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.

Evaluation of NRA tracking studies. Future projects and technical development

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.

The calibration of a semi-quantitative approach to fish stock assessment in the North West Region of the NRA

(1) A total of 45 sites was sampled, each being fished using the semi-quantitative and quantitative techniques. (2) A significant relationship existed between the semi-quantitative and Quantitative results for all age groups of salmonids (R2 83.4% to 96.1%, p < 0.0001). (3) The results from each site were categorised according to an existing classification system for quantitative and semi-quantitative data. The semi-quantitative component of this system was modified using the results of this investigation. The degree of error associated with sites classified semi-quantitatively was found to be slightly less when using the modified system for 0+ salmon, > 0+ salmon and 0+ trout, ranging from 10.5% to 30%. (4) Insufficient data points were available for the analysis of coarse fish data.

NRA North west salmonid microtagging programme 1987-1994

The microtagging programme began in 1987 using hatchery reared salmon originating from the rivers Caldew and Hodder and subsequently included the Lune (1988) and Ribble (1989). Microtagging of sea trout began in 1991 for the Lune and in 1993 for the Hodder. The report explores the NRA North west salmonid microtagging programme looking at methods, results and recommendations. The report provides salmon microtagging data and returns from 1987 to 1994.

Description of NRA tracking studies: tracking techniques and fish counter technology

The study began on the 7th January 1991 and was completed in June 1991. Two reports have been produced. This report published as R&D Note 33 describes NRA tracking studies, tracking techniques and fish counter technology. The second report published as R&D Note 34 evaluates NRA tracking studies and recommends future research. The latter will be used solely for NRA management purposes. This report briefly outlines the programme of the 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. 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. Further details of these techniques and their development are given in Sections 2 and 3. Section 4 summarises and assesses completed and current NRA tracking Studies. Complete project descriptions for the studies are contained in Appendix A. Section 5 discusses the scientific content of these studies in relation to similar work carried out elsewhere in the UK. Section 6 details the future development of tracking techniques. Tracking work on migratory salmonids has tended to concentrate largely upon the movements of adult salmon. Much of this report will therefore be concerned with salmon tracking studies. NRA studies involving sea trout are referred to where appropriate. The methodological problems of sea trout tracking studies are summarised in Section 2.1.3.

The NRA's role in wetland conservation

This is the NRA's role in wetland conservation report produced by the National Rivers Authority in 1995. This document is the third of a series of three R&D Notes produced as part of an integrated research programme addressing aspects of the NRA's role in wetland management and conservation. Chapter 1 considers the nature of the wetland resource and its definition. Chapter 2 presents the NRA's current legislative and policy framework relating to its role in wetland conservation. National and international legislation and agreements are considered, and particular attention is afforded to the potential implications of the 'Habitats Directive'. Chapter 4 presents key examples of operational casework involving wetlands. Differences in approach and external perceptions of the NRA's current and likely future role in wetland conservation are discussed within Chapter 5. Other issues highlighted in this report are: policy guidance required on NRA’s role in land drainage; standard of flood defence service for wetlands; cost-benefit analysis; strategies for halting and reversing the decline and degradation of wetland resource; and Catchment Management Planning.

Wetland resource evaluation and the NRA's role in its conservation. Classification of British wetlands

This is the Wetland resource evaluation and the NRA's role in its conservation: Classification of British wetlands report produced by the National Rivers Authority in 1995. This R&D document provides a clear classification for wetlands in England and Wales. The classification incorporates many of the existing ideas on the subject but avoids some of the problems associated with other classifications. A two-layered 'hydrotopographical' classification is proposed. The first layer identifies situation-types, i.e. the position the wetland occupies in the landscape, with special emphasis upon the principal sources of water. The second layer identifies hydrotopographical elements, i.e. units with distinctive water supply and, sometimes, distinctive topography in response to this. This system is seen as an independent, basic, classification upon which it is possible to superimpose additional, independent classifications based on other features (e.g. base-status, fertility, vegetation, management etc.). Some proposals for such additional classifications are provided.

Wetland resource evaluation and the NRA's role in its conservation. 1. Resource assessment

This is the Wetland resource evaluation and the NRA's role in its conservation: Resource assessment report produced by the National Rivers Authority in 1995. This R&D document provides a strategy for the assessment of the wetland resource of England and Wales. As a first step the report defines wetlands in their UK context. The following working definition is suggested: Wetland is land that has (or had until modified) a water level predominantly at, near, or up to 1.5 m above the ground surface for sufficient time during the year to allow hydrological processes to be a major influence on the soils and biota. These processes may be expressed in certain features, such as characteristic soils and vegetation. The report also summarises a hydrotopographical classification of wetlands. The report then develops a strategy for the establishment of a wetland resource Inventory based on a geographical information system (GIS) as a means of storing and manipulating site data from across England and Wales.

