979 resultados para Mekong River Commission


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This is the 7th Annual Report of the Rive Exe Scale Reading Investigation for the 1972 Season by the Devon River Authority. The object of this investigation is to examine, by means of scale reading, the biology of age classes of the salmon population of the River Exe. It reviews the methods used for the collection of scales and examination of the materials. It shows the results of the survey and the number of scales studied from each of the various sea-age classes, time of running with distribution of the sea-age groups throughout the season, fish sizes and smolt ages at migration. All is summarized in tables, and figures are included showing weight distributions for each age classes and frequency distributions.

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This is a Report on an Investigation of the Lower River Bovey. It contains general information about the lower River Bovy as well as a description of the methodology, observations on the river including plants, fish and invertebrates. An extended comparison with other similar river and conclusion which contains allusions to pollution evidences, fishing deterioration, and possible causes. It includes sampling stations location map, list of collected animals, record of brown trout caught and water analysis.

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This is the River Goyt & Etherow Crayfish Survey report from the Environment Agency held between August and November 2000. The report focuses on the need to verify the presence of the non-native American signal crayfish (Pacifastacus leniusculus) in the main River Goyt, and determine its distribution. Signal crayfish have been reported in the River Goyt after spreading from a known population centre in Hollywood End Brook, to the east of Marple Bridge. The report contains sections on results, discussion and a summary. The section on results shows maps of presence or absence of different crayfish species in River Goyt, and the Mersey/ Weaver river systems such American signal crayfish (Pacifastacus leniusculus) and European freshwater crayfish (Austopotamobius pallipes).

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This is the assessment and exploitation of eel (Anguilla anguilla. L) stocks in the River Thames and its catchment performed by the Polytechnic of Central London and The Thames Water Authority Research Project between April 1985 and April 1986. The report makes an examination of the pre-pollution history of the Thames eel fishing industry to permit an assessment of the recovery of the eel stock following the cleaning up of the Tideway. Archive material shows that the 19th Century stock was larger and more widely distributed than it is today, and the natural recruitment of elvers to the system is now much smaller. Sampling of commercial catches and trapping studies, including comparisons of different mesh sizes, have been undertaken in order to develop a statistical model of the Inner Estuary eel stock and its fishery. Local migrations and activity throughout the year are studied. Electro—fishing methods and eel traps are compared using mark-recapture techniques in order to develop an accurate means of assessing relative abundance and distribution. Work so far has concentrated mainly on the Rivers Darent and Roding but a preliminary distribution map for the whole catchment has been prepared. An experimental trapping site was established on the River Darent to investigate natural recruitment and up—river migration of elvers and juvenile eels. 1790 small eels were taken in 1985 providing information on the scale, timings and factors affecting the migration.

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This is the Argumentation of the River Derwent using Thirlmere produced by the Cumberland River Authority in 1972. This report focuses on the augmentation of the River Derwent by a limited discharge from the Thirlmere Reservoir in short terms. A Working Party of officers from both the Authority and the Corporation was established and experimental releases of water from Thirlmere were made in dry periods in order to assess more clearly their effect upon river flows, and on the level of Bassenthwaite Lake. This report contains the Working Party's evaluations, conclusions and recommendations.

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This is the River Ehen and Calder sub catchment management plan: Consultation Report September 1993 produced by the National Rivers Authority (NRA) North West Region in 1993. The report focuses on the management plan of both River Catchments Ehen and Calder, in North West England, UK. The Catchment Management Plan (C.M.P.) enabled the NRA to summarise the status of the catchment, identify the main issues and present its vision of the future. It provides a strategic policy framework for its Management and influences decision making leading to improvements in the water environment. The report contains sections on Description of Catchment, Catchment uses by NRA function, Target and objectives of the plan, Summary of Issues and Catchment Issues. The section on description of Catchment includes a general description, Transport, Geology, major services, summary of key details, area, topography, administrative details, main towns and population, water quality Sewage Treatment Works Trade effluent discharges, Water Resources, flood defence and land drainage and Fisheries.

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This is the River Ehen and Tributaries SSSI consultation Protocol for the Environment Agency with English Nature, produced in 1998. The Protocol is intended to provide for consistency of approach, to clarify responsibilities and help to streamline the statutory consultation and consenting procedures in which both organisations are involved. It provides guiding principles on the approach to management issues. Based on the operations likely to damage the special interest (OLDSI) which forms part of the SSSI notification, the protocol identified acceptable management activities which contribute to the special interest of the site and those which may adversely affect that interest. OLDSI includes activities such: land drainage consents, discharge consents, herbicides approvals, fish-stocking consents, fishing licences, abstraction and impoundment licences, consents to construct/test pump boreholes, integrated pollution Control Licences and Waste Management Licences, capital projects, flood defence maintenance works, water resources, fisheries, pollution control, ecology surveys and Recreation works.

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This is the Effect of water quality on coarse fish productivity and movement in the Lower River Irwell and Upper Manchester Ship Canal: a watercourse recovering from historical pollution report produced by the Environment Agency in 2003. The aim of this study was to investigate the impact of water quality upon coarse fish population dynamics in a lowland, urban watercourse. All of the research carried was undertaken in the lower River Irwell and upper Manchester Ship Canal, between February 1998 and December 2001. Of particular interest was the natural sustainability of the urban fishery given recent concern raised in the angling community over an apparent decline in coarse fish populations in lowland rivers. The research described in this report has concentrated upon the role of water quality in determining coarse fish population dynamics, and in particular: The impact of water quality upon fish growth and productivity; The impact of poor water quality and low dissolved oxygen concentrations upon fish distribution and movement; The impact of water quality upon the sexual development of fish.

