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Know Your Rivers - Salmon and Sea Trout Catchment Summary
River Wye
Introduction
This report describes the status of the salmon and sea trout populations in the Wye catchments. Bringing together data from rod catches, stock assessments and juvenile monitoring, it will describe the factors limiting the populations and set out the challenges faced in the catchment.
Action tables set out habitat improvements to restore freshwater productivity of salmon and sea trout populations. These tables also include some work which will be carried out by our partner organisations, not just Natural Resources Wales (NRW).
NRW has a duty, defined in the Environment (Wales) Act 2016 to have Sustainable Management of Natural Resources (SMNR) at the core of everything that we do. By applying the principles of SMNR in all of our activities - from agriculture, forestry and flood defence to development planning - we are undertaking catchment-wide initiatives that will deliver for fish stock improvements. Our reports highlight the importance of considering the whole catchment when identifying and addressing fisheries issues; and of working with partners.
NRW is committed to reporting on the status of salmon stocks in all of our principal salmon rivers for the Salmon Action Plans and condition assessments under the Habitats Directive in SAC rivers; all fish species in all of our rivers are reported for the Water Framework Directive (WFD). This report will fulfil these commitments and provide an informative and useful summary of stock status and remedial work planned, for our customers, specifically anglers, fishery and land owners; as well as our partners.
Catchment
The River Wye rises from an altitude of 741m in the Welsh mountains at Plynlimon and at 250km in length it is the 6th largest river in the UK. The principal tributaries are the Elan, Ithon, Irfon, Lugg and Arrow, and the Monnow. The Lugg and Arrow rise in Wales and then flow east through England before joining the Wye at Hereford, in addition significant parts of the Monnow catchment and main river Wye also lie within England.
Land-use in the catchment is predominantly agriculture (with some woodland and residential areas). Higher grounds and poorer soils to the north and west supporting largely monoculture conifer forestry and pastoral farming, give way to higher quality and more intensive arable agriculture in the south and east of the catchment. In the upper catchment the headwaters of the Elan River are impounded, creating the Elan Valley system of reservoirs.
The Wye catchment is one of great ecological value. It has many SSSIs and the main river and many of its tributaries are designated as a riverine SAC under the Habitats Directive for ten rare or threatened nationally and internationally important species. These species include seven fish species - Atlantic salmon; allis and twaite shad; brook, river and sea lamprey; and bullhead.
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The River Wye is a well-established and nationally significant salmon rod fishery with the most recent reported rod catch (2015) of 1212. Salmon are found throughout the Wye catchment except in the upper reaches of the Elan, above the reservoirs. Fish passes installed at numerous weirs across the Lugg and Arrow, and at Osbaston on the Monnow have opened up these catchments and have resulted in the inclusion of these catchments in the Salmon Conservation Targets. The Wye catchment has suffered from declining rod catches, and after some years of promoting voluntary catch and release, a Wye specific byelaw was introduced in June 2012 which mandated the release of all rod caught salmon.
A small number of sea trout are caught on the Wye (84 fish in 2015). Because sea trout rod catch is low and they are rarely targeted by anglers on the wye, we will not further consider sea trout within this report.
The River Wye and its tributaries are also a locally important brown trout, coarse fish and grayling fishery. Elver fishing takes within the tidal reaches of the Wye.
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Rod catches
The following graph shows the total declared rod catches, including numbers released or killed for salmon on the Wye, since 1960. Returns are collected from the Wye Owners Group, and more recently we use the data which the Wye and Usk Foundation (WUF) collect from the fishery owners. Release data is taken from the rod licence returns, these are likely to be a slight underestimate as the full returns are invariably lower than the owners returns.
The trend is dramatically downwards since the 1960s, but has considerable variability within it, peaking at 7854 in 1967 and dropping as low as 320 in 1992. Signs of an upturn in the trend are apparent in recent years.
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Salmon rod catch, River Wye1960-2015
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Monnow Fish Counter The Monnow catchment had been entirely inaccessible to migratory fish for the best part of
300 years, due to the large weir at Osbaston. In 2008 we installed a pool and traverse fish
pass and a Vaki river watcher fish counter to assess the extent of the re-colonisation of the
catchment. The Vaki fish counter produces images using infrared light. As fish pass through
the infrared scanner plates an image is produced. Underwater cameras were also installed
to help with species identification. With the opening of Osbaston fish pass and the removal
of Kentchurch weir (in 2011), 200km of the river Monnow catchment have become
accessible for migratory fish. Since Osbaston fish pass was opened, salmon and large
numbers of brown trout have been recorded migrating upstream.
