Recognizing of Ichthyophon and investigation of feeding and effects of water temperature, salinity and electrical conductivity on the population dynamic of Barbus grypus in the Dalaki and Helle river

This study was carried out for recognized ichthyophon and investigation of feeding and effects of water temperature, salinity and electrical conductivity on the population dynamic of Barbus grypus in the Dalaki and Helle river. In the study period, 2949 Barbus grypus was cached. The most of total length frequency was 200 to 300 mm and 2 to 3 years old. The oldest fish was8 years old with 756 mm total length. Fecundity was 950 upto 57400 oocyt per fish. Station no. 6 and 7 showed more temperature, fecundity and GSI than other stations. Females adulated before then males. Multiple stepwise regression of fecundity and RE (reproduction effort) showed significant correlation. Fishes of the upper parts of stream was more L than down stream stations. Condition factor of males was more than female, and for down stream stations was better than the other stations. Barbus grypus is omnivorous. Ichthyophon of Dalaki river include 4 family and 9 species that Capoeta capoeta intermadia was more than others species, but in the Helle river was 5 family and 9 species, that Liza abu zarudni was more than others.

Population dynamics of Terapon jarbua (Forskal) in coastal area of Pakistani waters

Terapon jarbua is a widely distributed species in Pakistani inshore waters. It is well cherished by local coastal population. Present study is an attempt to determine some parameters of the population dynamics of the species in Pakistani waters. Analysis of data shows that the species attains asymptotic length (Loo) at 33.2 cm and have growth curve (K) of 0.62. Total mortality coefficient (Z) comes to 1. 67 per year, natural mortality coefficient (M) is estimated as 1.23 per year. The fishing mortality (F) is about 0.44 per year; whereas exploitation rate E=0.26.

A baseline survey of water quality, invertebrates, fisheries and socioeconomics on Lake Edward for proposed seismic surveys in block 4B : Final report

The National Fisheries Resources Research Institute (NaFIRRI) on behalf of OPEP Consult Ltd undertook a baseline survey of the transition zone (basically along the shoreline) and near shore habitats of the Uganda apart of Lake Edward and Kazinga channel during December 2007 to January 2008. A major objective of the baseline survey was to generate baseline information on the aquatic ecosystem features related to the fisheries and socio-economics of the fish catch including issues raised by residents in the fish landing sites. Therefore, the baseline survey captured information on water quality, the aquatic invertebrate fauna, aspects of fish biology and ecology, the fish catch including facilities at fish landings, value in the catch and related fisheries socio-economic issues perceived by residents in the settled areas along the shores.

Some major unsolved aspects of the dynamics of African fisheries as related to questions of rational development and management

Studies of fish and fisheries in Africa fall in to four phases: the period of fisheries expeditions, ecological investigations, the development phase, and the period of mechanized exploitation. There is need to establish the taxonomic status and ecology of the varied components of the potentially important Haplochromis in Lake Victoria. A comprehensive study of their bionomics and life history, population structure, natality, recruitment and mortality coefficients should be undertaken. Emphasis lo be laid on the study of the ecology, especially breeding behaviour of the economically important c1upeids (Stolothrissa tanganciae and Limnothrissa miodon), in Lake Tanganyika. A comprehensive investigation into the migratory and shoaling behaviour of the Lake Victoria Tilapia to be initiated. Pre-impoundment studies to be undertaken to assess effects of hydroelectric projects of fisheries. Studies on parasites of economically important fishes to be stepped up to assess pathological effects and the biological basis for their control. The role of predators, e.g., Hydrocyon, Lates and Micropterus salmoides in commercial fish populations should be evaluated, and the knowledge gaincd used to effectively manage the fisheries in favour of the more desirable fish stocks.

The potential for further proliferation of water hyacinth in Lakes Victoria, Kyoga and Kwania and some urgent aspects for research

Shore environments of Lakes Victoria and Kyoga with potential for the establishment and proliferation of water hyacinth were identified. They are characterised by: (i) shelter from violent off-shore and along-the-shore wind and wave action (ii) flat or gentle slope under relatively shallow water, and (iii) a muddy bottom rich in organic matter. Such environments are strongly associated with emergent macrophytes of papyrus, Vossia sp and, at times Typha sp where Pistia stratiotes, species of ceratophyllum, myriophylum and nymphaea also occur. In Lake Kyoga association with Vossia sp facilitated establishment of water hyacinth even along wind-swept shores and promoted extension of mats of the two machrophytes into the open lake. Urgent research on water hyacinth is proposed in the areas of nutrient relations, weed biology and on its impact on the biodiversity resource, with particular emphasis on the fishery component. Findings from the research could facilitate formulation of weed control options and alternative resource management strategies. A regional approach to address the water hyacinth menace is highly recommended.

Knowledge, perceptions, impacts and roles of lakeside communities and institutions in the sustainable control of water hyacinth

The massive water hyacinth mats that covered water bodies in the 1990s had serious social and economic impacts. They affected fishing, transportation, water quality and health of fishing communities as well as production of goods and services of lake-based institutions (commercial establishments). At peak infestations, the communities and institutions were aware of and participated readily in control effort. However, after the major collapse of hyacinth in 1998, some of them relaxed in their control efforts. The status of knowledge, perception, impacts, preparedness and role of the lakeside communities and institutions to control the weed has, therefore, been monitored since the major resurgence of the weed to find out if the lakeside communities and institutions still perceive water hyacinth as a problem and the extent to which they are prepared to sustain control.

Environmental factors influencing composition, abundance and distribution of water hyacinth

Relationships between nutrient concentrations and water hyacinth biomass and composition have been studied in the shallow inshore bays of lakes Victoria, Kyoga and Albert. Additional information was obtained from Victoria Nile, Albert Nile and Kagera River. In this section, seasonal changes in nutrients and oxygen concentrations are used to explain changes in water hyacinth composition, biomass and distribution in Lake Victoria. Lake Victoria is of particular interest because it experienced strong hyacinth infestations in 1995, a sink in 1998 and resurgence in 2001. The lake has also been extensively sampled and provides time series data in nutrient, oxygen, mixing and thermal stratification which provide an opportunity to relate water hyacinth distribution and biomass to environmental factors. The possible origins and impacts of nutrient loads into Lake Victoria are also discussed in relation to water hyacinth proliferation and distribution especially in relation to known 'hot-spots'.

Contribution of biological control in management of water hyacinth

Biological control was foreseen as the long-term strategy for controlling water hyacinth in Uganda. Two species of weevils, Neochetina eichhorniae and Neochetina bruchi were imported into Uganda from Benin (West Africa) in 1993. A total of 600 weevils of each species were imported. The weevils were tested for specificity using key agricultural crops including maize, beans and bananas and were found to be water-hyacinth specific for their food and reproduction.