TAW CATCHMENT FRY INDEX FISH SURVEY 2016
River Taw
Report written by Adrian Dowding & Phil Turnbull
Rain-Charm House Kyl Cober Parc Stoke Climsland Callington Cornwall PL17 8PH Tel: +44 (0) 1579 372140 Email: info@wrt.org.uk Web: www.wrt.org.uk
With special thanks to the financial support from the River Taw Fisheries Association
and their members. Thanks to the North Devon Catchment Partnership and supporting projects.
Taw Catchment Fry Index Fish Survey
2016
Contents 1.
Introduction .................................................................................................................................. 1 1.1 In-river works .............................................................................................................................. 2
2.
Field sampling and data analysis methods .................................................................................... 3
3.
Results........................................................................................................................................... 3 3.1
Summary ............................................................................................................................... 6
3.2 GIS mapping ................................................................................................................................ 7 4.
Discussion ..................................................................................................................................... 9 4.1
Discussion for Salmon ........................................................................................................... 9
4.3 Discussion for Trout .................................................................................................................. 13 5.
Conservation and River Improvement Strategy .......................................................................... 16 Recommended Actions ............................................................................................................... 19
Recommendations .............................................................................................................................. 23 6.
Acknowledgements..................................................................................................................... 25
7.
References .................................................................................................................................. 25
8.
Appendix ..................................................................................................................................... 26 Taw Catchment Salmon Classification Map 2016 ........................................................................... 26 Taw Catchment Salmon Classification Maps 2013-16..................................................................... 27 Taw Catchment Trout Classification Map 2016 .............................................................................. 28 Taw Catchment Trout Classification Maps 2013-16 ........................................................................ 29 Taw Catchment Salmon Conservation Strategy Map 2016/17 ....................................................... 30 Taw Catchment Trout Conservation Strategy Map 2016/17 ........................................................... 31
Table 1 Semi-quantitative abundance categories for salmon fry (Crozier & Kennedy, 1994) ............... 3 Table 2 River Taw Survey sites and classifications for 2016 .................................................................. 4 Table 3 Comparative salmon fry results 2013-16.................................................................................. 9 Table 4 Comparative salmon fry results 2013-16. .............................................................................. 13 Table 5: Average fry index class for the River Taw sub-catchments, including Conservation Strategy status. Water Framework Directive fish status data based on latest data. ........................................ 18 Table 6: Recommended actions for the River Taw sub-catchments. ................................................. 20
Taw Catchment Fry Index Fish Survey
2016
1. Introduction Measuring the state of fish populations in a river is essential to manage not only the fishery as a whole, but to gauge the health of the river and to predict future river issues that may require attention. The Westcountry Rivers Trust (WRT) performed semi-quantitative fry index electrofishing surveys across the length and breadth of the Taw catchment in order to assess the juvenile populations of salmonids which are generally recognised as the most sensitive populations of fish to poor water quality, sedimentation and pollution events. This was the fourth year of fish monitoring of this type and goes someway to establishing a longerterm data set for the catchment which is extremely valuable for keeping a continued ‘monitoring of the pulse’ of the rivers. 2015 is the first year the surveys were carried out on a 60-site scale as the surveys have evolved around projects over the previous two years, but there is a good overview picture now forming which will aid in establishing areas to concentrate conservation efforts. The surveys were designed to complement the Environment Agency (EA) electric fishing monitoring undertaken annually, although both data sets use different methodologies with the primary difference being the use of fully quantitative depletion methods used by the EA and a semiquantitative fry index method used by WRT (to be detailed in Field sampling and data analysis methods section). The strength of the fry index survey is to enable a quick, affordable baseline semi-quantitative catchment-wide view of the fry (the first year or 0+ age group cohort) life stage only. As this survey is indicative of a single year, it is important to interpret the results with caution, however by looking at the first year life stage of fish there is merit through indications of how successful last year’s spawning was or how fluctuations in juvenile stock will transpose to future year’s breeding stock. This electro-fishing survey will aid as a tool to monitoring and inform appropriate habitat restoration works when funding is available. Survival of salmonid fry to the end of the first summer is known to be poor. Up to 90% of the alevins that emerge from redds will not survive. Even in good quality habitat with a rich food supply, high densities of fish will undergo strong competition for resources with each individual trying to gain a profitable feeding station. The fry index surveys are used as a coarse measure of fry abundance at each particular site. For each single year it also gives a broad indicator of salmonid spawning success across a catchment. The semi-quantitative methodology is primarily used as a means of guiding conservation and fisheries actions on the ground. It is less accurate than fully-quantitative depletion methodologies or single catch netted semi-quantitative surveys. Nevertheless, what this method lacks in terms of accuracy it makes up for in speed and efficiency. It is based on scientific study and can be calibrated to individual catchments by comparison to fully quantitative statistics. Using this method fisheries managers are able to trial and test conservation measures to best fit the catchment, using a repeating cycle of affordable monitoring and action, building site-specific knowledge and improvements over time. This flexible and responsive approach is known as ‘adaptive management’. 1|P age
Taw Catchment Fry Index Fish Survey
2016
In general, the rivers of North Devon are typically short and steep in the headwaters with a spate (or flashy) characteristic nature. The upland reaches tend to be moorland (e.g. Dartmoor, Exmoor, Witheridge) where rainfall falls on the oligotrophic moorlands and flows quickly downstream picking up little in the way of nutrients until it meets the lower sections of the main tributaries. Once out of the short upland sections the water flows through mid and lowland valleys where agriculture and forestry are the main surrounding land use with intermittent villages and towns before reaching the Taw and Torridge Estuary near Barnstaple. Typically, these rivers have the following issues relating to the success of salmonid fish: • • • •
Barriers to migration. Lack of functioning habitats. Degraded habitats (particularly at vital life cycle stages). Anthropogenic pressures in terms on modifications to aquatic environments, inputs from adjacent land management and infrastructure.
