EIFAC NATIONAL REPORT FOR THE UNITED KINGDOM

FOR INTER-SESSIONAL PERIOD 1 JANUARY 1986 – DECEMBER 1987

K.T. O'Grady
Ministry of Agriculture, Fisheries and Food
Fisherie Division II
Great Westminster House
Horseferry Road
London SWIP 2AE

Note: a number of subject area 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. Assessment of stock

In the main this area is covered by water authorities and government agencies and the assessment of the status of stocks is usually intended to answer specific questions such as: is there a decline in the fishery or is the level of exploitation appropriate. Redd counts have been undertaken on the Tees, Wear and Tyne by Northumbrian Water with specific detailed studies on the North Tyne. Parr surveys are also on-going in this area and rapid electric fishing surveys from 53 sites indicate that the mean basic productivity has changed little and that some river Coquet sites are particularly productive. Abnormally low juvenile salmonid population densities have been investigated by North-West Water on the river Wenning and at river Ribble nursery sites where there is an alledged decline. These assessments were made with a view to finding ways of improvement.

Juvenile survev in Wessex Water are in parallel with investigations into entrapment of smolts at water abstaction points. This aspect is also receiving attention in Thames Water where it is hoped that experiments with Wolf-grid type traps will indicate the potential losses of smolts to water intakes. A smolt trap has enabled Yorkshire Water to confirm the existence of a limited smolt run on the river Ure in the absence of stocking since 1975. Assessment of stocks and detailed salmon population studies continue on the Tummel and North Esk (DAFS) and traps are employed on the Bush to count runs of adults and smolts (DANI). This organisation is also assessing annually marine survival and freshwater stock/recruitment relationships of salmon. Redd counts are also made in all of the main catchments and an attempt is being made at an overall assessment of the economic value of juvenile salmonid nursery habitat in Northern Ireland.

MAFF's National tagging programme for salmonids is, developing further with, the supply of micro-tags, advice and assistance on equipment. MAFF acts as a clearing home for tag returns. The overall micro-tagging programme is intended to help with the assessment of the relative contribution of specific rivers to the inshore and high seas salmon fisheries. The population dynamics of salmonids and other fishes is being investigated in a number of rivers in South-West Water whilst Welsh Water are monitoring the year to year variation in juvenile salmonid abundance and smolt output. Long-term stock and fishery performance is underway on the Welsh Dee with possible future developments in trapping. To date 120,000 parr and smolts have been tagged in Wales in order to evaluate their contribution to various fisheries and the effectiveness of stocking programmes. Additional studies by Welsh Water include the characterisation of spawning grounds and an assessment of the extent and quality of the still water trout resource.

Fish counters continue to be developed for the enumeration of upstream migrants and MAFF, DAFS, Welsh Water, North West Water, Southern Water and the Freshwater Biological Association are all involved. In particular the last organisation is concerned with computer enhancement and validation. FBA's river Frome counter still operates and the investigation of factors affecting salmon stocks in Southern Chalk stream continues.

The application of radio tracking to investigations of adult salmon migration is now widespread with MAFF and Water Authority investigations - eg. South West Water, Wessex Water and Welsh Water. These studies are not only to determine movement in rivers and from estuaries as there are increasing attempts to use radio-tagged fish to determine the effectiveness of various installations such as fish counters. A national programme on the genetic integrity of salmon stocks is about to commence (MAFF).

There are also numerous attempts to assess coarse fish stocks. The Tees estuary has been sampled and growth and population studies of its coarse fish made (Northumbrian Water). North West Water have concentrated largely upon surveys of marginal rivers in order to determine fishery status. Yorkshire Water also routinely survey coarse fishes with recent emphasis on fry. Much of the day-to-day survey data collected on coarse fishes by Thames Water is now computerised with effective field data logging of survey results.

