1000 resultados para Hydrogeology -- Catalonia -- Onyar (River)
Resumo:
The River Darwen is a highly impacted Lancashire river with very little known about its fishery interest above the impassable weir at Salmesbury Bottoms. Below the weir there are populations of coarse fish around the confluence with the River Ribble. To the knowledge of local bailiff staff, prior to 1996 the fish population in the middle and upper River Darwen had never been surveyed by electric fishing. In order to address this lack of knowledge, a survey was undertaken during the summer of 1996 with the aim of evaluating the salmonid and cyprinid fish population in the river. Twenty two sites were surveyed by electric fishing between June 11th and July 11th 1996. Information was gathered on the presence and density of fish populations in the river catchment, and analysed according to the National Fisheries Classification Scheme in order to determine how these populations compare nationally with sites of similar habitat features. From this report, recommendations were made to improve and develop the fishery potential in relation to water quality and habitat prioritising areas classed as being Ashless. It was recommended that juvenile coarse fish should be stocked in the Houghton Bottoms area. This area has excellent fishery habitat and was found to contain a minor coarse fish population. Water quality in this stretch of river was thought to be good enough to establish a major coarse fish population. Fish were introduced for the first time in 1998 at Houghton Bottoms from the Agency's Leyland Fish Farm. 3000 each of Roach, Chub and Dace were introduced. Further fish introductions occurred in 2000 with the stocking of 1000 Chub, again from the Agency's Leyland Fish Farm in the Lower Darwen and Witton areas of the main river on a trial basis.
Resumo:
The aim of this study was to assess the suitability of Foxhouses and Grizedale Becks as nursery habitat for juvenile salmon. A comprehensive fish stock assessment survey of the Wyre catchment was carried out by the NRA in 1992. This survey found that juvenile salmon were absent from two sites studied in Foxhouses Beck. In one site in Grizedale Beck, 0+ salmon were found at very low densities. Juvenile trout were found in all three sites studied in 1992. On the basis of the results of the 1992 survey, these two becks were stocked in 1994 with 0+ salmon reared from Lune broodstock at the NRA's Witcherwell Hatchery. These salmon were stocked at a known density, following a pre-stocking survey. This report examines and compares the results of the pre-stocking survey consisting of fourteen sites in the two becks, carried out between 12/04/94 and 27/04/94 and a post- stocking survey of six sites, carried out between 12/10/94 and 19/10/94. Flow, habitat and in-river obstructions have been shown to affect juvenile salmonid densities. A habitat description is provided for each site surveyed during the course of this study.
Resumo:
Adult salmon and sea trout rod catches in the River Wyre have been subject to considerable variability over the years. Annual rod catches ranging from 6 to 401 have been reported since records began in 1905. It has long been suspected that the physical nature of the catchment, combined with anthropogenic influences, has resulted in a deleterious effect on the Wyre fishery. Acidification problems in the head water streams (Marshaw Wyre and Tarnbrook Wyre) have been reported and are thought to threaten salmon juvenile survival. The construction of Abbeystead Reservoir and an increased tendency towards rapidly rising water levels during storms (flashiness) 1 are thought to have a significant impact on spawning gravel quality and quantity, both of which are thought to be deteriorating. As part of an overall desire to maintain and improve the migratory salmonid population in the River Wyre, this project has been commissioned to investigate remedial action which may improve and enhance spawning success, leading to an eventual improvement in the status of adult stocks. The primary objective is to establish whether the quantity and/or quality of available spawning gravels are limiting migratory salmonid productivity. The investigations undertaken confirm the general observation that useable spawning gravels appear to be in short supply in the River Wyre, and may be the limiting factor influencing returning adult stock.
Resumo:
This report seeks to briefly provide geomorphological guidance over the introduction of 'habitat enhancement' features for fisheries improvement which is an expanding area of interest throughout the region. This document is a primary attempt to draw together the salient details from the large quantity of literature published in recent years with reference to boulder introduction and to groyne/deflector placement in NW rivers. Secondly the potential introduction of such features is assessed, with reference to the proposed works at Carhead on the Eden.