This report is to inform fisheries associations and catchment partner groups of the results from the surveys undertaken by WRT in 2016 and to advise on fish habitat improvements and management. WRT and the wider catchment partnership will work towards a full Catchment Fisheries Programme in the future.
1.1 In-river works As a result of the TAW (Taw Access over Weirs) project (2009-2015) and the TRIP (Taw River Improvement Project, 2012-2015) a number of improvements have been made to fish passage, habitats and water quality throughout the Taw catchment. By continued work with the catchment partnership, continuous effort to protect the river is ongoing through measures such as: • • • • • • • •
Technical and non-technical multi-species fish passes installed at 12 locations Fencing out livestock and creating river buffer strips along the riparian corridor Coppicing riparian trees Coarse or Large Woody Debris management and natural bank revetment Wetland re/introduction and sediment settlement Farmyard infrastructure improvements Farm advice on good practice and benefits In-river gravel cleaning for the primary salmonid fish spawning season
These works allow for improvements in stream ecology, improved water quality, increased flood attenuation, and are considered in the discussion. Further works are planned for the River Taw as part of the Catchment Based Approach (CaBA) during 2015-2020 in partnership with the statutory authorities, non-governmental organisations, voluntary organisations such as fishing associations and clubs, and WRT. These works are intended to continue improving water quality and quantity, habitat and ecology in the River Taw to mitigate the effects of the decreasing trend in fish populations.
2|P age
Taw Catchment Fry Index Fish Survey
2016
2. Field sampling and data analysis methods Each site was electro-fished by a two-person team using an electrofishing single anode backpack. The surveys were fished at the same settings of 50Hz with a voltage setting appropriate to the conductivity of the water. The operatives fished continuously for a standard five minutes within fry habitat where sufficient area was available. All salmonids were identified to species and fork length was measured and recorded. Numbers or density estimates were recorded for all other species captured. Habitat features such as land use, substrate type and shading were recorded at each site. Based on the lengths of fish captured during the survey, first year ‘fry’ life-stage fish were determined by working out the length frequency and separating the age class based upon the modal distributions. Fry numbers recorded at each site were classified as excellent to poor (or absent) according to the methodology by Crozier & Kennedy (1994) (Table 1). The classification scheme has been taken from the original salmon fry index provided within this paper and was derived through establishing a relationship with equivalent fry numbers captured within quantitative surveys at sample sites within Ireland. Within this assessment report, the salmon fry classification has been used as a surrogate for trout fry. Results should therefore be treated with some caution. It would increase the robustness of the method to be calibrated to local conditions, and for trout, to conduct the method alongside Environment Agency quantitative electric fishing surveys in future years.
Table 1 Semi-quantitative abundance categories for salmon fry (Crozier & Kennedy, 1994) Density Classification
Semiquantitative (n/5min fishing)
A (excellent) B (good) C (fair) D (poor) E (absent)
>23 11-23 5-10 1-4 0
Quantitative (n 100m2) >114.7 69.1-114.6 41.1-69.0 0.1-41.0 0
Any fry that were missed or escaped during electro-fishing were noted and assigned to either the trout or salmon group depending on the relative percentage of each species recorded at the site.
3. Results WRT surveyed 60 sites and 69 sites within the River Taw catchment as part of the 2015 and 2016 season, respectively. These sites were increased in number from previous electric fishing surveys due the desire to further the accuracy of catchment-scale data. Table 2 shows the results from the surveys based on Salmon classifications as determined in Crozier and Kennedy (1994) above.