Vaki image of a Salmon
Camera image of a Salmon
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Stock Status
Conservation of Salmon
Salmon stock status is assessed through the use of ‘Conservation Limits’ (CL) which provide an objective reference point against which to assess the status of salmon stocks in individual rivers. The numbers of salmon a river can produce (and consequently the catches that the stocks support) are a function of the quality and quantity of accessible spawning and rearing area. This is why, in general, big rivers have larger catches and have correspondingly bigger total spawning requirements (or Egg Deposition Targets - EDT) than small rivers. Thus, for any given rivers there should be an optimum level of stock which the CL seeks to protect. The Conservation Limit represents the number of eggs that must be deposited each year within a given catchment in order to conserve salmon stocks in the future.
The Conservation Limit for the Wye is set at 38.57 million eggs, represented by the red line on the graph. The current estimate of number of eggs is being deposited is marginally below the Conservation Limit which puts the Wye salmon stock ‘Probably At Risk’ but with an improving trend. In 5 years’ time, the predicted status of the Wye salmon stock will be ‘Probably Not At Risk’. Based on current and predicted trends, the Wye salmon stock will continue to improve. This is a very positive improvement on recent years.
To describe the estimate of compliance as salmon available to spawn; we would need around 8000 salmon running the river to spawn to meet the conservation limit, our estimate for 2015 was 7300 fish.
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Estimates of egg deposition, and compliance with conservation limit
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Juvenile Abundance Monitoring
The following maps show the results of the routine juvenile salmonid population surveys from 2015 in Wales and England. The surveying programme (and responsibility for the river) is split between Natural Resources Wales, who are responsible for the Welsh Wye, and the Environment Agency on the English side. Results from the Monnow salmon investigations can be seen in the Appendix.
The symbols display the National Fish Classification Scheme (NFCS) grades which have been developed to evaluate and compare the results of fish population surveys in a consistent manner. The NFCS ranks survey data by comparing fish abundance at the survey sites with sites nationally where juvenile salmonids are present. Sites are classified into categories A to F, depending on densities of juvenile salmonids at the site. The following table shows the values and classification of NFCS.
Grade Descriptor Interpretation
A Excellent In the top 20% for a fishery of this type
B Good In the top 40% for a fishery of this type
C Fair In the middle 20% for a fishery of this type
D Fair In the bottom 40% for a fishery of this type
E Poor In the bottom 20% for a fishery of this type
F Fishless No fish of this type present
Juvenile salmon were recorded in at 22 of 28 Wye sites in 2015; the exceptions being the sites on the Monnow and upper Lugg and upper Arrow catchments.
Salmon have never been recorded at the three Monnow sites due to man-made barriers, some but not all of which have now been made passable or removed. The Lugg, Arrow and Hindwell brook sites also have migration barriers, and records of salmon are patchy in these areas.
Eleven of the 28 sites had salmon fry classifications of Excellent (A) or Good (B), although salmon parr classifications were considerably lower, with none Excellent and just three Good.
Juvenile brown trout were recorded at 27 of 28 Wye sites in 2015; the exception being the site on the Ithon at Dol y Dre which has only had three records of trout since 1985 and none since 2004.
Just eight of the 28 sites had trout fry classifications of Excellent (A) or Good (B), and as seen with the salmon parr, trout parr and adult (>0+) classifications considerably lower, with none Excellent and just two Good.
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Juvenile salmon distribution within the Wye catchment
In 2014 a full spatial programme, comprising 179 sites, was undertaken on the Wye. The distribution of juvenile salmon from these surveys is shown in the map below. Data from a further 44 sites surveyed in 2013 in the Irfon catchment as part of the ISAC project; and 18 in 2013 and 2015 on Monnow and Lugg are also included for a more complete picture. As can be seen, juvenile salmon were recorded at most of the sites in the catchment (162/241). The majority of sites with salmon absent are on the upper Lugg, Lugg and Arrow tributaries, the Frome and Lodon, and the Monnow catchments, all of which have migratory access problems that are not yet fully resolved. It is worth noting that for the first time in many years, salmon were found at every site on the main Lugg and Arrow up to the English / Welsh border. NB – the absences which appear on this map to be on the River Lugg downstream of Hereford are in fact on the Wellington and Moreton Brooks.
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Juvenile Trend Analysis
Trends in the population data for juvenile salmon and brown trout were assessed using Bayesian statistical linear and non-linear models.
