17 resultados para Functional Requirements for Authority Data (FRAD)

em Aquatic Commons


Relevância:

40.00% 40.00%

Publicador:

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.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

The Ribble estuary (North West England) is sampled for water quality twelve times a year. The suite of parameters used for baseline monitoring is only analysed four times a year on the designated sampling sites. The sampling locations are shown in Figure 1, and their descriptions are found in Appendix 1. The baseline monitoring stations have been chosen to respond to regional, national and European requirements. The suite of parameters to be analysed in the laboratory is listed in Tables 1 and 2. Appendix 2 lists the environmental quality objectives (EQOs) and standards (EQSs) for estuaries and coastal waters. These values will help in interpreting the collected data from the Ribble surveys.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

This is the assessment of the flow requirements for upstream migration of salmonids in some rivers of North West England produced by the North West Water Authority in 1985. This report focuses on the automatic fish counters operating on the resistivity principle used for several years in North West England. This report aims to investigate the flow requirements for upstream migration of salmon and migratory trout. The data obtained confirmed that during summer months most fish movement occurs in the higher range of the available flows, but the migration flow range varied from year to year, depending on prevailing river levels. Of the other environmental variables measured, only water temperature and incident light intensity appear to have any direct association with fish movement. Information on migration flow ranges were used in conjunction with computer simulations of the effects of abstraction proposals on historical flows to assess the implications of these proposals for migratory fish.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

This report looks at the upstream movement in the River Lune of 9704 salmon which were monitored in the years 1960-1966. It explores the Broadraine Weir near Kirby Lonsdale with its fish monitoring station, the visual counting and trapping salmon, electronic monitoring of fish, and analysis of river flows.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

During 1993, a comprehensive data set of scale readings, length and weight measurements was established for migratory salmonids on the River Lune. This information was collected using three methods of fish capture: 1. The Lune estuary commercial nets. 2. River Lune Forge weir fish trap. 3. River Lune rod catch scale returns. Additional information was contributed by the Kent, Leven and Duddon rod and commercial fisheries. The data shows that the salmon stock in 1993 was dominated by two year old smolts. This varies from year to year. The sea trout population displays a normal population curve in terms of numbers of fish in each age and weight class. The growth rate of salmon and sea trout is very similar even though salmon have the benefit of high sea feeding.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The River Ribble bailiff team completed a total of 377 salmonid creel censuses by interviewing anglers fishing on the banks of the Rivers Ribble and Hodder during 1994. The study was undertaken for a number of reasons: (i) , To determine which areas of the river were fished by anglers. (ii) To ascertain which fishing methods were used in these areas. (iii) To identify the success of each fishing method within each area of the River Ribble system. In a limited 1993 sampling programme, 55 censuses were carried out. Results from these indicated that fishing with worm as bait was the most common method (39% of anglers interviewed) and also resulted in the greatest number of salmon being caught (61% of all salmon). The 1994 census data were collected from all areas of the Ribble system during the months of June to October. The data presented here are for anglers fishing for salmon only or for those fishing for salmon and sea trout at the same time. All of the fish caught were salmon.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The Ribble catchment is the largest and most diverse river system within National Rivers Authority (NRA), North West's Central Area. The river is approximately 100km in length and rises in a limestone area west of the Pennines. This report examines changes in the size and composition of the salmon and sea trout catches from the Ribble migratory salmonid fisheries during the years 1937 to 1991. Comparisons are made between the rod and net fisheries for both salmon and sea trout of the Ribble and Hodder. Patterns of catches shown by the Ribble fisheries are compared with those of other individual rivers and with patterns for the North West Region as a whole. An attempt is made to identify if any relationship exists between catch and stock abundance. Catch patterns shown by the Ribble and Hodder salmon fisheries are compared with electronic resistivity counter data from the two rivers. Annual salmon catch patterns and redd count data are compared both locally and regionally. Recommendations for future studies are made in the light of the report's findings.

Relevância:

30.00% 30.00%

Publicador:

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.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

1000 log books were issued to anglers of which 236 were returned, those from the rivers Derwent, Kent, Lune and Ribble accounted for the vast majority. The Derwent had the highest catch rate of these rivers: one salmon every 13.89 hours followed by the Lune, Kent and Ribble at 16.39, 18.87 and 35.71 hours, respectively. For sea trout the Lune, Derwent and Ribble had a catch rate of approximately one fish every 10.0 hours (9.8, 10.0 and 10.64 hours),and for the Kent one fish per 16.1 hours fished. Salmon angling visits were, in general,longer than those for sea trout being between 2 and 6 hours as opposed to 2 to 4 hours. On the majority of visits (>80%) no fish were caught and was the same for salmon and sea trout. For salmon the majority of fish were caught on fly, spinner or worm, and the least on prawn. For sea trout fly predominated. The majority of salmon caught were less than 91b in weight and were presumed to be grilse (1 sea winter). The majority of the sea trout caught weighed between 1 and 31b. The pattern of catch, effort, CPUE, abundance and catchability for salmon and sea trout were modelled using the data from the rivers Derwent, Kent and Lune. Flow significantly influenced catch, effort and catchability of salmon which had entered in a particular month. For sea trout flow was not significantly correlated with any of the dependent variables. The catchability coefficient for salmon, determined from the total number of fish, remained relatively constant over the period June to October indicating that CPUE was a reasonable measure of within season abundance. This was not found to be the case for sea trout.