3|P age
Taw Catchment Fry Index Fish Survey
2016
Table 2 River Taw Survey sites and classifications for 2016 Taw River:
Site Name:
2016 Trout Class
2016 Salmon Class
Taw
Belstone Tor
Fair
Absent
Taw
Cheese Factory
Poor
Good
Taw
Coldridge Bridge
Absent
Poor
Taw
Haywood Bridge, Ford Farm
Absent
Absent
Taw
N Wyke Weir
Poor
Fair
Taw
Newland Bridge
Poor
Fair
Taw
North Wyke Track
Absent
Fair
Taw
Old Pumphouse
Poor
Fair
Taw
Rowden Leat
Absent
Fair
Taw
Sheepfold
Poor
Absent
Taw
Skaigh Woods
Poor
Fair
Taw
Taw Bridge
Poor
Poor
Taw
Taw Green Mill
Fair
Poor
Taw
The Viaduct
Poor
Good
Yeo (Lapford)
Hayne Bridge
Absent
Absent
Yeo (Lapford)
Broadnymett Moor
Absent
Absent
Yeo (Lapford)
Yeo Bridge
Absent
Absent
Knathorne/Ashbrook
Railway Confluence
Absent
Absent
Taw
Chenson Pool
Absent
Absent
Taw
Eggesford Barton
Absent
Absent
Taw
Eggesford Station
Poor
Poor
Taw
Fox & Hounds
Absent
Poor
Taw
Rashleigh Barton
Absent
Absent
Taw
Rashleigh Mill
Absent
Absent
Taw
Old Woollen Mill
Poor
Good
Dalch
Deneridge Bridge
Absent
Absent
Dalch
Hele Bridge
Absent
Absent
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Taw Catchment Fry Index Fish Survey
2016
Taw River:
Site Name:
2016 Trout Class
2016 Salmon Class
Dalch
Calves Bridge
Absent
Absent
Little Dart
Cheldon Bridge
Absent
Absent
Little Dart
Edgelake Bridge
Absent
Absent
Little Dart
Park Mill
Poor
Poor
Little Dart
Bradford Mill
Poor
Absent
Sturcombe
Bradford Pond
Poor
Absent
Sturcombe
Crowdhole Bridge
Poor
Absent
Taw
Kersham Bridge
Poor
Absent
Huntacott
Kempland Farm Cottage
Poor
Absent
Huntacott
d/s Huntacott Bridge
Poor
Poor
Mole
Satterleigh Barton Brash Site
Poor
Poor
Mole
Great Hele Barton
Absent
Fair
Mole
Confluence
Absent
Poor
Mole
Bicknor Bridge
Fair
Poor
Mole
Exmoor Trout
Fair
Poor
Mole
South Wood
Excellent
Poor
Mole
North Radworthy
Good
Absent
Waddington Brook/Catham Lake
Spittle, d/s pipe bridge below confluence
Poor
Absent
Colley Lake
Hele Woods u/s Howards Bridge
Poor
Absent
Yeo (Molland)
Yeo Fm, Hilltown
Poor
Good
Yeo (Molland)
Bottreaux Mill
Absent
Poor
Yeo (Molland)
Yeo Mill, West Anstey
Poor
Absent
Little Silver Stream
U/S Milltown Bridge, Meshaw
Poor
Poor
Crooked Oak
Eastwood Coppicing Site
Absent
Poor
Hacche
RocknRapid
Poor
Absent
Hacche
Marsh Hall
Absent
Absent
Hacche
Stony Bridge
Absent
Absent
Bray
d/s Filleigh Weir
Absent
Poor
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Taw Catchment Fry Index Fish Survey
2016
Taw River:
Site Name:
2016 Trout Class
2016 Salmon Class
Bray
Little Bray
Good
Poor
Bray
Challacombe
Good
Absent
Holewater
Berry Bridge
Poor
Absent
Holewater
Lower Hall Fm
Poor
Poor
Swimbridge
Hunacott
Absent
Absent
Hawkridge Brook
Woodland Farm
Poor
Absent
Bradiford Water
u/s Tutshill Weir
Poor
Absent
Bradiford Water
d/s Tutshill Weir
Poor
Absent
Knowle Water
Luscott Barton
Fair
Absent
River Caen
The Castle, Knowle
Poor
Absent
Langham Lake
Langridgeford
Poor
Absent
Mully Brook
d/s Woodrow Bridge
Poor
Absent
Mully Brook
Hansford Bridge
Poor
Absent
Hollocombe
Densham
Absent
Absent
3.1 Summary Salmon Atlantic salmon fry were absent from many sites in the 2016 survey. South of North Tawton gave the most consistent higher scores, with one “good” classification on the downstream site of the Molland Yeo. Where a “good” classification was awarded, notable quality of habitat existed, with highly suitable gravel matrices and good flow combine to give relatively clean riffle for egg survival and fry habitation. Where absent, high levels of sedimentation, over shading and smothering algal growth characterised the benthic habitat. Areas of low flow, found in most of the upper reaches, were generally negatively correlated with fry abundance.
Trout Trout fry abundance was similar to that of salmon fry, with many sites producing no trout fry. The South Wood site scored an “Excellent”, most likely due to the proximity to Exmoor and limited impact on water quality from surrounding land use. The Challacombe site produced a “good” score with the absence of salmon fry, however this site is at the far upstream reach of the River Bray, and therefore primarily brown trout habitat.