The linear model fits a straight line to the data in order to determine whether a trend (upwards or downwards) is present. The statistical significance of the trend is denoted by the P value, P>0.975 indicates a statistically significant upward trend (or a 97.5% chance of an upward trend) and P<0.025 indicates a statistically significant downwards trend (or a 97.5% chance of a downwards trend). The non-linear model fits a curved line to the data, which may be more informative in long data sets of naturally fluctuating fish populations. It can highlight particular times within the data series where upwards or downwards trends have been more evident; however no statistical significance can be calculated for these trends.
The data used comprised historic quantitative salmonid surveys from the Welsh Wye catchment, excluding those associated with stocking, habitat improvement or impact assessments; this totalled 466 surveys since 1985. Both species were analysed using both a linear and non-linear model on the 31 year data set (1985 – 2015), and just the linear model on the 14 year data set (2002 – 2015). The latter data set using data only from surveys conducted annually as part of the revised Core Fish Monitoring Programme, and totalling 283 surveys.
It is important to remember that these trends will fluctuate year on year, and should be considered as part of a bigger analysis, including for example rod catch and habitat availability.
Salmon
In line with the decline in rod catch, juvenile salmon densities have shown a highly statistically significant decline since surveying began in 1985; this long-term downward trend is equally evident in both salmon fry and parr densities. This trend appears to be reversed in the short-term dataset with juvenile salmon densities showing a strong (P = 0.927) chance of an upward trend since 2002; this short-term upward trend is evident in both fry and parr to a similar extent. This upturn is also evident in the non-linear analysis, which suggests a steep decline until the late 1990s, a plateau followed by an unsteady, but increasing trend since about 2005/6. This increase is likely to reflect a range of interventions in the catchment, home waters, and further afield.
Brown Trout
In parallel to the trend observed in juvenile salmon, densities of brown trout in the Wye catchment have shown a highly statistically significant decline (P = 0.018) since surveys began in 1985. This decline seems to be driven largely by a decrease in trout parr and adults rather than trout fry, which have remained relatively stable in numbers over this timeframe. It should be noted that adult densities are always low and variable in these surveys, which are targeting juvenile populations. The non-linear analysis indicates a sharp and relatively consistent decline from 1985 to the turn of the century, where densities level off and then start to increase; the short-term dataset gives a statistically significant (P = 0.996) chance of an upward trend since 2002. Again, this is largely driven by increasing fry densities, although >0+ densities have also shown some improvement.
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Juvenile Salmon Trends
Linear analysis of salmon population in Wye catchment, 1985 to 2015 (P = 0)
Non-linear analysis of salmon population in Wye catchment, 1985 to 2015
Linear analysis of salmon population in Wye catchment, 2002 to 2015 (P = 0.9271)
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Juvenile Brown Trout Trends
Linear analysis of brown trout population in Wye catchment, 1985 to 2015 (P = 0.0184)
Non-linear analysis of brown trout population in Wye catchment, 1985 to 2015
Linear analysis of brown trout population in Wye catchment, 2002 to 2015 (P = 0.9962)
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Fisheries Actions – Wye
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Site Action Benefits Lead Partner(s) Timescales for delivery
Monnow
Barriers in Wales to be addressed:
Crucorney Weir (SO3172220959) rock ramp below weir; work is waiting suitable legal mechanisms for delivery
Barriers in England to be addressed:
Monnow at Clodock (SO3269427496) - managed through enforcement action.
The last remaining significant barriers to salmon migration in the Monnow catchment. Making them accessible increases the spawning habitat available to salmon and trout; improving population size and viability.
NRW
EA
WUF
WUF
2017
2016
Lugg
Barriers in Wales to be addressed:
Dolley Green Weir (SO275655) – lowering or removal. Alternative Mitigation Action
Gerwen (tributary) pipe bridge at SO223677 TBC
Belddfa (tributary) weir/pipe bridge at SO207684 TBC Barriers in England to be addressed, funded from FCRM Environment linked funding:
Ballsgate (SO418660) fish passage option and build
Lugg Green (SO451619) reduction easement
Crowards Weir (SO484605) option appraisal
Coxall Weir (SO477606) option appraisal
Gilberts Weir (SO465613) option appraisal
Holgate (SO462613) option appraisal
Lyepole Weir (SO392651) removal option appraisal
More habitat accessible to salmon and trout; increased population size and viability.
