveniles and this could result into localized recruitment overfishing. Drawing examples from what is happening to the fishery in Pilkington Bay, it is necessary to carry out research on the stocks, gear and suitable fishing crafts before light fishing spreads to most parts of the lake.

The future prospects for the Lake Victoria fishery

The annual fish yields from Lake Victoria have been increasing when the species diversity was dramatically declining. The new fishery is dominated by the introduced predator (Lates niloticus Linne), the exotic herbivore (Oreochromis niloticus Linne) and an indigenous zooplanktivore (Rastrineobola argentea Pellegrin). While the three predominant fish species could sustain the high catch levels, the future viability for the fishery will depend on prudent exploitation regimes and effective management and conservation strategies.

The socio-economic aspects of the fishing communities of Lake Victoria, Uganda

A baseline survey of the fishing communities was conducted in 2005/06 as one of the main studies under the Socio-economic Research and Monitoring Working Group on Lake Victoria. The overall objective of the survey was to provide a deeper understanding of the broad socio-economic characteristics and well being of the different stakeholder groups immediately dependent on the Lake Victoria fisheries. An understanding of socioeconomic status of the fishery primary stakeholders, who include fishers, artisanal processors and traders, is essential for any subsequent periodic evaluation of development. During the survey, a total of 1,235 respondents were interviewed, at 34 landing sites in all the Ugandan districts on Lake Victoria. The purpose of this fact sheet is to provide information on the fish landing beaches, people involved in fisheries, their livelihood activities and facilities available to them.

Lake Victoria fisheries catch assessment survey (CAS) information June 2006

The National Fisheries Resources Research Institute (NAFIRRI), the Department of Fisheries Resources (DFR) and the districts in and around Lake Victoria jointly conduct Catch Assessment Surveys (CAS) with a major objective of providing information on the magnitude of fish catches in the lake. Fisheries contribute as high as 12% to Uganda's GDP. Catch assessment surveys are some of the avenues used to collect information for monitoring fish population dynamics as well as the magnitude, distribution and trends of fishing effort and fish catches. They are necessary for making sound decisions for the management of Lake Victoria fisheries. This information provides the Catch Per Unit of Effort (CPUE). The CPUE is used together with frame survey data to estimate total fish catches.

Investigations of the present factors affecting the population characteristics and relative abundance of nile perch (Lates niloticus) at selected trawling sites of western part of Lake Victoria, Uganda, Kagegi Gulf

This report is based on the investigation of the factors affecting population characteristics and relative abundance of Nile perch in selected sites of Kagegi Gulf Lake Victoria Uganda in the month of November 2006. Nine (9) stations were sampled at depth strata of 0-10, 10-20, 20-30 and 30-40 m the mean catch rates were as follows; 8.75±5.5, 4.77±2.3, 6.33±0.3 and 1.34±1.1 tonnes per square kilometer respectively. The catch rates differed at various depth levels with p-value of 0.2940 at 5% level of significance. Limnological parameters were temperature 25.15±0.28, 23.68±0.20, 24.74±0.13 and 25.3±0.20°C; pH of 8.0±0.00, 7.7±0.11; 7.66±0.33 and 6.32±0.14, dissolved oxygen 7.37±0.24, 6.44±0.30, 6.32±0.14 and 6.22±0.14 mg/l; Total nitrogen 589.82±97.2, 514.34±68.8, 690.44±257.8 and 809.03±45.02 µgL-respectively with a p-value of 0.4392 at 5% level of significance. Prey type of Nile perch indicated 65.2% of haplochromine in 0-10 m depth and other strata >10 metre were dominated by Caridina nilotica. Generally investigations indicated that the catch rates of Nile perch at Kagegi gulf in various depth strata probably depended on both the physical and chemical parameters mentioned above.