Angler catch data has received greater recognition as a source of information on coarse fish populations. Severn Trent Water, Humberside College and Yorkshire Water are all employing angler census and angler catch statistics for fishery management purposes. Angling match returns have been especially useful for studies of medium and long term trends in catches. A new programme on coarse fisheries in East Anglia has commenced with a collaborative project on Eastern Rivers between Anglian Water and FBA. The latter are also engaged in a base-line study of coarse fish in the Hampshire Avon and the management and ecology of coarse fish population in North West England. Eel population dynamics are being researched by MAFF and FBA.

2. Enhancement of stocks

An evaluation of stock enhancement techniques is being carried out by MAFF and will entail detailed studies of mortality and movement of 0 group salmon. The project will seek appropriate enhancement methods for both natural and introduced fry. Severn-Trent Water are now examining the feasibility of re-introducing Atlantic salmon to the Trent whilst North West Water are opening up the river Caldew to salmon by constructing fish passes at impassable weirs. This river is also subject to a programme of stocking with salmon parr and smolts. Northumbrian Water's enhancement of salmon through trout removal in Weardale burn suggests a potential for improving Wear salmon runs by about 8%.

An extensive programme by DANI has considered the survival of juvenile salmonids at varying stocking densities and at high and low levels of intra-specific competition. Optimum survival was achieved at a stocking density of about 5 individuals per sq m. Emphasis was also placed upon habitat surveys that were to be used in the planning of the enhancement programme, which continues to include annual planting of swim-up fry in suitable habitat where there is no natural spawning. Enhancement by DANI has also included the rehabilitation of salmonid habitat after land-drainge work because of the generally lower densities of fry that result.

Anglian water has introduced artificial reefs to some lowland river sites with the aim of improving fish stocks through the provisions of refuges. Initial results from this are promising as the rivers in question often have limited habitat structure.

3. Exploitation of stock

MAFF participates in the international programmes on the exploitation of salmon off Greenland and Faroes as well as studying the pattern of exploitation of salmon and sea trout off the North East coast. Tagging of wild and hatchery smolts is maintained and microtag returns have been 300 in 1986 and 1,000 in 1987. This department also continues to report the collated annual catch statistics for commercial and rod caught salmon and sea trout in England and Wales. Validation of the definitive version of declared sport and commercial catches for the period 1951–1982 continues and is being finalised for publication.

DAFS also reports annual salmon and sea trout catch statistics for Scotland and the level of exploitation of various fisheries through use of external tags. This is particularly relevant to the river North Esk and the Caithness and North Scottish coast. The catch statistics of the river Tay are currently being examined by the University of Aberdeen.

DANI also has a micro tagging programme and returns are evaluated to assess the relative importance of local and high seas exploitation of salmonids whose origin is in Northern Ireland. As elsewhere in the UK commercial catch statistics and rod permit sales are collated.

Studies on Lough Neagh by the University of Ulster monitor the eel fishery and examinine the problems of the commercial perch fishery. In this latter case difficulties may arise because the current takeable size is less than that of female maturity. The commercial pike fishery of Lough Earne is also being appraised. In England the Polytechnic of Central London and Thames Water are collaborating on a study of the commercial eel fishery in the Thames estuary in order to obtain information on levels of exploitation and data useful in determining the management of this fishery. Northumbrian Water has collected catch returns in greater detail which has led to improved analysis. A statistical analysis of salmon and sea trout rod catches is also underway.

Severn Trent Water is conducting further investigations into the exploitation of the river Severn elver population. In particular the implication of this for the eel populations are being studied. Catches in relation to temperature are also being scrutinised with the object of formulating a management strategy. Welsh Water are using tagged wild and hatchery salmon parr and smolts in a consideration of the contributions made by some juvenile population to the Usk and Irish drift net fisheries. The distribution of the migratory salmon rod catch of the river Tawe and the catch per unit effort are being evaluated through the use of anglers' log books. A comparison of netting and anglers' catches indicated that a high proportion of stocked fish were caught by anglers.

A collation of current stocking practices and exploitation at large reservoir trout fisheries was made by WRC.