Relevância:

30.00% 30.00%

Publicador:

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.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Fish tracking is a valuable technique for the provision of detailed information on the behaviour patterns of individual fish especially during estuarine and riverine migration. 2. Tracking studies help in the provision of a comprehensive description of the variety offish behaviour patterns in response to factors such as water flow, obstructions and water quality. 3. There are advantages to be gained by complementing fish tracking studies with data collected from fish counters and vice versa. 4. An overall evaluation of NRA fish tracking projects is presented in the wider context of NRA strategic research objectives. 5. The requirement for future development of tracking equipment, improved data analysis techniques, better communication and more immediate report preparation is identified. 6. Individual project evaluation is given for NRA (or the appropriate Water Authority predecessor) tracking studies conducted on the Ribble estuary, the River Tamar, River Torridge, Rivers Test and Itchen, River Lodden, the Welsh River Dee, River Glaslyn, River Taff, River Tawe, River Tywi, River Usk, Rivers Avon and Stour and the River Frome. 7. An outline for future strategic research is provided which identifies particular areas for study:- i) Identification of environmental factors which control the entry of fish into rivers. ii) Improvement of the understanding of the relationship between water flow and upstream movement of salmonids. iii) Examination of the detailed movements and behaviour of fish in relation to obstructions. iv) Closer definition of water quality requirements for salmonid fish. v) Definition of habitat preferences of salmonids in rivers. vi) Subsidiary topics such as the movements of non-salmonid fish and the downstream migration of kelts and juvenile salmonids.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The Wyre estuary is sampled for water quality four times a year. The sampling locations are shown in Figure 1, and their descriptions are found in Appendix 1.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Research on assessment and monitoring methods has primarily focused on fisheries with long multivariate data sets. Less research exists on methods applicable to data-poor fisheries with univariate data sets with a small sample size. In this study, we examine the capabilities of seasonal autoregressive integrated moving average (SARIMA) models to fit, forecast, and monitor the landings of such data-poor fisheries. We use a European fishery on meagre (Sciaenidae: Argyrosomus regius), where only a short time series of landings was available to model (n=60 months), as our case-study. We show that despite the limited sample size, a SARIMA model could be found that adequately fitted and forecasted the time series of meagre landings (12-month forecasts; mean error: 3.5 tons (t); annual absolute percentage error: 15.4%). We derive model-based prediction intervals and show how they can be used to detect problematic situations in the fishery. Our results indicate that over the course of one year the meagre landings remained within the prediction limits of the model and therefore indicated no need for urgent management intervention. We discuss the information that SARIMA model structure conveys on the meagre lifecycle and fishery, the methodological requirements of SARIMA forecasting of data-poor fisheries landings, and the capabilities SARIMA models present within current efforts to monitor the world’s data-poorest resources.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Due to a lack of data on vessel costs, earnings, and input use, many of the capacity assessment models developed in the economics literature cannot be applied in U.S. fisheries. This incongruity between available data and model requirements underscores the need for developing applicable methodologies. This paper presents a means of assessing fishing capacity and utilization (for both vessels and fish stocks) with commonly available data, while avoiding some of the shortcomings associated with competing “frontier” approaches (such as data envelopment analys

Relevância:

30.00% 30.00%

Publicador:

Resumo:

This is the Cheshire stillwaters. Summary results of 1997 data Oak Mere, Betley Mere and Marbury Big from the National Rivers Authority, June 1998. In May 1997, a Stillwaters meeting was held to discuss the way forward in stillwaters monitoring. It decided upon the establishment of a three year rolling programme, in which three stillwaters would be monitored three times a year, every third year. The stillwaters where chosen due to water quality (i.e potential polluted / sensitive waters), fisheries and ecological interests. The Still waters chosen for the first year (1997) were Oak Mere, Betley Mere and Marbury Big Mere. The surveys were aimed to produce a comprehensive study of the still water through monitoring a variety of parameters. Algal, zooplankton and water chemical samples were taken three times a year, (April, July and September). In addition, fisheries surveys were taken in July and marginal invertebrate surveys taken in September.