The River Lune strategic stock assessment survey 1991 with particular reference to salmonids

In the past stock assessment surveys were generally reactive in response to a particular problem e.g. a pollution incident and as such were limited in the information they provided. A programme of strategic stock assessment would be more beneficial, providing up to date information on the status and composition of the stock. On a national level this could reveal trends in population dynamics and enable comparisons to be made between key rivers and between regions. The Stock Assessment Task Group (1991) has recommended annual strategic surveys for juvenile salmonids and triennial strategic surveys for coarse fish and non- migratory salmonids. The aim of this pilot study was to gain information on species distribution and their relative abundance within the River Lune catchment, and to compare the findings with the surveys carried out between 1981-1985. This would provide valuable information on the current status of the stock and provide an indication of the resources required to conduct such strategic surveys on other river catchments in the North West Region of the National Rivers Authority.

The juvenile salmonid populations of the River Lune catchment, 1981 to 1985

The aim of this study was to assess the status of the juvenile salmonid populations of the River Lune and its tributaries. There was special emphasis on juvenile salmon stocks in view of the implementation of a net limitation order in 1980. The number of licensed instruments were reduced as follows: (1) Drift, hang or whammel nets - from 12 to 10 (2) Draft or seine nets - from 3 to 1 (3) Heave or haaf nets - from 4 6 to 2 6 For the purpose of this report, the River Lune system has been divided into 13 subcatchments and these are examined with a view to detecting any trends in the data such as subcatchment productivity, partitioning between salmon and trout nursery streams, and whether the restrictions on salmon fishing had any discernible effects on juvenile salmon productivity. The effect of flow and instream obstructions on salmonid densities are also investigated as these have been shown to be important factors affecting abundance. Throughout the study period a programme of enhancement stocking took place primarily with salmon ova and fry. The possible impact of this on the results of the surveys has been assessed. The distribution and abundance of juvenile salmon was found to be relatively consistent in each of the 13 subcatchments studied over the 1981-1985 period.

A summary report on juvenile salmonid populations of the River Lune catchment, 1981 to 1991

This report summarises the fisheries electrofishing survey work undertaken on the River Lune, England, in the period 1981-85 and 1991. As part of a long term monitoring programme by the National Rivers Authority, juvenile surveys, with the emphasis on salmonids, have been carried out on the River Lune on a number of occasions since 1981. The latest survey in 1991 now gives the opportunity to assess what, if any, changes have occurred in the juvenile populations across the last 11 years and how future fisheries management may impact on the River Lune as a fishery. The areas of trout and salmon, fry and parr production will be considered in detail, as will adult trout populations. Water quality issues will be mentioned briefly as will habitat issues, where they are deemed to be important in affecting fish densities.

A report on the population structure of adult salmon and sea trout in the River Lune using scale samples - with reference to historical data.

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.

Report on the collection of salmon creel census data from Rivers Ribble and Hodder

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.

An analysis of the historical catch data from the migratory salmonid fisheries of the River Ribble

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.

Report on the analysis of salmon scale samples returned by anglers on the Rivers Ribble and Hodder

Fisheries technical staff from the North West Central Area of the National Rivers Authority (NRA) currently provide a service for the ageing of salmon scales from fish caught by anglers on the Rivers Ribble and Hodder in order to gather information on the biological characteristics of the salmon population on the River Ribble system in terms of weight, freshwater age and sea age. At the beginning of each fishing season, scale envelopes are distributed by the NRA to angling clubs and some individual anglers. Scales taken from salmon caught on the rivers are returned to the NRA Central Area Office by the anglers, or more often, by NRA bailiffs. The age of each fish caught is then determined by the identification and counting of annuli for both the river and sea zones on the scale. Information is provided by the angler on the scale packet concerning the length and weight of the fish caught, and the date, location and method of capture. Both this information and the age of the fish is recorded on a database. These data can be used to investigate the distribution, and exploitation patterns of the different age classes of the salmon stock within the river system. This report is principally concerned with the scale samples received in 1994, although comparison is also made with samples from 1993 and 1992. References to data will all relate to that received in 1994 unless an alternate year is stated.