4. Basic Biology, physiology and biochemistry

Much of the research in this area was conducted by academic institutions. Humberside College have embarked upon a study of the physiological and behavioural response of fish to electricity; telemetric measurement of heart rate in pike has allowed the University of Aberdeen to estimate metabolic rate and to begin to study pike feeding behaviour in semi natural situations. Foraging behaviour of Atlantic salmon has also been studied by the University of Glasgow where the physiology of salmonids is also under scrutiny. Acidity is also the subject of investigation, especially episodes and the inter-action of low pH, Al and heavy metals and their effect upon physiology, osmoregulation, growth and survival, at CEGB, Lancaster University and Nottingham University.

Coarse fish studies are on-going at the FBA - minnows, bullheads and perch in Windermere - whilst UWIST is examining the life-history dynamics of perch from this lake. Pituitary function is also being studied at UWIST and Sheffield City Polytechnic has projects on prostaglandin and its physiological function in eels, and calcitonin and plasma electrolyte balance in pike. Other physiological studies include one on eel red blood cells at the University of Bath. Ultrastructure of muscle and the electrophoretic characterisation of UK and European eels are being undertaken by the University of Salford. Analagous genetic variation and population differentiation studies are currently undertaken on salmonids by Queen's University, Belfast. However, here isozyme and meristic analysis of genetic differentiation is studied in addition to restricted endonuclease analysis of mitochondrial DNA.

Colour vision and visual development studies in brown trout are being carried out at Queen Mary College where the regions of the cyprinid brain concerned with the storage and formation of memory are being investigated. Fish nutrition and energy balance research continues at King's College. Studies that are more ecological eg. the foraging behaviour of stoneloach and the ecological effects of pike predation are undertaken at the University of Leicester. General studies on perch and roach populations (University of Bristol) and perch population dynamics (University of Exeter) are also on-going and many aspects of the biology and physiology of coregonids are being researched at the University of St Andrews.

A wide range of fish behaviour studies continues to be developed at the University College of North Wales. Some of the non-university work is of a basic nature also. Yorkshire Water are attempting to identify characters that could be employed to reliably identify salmon, sea trout and their hybrids and to assess the extent and effects of such hybridisation in the river Esk. The distribution and density of brown trout is being established in some rivers by Wessex Water, whilst Severn Trent are engaged in a study of the interaction of introduced salmon on resident trout. So far the indications are that introduced salmon are not deleterious to trout. This water authority is also monitoring the spreading distribution of pikeperch. North West Water has in hand investigations into the survival and hatching rate of salmon ova whereas egg drift and the effect of mechanical shock on eggs are studied by the FBA.

II. Fish Cultivation and Disease (Sub-Commission II)

1. Cultivation

Improving the performance of farmed trout is the objective of much of the MAFF work on cultivation. This encompasses evaluation of domesticated strains of rainbow trout and their hybrids, and a co-operative study with UWIST and Brunel on growth hormones. It further entails triploid work, the extension of the seasonal spread of spawning times - especially through endocrine studies - and the control of sex ratios. The last study giving limited success (15–20%) in the production of ducted homogametic males. Work on the inbreeding of F1 generations with hybrid vigour is a central component of the genetics programme. The production of all female stock is now widespread in England and Wales. A new quarterly report “Trout News” is now produced by MAFF and this gives advice to trout farmers. Hatchery strains, the production of sterile brown trout, optimum conditions for the induction of triploidy and genetic markers in brown trout are the main areas studied by DANI - which continues to operate two trout farms for brown and rainbow trout restocking in Northern Ireland.

Academic institutions also continue research on fish cultivation. The University of Southampton is researching the introduction of novel genes into rainbow trout (Transgenics). The University of Aston has on-going studies of photoperiod control of trout reproduction with the view to obtaining an all year round supply of eggs and fry for trout farms. Other Aston studies include: the effects of diet on fecundity; the control of yolk incorporation; larval feeds, coarse fish reproduction; sex reversals and smoltification control. The implications of commonly used anaesthetics for metabolism is being studied at NE Surrey College. Water Authority research and development continues on a variety of aspects of the cultivation of both coarse fish and salmonids.