NRW
WUF WUF
EA
WUF
WUF
2016/17
TBC TBC
2016/17 2016 2018 2016
2016/17 2016/17 2016/17
Arrow
Barriers in Wales to be addressed:
Llanpica Weir (SO2330750258) – lowering or rock ramp. Alternative Mitigation Action
Barriers in England to be addressed:
Turners Mill (SO298564), to be managed through enforcement action.
More habitat accessible to salmon and trout; increased population size and viability.
NRW
EA
WUF
2016/17
2016
Fisheries Actions – Wye
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Garth Dulas (Irfon)
Maintenance on fish pass at Garth to improve fish migration Habitat remains accessible to spawning salmon and trout
NRW WUF 2016
Aran (Ithon)
Barriers to be addressed:
Fernant (A470 crossing). Falls with fence causing a blockage.
A483 (SO0888073670). Pipebridge
Dolau tributary. Stone weir in village
More habitat accessible to salmon and trout; increased population size and viability.
NRW WUF
TBC
Upper Ithon (other sites in the Wye to be confirmed)
Habitat improvement As part of the Keeping Rivers Cool initiative, sites have been identified for fencing in order to promote natural re-generation of trees/shrubs leading to increased shade and associated reductions in temperatures. Alternative Mitigation Action.
Cooler, cleaner rivers, mitigating climate change and so benefitting salmon and trout spawning and egg/juvenile survival.
NRW WUF 2016/17
Whole catchment
Habitat Improvement Financed by fisheries improvement funds from Rod Licence Revenue; the Joint Working Partnership Fund and Competitive Fund
Riparian improvements
In-stream habitat work
Invasive plant control
Farm liaison - better land management practices
Reduced siltation, improved spawning gravels. Improved juvenile habitat. Restoration of favourable condition.
NRW EA
HWT WUF NE FC
2016
Severn Estuary
Manage Exploitation Management of the Severn Estuary mixed stock net fishery.
Allowable catch for the Historical Instruments is dictated by management levels set in the habitats regulatory assessment to protect Wye Salmon stocks
EA NRW NE
Ongoing until 2018 review of
NLO
Fisheries Actions – Wye
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Whole catchment
Agriculture Focusing on the Llynfi, Trothy and Ithon catchments in Wales; Lugg in England
Wet weather inspections
Water quality investigations
Farm compliance checks and associated enforcement.
Referral to Rural Payments Agency (RPA) when x-compliance breaches identified – England
Improved water quality for salmon and trout
NRW EA
WUF FC
MCC ADAS GWT
Ongoing
Whole catchment
Water Framework Directive We will continue to monitor the status of the environment and investigate causes of failures. Refer to Severn River Basin Management Plan for more details https://www.gov.uk/government/publications/severn-river-basin-district-river-basin-management-plan
Water environment protected and improved. More WFD waterbodies achieving Good Ecological Status.
NRW EA
WUF WCP
Ongoing
Whole catchment
Wye Catchment Partnership Continue to develop a broad based partnership of interested parties & bodies with the objective of addressing all the issues affecting the Wye catchment, specifically to improve water quality and quantity. Refer to Wye Catchment Partnership for more details www.wyecatchment.org
Improved water quality in the Wye catchment. Projects effectively developed and delivered. Opportunities and issues highlighted and discussed.
NRW WUF
EA Ongoing
Fisheries Actions – Wye
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Whole catchment
Habitats Directive Review of Licenced Abstraction Consents NRW licences water abstractions from the river Wye. Over several years we have been reviewing these licences to ensure they do no harm to the features of the Wye Special Area of Conservation (SAC). Salmon are a feature of the Wye SAC. Many agricultural licences have already been changed. Changes for the remaining water company licences are now being completed.
Enough water will remain in the river to allow salmon and other features of the SAC to thrive.
NRW EA
DCWW STW WUF
Licence changes
2016
Compliance by 2018
NRW Natural Resources Wales NE Natural England MCC Monmouthshire County
Council EA Environment Agency WCP Wye Catchment Partnership GWT Gwent Wildlife Trust DCWW Dwr Cymru Welsh Water STW Severn Trent Water FC Farming Connect WUF Wye and Usk Foundation HWT Hereford Wildlife Trust
APPENDIX
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In 2014 and 2015 we undertook investigations into the spread of salmon in the Monnow catchment. This follows the installation of the fish pass at Osbaston (2008) and the removal of the weir at Kentchurch (2011). In 2015, several 5-minute riffle surveys were carried out in addition to the three temporal (one Welsh W020 and two English Llanveynoe and Abbey Dore Court) sites in the catchment. The following map shows the results of this investigation using a simple presence absence of juvenile salmon.
