The effects of water quality on freshwater fish populations - final report

There is a need to determine quantitative relationships between fishery status and water quality in order to make informed judgements concerning fishery health and the setting of environmental quality standards for fishery protection. Such relationships would also assist in the formulation of a system for classifying fisheries. A national database of fisheries and water quality has been collated from the archives of pollution control authorities throughout the UK. A number of probable and potential water quality effects on fish populations have been identified from a thorough analysis of the database, notwithstanding large confounding effects such as habitat variation and fish mobility, and the generally sparse nature of water quality information. A number of different approaches to data analysis was utilised, and the value of each has been appraised. Recommendations concerning the integration of water quality assessment approaches have been made and further research on fishery status, and its measurement, in relation to water quality has been suggested.

The proposed Lune net limitation order 1999 and associated byelaws

The River Lune rises in the hills around Tebay in thje North of England and runs through rural farming country to Morecambe bay. It is generally considered as a river of high purity and unspoiled nature. The salmon fishery was at one time considered amongst the best in England and Wales, with very high catches to both rod and net fishermen. During the late 1960's the disease UDN decimated the stock. Since then there has been a recovery of the stock, but this is considered by most anglers and netsmen to be a partial recovery of some of the previous stock components. In recent years anglers and netsmen have voiced their concerns over the Lune stock and have lobbied for action to improve the Lune fishery. This net limitation order (NLO) and the separate byelaw in conjunction with habitat improvement are proposed as part of the strategy for future conservation and management of this salmon fishery. The fishery is currently exploited by 37 licensed netsmen, the highest number of any single estuary in England and Wales. There are 26 haaf, 10 drift and 1 seine nets available. Current estimates of the rod fishery are that 1100 to 1400 anglers fish 14 000 days per year. The River Luhe is one of the few rivers within England and Wales that has the benefit of an accurate fish counter. The counter is at Forge Weir approximately 4 km upstream of the tidal limit. The counts, together with records of the catches from the rod and net fishery, enable a reasonably accurate assessment of both rod and net exploitation. Extensive surveys of the juvenile population, carried out in 1991 and 1997, provide additional information. The purpose of this document is to describe and explain the current state of the salmon population in the River Lune and in doing so, demonstrate the current need for stock conservation. A second purpose is to demonstrate that the proposed NLO and byelaw package should allow the salmon population to reach its conservation target (spawning escapement target).

A working guide to the assessment, implementation and post project monitoring of fisheries habitat improvement schemes in South Cumbria

Due to changes in land use over the last century, the physical nature of many streams and rivers in the British Isles has probably changed. In some cases this change may be large for example as a result of flood defence schemes and is easily observed, whilst in other cases altered land use, farming, forestry or urbanization may have resulted in more subtle changes to river features. This working guide draws together a way of assessing habitat in any stream or river and determine sites or reaches on the assessed watercourse that may benefit from habitat improvement schemes. It will determine a method of measuring existing habitat in a broad sense, whilst referring to R and D studies currently being undertaken in this area. A method of prioritising any proposed habitat restoration work will be suggested. The limitations of fisheries improvement schemes in terms of cross functional acceptance (flood defence and conservation) will be examined along with suggested proposals for some example watercourses. The need for pre and post enhancement monitoring will be discussed as will the requirement for maintenance programs on schemes. Finally methods for determining the cost benefits of small schemes will be examined, compared to other currently used enhancement strategies. This will allow small scale revenue schemes to be used to back up pre project cost benefit analysis as required in future capital submissions.

Environmental quality standards to protect identified uses of controlled waters: salmonid fisheries, cyprinid fisheries, migratory fisheries, commercial harvesting of marine fish for public consumption, commercial harvesting of shellfish for for public consumption

This report considers the development of environmental quality standards (EQSs) for the salmonid fishery, cyprinid fishery, migratory fishery, commercial harvesting of marine fish for public consumption and commercial harvesting of shellfish for public consumption uses of controlled surface waters. Previous reports have been used to identify those parameters necessary for the maintenance of these five uses. Each water use is considered in a separate section within which identified parameters are discussed and standards proposed, a summary of the proposed standards is presented at the beginning of the relevant section. For salmonid, cyprinid and migratory fisheries, EQSs for substances in water have been proposed for the protection of these fisheries. For the commercial harvesting of marine fish and shellfish for public consumption uses 'Warning Levels' of substances in waters have been proposed. These 'Warning Levels' have been proposed by considering data on bioaccumulation and food standards and aim to prevent acceptable intake values and concentrations in fish/shellfish flesh exceeding statutory or recommended levels. For the commercial harvesting of marine fish for public consumption it has been concluded that the current EQSs for most List II substances for the protection of salt water life should be adequately stringent to protect this use, however for the commercial harvesting of shellfish for public consumption, these List II EQSs do not appear adequate to protect this use and more stringent 'Warning Levels' have been proposed. For all five uses considered in this report there has been found to be limited information on a number of the parameters considered and in general for indigenous species, this has been found to be especially so when considering migratory fisheries and the commercial harvesting of marine fish and shellfish.