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Taw Catchment Fry Index Fish Survey
2016
3.2 GIS mapping
Figure 1: Location of survey sites (left) and relative catch for brown trout and Atlantic salmon (right)
Figure 2: Total Atlantic salmon catch (left) and salmon classification (right) 7|P age
Taw Catchment Fry Index Fish Survey
2016
Figure 3: Total brown trout catch (left) and trout classification (right)
Previous years GIS classification results can be seen and compared in the Appendix. The GIS maps for both salmon and trout (Figure 1) reveal the highest abundance for young of the year (0+) fish is located in the North East of the River Taw catchment. The South of the catchment is also highlighted as holding reasonable 0+ abundance in the Upper Taw WFD waterbody. Both areas consist of headwaters close to moorland protected under National Park status, providing less impacted water quality and sediment input. It appears the rivers Bray, Mole and upper Taw provide the main areas for recruitment, with the lower reach of the river Yeo (Molland) showing good relative catch. Both the GIS maps for salmon and trout separately (Figures 2 and 3, respectively) suggest the river Yeo (Lapford) contains very low 0+ salmonid abundance, and requires immediate attention if fish populations in this area are to be sustained long term. Atlantic salmon recruitment appears to be limited throughout the catchment, restricted to areas of least impact, or 0+ habitat supplied with suitable percentages of higher water quality. Brown trout recruitment appears more widespread, as expected due to the relative higher adaptability and decreased sensitivity to habitat degradation of this species. However, Figure 3 indicates Brown trout recruitment success is still far below desirable levels. For more information on improvement strategies, refer to the Conservation Strategy section below.
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Taw Catchment Fry Index Fish Survey
2016
4. Discussion More sites were surveyed in 2016 than previous years giving us valuable data on a catchment scale and starting to show a monitoring trend. There is an established baseline upon which we can build to show a consistent annual reflection of the fish health in the catchment. As the data sets continue and develop over time more sites may be added to define more detail in an area, or similarly, some sites may be deducted from areas with higher density monitoring. It is, however, important to maintain the full catchment coverage in order to monitor and detect issues or negative trends in the early stages and implement adaptive management on an annual basis. Tables 3 and 4 show the classification comparison from 2013 – 2016 for salmon and trout respectively, based on Westcountry Rivers Trust data, collected through semi-quantitative surveys.
4.1 Discussion for Salmon Table 3 Comparative salmon fry results 2013-16. Taw Catchment
Site Name
2013
2014
2015
2016
Taw
Haywood Bridge, Ford Farm
Poor
Fair
Poor
Absent
Taw
Newland Bridge
N/A
Fair
Fair
Fair
Taw
The Viaduct
Good
Fair
Fair
Good
Taw
Cheese Factory
Fair
Fair
Poor
Good
Taw
North Wyke Track
Good
Excellent Good
Fair
Taw
Rowden Leat
Fair
Good
Good
Fair
Taw
Ken’s Meadow
Fair
Good
Poor
N/A
Taw
Old Pumphouse
N/A
Poor
Fair
Fair
Taw
N Wyke Weir
Fair
N/A
N/A
Fair
Taw
Old Woollen Mill
Excellent
Excellent Excellent
Good
Taw
Taw Green Mill
Fair
Fair
Poor
Poor
Taw
Skaigh Woods
Absent
Fair
Poor
Fair
Taw
Sheepfold
Absent
Absent
Absent
Absent
Taw
Belstone Tor
Absent
Absent
Absent
Absent
Taw
Taw Bridge
N/A
Good
Good
Poor
Taw
Coldridge Bridge
N/A
Good
Fair
Poor
Yeo (Lapford)
Dragdown Hill
N/A
N/A
Absent
N/A
Yeo (Lapford)
Hayne Bridge
N/A
N/A
N/A
Absent
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Taw Catchment Fry Index Fish Survey
2016
Taw Catchment
Site Name
2013
2014
2015
2016
Yeo (Lapford)
Broadnymett Moor
N/A
N/A
Absent
Absent
Yeo (Lapford)
Yeo Bridge
N/A
N/A
Poor
Absent
Yeo (Lapford)
Nymet Bridge
N/A
N/A
Poor
N/A
Knathorne/Ashbrook
Knighty Brook Bridge
N/A
N/A
Absent
N/A
Taw
Chenson Pool
N/A
Excellent Fair
Absent
Taw
Eggesford Barton
N/A
Excellent Fair
Absent
Taw
Eggesford Station
N/A
N/A
N/A
Poor
Taw
Fox & Hounds
Absent
Fair
Poor
Poor
Taw
Rashleigh Barton