Resumo:
Yorkshire Water Services (YWS) are currently granted a Time Limited Licence (TLL) for abstraction at Kilgram Bridge which is due for renewal in 1999. The Environment. Agency requires information on fish populations with regards to drought conditions and any possible effects that abstraction may have when considering licence renewal. In' order to evaluate any effects of drought and abstraction a three year study was instigated to examine fish populations. Surveys were conducted at nine main River Ure sites and two tributaries in which the triennial rolling programme formed the basis of site selection. Multi-method sampling techniques were carried out at several sites in order to evaluate capture efficiency. High densities of brown trout juveniles were observed in the tributaries with an indication that fish had become crowded as a result of low flows. Recruitment of brown trout in the tributaries was not directly related to flow levels in the main R. Ure. However, it is concluded that salmonids are at risk during drought flows and high temperatures from increased susceptibility to disease, predation, poor water quality and the direct lethal effect of high temperatures in shallow water.
Resumo:
The basis for undertaking this study was to examine factors and potential impacts affecting fish and fishing in relation to low flow drought conditions and what other impacts may arise as a result of further reduced flows resulting from abstraction. The study formed the basis of a three year project to concentrate on effects relating to potable water abstractions at Moor Monkton by YWS. To fully evaluate the possible effects on fisheries the study set out to encompass fish population surveys from fry to adult stock, analysis of angler catch data, reports from anglers and river reports from Environment Agency Fisheries staff. In order to evaluate any effects of drought and abstraction a three year study was instigated to examine fish populations. Fish population surveys were conducted at six sites in which the triennial rolling programme formed the basis of site selection. Multi-method sampling techniques were carried out at several sites in order to evaluate capture efficiency. Roach were prolific above the weir at Linton-on-Ouse, with gudgeon, perch and small bream also well represented. Roach dominated catches on the R.Ouse below Linton, with perch and bleak also relatively abundant. Low flows were not thought to be directly correlated to successful recruitment of coarse fish, rather the associated high temperatures during drought conditions showing a strong positive effect with most species exhibiting growth rates above their long-term average. At this stage in the study there are no clear indications that the drought has caused any deleterious effects to coarse fish populations or marked changes in species composition, with evidence of good recruitment by several species, indicating that the higher temperatures have generally been beneficial to recruitment. However, the indication that dace did not benefit as well as other coarse fish under these conditions may suggest some species are affected more than others. The successful strong recruitment of most coarse fish suggests that, in future, fisheries will be supported by the 1995 year-class.
Resumo:
This investigation was carried out to provide information on fish stocks and angling activity during 1997 in relation to the drought and, in particular, flows as influenced by Time Limited Licences. These abstractions will be for review in 1999. This report extends and updates the data presented for 1996. Fish population surveys (including eels) were undertaken on the main river and selected tributaries. Angler caught brown trout were examined, angler catch data have been reviewed, and observations by Environment Agency fisheries staff collated. It appeared that in River Wharfe both the fish populations and individual fish appeared to be in good condition and limited changes had occurred since the 1996 survey.
Resumo:
The aim of this study was to investigate the historical catch record from the Castle Fishery on the River Derwent over the period 1923 - 1989, to determine if changes had taken place in the composition of the catch and to examine the influence of flow on the performance of the fishery. The River Derwent is situated in West Cumbria, North West England. It flows from its source on Scafell Pike (NGR NY 229 089) westwards discharging into the Irish sea at Workington, a distance of 52 km. Over its length it receives water from an additional 214 km of stream, 5 large lakes and approximately 30 small tarns. The catchment drains a total area of 663 km2. The study concludes that through the time period there was considerable variation in catch between years. The trend was for the catch to increase steadily over the period 1923 - 1958, declining rapidly in 1959, after which catches increased steadily reaching a peak in the mid-sixties, before declining towards the end of the decade. During the seventies and eighties catches remained relatively stable at between 300 - 600 salmon per year until 1988 when over 2000 salmon were reported caught, the greatest number in any year over the study period.
Resumo:
The report presents the Environment Agency's 5 year Salmon Action Plan for the River Kent for the period from January 2001, providing the background to the plan, responses to the public consultation given, and proposed actions.