Review of NRA tracking projects on salmon, Salmo salar L., and sea trout, Salmo trutta L

The report briefly outlines the programme of the National Rivers Authority (NRA), placing the Fisheries programme in the context of the work of the NRA as a whole, and viewing the tracking work against the broader requirements of the NRA Fisheries research programme. All regions of England and Wales are considered. Two techniques currently exist for studying the detailed timing and extent of movements of adult salmon: tracking of individually identifiable fish, and counting the numbers of fish moving past a fixed point in the river. The development of tracking techniques and the integrated use of tracking and fish counters is briefly reviewed in Section 3. Further details of these techniques are given in Appendices. Section 4 summarises and assesses completed and current NRA tracking studies. Section 5 discusses the scientific content of these studies in relation to similar work carried out elsewhere in the UK. The NRA programme of tracking studies is evaluated in Section 6. Section 7 discusses future fisheries projects and Section 8 details the future development of tracking techniques. Finally, recommendations arising out of this review are summarised in Section 9.

Salmon stocking by the Lancashire River Authority: investigations into the requirements and methods best suited to the area

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.

Fisheries statutory instruments 1950-93 [collection of salmon and fisheries legislation with special respect to Cumbria]

This document is a collection of legislative documents relating to fisheries, especially Statutory Instruments, with special regards to the county Cumbria in the north of England. This includes Orders on salmon and trout spanning the years 1950-1993.

The ecology and management of the European grayling Thymallus thymallus (Linnaeus). Interim report

The European grayling, Thymallus thymallus, is a highly under-rated freshwater fish, particularly in the United Kingdom. As such, little scientific research has been conducted on its biology, ecology or specific management plans, in comparison to the related species, salmon, Salmo salar L. and brown trout, Salm.o trutta trutta L. or the nearest relative to T. thymallus, the Arctic grayling, Thymallus arcticus (Walbaum), whose life history has been well documented in view of its high ranking by anglers, as a game fish. However, the importance of sound scientific research cannot be over stressed for this species, which can potentially provide an excellent fishery and source of income in salmonid depauparate rivers. The aim of this report therefore, is to review all available information on the biology, ecology and management of the European grayling, T. thymallus, incorporating findings for T. arcticus to bridge subjects where the literature is scarce, and propose management strategies for T. thymallus in the United Kingdom, bridge subjects where the literature is scarce, and propose management strategies for T. thymallus in the UK.

Investigations into migratory fish propagation in the area of the Lancashire River Board

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.

Report on an egg bioassay experiment

In October 1992, a fish population survey of the Swanside Beck system revealed that the densities of juvenile salmon present in the beck were generally poor. The survey highlighted that a potential reason for this may be due to a lack of spawning substrate resulting from siltation. Numerous workers have found that increased levels of A salmonid egg box experiment of Swanside Beck carried out in the spring of 1994, revealed that the survival rates in the majority of sites were good. While the in-site variability was relatively high, mean survival rates remained in excess of 70%. As a result egg survival rates were eliminated as the reason for low juvenile salmonid production. The only site with a relatively low survival rate was Swanside Beck downstream of Cowgill Beck. However, even at this site siltation was eliminated as the cause of the increased mortality rate. It is recommended that a salmonid stocking of Swanside Beck should be carried out this year. This should be followed by an electric fishing survey to evaluate juvenile salmonid survival rates.

Summary document of the work being done in 1992-1993 regarding the migratory salmonid fisheries of the River Ribble catchment

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.

An analysis of migratory salmonid catch effort data, derived from anglers' log books, 1991

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.

An evaluation of the survival of Atlantic salmon (Salmo salar L.)fry stocked in eight streams in the North West of England.

Eight streams from the North West of England were stocked with Atlantic salmon (Salmo salar L.) fed fry at densities ranging from 1 to 4/m2 over a period of up to three years to evaluate survival to the end of the first an d second growing periods and hence assess the value of stocking as a management practice. Survival to the end of the first growin g period (mean duration of 108 days) was found to vary between 7.8 and 41.3% with a mean of 22% and CV of 0.44. Survival from the end of the first growing period to the end of the second growing period (mean duration of 384 days) ranged from 19.9 to 34.1% with a mean of 26.3% and CV of 0.21. Survival was found to be positively related to 0+ trout density (P < 0.05) and negatively related to altitude (P < 0.05). A comparison of the raw survival data (non standardised with respect to duration of experiments) with that from other studies in relation to stocking densities revealed a negative relationship between fry survival and stocking density (P < 0.05). Densities in excess of 5/m2 tended to result in lower levels of survival. Post stocking fry dispersal patterns were examined for the 1991 data. On average 86.7% of the number of fry surviving remained within the stocked zone by the end of the first growing period. With the exception of one stream there was little in the way of dispersal beyond the stocked zone. The dispersal pattern approximated to the normal distribution (P < 0.05). It was estimated that stocking can result in a net gain of fish to a river system compared with natural productivity, however the numerical significance of this gain and its cost effectiveness need to be determined on a river specific basis.

Electric fishing survey of the gravel addition sites on the River Wyre, Grizedale Beck and Joshua's Beck.

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.

Concepts of spawning targets

This report discusses the concepts of spawning targets. Spawning target setting is based on the fact that the number of smolts produced by any given river is constrained by habitat availability. This means smolt numbers depend on spawner numbers up to a point, but thereafter smolt production reaches a ceiling. It has been shown, in some rivers at least, that the relationship between egg deposition and smolt production may approximately be described by a mathematical equation. The equation will vary between rivers and there is uncertainty over its exact form. The concept of Maximum Gain (MG) is explained and its application in fisheries management discussed. The author also critically examines the concept of Density Independent Mortality (DIM).