N/A
N/A
N/A
Absent
Taw
Rashleigh Mill
N/A
N/A
N/A
Absent
Dalch
Deneridge Bridge
N/A
N/A
Absent
Absent
Dalch
Hele Bridge
N/A
N/A
Absent
Absent
Dalch
Calves Bridge
N/A
N/A
Absent
Absent
Dalch
Railway Confluence
N/A
N/A
Absent
Absent
Little Dart
Cheldon Bridge
N/A
Absent
Absent
Absent
Little Dart
Edgelake Bridge
N/A
Absent
Fair
Absent
Little Dart
Park Mill
N/A
Fair
Fair
Poor
Little Dart
Bradford Mill
N/A
Absent
Poor
Absent
Sturcombe
Bradford Pond
N/A
Fair
Poor
Absent
Sturcombe
Crowdhole Bridge
N/A
Poor
Poor
Absent
Taw
Kersham Bridge
N/A
Fair
Fair
Absent
Huntacott
Kempland Farm Cottage
N/A
N/A
Absent
Absent
Huntacott
d/s Huntacott Bridge
N/A
N/A
Poor
Poor
Mole
Satterleigh Barton
Poor
N/A
Poor
Poor
Mole
Great Hele Barton
N/A
N/A
N/A
Fair
Mole
Confluence
N/A
N/A
Poor
Poor
Mole
Bicknor Bridge
Poor
Good
Poor
Poor
Mole
Exmoor Trout
Absent
Absent
Absent
Poor
Mole
South Wood
Poor
Fair
Poor
Poor
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Taw Catchment Fry Index Fish Survey
2016
Taw Catchment
Site Name
2013
2014
Mole
North Radworthy
N/A
N/A
Waddington Brook/Catham Lake
Spittle, d/s pipe bridge below confluence
N/A
N/A
N/A
N/A
Colley Lake
Hele Woods u/s Howards Bridge
Yeo (Molland)
Yeo Fm, Hilltown
N/A
Yeo (Molland)
Bottreaux Mill
Yeo (Molland)
2015
2016
Poor
Absent
Absent
Absent
Fair
Absent
N/A
Good
Good
N/A
N/A
Absent
Poor
Yeo Mill, West Anstey
N/A
N/A
Absent
Absent
N/A
N/A
Little Silver Stream
U/S Milltown Bridge, Meshaw
Absent
Poor
Crooked Oak
Eastwood Coppicing Site
N/A
N/A
Fair
Poor
Hacche
RocknRapid
N/A
N/A
N/A
Absent
Hacche
Marsh Hall
N/A
N/A
N/A
Absent
Hacche
Stony Bridge
N/A
N/A
N/A
Absent
Bray
d/s Filleigh Weir
N/A
N/A
Good
Poor
Bray
Little Bray
N/A
N/A
Fair
Poor
Bray
Challacombe
N/A
N/A
Good
Absent
Holewater
Berry Bridge
N/A
N/A
Poor
Absent
Holewater
Lower Hall Fm
N/A
N/A
Poor
Poor
Holewater
Lindleham Bridge
N/A
N/A
Poor
N/A
Swimbridge
Hunacott
N/A
N/A
N/A
Absent
Hawkridge Brook
Woodland Farm
N/A
N/A
Absent
Absent
Bradiford Water
u/s Tutshill Weir
N/A
N/A
N/A
Absent
Bradiford Water
d/s Tutshill Weir
N/A
N/A
N/A
Absent
Knowle Water
Luscott Barton
N/A
N/A
N/A
Absent
River Caen
The Castle, Knowle
N/A
N/A
N/A
Absent
Langham Lake
Langridgeford
N/A
N/A
Absent
Absent
Mully Brook
d/s Woodrow Bridge
N/A
N/A
Absent
Absent
Mully Brook
Hansford Bridge
N/A
N/A
Absent
Absent
Hollocombe
Densham
N/A
N/A
Absent
Absent
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Taw Catchment Fry Index Fish Survey
2016
A general decrease in abundance was witnessed across the catchment. Most notable was a drop from good to absent at Challacombe, and a loss of the sole excellent score to good at the old woollen mill, North Tawton. However, the other North Tawton sites saw an increase in score, with a 2015 poor score changing to a 2016 good score at the Cheese factory site. Furthermore, a handful of sites where a complete absence was recorded last year produced poor scores, indicating presence. However, due to the semi-quantitative methods employed, this is to be interpreted as likely continuation of very low salmon densities, unless confirmed by future surveys. The majority of sites fished showed evidence of extensive habitat degradation in the form of high sediment loads, over-shading, and algal growth. The low flows witnessed in 2016 may explain the drop in observed scores, as this would exacerbate the issues contributing to poor habitat availability. The extent of habitat degradation was clearly related to salmon fry abundance, particularly sedimentation. Areas of good light penetration, good flows, limited algal growth but high sediment content (for example sites North of Barnstaple) produced little to no salmon fry. There wasn’t a notable observed correlation with immediate arable or pasture land use and abundance of fry, however where extensive riparian buffer zones existed overhanging marginal vegetation provided shelter for parr, and sedimentation appeared reduced. The River Yeo (Lapford) returned a total absence of salmon fry. This river system is particularly characterised by high sediment loading from severe bank erosion, high arable land use in places, and uncontrolled cattle access. Other lowland tributaries generally showed similar impacts, sometimes