Anglian Water has studies of induced spawning of coarse fish and optimisation of pond production of coarse fishes. Severn Trent Water have largely completed their studies of the optimal husbandry of coarse fish fry and the findings are incorporated into the production process. Yorkshire Water have also completed studies on the induction of spawning and early rearing in 8 species of coarse fish. Grass carp culture research by Thames Water is in its final stages. The further development of heated recirculated water cyprinid rearing system is being undertaken by Wessex Water. Their studies also encompass induced spawning and rearing-on of fry in ponds covered by polythene tunnels.

A new project by Yorkshire Water focusses on varying the spawning time of rainbow trout and brown trout in order to optimise the use of hatchery facilities. Welsh Water are also reviewing the methodology of holding brood stock of salmon and sea trout for extended periods. This has been done successfully in cages held in a water supply reservoir by Thames Water - forty adult salmon were successfully stripped but attempts at reconditioning were disappointing. Thames Water also continued to successfully rear salmon smolts in cages in reservoirs. A 13% smolt rate and 78% survival rate resulted from overwintered parr. Northumberian Water are undertaking studies on the retention of adult salmon, for propagation, in a cooled seawater recirculation system at Kielder hatchery. The work at this hatchery also entails attempts to increase juvenile salmonid growth rate through feeding regime. To date a 30% increase over the previous growth rates obtained has been achieved.

2. Disease

Projects on fish diseases and parasites are in hand at a number of Universities. Water authorities continue to monitor disease and parasites with a view to preventing their spread. MAFF, DAFS and DANI play a regulatory role in these control measures, through site inspections and examination of fish tissue. Much of the disease work relates to farmed fish. Losses on trout farms were attributed to ERM, IPN, BKD, whereas on salmon farms, furunculosis and pancreatitis were the main disease problems. The cause of disease was identified in 80–90% of cases investigated by MAFF. Investigations into the inter-relationship between wild and farmed fish were confirmed for BKD, PKD and IPN.

Renibacterium was detected in non-salmonids adjacent to a freshwater cage farm affected by BKD but further testing on migrating salmonids and wild fish gave no further evidence of its presence in wild. Anguillicola crassa has been identified and found in 4 of 40 rivers. There have been no new outbreaks of crayfish plague although monitoring of native crayfish populations continues especially by Wessex Water. MAFF has confirmed the myxosporean aetiology of PKD which shows close affinity for the Sphaerosporidae and continues the development of diagnostic techniques. Rapid tests for VHS, IPN, ERM, IHN and SVC have been developed. Purification of the PKD organisms has been unsuccessful but advances have been made to the isolation medium for Yersinia. Field trials into the therapeutic effects of malachite green on PKD in rainbow trout were successful. Field and laboratory trials are also underway to determine the effects of Vitamin E in diet on disease susceptibilities as are pharmacokinetic studies in antibiotics in trout. A twelve months survey of the susceptibility of aquatic bacteria to a range of antimicrobials used in fish farming or medicine shows no evidence that they result in significant environmental stress.

The causes and prevention of coarse fish ulcer disease is now the subject of a joint Anglian Water/University of Essex project. Yorkshire Water continues to determine the distribution of potentially harmful parasites, notably Ergasilus, Bothriocephalus and Sanguinicola. This last parasite is also the subject of a joint Thames Water and Royal Holloway and Bedford New College project. This carp blood fluke is routinely maintained for laboratory studies now that the intermediate snail host has been identified. This collaborative study has also been extended to a joint investigation into the ecology of Ergasilus in salmonids and coarse fishes.

The University of Stirling is conducting investigations into: pancreatic disease of farmed salmon; the development of a treatment for PKD; immunity in salmon fry; the immunology and cell surface properties of ERM and further development of a rigorous test for furunculosis. Studies of the life cycle of Rhipidocotyle, and the transmission of Echinorhynchus, especially through the susceptibility of capture of the intermediate host by trout are being undertaken by Leeds University. Diplostomum and Apatemon are the subjects of research at the University of Aberdeen.

