UNITED KINGDOM

by

K. T. O'Grady
Water Research Centre, Medmenham, P.O. Box 16 Marlow, Bucks SL7 2HD

Note: A number of subject areas are inter-related to the extent that full coverage of some areas may only be possible by consulting the text for more than one sub-commission.

I Fishery Biology and Management (Sub-commission I)

1. General

About half of the projects under this heading were concerned with the assessment, enhancement and exploitation of both commercial and non-commercial fish stocks. Much of the research on non-commercial aspects was undertaken by the ten Water Authorities (WAs) which have a responsibility to improve, maintain and develop fisheries as well as give regard to their conservation. Government Agencies, ie Ministry of Agriculture, Fisheries and Food (MAFF), Department of Agriculture and Fisheries for Scotland (DAFS) and Department of Agriculture for Northern Ireland (DANI), continued research on aspects of commercial stocks and basic biology where this was relevant to exploitation. Most of the work on basic biology (about one third of the projects) was undertaken by Academic Institutions. However, there were over 30 projects involving collaboration between Academic Institutions and other bodies where basic biological information was needed for management problems. Fish physiology and biochemistry were largely confined to Academic Institutions except where there were relevant environmental aspects.

2. Assessment of stocks

The importance of quantifying home-water stocks of migratory salmonids was recognised by research by MAFF, DAFS and DANI who also undertook juvenile studies in fresh water where this had a direct bearing on evaluating the size of the commercial stock. Research on the abundance and distribution of eels was also undertaken by these Government agencies and the WAs, although the bulk of the latters' effort has been related to the assessment of coarse fish stocks; by survey and by means of anglers' catch data. Assessment of these stocks was often in relation to the development of Water Resources (see III) but longer term quantitative studies by fish-counter and by survey have been started in some WAs. These complemented the existing long-term studies of the Freshwater Biological Association (FBA). Methodology, gear and methods of estimating population size have formed part of some of these assessment exercises especially where this concerned deep water.

3. Enhancement of stocks

Studies have been made of the efficiency of supplementing juvenile stocks of migratory salmonids; fry planting and smolt rearing (DAFS); large scale stocking of salmon fry where there was no spawning (DANI) and the use of artificial spawning substrates and a desk study of N American enhancement practices (MAFF). Thames Water assessed salmon spawning sites with a view to enhancing the restored salmon run in the River Thames and Welsh Water evaluated the effects of river obstructions and water flows upon migrating salmonids. Yorkshire Water supplemented the smolt run on the Esk with hatchery reared smolts. Much WA effort went into the enhancement of coarse fish stocks by means of habitat modification and the mitigation of the effects of land drainage and engineering work. In addition to such physical/structural modifications, chemical modifications such as liming were employed to attempt to elevate levels of fish production.

4. Exploitation of stocks

A significant step in this area has been in the collection of salmon and migratory trout nominal catch statistics. These are gathered by WAs in England and Wales and collated onto computer file by MAFF at Lowestoft (1). This should improve accuracy and reduce transcription errors and may lead to standardised collection procedures. The extent of commercial exploitation of salmonids and eels has been examined by MAFF, DAFS and DANI. In particular, tagging programmes, including microtagging, have been employed in relation to the distant exploitation of home-water salmonid stocks. Where conservation measures have been implemented to prevent over-exploitation, eg North West Water, juvenile surveys are underway to measure the effect upon recruitment. There has been evaluation of gear including net materials and trap performance. The effects of elver exploitation on the eel population of the River Severn is being measured (Severn Trent Water). Much WA effort into recreational fisheries continues and anglers' catch rates have been the subject of research into the exploitation of coarse fish populations and non-migratory trout populations.

5. Basic biology

Research was concentrated largely on juvenile studies, interactions and movement. Studies of the early stages of salmonids have been concerned with recruitment in relation to variation in stocks and competition between brown trout and salmon, especially where salmon are introduced. Population dynamics and movement of salmonids, coarse fish and eels were all studied, in particular eel and elver migration and the downstream dispersal of juvenile stages of coarse fish and salmonids. Acoustic tags were employed to study the upstream migration of adult salmonids. The inter-relationships between eels and cyprinids and the effect of introduced species such as zander and grass carp upon the indigenous fish populations were also of importance. The interactions of fish with other trophic levels such as zooplankton and macroinvertebrates were the subjects of several studies.