magnified through receiving high nutrient run-off into low flowing, naturally small streams. River systems generally showing signs of less sedimentation, such as the Rivers Bray and Mole, were dominated by trout, suggesting these systems are utilised by sea trout when relating to migratory salmonids. The River Yeo (Molland) produced a good score for salmon at the downstream site, where a classically suitable salmon spawning riffle (good gravel matrix, flows, hydrologic potential and holding water) is situated. Further upstream, the channel evidenced increased accumulations of sediment, algal growth and eroding banks. This degradation may negatively impact future salmon spawn survival in the North East of the Taw catchment if sediments and nutrients settle in currently viable riffle habitat downstream. The highest densities of salmon fry were recorded South of North Tawton, where proximity to the Dartmoor headwaters likely produces increased water quality over more lowland water sources. This area should continue to be protected and improved to provide annual penetration of migrating salmon to upstream areas. The area around North Tawton should be noted for its current importance for spawning of salmonids and should be improved and protected in accordance. The Little Dart system produced a near absence of salmon fry, where fair scores have previously been recorded. On site observations concluded low flows to be the main contributing factor in 2016. A degree of variation in classifications is expected over survey years, however a general trend of decreasing salmon fry abundance is evident when comparing data from 2013 through to 2016. This is particularly noticeable in the middle Taw near Eggesford Station, where classifications have dropped from Excellent to Absent in two years. Continual monitoring is essential to confirm whether this is a more permanent change, or a temporary fluctuation.
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Taw Catchment Fry Index Fish Survey
2016
4.3 Discussion for Trout Table 4 Comparative salmon fry results 2013-16. Taw Catchment
Site Name
2013
2014
2015
2016
Taw
Haywood Bridge, Ford Farm
Absent
Absent
Absent
Absent
Taw
Newland Bridge
N/A
Poor
Absent
Poor
Taw
The Viaduct
Absent
Absent
Poor
Poor
Taw
Cheese Factory
Poor
Poor
Poor
Poor
Taw
North Wyke Track
Poor
Poor
Absent
Absent
Taw
Old Woollen Mill
Poor
Fair
Fair
Poor
Taw
Rowden Leat
Poor
Fair
Absent
Absent
Taw
Ken’s Meadow
Absent
Poor
Poor
N/A
Taw
Old Pumphouse
N/A
Poor
Poor
Poor
Taw
N Wyke Weir
Poor
N/A
N/A
Poor
Taw
Taw Green Mill
Poor
Fair
Fair
Fair
Taw
Skaigh Woods
Poor
Poor
Poor
Poor
Taw
Sheepfold
Absent
Poor
Poor
Poor
Taw
Belstone Tor
Poor
Fair
Poor
Fair
Taw
Taw Bridge
N/A
Absent
Poor
Poor
Taw
Coldridge Bridge
N/A
Absent
Absent
Absent
Yeo (Lapford)
Dragdown Hill
N/A
N/A
Absent
N/A
Yeo (Lapford)
Hayne Bridge
N/A
N/A
N/A
Absent
Yeo (Lapford)
Broadnymett Moor
N/A
N/A
Poor
Absent
Yeo (Lapford)
Yeo Bridge
N/A
N/A
Poor
Absent
Yeo (Lapford)
Nymet Bridge
N/A
N/A
Poor
N/A
Knathorne/Ashbrook
Knighty Brook
N/A
N/A
Absent
N/A
Taw
Chenson Pool
N/A
Poor
Poor
Absent
Taw
Eggesford Barton
N/A
Absent
Absent
Absent
Taw
Eggesford Station
N/A
N/A
N/A
Poor
Taw
Fox & Hounds
Absent
Absent
Absent
Absent
Taw
Rashleigh Barton
N/A
N/A
N/A
Absent
Taw
Rashleigh Mill
N/A
N/A
N/A
Absent
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Taw Catchment
Site Name
2013
2014
2015
2016
Dalch
Deneridge Bridge
N/A
N/A
Poor
Absent
Dalch
Hele Bridge
N/A
N/A
Absent
Absent
Dalch
Calves Bridge
N/A
N/A
Absent
Absent
Dalch
Railway Confluence
N/A
N/A
Poor
Absent
Little Dart
Cheldon Bridge
N/A
Absent
Absent
Absent
Little Dart
Edgelake Bridge
N/A
Poor
Absent
Absent
Little Dart
Park Mill
N/A
Poor
Absent
Poor
Little Dart
Bradford Mill
N/A
Fair
Absent
Poor
Sturcombe
Bradford Pond
N/A
Fair
Absent
Poor
Sturcombe
Crowdhole Bridge
N/A
Poor
Poor
Poor
Taw
Kersham Bridge
N/A
Absent
Absent
Poor
Huntacott
Kempland Farm Cottage
N/A
N/A
Absent
Poor
Huntacott
d/s Huntacott Bridge
N/A
N/A
Absent
Poor
Mole
Satterleigh Barton
Absent
N/A
Absent
Poor
Mole
Great Hele Barton
N/A
N/A
N/A
Absent
Mole
Confluence
N/A
N/A
Absent
Absent
Mole
Bicknor Bridge
Absent
Poor
Poor
Fair
Mole
Exmoor Trout
Poor
Absent
Absent
Fair
Mole
South Wood