The inter-relationship between parasites found in fish farms and wild fish populations of the Test and Itchen continues to be studied by Southampton University. Antisera for bacterial infections of trout and salmon and phagocyte studies are being developed at NE Surrey College.

The parasites of coarse fishes are the subject of a variety of University projects. At Keele: the immune responses of, cyprinids to metacestodes, and of some coarse fish species to ligulosis are being undertaken as is the determination of the degree of influence Ligula has upon the reproductive systems of cyprinids. Another study of Ligula at the University of Exeter concentrated on the population dynamics and inter-action with the host fish - roach. This study suggests that fish numbers determine parasite numbers to a greater degree than Ligula controls the size of the roach population. Competitive inter-action between acanthocephalans, acanthocephalans in eels and the morphology, infectivity and pathenogenicity of Pomphorhynchus are also the subject of studies at Exeter University which is also continuing a study on the distribution and biology of the parasites of freshwater and migratory fishes.

The physiological response of fish to environmental stress and studies on skin in relation to ectoparasite loading are being investigated by the Freshwater Biological Association. Their work also extends to Saprolegnia and Salmincola gordoni a little known parasite of trout. King's College has research projects on eel and nematode endoparasites.

III Fish and Polluted Water (Sub-Commission III)

1. Water Quantity

Many of the projects under this heading were linked with studies on stock assessment and enhancement (see sub-commission I) in relation to existing and future water resource developments. Continued pressure to abstract river water has necessitated further work on fish and fisheries and the influence of modified flow regimes. In the main, these studies have been undertaken by water authorities virtually all of which have current research projects considering fisheries and ecological aspects of abstraction and modified discharge regimes. There are a number of collaborative projects between the water authorities and academic and research institutions. Examples of these are: a characterisation of flow pattern in relation to the distribution and abundance of coarse fish fry (Anglian Water/University of East Anglia); an investigation of reservoir discharge on, spawning success, hatching, in-gravel and juvenile survival in the river Tyne (Northumbrian Water/University of Newcastle); resolution of the residual flow required in chalk steams to ensure salmon migration (Southern Water/Freshwater Biological Association). MAFF has also been active here with the application of radiotagging techniques in order to follow salmon and migratory trout in rivers and from estuaries into rivers in relation to discharge and release of water from reservoirs. Other applications of the radio tagging of migratory salmonids have been on the rivers Torridge and Tamar (South West Water) in conjunction with other kinds of survey. Similarly the pattern of movement through space and time has been studied for Hampshire Avon salmon (Wessex Water).

In addition to tracking methods Welsh Water has examined: the effect of abstractions on fisheries; the impact of land drainage rehabilitation; and fish counter performance and validation. This last problem has also been the subject of R & D by MAFF and also FBA, whilst the affects of river regulation on fisheries continues to be studied by Humberside College and also by Yorkshire Water. The latter have also considered additional factors such as land-use and water quality jointly as possible causes of poor angling.

2. Water Quality

Pesticides have continued to receive attention: MAFF, Welsh Water, DoE and the Institute of Hydrology are collaborating to study the run-off of selected pesticides from fields at an experimental farm. Preliminary studies by MAFF on Tecnazene (a fungicide used on stored vegetables) give an indication of the acute toxicity (270μg/l) and no observed effect concentration (1μg/1) for rainbow trout (MAFF). Tri-butyl-tin studies have continued and with its withdrawal from some antifouling paint applications a study of biological recovery is underway (MAFF). Pesticide levels in fish were also monitored by Severn Trent and Yorkshire water, the latter in the particular context of industrial rivers.

The measurement of the occurrence and effects of inorganic and organic contaminants in Scottish waters has continued with emphasis on the role of acid precipitation and afforestation in surface water acidification (DAFS). This assessment is expanding to cover the additional effects of other land-use changes on freshwater and migratory fishes.

