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.

Nota acerca de una especimen del género Potamotrygon (Chondrichthyes, Potamotrygonidae).

Its deal with the study of a sample of "river ray" of the Potamotrygonidae family procured in the Colastiné river (Midle Paraná)showing an external morphology relating it closely to two species of said family: Potamotrygon falkneri Castex y Maciel, 1963 and P. menchacai Martínez Achembach, 1965.

Water quality objectives as a management tool for sustainability

The aim of this paper is to explore the potential role that quality objectives, particularly when backed by statutory force, may play in the sustainable management of river water quality. Economic valuation techniques are discussed, as well as the theory of "critical natural capital". A brief history of water quality legislation includes the implementation of the National Water Council classification in 1979, and the statutory water quality objectives introduced under the Water Resources Act 1991.

Upland hill farming for water, wildlife and food

The economic, environmental and social benefits of more sensitive land use practices that protect or restore the natural functions of river catchments have been widely discussed. Changing land use has implications for a wide range of other biological communities. Some studies have already been undertaken on the benefits of sensitive farming at the catchment scale in England and Wales. However, there is a gap in these studies at the local scale, and particularly for upland farms from which headwaters arise. This article documents a case study relating to a successful partnership in Cumbria, UK, set within the wider context of catchment management. Whilst the case study is not highly detailed, and some costs have been described in outline only to protect confidentiality and commercial sensitivity, it provides some generic lessons and may therefore be useful in informing more sustainable policy-making. High Hullockhowe Farm near Haweswater, which was used a the case study highlighting changes in farm practise, costs and benefits, water resources and biodiversity. The authors relate the case study to wider policy implications.

Using RIVPACS for studies on conservation and biodiversity

Invertebrate conservation relies not only on public support and political will, but also on possessing an adequate understanding of the distribution and ecology of invertebrate species and communities. In the UK, RIVPACS is making an important contribution to assessing the conservation importance of river invertebrate assemblages. So far, work has largely centred on using RIVPACS as an integral part of SERCON (System for Evaluating Rivers for Conservation), in which data collected using the standard RIVPACS method are interpreted with reference to conservation criteria such as species richness and representativeness. Applications of RIVPACS to other areas of conservation - whether providing information on the ecological requirements of rare species, monitoring the success of river restoration projects, or making broader assessments of sustainability - are probably more limited, but merit further examination. It is important to develop closer links between RIVPACS and techniques such as SERCON and RHS (River Habitat Survey) in order to maximise the benefit each can bring tostudies on conservation and biodiversity. It should also be recognised that there are limitations in transferring such systems to other countries where approaches to nature conservation may be very different.

Fish bioecology in relation to sediments in the Mekong and in tropical rivers

Sediments are an essential component of rivers and of their biological functioning. In addition to their influence on river geomorphology (maintenance of river forms and habitats such as pools and sand bars), sediments also include nutrients, detritus and organic debris of various sizes which interact with the river’s different life forms, including fish. The interaction between sediments and aquatic organisms, directly or indirectly through the effects of sediments on physical habitats, unquestionably influences the biodiversity and productivity of a river. The current report reviews the interactions between sediments and fish in tropical rivers and in the Mekong, and focuses more specifically on a reduction of sediment loads following dam const

Lune, Wyre & Furness Fisheries Advisory Committee 5th May, 1975

This is the report from the Lune, Wyre and Furness Fisheries Advisory Committee meeting, which was held on the 5th May, 1975. It covers information on fishery byelaws, Eel trapping, and a report by the Unit Fisheries Officer on fisheries activities. This section includes work on stocking, fisheries management, fish mortalities, migratory fish runs for the Rivers Lune, Wyre and Furness during 1974. Catch returns and spawning information for 1974 are also covered aswell as biological work and the approval of River Leven work. Other areas looked at include licence duties and inportation of live freshwater fish. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.

West Cumbria Special Fisheries Advisory Group 9th March, 1983

This is the report from the West Cumbria Special Fisheries Advisory Group meeting, which was held on the 9th March, 1983. The report contains sections on Fish Passes at Yearl Weir River Derwent, Ennerdale, and Ehen; River Calder abstraction and augmentation from boreholes; and the augmentation of River Ehen by minewater to support increased abstraction by BNFL. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.

East African Freshwater Fishery Research Organization Annual Report 1961

The Annual report presents Scientific work carried out during the report year 1961 under the following: Scientific Work of the Organization Fisheries of Lake Victoria Commercial records Population analysis Rational exploitation Other species of Tilapia Small mesh gill net fisheries Bagrus docmac Investigation Lates Investigation Breeding studies on T. zillii & T. nigra The culture of Tilapia in ponds Migration of River Fish Hydrology and Algology Gear Research Buoy releases Vertical gill nets and lastly publications.