Poor
Good
Fair
Excellent
Mole
North Radworthy
N/A
N/A
Poor
Good
Waddington Brook/Catham Lake
Spittle, d/s pipe bridge below confluence
N/A
N/A
N/A
N/A
Colley Lake
Hele Woods u/s Howards Bridge
Yeo (Molland)
Yeo Fm, Hilltown
N/A
Yeo (Molland)
Bottreaux Mill
Yeo (Molland)
Excellent Poor Absent
Poor
N/A
Poor
Poor
N/A
N/A
Absent
Absent
Yeo Mill, West Anstey
N/A
N/A
Fair
Poor
Little Silver Stream
U/S Milltown Bridge, Meshaw
N/A
N/A
Absent
Poor
Crooked Oak
Eastwood Coppicing Site
N/A
N/A
Absent
Absent
Hacche
RocknRapid
N/A
N/A
N/A
Poor
Hacche
Marsh Hall
N/A
N/A
N/A
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Taw Catchment
Site Name
2013
2014
2015
2016
Hacche
Stony Bridge
N/A
N/A
N/A
Absent
Bray
d/s Filleigh Weir
N/A
N/A
Poor
Absent
Bray
Little Bray
N/A
N/A
Poor
Good
Bray
Challacombe
N/A
N/A
Fair
Good
Holewater
Berry Bridge
N/A
N/A
Absent
Poor
Holewater
Lower Hall Fm
N/A
N/A
Good
Poor
Holewater
Lindleham Bridge
N/A
N/A
Fair
N/A
Swimbridge
Hunacott
N/A
N/A
N/A
Absent
Hawkridge Brook
Woodland Farm
N/A
N/A
Absent
Poor
Bradiford Water
u/s Tutshill Weir
N/A
N/A
N/A
Poor
Bradiford Water
d/s Tutshill Weir
N/A
N/A
N/A
Poor
Knowle Water
Luscott Barton
N/A
N/A
N/A
Fair
River Caen
The Castle, Knowle
N/A
N/A
N/A
Poor
Langham Lake
Langridgeford
N/A
N/A
Absent
Poor
Mully Brook
d/s Woodrow Bridge
N/A
N/A
Fair
Poor
Mully Brook
Hansford Bridge
N/A
N/A
Absent
Poor
Hollocombe
Densham
N/A
N/A
Poor
Absent
The trout classification scores show as generally lower than expected for the Taw catchment, being a system primarily known for salmonid species. There appears to be variation regarding increases or decreases compared to 2015 catches. Being a species that can fully mature within the river system, local migration is common due to various pressures, and therefore direct site comparison has potential to annually fluctuate. However, a broad picture reveals generally low fry counts throughout the Taw system, indicating the habitat degradation by sediments and loss of suitable habitats. Of particular note is the reduction from Excellent to Poor for site 62 on the Catham Lake. This site presented high levels of sediment compared with 2015, and severe low flows. A severe drop in abundance suggests sudden unsuitability as habitat in 2016, which may indicate either local migration to deeper areas, magnified impact of existing inputs due to low flows, or new negative input affecting fish and/or water quality. The Lower Hall Farm site on the Holewater also reduced from Good to Poor, with no immediate evidence to suggest why this may be. Southwood, Challacombe and the Little Bray showed dominance by trout, reflecting the suitability for migratory trout over salmon this high up the catchment, and good habitat quality due to proximity to Exmoor. Protection of these areas is important to ensure continued recruitment in the catchment.
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Continual monitoring is necessary to identify trends and recognise natural fluctuations in the Taw brown trout populations. However, where four years of data has been collected at sites on the main Taw, a downward trend similar to that observed with the Atlantic salmon data is discernible.
5. Conservation and River Improvement Strategy The above evidence needs to be used to provide the most effective outcomes in dealing with the state of fish populations and our catchment river’s health in general. Using the Fry Index classifications there needs to be priority areas within the catchment that are targeted for conservation activity. This strategy broadly follows the Defend/Repair/Attack concept developed by Ronald Campbell of the Tweed foundation, and has been applied locally in the Exe catchment by the RETA project. The fry productivity of the rivers is assessed by a combination of data over the last five years’ semiquantitative electrofishing results, alongside EA quantitative electrofishing sites where possible. These results are then applied in context of existing knowledge (e.g. plans, habitat walkover surveys, and genetic data) to produce assessments and recommendations for each sub-catchment of the river. These sub-catchments are classified according to three levels: Defend, Repair, and Restore.