The effect of hook size on the catch rate and size of the Nile perch Lates niloticus (Linne) fishery in the Napoleon Gulf, Lake Victoria, Uganda

This study was undertaken in Napoleon gulf, Lake Victoria Uganda from July – December 2009. It was conducted in four landing sites; Bukaya (0.41103N, 33.19133E), Bugungu (0.40216N, 33.2028E), Busana (0.39062N, 33.25228E) and Kikondo (0.3995N, 33.21848E) all from Buikwe district (Formerly part of Mukono district). The main aim was to determine the effect of both hook size and bait type on the catch rate (mean weight) and size composition of Nile perch (Lates niloticus) (LINNE) fishery in the Napoleon Gulf, Lake Victoria. The main hook sizes investigated during the experiment were 7, 8, 9, 10, 11 and 12 that were dominantly used in harvesting Nile perch in Napoleon Gulf, Lake Victoria. In this study length, weight and bait type data were collected on site from each boat at that particular fishing spot; since most fishermen in the Napoleon Gulf could sell their fish immediately the catch is caught there and then. The results indicated a total of 873 Nile perch fish samples collected during the study. Statistical tests, descriptive statistics, regression and correlation were all carried out using the Statistical Package for the Social Sciences (SPSS) in addition to Microsoft excel. The bait types in the Gulf ranged from 5-10 cm Total length (TL) haplochromine, 24.5-27 cm TL Mormyrus kannume and 9-24 cm TL Clarias species. The bait types had a significant effect on the catch rate and also on the size composition the fish harvested measured as Total length (ANCOVA F=8.231; P<0.05) despite the fact that bait type had no influence on mean weight of fish captured (ANCOVA F=2.898; P>0.05). Hook sizes used by the fishers had a significant effect on the both the size (TL) composition (ANCOVA F=3.847; P<0.05) and the mean weight (ANCOVA F=4.599; P<0.005) of the Nile perch captured. Investigations indicated hook sizes seven (7) and eight (8) were the ones that harvested the Nile perch above the slot size of 50 cm total length. In general hook sizes indicated to be the main drive in the harvesting of the Nile perch though bait type also contributed toward that. Generally there is need for management to put a law in place on the minimum hook size to be used on the harvesting of the Nile perch and also monitored by the Fisheries Management as a regulatory measure. In addition to that aquaculture should be encouraged to farm the fish for bait at a higher scale in the region in order to avoid depleting the wild stocks already in danger of extinction. Through this kind of venture, both biodiversity conservation and environmental sustainability will be observed in the Lake Victoria basin.

The effect of Lampara net on the catch rates and size of the fishing harvest of Rastrineobola argentae (mukene) in selected parts of Lake Victoria, Uganda

This study was undertaken in Napoleon gulf, and part of the off shore area of Lake Victoria Uganda in the landing site of Lufu in Buvuma district in the month of October 2015 for three days of sampling. It was conducted in four landing sites; Busana, Kikondo from Buikwe district and Lufu landing site from Buvuma district. The main aim was to determine the effect of Lampara net on the catch rate and size of the Rastrineobola argentae (mukene) harvested on Lake Victoria using various mesh sizes. The study focused on the 5mm and 10 mm mesh sizes of the Lampara net. A total of 109 boats were sampled; from the 5 mm mesh sizes indicated catch rates of 78-200 kg/boat/day and yet for 10 mm mesh size was at 248 kg/boat day. Statistical tests were carried out on the these two mesh sizes using One way Anova and indicated in catches was (Anova F=7.476; P<0.05) and for the price values was (Anova F=5.488 ; P<0.05). This is an indication that despite the fact that the mukene fishery is on the increase, a time will come when it also be depleted so a need to use the rightful fishing gear of 10mm mesh size is advisable for the biodiversity conservation.

Age, growth, tagging of tilapia spp. and reproductive biology of siluroid catfishes in Lake Victoria

This report encompasses the time period 1 September 1973 through 31 July 1975. The research Officer's tour of duty officially terminated 30 September 1975, consisting of a regular 2-year tour of duty with three month extension of contract. During this time research into age and growth of several tropical species of fishes was conducted. In addition a closely related tagging program was initiated in order to determine both growth and movements of fishes. Lastly, some effort was directed towards aspects of the basic biology of several of the siluroid catfishes. This report delineates the relative effort into and success of the various research projects; presents results of research not previously offered, summarizes findings, and makes recommendations for future research endeavour. Two annual reports along with quarterly reports up to 30 June 1975 have been produced and are on file both at Headquarters in Jinja and the Kisumu Sub-station. These only will be referred to in some instances and built upon in others. Opinions offered, conclusions drawn and recommendation given within this report are solely those of the research officer employed in an official capacity for E.A.F.F.R.O.

