Impacts of fishery activities on lake shore environment and options for sustainable management

Over the years, degradation of the lakeshore resources has been going on due to human induced activities. Human activities notably house construction, fish smoking, boat construction and cooking at the landings impact the tree and forest cover along the lakeshore and Islands. The survey was conducted in ten districts surrounding Lake Victoria and the landings sampled were selected with the help of the District Fisheries Officers. Data was obtained from selected fishermen and Key informants at these landing sites. The study examined the extent of knowledge on importance, utilization, threats and conservation of trees/forests at the landings. Results showed that the fishers (98%) were aware of the benefits derived from the trees/forests. According to the respondents, the most commonly used tree species for boat construction were Mvule (40%), Mkibu (20%), Musizi (17%) and Mpewere (11 %). This was mainly because these trees were durable. For house construction, Nsambya (25%), Musizi (24%) and other materials (12%) were the most commonly used. For other activities like fish smoking and cooking at the landing, the Fisherfolk used any type of tree species readily available at the landings. As regards the status of the trees at the landings, most of the respondents (72%) J agreed that due to some fishery related activities some tree species had reduced more than others in the vicinity of most landings. Most respondents said that the, most reduced tree species around the landings were Mvule (36%) and Musizi (22%). Among the fishery related activities that had a significant impact on the trees/forests, construction of houses (44%) and boats (22%) emerged uppermost. Other activities such as fish smoking (14%) and cooking (12%) had the least impact on trees/forests. Generally, there was extensive reduction of trees at the landings. Therefore there was need to regulate cutting of trees and to have specific programmes targeting afforestation at and around fish landings.

Annual report on fish production Lake George, Edward and Kazinga Channel (Kichamba Region) 1993/1994

This report gives details of catch assessment statistics of Lakes George, Edward and Kazinga channel plus minor Lakes in western Uganda. Eight districts are covered namely:-Kasese, Bushenyi, Rukungiri, Kabarole, Ntungamo, Mbarara, Kabale and Kisoro. Of the eight districts major lake fishery is in the first four, the rest minor lake fishery as shown below:-Ntungamo- Nyabihoko and Nyakiyanja, Mbarara-Mburo, Kachere and Nakivale, Kisolo- Mutanda, Mulehe, Chahafi and Kayumbu) and Kabale Lake Bunyonyi). Data on Lake Bunyonyi was not availab1e for both 1993/94; however reports say fewer Clarias are caught using basket traps and hooks.

Diet seasonality and overlap of Chrysichthys species on Lake Kainji, Nigeria

Seasonality and overlap of diet of Chrysichthys species in Kainji Lake was studied for a period of one year. A total of two hundred and forty five Chrysichthys nigrodigitatus and one hundred and nineteen Chrysichthys auratus longifilis were used during the study. Chrysichthys species food items ranged from plant to animal materials. Seasonal variations of diet showed that plant material dominated the diet of both species in rainy and dry seasons. While zygoptera and Lumbiculus were absent in the diet of Chrysichthys auratus longifilis in rainy season, zygoptera and nematode were absent in dry season. There was significant correlation (p< 0.01) of the items between the two species. There was also high level of association between their diets, which indicated that both species have similar diet. Lake Kainji is a good environment for the survival of Chrysichthys species. KEYWORDS: Chrysichthys species, overlap, diet, seasonality, Kainji Lake, Nigeria

Rapid assessment of the fish biodiversity of the Mburo-Nakivali wetland systems and Opeta-Bisina wetland systems, Uganda

There are 46 different fish species in the Lake Kyoga basin with some of them endemic. The Nile Perch (Lates niloticus) was introduced into the main Lake Kyoga, Nakuwa and Bisina in the late 1950s to increase the fish production. The Nile Perch profileration in lakes Kyoga and Nakuwa led to the almost complete elimination of many native fish species such as Orechromis esculentus and variabilis, Mormyrus kanumme, Schilbe mystus and several Haplochromines species. Lakes Mburo, Kachera, Nakivali and Kijjanebalora are part of the complex system of lakes separated from Lake Victoria by extended swamps known as the Koki lakes, some of the satellite lakes in the Lake Victoria basin. The fisheries of these lakes are important as they contribute to government efforts of increasing food security, poverty reduction and conservation of natural resource base. These lakes are important biodiversity areas because some of these lakes have been found to contain the native tilapiine Oreochromis esculentus (Ngege), absent or threatened with extinction in the main Lakes Victoria and Kyoga. It’s also important to note that this species is only unique to the Victoria and Kyoga lake basins (Graham, 1929, Worthington, 1929). The values of some of these lake fisheries are however, threatened by human activities such as over exploitation, introduction of exotics especially water hyacinth that is already present in River Rwizi and habitat degradation among others.