Acidity and chemistry of rainfall is now monitored at three additional sites in Northern Ireland (DANI). Water authorities and academic institutions also continue with projects related to acid water: the University of East Anglia continues to study acid stream ecology whilst UWIST and UCW examined respectively acid and Al episodes and the effects of acid waters upon life history traits. Severn Trent and NWWA have both examined pH and the status of stocks, especially in relation to afforestation (ST) and the influence of catchment liming (NWWA). This process seems to have a beneficial effect on pH. There has also been evidence of inhibitions of migration following spate induced low pH. The liming of lakes and the alteration of acidity and run off has been investigated in the Llyn Brianne Catchement Study project jointly by Welsh Water and UWIST. The water quality of acid water, especially organic and inorganic Al and inter-gravel water quality are part of a CEGB study in which the influence of liming is also studied.

Physiological aspects of acidity have been studied by a number of Academic Institutes. The development of fisheries in upland acid lakes has been considered; Severn Trent and Yorkshire Water have used American brook trout whilst Welsh Water have experimented with different strains of brown trout.

More specific toxicological studies on heavy metals have been undertaken at UWIST, the University of Bath and King's College whilst WRC has continued to study the toxicity to carp of Cu, Ni and Arsenite and the toxicity of NH₃ to early life stages of carp and rainbow trout. Welsh Water has also undertaken a study of NH₃ in a river in relation to fisheries and non-point sources.

The impact of fish farm effluents has also received attention. WRC has reviewed the problem and monitored antibiotics in fish farm effluents whilst the University of Aston has researched the settling of solids from fish farms and the University of Stirling continues to assess the environmental impact of cage-culture.

Heavy metal burdens of fishes have also been monitored and a joint study of eels is underway between Anglian Water and and the University of Essex whilst a MAFF study of organochlorides, metals and other contaminants in eels from Water Authority areas is nearing completion.

The more general problem of eutrophication continues to be studied by the University of East Anglia in the Norfolk Broads. In Northern Ireland N + P inputs and budgets have been the subject of a number of projects (DANI) which also incorporate alagal studies. Investigations have covered the loss of N from grassland and the fate of N + P in upland and lowland rural catchments and the impact of sewage effluent upon Lough Neagh. In this last study the P-reduction process has markedly reduced P inputs to the Lough and the effect of this has been a decline in SRP and peak chlorophyll a from 1981 to 1986. About 200 small lakes have now been surveyed by DANI and the relationship between gross chemistry and regional geology is being studied.

IV. Production statistics

Note: These are nominal catch statistics based on reported catches of round fresh weight (tonnes)

* Including non migratory S. trutta

** Not available

- Does not apply

V. BIBLIOGRAPHIC REFERENCES

A great number of fish and fisheries related papers of UK origin are published each year in journals that are widely available. Therefore, no attemptis made in this report to duplicate this in the interests of brevity and because of the considerable effort that this would entail.

EIFAC OCCASIONAL PAPERS ISSUED
DOCUMENTS OCCASIONNELS DE LA CECPI PUBLIES

EUROPEAN INLAND FISHERIES ADVISORY COMMISSION (EIFAC)

EIFAC documents are issued in three series:

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Report of each session in English and French

EIFAC Technical Papers

Selected scientific and technical papers, including some of those contributed as working documents to sessions of the Commission or its Sub-Commissions. Published in English and French, or one of these languages.

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Papers of general interest to the Commission. Published in the language submitted, either in English or French; sometimes in both languages.

Copies of these documents, when still available, can be obtained from:

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Documents scientifiques et techniques sélectionnés comprenant certains documents de travail présentés aux sessions de la Commission ou de ses sous-Commissions. Publiés en français et en anglais, ou dans l'une de ces deux langues.

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Documents d'intérêt général pour la Commission. Publiés dans la langue d'origine, soit en français, soit en anglais; parfois dans ces deux langues.

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