Adoption of catamaran fishing method for mukene (Rastrineobola argentea) in off shore waters of Lake Victoria

This report presents information on the development of a system for commercial harvesting of Rastrineobola argentea (Mukene) in Lake Victoria. The objective of this work is to develop a system for commercial Harvesting of Mukene with: •Targeted output above 1,000 kg per working night per boat. •Target area to be off shore waters of Lake Victoria. •Drying under hygienic conditions for production of high quality poultry and animal feeds. •Supply to be continuous with predicable prices

Commercialization of the fisheries of Lake Victoria and its implications for local livelihoods

The purpose of this paper is to examine the impact of commercialization on the livelihood of local people. The paper attempts to provide an understating of the key elements of the local livelihoods and how they are affected by the process of commercialization within fisheries.

Lake Victoria Fisheries Service Annual Report 1959/60

The Annual report provides information on work carried out on Lake Victoria by the Lake Victoria Fisheries Service during the period 1959/60. It provides annual catch statistics, fisheries control and legislation.

Aquatic weeds hotspots in the Lake Victoria basin Uganda and on Lake Kyoga: implications for their management

Proliferation of invasive aquatic weeds has developed into a major ecological and socio economic issue for many regions of the world. As a consequence, inference on where to target control and other management efforts is critical in the management of aquatic weeds (Ibáñez et al., 2009). Notwithstanding, aquatic systems in Uganda in general and in the basins of Lakes Victoria and Kyoga in particular, have fallen victims to aquatic weeds invasion and subsequent infestation. If these aquatic weeds infestations are to be minimized and their impacts mitigated, management decisions ought to be based on up-to-date data and information in relation to location of infestation hotspots. Aquatic systems in the basins of the two production systems are important sources of livelihoods especially from fish production and trade yet they are prone to infestation by aquatic weeds. Thus, the invasion and subsequent infestation of aquatic ecosystems by aquatic weeds pose a major conservation threat to various aquatic resources (Catford et al., 2011; Kayanja, 2002). This paper examines the extent to which aquatic weeds have infested aquatic ecosystems in the basins of Lakes Victoria and Kyoga. The information is expected to guide management of major aquatic weeds through rational allocation of the scarce resources by targeting hotspots.

The declining state of the gillnet fishery in Lake Victoria, Uganda

Lake Victoria had a multi-species fishery dominated until the 1970s by the tilapiine and the haplochromine cichlids (Kudhongania and Cordone, 1974). From about 1930 to 1960, the fisheries of Lake Victoria were managed by controlling the mesh size of gill nets. Gill nets of stretched mesh sizes less than 127 mm (5 inches) were prohibited as they cropped immature Oreochromis esculentus (Ngege), the most important commercial species on the lake (Graham, 1929). The catch per night in the legal 127 mm mesh nets was over 30 fish of O. esculentus prior to 1921 but dropped to 6 and 1.5 fish in 1928 and 1954, respectively, (Beauchamp, 1955), indicating overfishing of the stocks. The overall aim of the survey was to determine the available fish stocks being harvested by the gill net fishery. The specific objectives included the determination of the species composition and catch levels. Gill nets of mesh sizes from 25.4 mm (1 inch) to 228.6 mm (9 inches) were used.

The changing fisheries of Lake Victoria, Uganda

Lake Victoria had a complex multi-species fishery dominated until the late 1970s by the tilapiine and haplochromine cichlids but with important subsidiary fisheries of more than 20 genera of non-cichlid fishes. Since the 1980s, however, the fishery has been dominated by the Nile perch (Lates niloticus), Nile tilapia (Oreochromis niloticus eduardianus) both introduced into the lake during the late 1950s and early 1960s and Rastrineobola argentea, a pelagic cyprinid. Although the actual landed commercial catch figures from the Uganda sector of the lake point to the increased landings since 1984, the catch rates in the experimental trawl fishery and mean weight of fish in both experimental trawl and commercial fishery have been on the decline.

The impact of exploitation, competition, and predation on the changing stocks of Lake Victoria

The dramatic decline in fish species diversity in Lake Victoria has been attributed to predation by Nile perch, Lates niloticus Linne, without sufficient justification. Exploitation, interspecific competition and hybridization had profound impact on the decline of the indigenous commercial fish species. The roles of exploitation, competition and hybridization, and of predation by the Nile perch on changes in species diversity have been discussed. Lates was largely responsible only for the decline of the haplochromine stocks.