Modeling the effect of striped bass (Morone saxatilis) on the population viability of Sacramento River winter-run chinook salmon (Onchorhynchus tshawytscha)

We estimated the impact of striped bass (Morone saxatilis) predation on winter-run chinook salmon (Oncorhynchus tshawytscha) with a Bayesian population dynamics model using striped bass and winter-run chinook salmon population abundance data. Winter-run chinook salmon extinction and recovery probabilities under different future striped bass abundance levels were estimated by simulating from the posterior distribution of model parameters. The model predicts that if the striped bass population declines to 512,000 adults as expected in the absence of stocking, winter-run chinook salmon will have about a 28% chance of quasi-extinction (defined as three consecutive spawning runs of fewer than 200 adults) within 50 years. If stocking stabilizes the striped bass population at 700,000 adults, the predicted quasi-extinction probability is 30%. A more ambitious stocking program that maintains a population of 3 million adult striped bass would increase the predicted quasi-extinction probability to 55%. Extinction probability, but not recovery probability, was fairly insensitive to assumptions about density dependence. We conclude that winter-run chinook salmon face a serious extinction risk without augmentation of the striped bass population and that substantial increases in striped bass abundance could significantly increase the threat to winter-run chi-nook salmon if not mitigated by increasing winter chinook salmon survival in some other way.

Age, growth and life history of Klamath River Basin steelhead trout (Onchorhynchus mykiss irideus) as determined from scale analysis

Adult steelhead (Oncorhynchus mykiss irideus) scales were analyzed from eight fall-run, two spring-run, and one winter-run stocks within the Klamath-Trinity River system, from 1981 through 1983, to provide basic information on age, growth, and life history. The higher degree of half-pounder occurrence of upper Klamath River steelhead stocks (86.7 to 100%) compared to Trinity River steelhead stocks (32.0 to 80.0%) was the major life history difference noted in scale analysis. Early life history was similar for all areas sampled with most juveniles (86.4%) remaining in freshwater during the first two years of life before migrating to sea. Repeat spawning ranged from 17.6 to 47.9% for fall-run, 40.0 to 63.6% for spring-run, and 31.1% for winter-run steelhead. Mean length of adults at first spawning was inversely related to percent half-pounder occurrence in each stock. Ages of returning spawners, back calculated lengths at various life stages, and growth information are presented. (PDF contains 22 pages)

Flow and chemical characteristics of the St. Johns River at Jacksonville, Florida

This report will be of substantial value to water managers in developing the St. Johns River as a multiple resource. Evaluation of the capacity of the river to accept pollutants without adversely affecting other uses requires detailed data of flow and chemical characteristics and an understanding of how they interact. (66 page document)

Wetland Habitat Types of the Carmel River Lagoon.

This is a report delivered to California Department of Parks and Recreation. The purpose of this report is to document and describe the presence, location, and general characteristics for each of the wetland types currently found in the lagoon area. Comments are also made on the general use by different fauna. (Document contains 15 pages)

Interim report on geology and ground-water resources of Indian River County, Florida

In the area of this investigation a partial inventory was made of the estimated 2,000 existing wells to obtain information on location, depth, and yield of representative wells. Also, data were obtained on the quality of water from the various aquifers, and on the fluctuation of water levels in certain wells in the Floridan aquifer. The hydraulic characteristics of the Floridan aquifer at several sites were determined by means of pumping tests. (PDF has 80 pages.)

Invasion of Egeria into the Hawkesbury-Nepean River, Australia

The Hawkesbury-Nepean River in New South Wales (NSW), Australia, is the largest river system in the Sydney metropolitan area, and it drains most of the developing areas to the west. This catchment is under increasing pressure from urban expansion and the river frequently experiences extended periods of low flows due to a combination of extensive river regulation and the Australian temperate climate. Added to this, the river and several of its tributaries receive treated sewage and stormwater from various sources. Habitats and biota within the Hawkesbury-Nepean River catchment have been altered since European settlement and many introduced species have spread throughout the terrestrial and aquatic environment (Recher et al. 1993). Submersed macrophyte assemblages within the river have undergone significant changes in their distribution and abundance due to eutrophication, habitat alteration and changes to river flows (Recher et al 1993). Anecdotal evidence and some early unpublished studies suggest that egeria (Egeria densa Planchon), introduced from South America as an aquarium plant, was present in the Hawkesbury-Nepean River prior to 1980. Sainty (1973) reported a persistent and troublesome infestation over a number of years at Wallacia in the upper Nepean River. Here, as part of a larger study on the ecology of macrophyte and invertebrate assemblages associated with anthropogenic disturbance in the Hawkesbury-Nepean River, we document the rapid spread of egeria since 1994. Significant increases in egeria biomass were also found, and we present preliminary evidence which suggest that the native ribbonweed, vallisneria (Vallisneria americana Michx.) is being displaced.