Fish pass design - criteria for the design and approval of fish passes and other structures to facilitate the passage of migratory fish in rivers

Many of British rivers hold stocks of salmon (Salmo salar L.) and sea trout (Salmo trutta L.) and during most of the year some of the adult fish migrate upstream to the head waters where, with the advent of winter, they will eventually spawn. For a variety of reasons, including the generation of power for milling, improving navigation and measuring water flow, man has put obstacles in the way of migratory fish which have added to those already provided by nature in the shape of rapids and waterfalls. While both salmon and sea trout, particularly the former, are capable of spectacular leaps the movement of fish over man-made and natural obstacles can be helped, or even made possible, by the judicious use of fish passes. These are designed to give the fish an easier route over or round an obstacle by allowing it to overcome the water head difference in a series of stages ('pool and traverse' fish pass) or by reducing the water velocity in a sloping channel (Denil fish pass). Salmon and sea trout make their spawning runs at different flow conditions, salmon preferring much higher water flows than sea trout. Hence the design of fish passes requires an understanding of the swimming ability of fish (speed and endurance) and the effect of water temperature on this ability. Also the unique features of each site must be appreciated to enable the pass to be positioned so that its entrance is readily located. As well as salmon and sea trout, rivers often have stocks of coarse fish and eels. Coarse fish migrations are generally local in character and although some obstructions such as weirs may allow downstream passages only, they do not cause a significant problem. Eels, like salmon and sea trout, travel both up and down river during the course of their life histories. However, the climbing power of elvers is legendary and it is not normally necessary to offer them help, while adult silver eels migrate at times of high water flow when downstream movement is comparatively easy: for these reasons neither coarse fish nor eels are considered further. The provision of fish passes is, in many instances, mandatory under the Salmon and Freshwater Fisheries Act 1975. This report is intended for those involved in the planning, siting, construction and operation of fish passes and is written to clarify the hydraulic problems for the biologist and the biological problems for the engineer. It is also intended to explain the criteria by which the design of an individual pass is assessed for Ministerial Approval.

Rivers Ribble and Hodder - habitat improvement

In order to improve the habitat of the Rivers Ribble and Hodder in the north west of England it is necessary to assess existing fish stocks. To assist the Ribble Fisheries Association a test census of stock has been made on the rivers Hodder and Ribble. The fish have been taken by electro fishing techniques. The following fish were collected over six days in September 1965: dace, chub, grayling, eel, salmon and trout. This short report summarises the findings of the survey.

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

Community management of Mekong River resources in Laos

The Mekong River is one of Asia's greatest rivers. It is the lifeblood of millions of small-scale farmers and fishers in China, Burma, Thailand, Laos, Cambodia and Vietnam. In the Lao People's Democratic Republic (Lao PDR), the river is particularly important because for the landlocked country, the Mekong is the Sea of Laos. In southern Lao PDR, fisheries for native fish species constitute an extremely important source of subsistence protein and income for local people. It has been estimated that wild-caught fish constitute at least 90% of the protein for lowland Laotians living next to the Mekong. Despite the extreme importance of fish to the diets and economics of communities along the Mekong, the resource, and the people who depend upon it, are in danger.

Roy of the Rivers (cartoon)

This is the Roy of the Rivers (cartoon) report produced by the National Rivers Authority (NRA) South West Region. This NRA document is a leaflet comic format which looks at the fishing and safe issues in rivers. This comic highlights the community policing to help guard the water environment. It gives a 24 hour emergency number and three steps to be followed in case of pollution, dead, distressed fish or suspects someone of illegally catching or selling fish.

The assessment of the flow requirements for upstream migration of salmonids in some rivers of North West England

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.

Chalk rivers: nature conservation and management

This is a handbook about Chalk Rivers Nature Conservation and Management from March 1999 by the Water Research Centre and commissioned by English Nature and the Environment Agency, primarly provides an objective basis for formulating conservation strategies for relevant Site of Special Scientific Interest (SSSIs) and Special Areas of Conservation (SACs). It was also seen as being applicable to chalk rivers more generally and has increasingly been regarded as important to the work of the Biodiversity Action Plan Steering Group on chalk rivers, which is led by the Environment Agency. This report contains information on characteristic wildlife communities, their habitat requirements and the ecological impact of activities that are relevant to the chalk river environment. It provides guidance on setting management objectives, options for mitigating impacts, and measures for the maintaining and enhancing the river channel, riparian and floodplain areas associated. The term `chalk river’ is used to describe watercourses dominated by groundwater discharge from chalk geology, including those that flow over a range of non-chalk surface geologies at various points along their length. England contains numerous examples of this river type, located in and downstream of areas of outcropping chalk in the south, East Anglia and up into Lincolnshire and Yorkshire. Indeed, England has the major part of the chalk river resource of Europe. A number of chalk rivers have been designated as Sites of Special Scientific Interest (SSSIs) and English Nature and Environment Agency work drawing up joint conservation strategies.