6. Physiology and biochemistry

There were in excess of 40 projects in this diverse area which included nutrition, muscle structure and function, osmoregulation and biochemical binding of heavy metals. Research into the physiology of stress in fish and the endocrine control of salmonid integument structure continued (FBA). Welsh Water collaborated on a study of the physiology of smolting and of adult trout exposed to acid stress.

II Fish Cultivation and Disease (Sub-commission II)

In all about 20% of projects were in this area.

1. Cultivation

The cultivation of coarse fish species for restocking purposes was continued by a number of WAs. A wide range of species was of interest and included carp, rudd, tench, chub, dace, bream, barbel and grass carp. The research carried out included the use of hormonal injection and the manipulation of environmental factors to bring forward spawning. A number of studies were directed at the optimisation of husbandry practices and covered lagoons and heated recirculated systems were employed for the growing-on of fry to stockable size. In particular these techniques were directed at producing grass carp of a suitable size for field trials on macrophyte control. Trials with this species continue under the control of a steering group. Waste hot water has been employed in the culture of carp and in situ enhancement of the propagation of riverine coarse fish has been attempted.

The cultivation of salmonids was widespread and smolt production for enhancement undertaken by DAFS and DANI, the latter with a view to sea ranching, whilst MAFF considered the use of gravel pits for extensive smolt production. Rearing of smolts was also undertaken by Northumbrian Water, Yorkshire Water, South West Water and Welsh Water.

Research on the effects of crowding on fish skin was also of relevance to fish cultivation.

Work on fish genetics in relation to fish culture was concerned with a) identifying genetic tags and producing breeding stocks of such tagged fish and b) with the production of sterile, single-sex or sex reversed trout and their growth rates.

2. Disease

There were over 20 projects in this area and research was undertaken on both the diseases and parasites of cultivated fish species and those associated with wild fish populations. Particular diseases that received attention from MAFF were Prolific Kidney Disease (PKD), Bacterial Kidney Disease (BKD) and Enteric Redmouth. Effort concentrated upon: pathogenesis, control, improved diagnoses and effects on the economies of rainbow trout farming. An evaluation of Malachite green and other fungicides was also made. Government agencies continued to inspect fish farms, eg DANI made visits twice per year, in order to licence disease free status. Specific disease studies relevant to fish farming were on the carp blood fluke Sanguinicola, the economic importance of enteric redmouth in trout and the pathogenicity to fish of the Saprolegniaceae. A number of studies have attempted to evaluate the consequences of the parasites and diseases of farmed fish for wild fish populations. In particular the epizootiology and transmission of these has received attention. Crayfish plague in the native species of crayfish has been monitored in rivers by Wessex Water and Thames Water and this disease was being kept under surveillance in relation to the introduction and distribution of exotic species. However, the bulk of the work was concerned with natural fish populations and the ecological significance of their parasites. Research in this area ranged from the bacterial diseases of cyprinids, to regional surveys of parasites and the population dynamics of the natural parasites of coarse and salmonid fishes. These studies were largely undertaken by WAs with significant inputs and collaboration from Academic Institutions. Two of the main objectives of this work were, a) to provide management information in relation to fish transfers, and b) to study the aetiology of various pathogens/parasites in relation to natural environmental factors in order to try to explain outbreaks of disease. Those parasites which are potentially dangerous or novel have been of particular interest. Taxonomic and ecological studies of specific groups have continued especially on acanthocephalans and tapeworms in coarse fish and on the crustacean parasites of fish. A new key to the Helminth parasites of freshwater fishes is planned.

III Fish and Polluted Water (Sub-commission III)

1. Water quantity

Many projects in this area were linked with the assessment and enhancement of stocks (see Sub-commission I). Therefore, it was not possible to discern accurately the number of projects within this category. However, a significant proportion of the assessment and enhancement work was connected with the development of water resources.