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This is the River Leven (at Newby Bridge) freeze coring report produced by Lancaster University in 2000. This study looks at fine materials in river Leven that may have to be considered detrimental to successful salmonid spawning. Following an observed decline in quality of salmonid fisheries at the site an investigation was initiated to assess the extent of ingress of fine sediments into the spawning gravels. A broader picture was sought by sampling both above and below the weir and close to both banks of the river. A comparison of the fine sediment from each sample site was undertaken. All the freeze cores used in this report contained distinct horizontal strata down through their length. The cores often penetrated into a highly compacted layer of light grey coloured material. The upper surface of this highly compacted layer is considered as a boundary between fine materials of different origin. Considerable variability was observed in the median grain size (D50) of the gravels from the cores. In addition variability was observed in the thickness of the upper less compacted layers. The role of regulated river flow across the weir in clearing fines from river gravels is briefly considered.

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This is the River Crake (at Bouthrey Bridge) freeze coring report produced by Lancaster University in 1999. This study looks at fine materials in river Crake at Bouthrey Bridge that may have to be considered detrimental to successful salmonid spawning. Following an observed decline in quality of salmonid fisheries at the site an investigation was initiated to assess the extent of ingress of fine sediments into the spawning gravels. Fine sediments from one potential source, upstream riverbanks, are also compared to those isolated from the spawning gravels. The percentage by weight of fine sediments for the six freeze cores, was found to be lower than first expected, given the visual appearance of the reach. However the fines were found to be distributed evenly down the cores with a marked absence of an upper, coarse gravel armour layer. In addition the median grain size (D50) of the six samples was generally low, falling to 6mm for core 5. The low median grain size and the absence of coarse grained upper strata are considered detrimental to the success rate of salmonid spawning.

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This is the River Irk intensive survey produced by the North West Water in 1986. This report focuses on the Intensive Survey carried out on the River Irk on 15 April 1986. The river Irk was one of the most polluted rivers in North West Water's area. In dry weather the bulk of the flow in the river originated from the 3 sewage works within the catchment (Castleton ETW, Royton ETW and Oldham ETW). The river Irk was badly affected by numerous unsatisfactory storm sewage overflows (SSOs) within the catchment. Several sewerage projects had been carried out within the Irk catchment especially in the Middleton area, where earlier major redevelopment of the old town centre took place between 1969 and 1976, at which time the main sewers were reconstructed. The survey was designed to investigate the changes in the water quality of the river Irk which take place during wet weather. Because of manpower and analytical restrictions the study on Wince Brook and the river Irk upstream of Wince Brook was limited to their bottom reaches.

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This is the Review of discharge consents, River Irwell catchment report produced by the North West Water Authority (NWWA) in 1979. The purpose of this Report is to make recommendations for the revision of consents for discharges within the catchment of the River Irwell, downstream and including the River Medlock in Manchester. This revision has the sole objective of recognising the present effluent and river water quality - proposals for long term river water quality objectives are to be put forward in other Reports. The report identifies the existing situation regarding the legal status of effluent discharges from Authority and non-Authority owned installations within the catchment, details the determinant concentration limits included in existing discharge consents (where appropriate) and proposes the limits to be included in the reviewed consents. The reviewed consents will reflect the quality of effluent achievable by good operation of the existing plant based on 1977 effluent quality data but taking into account any improvements, extensions etc. that have been or are about to be carried out and any known further industrial and/or housing development in the works drainage area.

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This is the Irwell: Story of an industrial river document produced by the North West Water in 1979. This report is a leaflet format document. It focuses on the historical evolution of River Irwell, since it was “born” the river Irwell, about three hundred million years ago when shallow seas covered most of south east Lancashire and Europe to present years. It looks at Irwell’s pollution, highlighting the Irwell’s lower stretches were some of the region was the most polluted due to the population growth and establishment of industrial activities i.e. Lancashire’s great cotton industry, breach and dye works, paper mills, tanneries, chemical and gas works. Wastes from these industries were discharged directly to the river, together with crude sewage from an ever increasing population. However over the years the condition of the Irwell was gradually improved.

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This is the report on the Effects of Water Quality in the Bassenthwaite Lake on Anglers Catches of Salmon and Sea-trout in the River Derwent April 1993 by the Institute of Freshwater Ecology. An analysis of the catch statistics for salmon and sea-trout in the Rivers Derwent and Cocker was undertaken in relation to available information on the algal water quality in Bassenthwaite Lake to test the hypothesis that poor catch returns were associated with a deterioration of water quality within the lake. Analysis of the catch statistics failed to reveal any correlation between water quality and catch returns for either species of fish and it is concluded that any water deterioration in Bassenthwaite Lake has not caused any major damage to the salmon and sea trout fisheries of the Derwent/Cocker system. This conclusion is supported by the analysis of the Windermere/Leven and Crake system, where no correlation could be found between lake water quality and downstream catches of migratory salmonid fish. However, the possibility still exists and such an effect might be detected by further field work on the macroinvertebrates and on the composition of potential salmonid spawning in the area.