The Rivers Avon & Erme SAP Consultation Document

This is the Rivers Avon & Erme Salmon Action Plan Consultation document produced by the Environment Agency in 2003. This document is part of a national initiative to produce action plans for the management of all the main salmon rivers of England and Wales by 2003. The aim of this plan is (i) to assess the status of the salmon stocks and fisheries of the rivers Avon and Erme - including the use of Conservation Limits as part of this process, (ii) to identify factors which may limiting stock and fishery performance and (iii) to propose remedial measures address these factors. The report pays attention on the external consultation of the Rivers Avon & Erme Salmon Action Plan (SAP). While the stocks of both rivers have exceeded their respective conservation limits occasionally in individual years, only the Erme has achieved a period of statistical compliance since 1993. It is possible that this situation is largely normal, due to the steep nature of the rivers, obstructions to migration and dependence on suitable flow conditions occurring at the right time of year. The decline of the spring-running component of the stocks has left the populations dependent on autumn flows for the success of the late running component. Actions required to improve compliance with Conservation Limits are proposed and prioritised. The urgent actions relate to the need to improve the consistency with which adequate numbers of salmon reach and utilise fully all the accessible areas of the river systems. This document is intended to be dynamic, with opportunities for review occurring at regular intervals. For example, as the science of fisheries management improves, particularly in the setting of Conservation Limits, so the targets may be altered to reflect any improved methodology.

The Rivers Avon & Erme SAP Final Plan

This is the Rivers Avon & Erme Salmon Action Plan Final document produced by the Environment Agency in 2004. The Rivers Avon and Erme Salmon Action Plan (SAP) has been produced after consideration of feedback from public consultation. The final plan provides a list of the agreed issues and actions for the next five years to maintain and improve the salmon stocks and fisheries of both rivers. Efforts have been made to identify possible sources of funding, partners and timescales. It indicates how the plan will be managed, including the process for reviewing stock status, issues, actions and progress. Low marine survival is currently a major factor limiting the numbers of salmon returning to spawn in both the Avon and the Erme. Actions to improve the accessibility of spawning areas and to maximise the productivity of spawning and nursery habitats are seen as priorities, which should help to offset the low marine survival. The quality of the information available to assess salmon stocks is recognised as a limiting factor in the management of salmon fisheries. The SAP aims also to promote long term collaboration between the Agency and other interested parties in managing the salmon stocks and fisheries of the Avon and the Erme.

Rivers Taw and Torridge scale reading investigation. 8th annual report for the 1972 season

This is the Rivers Taw and Torridge scale reading investigation: the 8th annual report for the 1972 season produced by Devon River Authority in 1973. The object of the investigation is to examine by means of scale reading the biology of age classes of the salmon populations of the Rivers Taw and Torridge. The report is arranged in sections as previously and tables referred to in the report form an appendix. Scales were collected only from fish taken during the normal open season, which in 1972 was 1st April - 31st August. A weekly close time was in operation for the nets, a period of 60 hours from 6 p.m. on Friday evening to 6 a.m. on the following Monday. Thirty six licences for draft or seine nets were issued for the 1972 season and netsmen submitted samples of scales collected direct.

Fish communities in rivers to be affected by Roadford Reservoir

This is the Fish communities in rivers to be affected by Roadford Reservoir report produced by South West Water Authority in 1978. Surveys were carried, out on the Rivers Wolf, Thrushel, Lew and Lumburn, which are likely to be affected directly and indirectly by the construction and use of Roadford Reservoir. Of the upper reaches of three rivers to be affected directly by water releases, two were found to support abundant stocks of salmon and trout, and the third was found to contain abundant stocks of trout and eels. The River Thrushel will be affected indirectly and in this river salmon and trout stocks were present in slightly lower abundance than in others. Population estimates, densities, mean lengths and approximate biomass values were calculated. Other species were present in all rivers, usually in great abundance.

Characterization of toxic impacts on living marine resources in tidal rivers of the Chesapeake Bay

In 1999, the Chesapeake Bay Program completed a survey of existing data on chemical contaminants and the potential for bioeffects in 38 tidal river systems of Chesapeake Bay. This review led to the identification of 20 areas for which there were insufficient data to adequately characterize the potential for contaminant bioeffects on the Bay’s living resources. The goal of the present study was to estimate the current status of ecological condition in five of these areas and thus help to complete the overall toxics inventory for the Bay. These five systems included the Chester River, Nanticoke River, Pocomoke River, Lower Mobjack Bay (Poquosin and Back Rivers) and the South and Rhode Rivers. This study utilized a Sediment Quality Triad (SQT) approach in combination with additional water-column contaminant analysis to allow for a “weight of evidence” assessment of environmental condition. A total of 60 stations distributed among the five systems, using a probabilistic stratified random design, were sampled during the summer of 2004 to allow for synoptic measures of sediment contamination, sediment toxicity, and benthic condition. Upon completion of all analyses, stations were assigned to one of four categories based on the three legs of the triad. Stations with high sediment quality had no hits on any of the three legs of the triad; those with moderate quality had one hit; those with marginal quality had two hits; and those with poor quality had hits for all three legs of the triad. The Pocomoke River had by far the largest proportion of the total area (97.5%) classified as having high sediment quality, while the Rhode/South system had the highest proportion (11.4%) classified as poor. None of the stations in the Chester River, Nanticoke River, and Lower Mobjack Bay systems were classified as poor. More than 65% of the area of each of the five systems was classified with high to moderate sediment quality. The Rhode/South system had 30.4% of total area classified with marginally to severely poor quality. The results of this study highlight the importance of using multiple indicators and a “weight of evidence” approach to characterize environmental quality and the potential bioeffects of toxic contaminants.

Time series analyses of biological and environmental variables for Suisun Bay and the Sacramento and San Joaquin rivers

EXTRACT (SEE PDF FOR FULL ABSTRACT): Arima analysis was used to compute cross-correlations between principal component axes that described environmental variables, chlorophyll concentration and zooplankton density for the Sacramento and San Joaquin rivers and Suisun Bay. ... Cross-correlations among the time series may provide information about links between environmental and biological variables within the estuary and the possible influence of climate.