The continued increase in abstraction of river water for potable, agricultural and industrial supply necessitated further work on fish and fisheries in relation to modified flow regimes. The Water Research Centre has been involved in studies of both reduced flow - in collaboration with the WAs, and high flows - in collaboration with the FBA and Department of the Environment (DoE). In particular, there was continued development of guidelines to enable the protection of fisheries from damage caused by changes in flow. In general, studies related to the quantification of pre-impoundment fish populations and especially studies of those parts of the habitat used for spawning and as a nursery area. This research was usually undertaken by WAs who also undertook work on the ecological effects of the release of stored water. Of specific interest was the effect of river regulation upon the movements of salmon and migratory trout and radio tagged (MAFF) adults have been tracked to provide information on such movements.

2. Water quality

The effects on freshwater fish of organic pollutants, such as industrial solvents and agricultural pesticides have been the subject of research by DAFS and MAFF. The latter operates a Pesticide Safety Precaution Scheme, now to become statutory within the Food and Environment Protection Act 1985, to evaluate the likely effects upon fish of new pesticides and new uses of existing pesticides. The effects of agriculture chemicals such as N and P in fertilisers and episodic pollutions associated with intensive live stock rearing and changes in land drainage have also received attention. The increase in environmental levels of N and P and their possible injurious effects on freshwater life have been studied in the context of eutrophication. The interaction of these elements with phytoplankton, zooplankton and fish have been studied in rural catchments such as Lough Neagh and the Norfolk Broads. Land use in rural areas and the consequences for fisheries have also been studied especially in those areas with moorlands and afforested catchments. The implications for fisheries of acid waters within these regions has also received attention. In general fisheries research in relation to acid waters has been in Scotland, Wales and North West England and has centred on juvenile studies. In particular, a study of the consequences of episodic variation in pH and low pH flushes has been undertaken as have studies on the effects of pH on stress and osmoregulation in fish. Research was also undertaken on the general effects of poor water quality on fish. The subject matter here has ranged from; the likely deleterious effects of fish farm effluents and cage rearing in lakes and reservoirs; changes in water quality that result from land drainage work; and surveys of marginal fish populations in relation to recovering industrially polluted rivers (North West Water and Yorkshire Water). South West Water have also undertaken a catchment survey of brown trout against a deterioration of water quality. The water quality requirements of upstream migratory salmonids has been investigated jointly by Water Research Centre (WRc), North West Water and the University of Aberdeen by means of tracking individuals carrying acoustic tags. A number of other studies have used tagged individuals to examine movement in relation to effluents. Studies on the possible toxic effects of chrysoidine dye to carp (used to dye anglers' maggot bait) by Yorkshire Water, Thames Water and WRc have so far given negative results. Further toxicity studies have been undertaken on the effects of a variety of pollutants upon coarse fish with a view to establishing the water quality requirements of non-salmonid fish in the context of the EC Directive on Protection of Freshwater Fish and on the Discharge of Dangerous Substances.

IV Production Statistics

Note: Nominal catch statistics based on reported catches of round fresh weight (tonnes). Values for eels for England, Scotland and Wales are best estimates.

* does not apply
- not available

V Bibliographic References

16 February 1984. “The future ecology of the Norfolk Broads”. Joint meeting of the British Ecological Society and the Linnean Society (some relevance to freshwater fish).

23–24 February 1984. Fish Farming Conference, Oban.

10–13 July 1984. “Feeding and Nutrition in fish”. International symposium of the Fisheries Society of the British Isles, Aberdeen.

10–13 September 1984. 15th Annual study course of the Institute of Fisheries Management, Stirling.

2 November 1984. Electric fishing seminar. Institute of Fisheries Management, Nottingham.

19–21 December 1984. Winter meeting of the British Ecological Society, Liverpool. (General ecology but of relevance to freshwater fish.)

21–22 February 1985. Fish Farming Conference, Oban.

1–3 April 1985. Fourth British Freshwater Fisheries Conference, Liverpool.

4–7 June 1985. “Effects of land use on fresh waters”. Joint Water Research Centre and World Health Organisation Conference, Stirling (some relevance to freshwater fish).

23–26 July 1985. “Scientific basis of inland fisheries management”. Fisheries Society of the British Isles Summer symposium, Cardiff.

16–19 September 1985. 16th Annual study course of the Institute of Fisheries Management, York.

16–19 December 1985. Winter meeting of the British Ecological Society, Edinburgh. (General ecology but of relevance to freshwater fish.)

In addition there have also been a number of smaller regional meetings on a range of subjects such as scale reading and assessing the value of fisheries, organised, in particular, by the Institute of Fisheries Management.