Resumo:
All species of fish are able to propagate and maintain their numbers provided that no adverse influence occurs to change the compatible environment, the salmon is no exception. Propagation of fish by artificial means has long been a subject of discussion amongst fishery workers and views have been expressed (both favourable and unfavourable) on the merits of the various methods employed. In an attempt to discover whether artificial propagation was necessary and also to find the best methods of propagation to adopt in the various rivers, a phased programme of investigation into natural spawning efficiency and the results obtained by various methods of artificial propagation was started in the Lancashire River Board area during 1957. The object being to seek information on: (1) The survival of ova from natural spawnings to the eyed and alevin stages. (2) The population density of feeding fry (from natural spawnings) at various intervals of development. (3) The viability of green ova and eyed ova- when planted artificially. (4a) The survival to 0+ parr from implants of eyed ova unfed fry and fed fry. (4b) Populations per unit area of 0+ parr from various planting densities of eyed ova, unfed fry and fed fry. Sampling stations were selected on the Rivers Ribble, Lune and Wyre watersheds for the purpose of marking and examination of natural salmon redds.
Resumo:
This report explores salmon propagation in the Lancashire River Board area (North West of England), looking at the Rivers Lune, Wyre, Ribble, and Hodder, showing salmon catch statistics, methods of propagation and habitat conditions investigations.
Resumo:
This document lists the work on salmonid fisheries in the River Ribble catchment in the north west of England which was done in 1992-93. The document includes the following: analysis of historical catch data from the River Ribble covering 1937-1991; Ribble and Hodder stock assessment surveys 1992-93 including Swanside Beck; Ribble catch data from game angling log books 1993; results of salmon scale sampling 1993; results of microtagging programme in Hodder and Ribble 1993; Waddow Weir dish counter data 1993; Winkley Hall (Hodder), Locks Weir and Waddow Hall (Ribble) fish counter data 1993; number of fish and ova from Witcherwell Hatchery 1993.
Resumo:
Although geographically the River Wyre lies between two rivers containing major migrations of adult salmon and sea trout, its rod & line fisheries have for a number of years produced exceptionally low catches. In order to determine the causes of this the Wyre Salmon and Sea trout Restoration Group (WSSRG) was conceived in 1994 as a partnership between the then National Rivers Authority (now Environment Agency), local landowners, angling clubs and interested parties. Two studies of 1994 and 1995 stated that there is a shortage of useable spawning gravels on the river. This is compounded by Abbeystead Reservoir acting as a gravel trap, the siltation of gravels on several side becks and problems with access to available gravels by returning adults. There was also perceived to be a need for accurate fishery data from the river encompassing redd counts, catch data and surveys of fry populations. The 1995 report suggested a number of management proposals which might be adopted in order to improve and create available spawning habitat for migratory salmonids. Funding was made available to create three spawning gravels on each of two side becks (Grizedale Beck and Joshua's Beck) and the addition of gravels to a site oh the main river below Abbeystead Reservoir. Modifications were also made to the fish pass at Abbeystead to allow easier passage of fish. These improvements were made in the autumn of 1995. Salmonid spawning redd counting was undertaken on the whole Wyre catchment in 1995/1996 and specific surveys by electric fishing on the gravel enhancement sites in the summer of 1996. This report details the current state of the improvement works that were undertaken and presents the results of electric fishing surveys in September 1996. A number of lessons have been learnt which will be of great benefit to the Fisheries Function in other parts of the Wyre catchment and the Central Area in general.
Resumo:
This paper deals with the development and use of biological reference points for salmon conservation on the River Lune, England. The Lune supports recreational and net fisheries with annual catches in the region of 1,000 and 1356 salmon respectively. Using models transported from other river systems, biological reference points exclusive to the Lune were developed; specifically the number of eggs deposited and carrying capacity estimates for age 0+ and 1+ parr. The conservation limit was estimated at 11.9 million eggs and between 1989 and 1998 was exceeded in two years. Comparison of juvenile salmon densities in 1991 and 1997 with estimates of carrying capacity indicated that 0+ and 1+ parr densities were at around 60 % of carrying capacity and may relate to the number of eggs deposited in 1990 and 1996 being approximately 70% of the target value. The paper discusses the management actions taken in order to ensure that the management target of the conservation limit being met four years out of five is delivered. It also discusses the balance between conservation and exploitation and the socio-economic decisions made in order to ensure parity of impacts on the rod and net fisheries. The regulations have been enforced since 1999 and the paper concludes with an assessment of the actions taken to deliver the management targets, over the last five years.
Resumo:
The problem of the Lancashire River Authority is one of deciding the river flow which will meet the requirements of the water engineer in his endeavour to secure water for the public and industry, demands of fish populations, and the needs of anglers. This report analyses salmon catch data from anglers in the River Lune (north west England) and relates it to flow range. The years 1956-1967 are covered.