Lake Nabugabo: a potential reservoir for mukene (Rastrineobola argentea)

"Mukene"Rastrineobola argentea occurs in lakes Victoria, Kyoga, Nabugabo and the Victoria Nile. On lakes Victoria and Kyoga the commercial fishery is well developed. While some fishing occurs at isolated places on the Victoria Nile, the species is yet to be exploited on lake Nabugabo although the potential exists. Experimental fishing (light fishing and beach seining) was conducted on Lake Nabugabo based at the Lake Nabugabo Holiday and Conference Center. Specimens obtained were analyzed for biological and fisheries parameters. Mukene on Lake Nabugabo still grows to a large adult size compared to the Lake Victoria populations. Size at first maturity at 42mmSL is close to that observed on Lake Victoria. Peak breeding occurred between August and January. Unlike on Lake Victoria, R.argentea in Lake Nabugabo is not infested by the cestode Ligula intestinalis that is common in these fishes. Catch rates of 9.8 kg/lamp/hr by the lampara net on this lake compare favorably with many parts of Lake Victoria and on Lake Kyoga where a commercial fishery exists. The amount of by-catch species in the catches however is high and does not therefore favour the establishment of the fishery on this lake. Human exploitation of mukene on Lake Nabugabo would also affect the Nile perch fishery which depends on the species as a source of food.

Lake Albert fisheries resources and their management strategy

Lake Albert/Mobutu lies along the Zaire-Uganda border in 43/57 per cent ratio in the faulted depression tending south-west to the north east. It is bounded by latitudes 1o0 n to 2o 20’ N and longitudes 30o 20’ to 31o 20’E. It has a width varying from 35 to 45 km (22 to 28 miles) as measured between the scarps at the lake level. It covers an area of 5600km2 and has a maximum depth of 48m. The major inflow is through the Semiliki, an outflow of Lake Edward, Muzizi and Victoria Nile draining lakes Victoria and Kyoga while the Albert Nile is the outflow. The physical, chemical and biological productivity parameters are summarized in Table 1. The scarp is steep but not sheer and there are at least 4 tracks leading down it to villages on the shore and scarp land scarp is a young one, formed as a result of earth movements of the Pleistocene times, and the numerous streams come down headlong down its thousand feet drop, more often than not in falls (Baker, 1954). Sometimes there appears to be a clean fault; and at other places there is the appearrence of step faulting, although this may be of only a superical nature .The escarpment’s composed of rocks belonging to the pre-Cambrian Basement complex of the content; but the floor of the depression is covered with young sedimentary rocks, known as kaiso beds. In their upper part these latter beds contains many pebbles; whilst low down the occurrence fossiliferous beds is sufficiently rare phenomenon in the interior plateau of Africa. The kaiso beds dated as possibly middle Pleistocene in age, are exposed in various flats on the shore, and they presumably extend under the relatively shallow waters of the lake. A feature of the shore is the development of sandpits and the enclosure of lagoons; and these can be observed in various stages of development at kaiso, Tonya, kibiro, Buhuka and above all, at Butiaba. On an island lake over 1100 km (700 miles) from the shores of the Indian Ocean one can thus study some of the shore-line phenomena usually associated with the sea- coast (Worthington, 1929). In the north, from Butiaba onwards, the flats become wider and from a continuous lowland as the lake shore curves away from the straight edge of the escarpment. At a height of just 610m (2000 feet) above sea-level, the rift valley floor at Butiaba has a mean annual temperature of 25.60c (780 f), from which there is virtually no seasonal variation; and and the mean daily range is only 6.50c (130f) (E.Afr. met. Dept.1953). With a mean annual rainfall of not much more than 762mm (309 inches) and only 92 rain days in ayear, again to judge from Butiaba, conditions in the rift valley are semi-arid; and the vegetation cover consists of grasses and scattered drought-resisting trees and bushes. Only near the stream courses does the vegetation thicken.

Fishing effort and fish yield over a 15 year period on Lake Victoria, Uganda: management implications

The National Fisheries Resources Research Institute (NaFIRRI), the Directorate of Fisheries Resources (DiFR), the Local Government fisheries staff and those from the Beach Management Units (BMUs) of the riparian districts to Lake Victoria regularly and jointly conduct Frame and Catch Assessment Surveys. The information obtained is used to guide fisheries management and development. We reveal the trends in the commercial fish catch landings and fishing effort on the Uganda side of Lake Victoria, over a 15 year period (2000-2015) and provide the underlying factors to the observed changes. The contribution of the high value large size species (Nile perch and Tilapia) to the commercial catch of Lake Victoria has significantly reduced while that of the low value small size species, Mukene has increased over a ten year (2005-2015)period. The information is intended to update and sensitize the key stakeholders on the status of the Lake Victoria fisheries. In addition, the information provided is expected to guide policy formulation and management planning by the fisheries managers at all levels including the BMUs and Landing Site Management Committees (LSMCs), the Local government fisheries staff and the Directorate of Fisheries Resources. The information is anticipated to create awareness among the lakeside fisher communities to reverse the current trend in fish declines.