Observations on the taxonomy and biology of Lates (Cuvier 1828) in Lake Albert

Both in terms of commercial landings and biological importance, the Nile Perch is one of the most prominent fish in Lake Albert. It can bear considerable further exploitation, is the source of stockings elsewhere, and it is, therefore, important to know whether more than one species is being dealt with, and, if so, what differences there are in the ecology of the different species.

Report on Lake Wamala fisheries catch assessment survey 2012

Lake Wamala is one of the small lakes in Uganda, and lies between latitudes 0o 15; and 0o 25' N 31o 45' to longitude 32o 00' E, longitude and at an altitude of 1000m above sea level. Following ths 1961 heavy rains the lake expanded from about 100 to 118 sq. km and the swamps covered almost 60 sq km (Okaranon 1993). This lake was first stocked with Oreohromis niloticus eduardianus populary known as Oreohromis niloticus then Oreochromis leucostictus and then Tilapia zillii then after that it was officially opened for commercial fishing in 1960. Despite of the commercial fishery there used to be subsistance fishing that was mainly by the use of wires and hooks and targeted the Clarias and Protopterus species. The lake fishery used to be highly profitable after the opening in 1960; though in 1970s the fishers started complaining of the declining state of the fishery. At that time the O. niloticus had gone down to less than 1 kg per net per night by 1975 (Okaranon 1993). Due to it led to scientists undertake fisheries surveys in 1975/78 and later 1988/92 then later on there subsquent survey in 2003. Since that time there has been no work done until March 2012 that both catch assessment and frame surveys undertaken to ensure that management issues are addressed concerning this riparian water body. The main objectives of the survey were:- To assess fish production levels in the commercial fisheries of Lake Wamala (Catch Assessment). To assess the fishing effort and facilities available at the fish landings that supports the fisher folks.

Report of Lake Wamala fisheries frame survey 2012

Lake Wamala, a small lake (180 km2) located in Central Uganda and believed to have been part of the main Lake Victoria and only got separated about 4000 years ago, has already undergone different levels of fisheries evolution that warrant using it as a case study to inform changes in other systems. Using resources provided by the Lake Victoria Environmental Management Project (LVEMP) II, under the Applied Research Facility, we evaluated the fishing inputs, socio-economic infrastructure and analyzed trends in fishery benefits to guide evolution of management advice. A frame survey was conducted on the entire lake (13th - 23rd March 2012) enumerating all fishing factors and enlisting available and accessible socio-economic infrastructure along the shores of the lake. The lake traverses districts (Gomba, Mityana, and Mubende) with its largest portion lying in Mityana. There are 26 established fish landing sites and about 600 fishers with a similar number of boats on the lake. The total number of boats on the lake is almost equal to the number of fishers; illustrating the common type (paracute) and size (Small, about 4 m) of boats and hence a fishing crew structure of one fisher per boat. Main fishing gears are Gillnets targeting the tilapia (Ngege) and long line hooks (Protperus, Mamba, and Clarias, Male). Almost equal number of boats used the two main gears on the lake (about 300 each). 97% of the gill nets on the lake are small (3.5” (8.9 cm – 4.5” – 11.4 cm) stretched mesh size while 98% of the hoots are large (< size 10). The implication is gill net fishers target small tilapia while long line fishers aim at the large mamba and male. Generally the lake has poor socio-economic infrastructure compared to other lakes of Uganda probably due to its geo-morphological setting. The lakes fishing factors have continued to expand with the ever increasing population. There may be need to check the continued entry into the fisheries especially if the increasing effort does not translate into increase in fishery yield.

Comparative electrophoretic patterns of lactase dehydrogenase and malate dehydrogenase in five Lake Victoria cichlid species

Biochemical techniques designed to compare species on the basis of protein differences were started by NUTTALL (1904) who used immunological methods to compare the serum of humans with that of other primates. Since then more refined techniques have led to better results at the protein level in taxonomy, The analyses of proteins are considered to be the simplest indirect approach to understanding the structure and function of the genetic material, deoxyribonucleic acid (DNA). Interest in these analyses arises because of the close relationship between protein structure and gene structure. Thus by comparing the properties of homologous proteins from different taxa one is in essence comparins their genes (GORMAN er al., 1971). It is now an established fact that genetic information coded in molecules of DNA is translated through a series of reactions in the structure of proteins which form the principal morphological units of the animal body at the molecular level of organization (SIBLEY, 1952). A convenient method of comparing molecular differences between species is to measure the electrophoretic mobility of proteins in a starch gel medium (ASPINWALL and TSUYUKI, 1968) or acrylamide gel (RAYMOND and WEINTRAUB, 1959; BOUCK and BALL, 1968). Proteins with enzymatic properties can be compared on the basis of catalytic activity in the presence or absence of inhibitors (KAPLAN et al., 1959); BAILEY et al., t 1970). A combination of gel electrophoresis and histochemical enzyme detection techniques (HUNTER and MARKERT, 1957) makes it possible to combine electrophoretic mobility anti catalytic activity comparison, Enzyme patterns exhibited in starch gel or acrylamide gel have been used to classify different species. BOUCK and BALL (1968)working with lactate dehydrogenase in species of Trout found that each Trout species had LDH pattern characterbtic of that species. ASPINIWALL and TSUYUKI (1968) used muscle protein electrophoretic patterns to identify hybrid fishes. TSUYUKI and ROBERTS (1963) and TSUYUKI et al. (1964-65) found that myogen protein patterns in fishes were species specific. The myogen patterns within one family were remarkably parallel with the existing morphometric classification and these patterns constituted a single criterion by which the fishes could be identified. The fish used in these investigations were collected from shallow waters (10 metres) of Lake Victoria in two areas, Jinja and Kisumu, using gillnets and beach-seines. The study included ten specimens of each of the following specIes: (l) Haplochromis michaeli (2) Haploehromis obems (3) Astatoreochromis ulluaudi (4) Tilapia zillii and (5) Tilapia nilotica.

Analysis of fish catch data from 1985 to 1994 in the Kenyan inshore marine waters

Fish landing data collected by the Kenyan Fisheries Department from the nearshort coastal marine waters from 1985 to 1994 were statistically analyzed to determine trends in the traditional fisher's catch. Over the ten year period a significant decline occurred for total catch and for catches of seven commercially important fish families: Lethrinidae, Siganidae. Lutjanidae, Scaridae, Carangidae, Scombridae and Mullidae. 1994 registercd the lowest catch over ten years. The total catch for all the fish declined from a mean annual catch of 6150 metric tonnes in the 1980's to a mean of 5141 metric tonnes in the 1990's with the catch for 1986 being 2 times higher than that of 1994. Although Mombasa district had the highest mean annual landing, its total landings like that of Lamu and Kwale districts decreased over the years. However, Kilifi district showed a steady increase in catches over the years. The changes in fish landings is thought to be caused by lack of appropriate fishing regulations, leading to overfishing of the lagoonal reefs beyond their maximum sustainable yields.