Defend These areas have good fish stocks and habitat, and need safeguarding actions to ensure no decline occurs. Repair These areas have moderate fish stocks, and fish habitat in a moderate condition; these areas need assisted habitat recovery to move them into the Defend category. Attack These areas have poor fish stocks, and the habitat is significantly degraded. These areas need drastic intervention such as habitat reengineering in order to improve their status. Please note these do not relate to the Water Framework Directive (WFD) classifications.
Whilst this provides a useful structuring framework, and something of a ‘traffic lights’ system, reality is always complex and lies on a continuum between these extremes. A useful way to visualize this continuum is the inverted pyramid figured below. The goal of this report is to move the subcatchments of the Taw up the pyramid from the unstable point (i.e. Poor fish stocks and habitat) to the broad top of a healthy, natural riverine ecosystem. Where the populations are in a very poor state radical actions may be required to see a change. Conversely, where the stocks are already good, major interventions such as habitat re-engineering or the possibility of stocking operations would be inappropriate. Actions to achieve these improvements can be divided between ‘fish stock actions’ such as fish translocations or bag limits for anglers and ‘fish habitat actions’ such as
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removing barriers to migration or coppicing. In many situations, both types of action will be required. Such actions can involve the third and volunteer sectors as well as statutory bodies, for example a fishing club may choose to adopt catch and release in a poorly performing tributary, but only maintain bag limits on those that are doing well, without the EA having to resort to Bylaw restrictions.
Figure 4: Fish conservation management developed by the Tweed Foundation.
Table 5 shows the management recommendations for the Taw catchment, divided into its subcatchments. Conservation strategy recommendations have been made in accordance with the current Fry Index results following the above attack/defend continuum. It may be of benefit to assess if these geographical divisions of the Taw into sub-catchments are biologically divided as well (i.e. separate fish populations per sub-catchment). This can be achieved by using genetic markers to identify the populations within the catchment. The Water Framework Directive fish category status has been included for comparison. It is apparent that the data collected by Westcountry Rivers Trust contrasts with the WFD status for most sub-catchments. The upper Taw and River Bray data appear to agree. The discrepancies observed may be due to older data used for WFD status, particularly poignant when considering the recent decrease in abundance observed through Westcountry Rivers Trust data. Furthermore, WFD status data is based on a small frequency of fully quantitative surveys, whereas the Fry Index Class data is based on catchment wide semi-quantitative surveys. Different data sets act as complimentary to help build a more complete understanding. WRT suggests deciding action plans based on catchment scale data to increase effectiveness and efficiency regarding resource management.
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Table 5: Average fry index class for the River Taw sub-catchments, including Conservation Strategy status. Water Framework Directive fish status data based on latest data. Average Fry Index Class Conservation Strategy
Sub-Catchment
Trout Upper Taw
Salmon
Water Framework Directive WFD Fish Status
Poor
Fair
Attack/Repair
Repair
(2015 cycle 2)
Absent
Absent
Good
Attack
Attack
(2015 cycle 2)
Absent
Poor
Attack
Attack/Repair
Absent
Absent
Poor
Attack
Attack
(2015 cycle 2)
Poor
Absent
Good
Attack/Repair
Attack
(2014 cycle 1)
Fair
Poor
Repair
Attack/Repair
Poor
Fair
Attack/Repair
Repair
Little Silver Stream
Poor
Poor
Attack/Repair
Attack/Repair
Crooked Oak
Absent
Poor
Attack
Attack/Repair
Good
Poor
Yeo (Lapford)
Mid/Lower Taw
Dalch
Little Dart
Mole
Yeo (Molland)
Bray
Repair/Defend Attack/Repair Langham Lake
Moderate
Poor (2014 cycle 1)
Good (2014 cycle 1) Good (2014 cycle 1) High (2015 cycle 2) Good (2014 cycle 1) Good (2014 cycle 1)
Poor
Absent
Good
Attack/Repair
Attack
(2014 cycle 1)
Reasons for not achieving Good Probable migration barriers
n/a
Not available Probable sewage discharge, probable mixed agricultural, suspected migration barrier n/a
n/a
n/a
n/a
n/a
n/a
n/a`
Table 6 identifies key recommended actions related to the attack/defend Conservation strategy outlined above. A description of the recommended actions, outlining the key objectives for each action, is included below.
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Recommended Actions FENCING: Riparian zones identified as receiving significant livestock access, with apparent habitat degradation, should be fenced to limit trampling and bank side poaching. To include measures ensuring livestock drinking water supply is not impacted. Effective buffer strips dependant on site characteristics is advised. COPPICING: Targeted selective coppicing of woodland and abandoned riparian coppice adjacent to juvenile habitat riffles should be carried out. This will increase primary productivity and food source for juvenile fish. Shade should be maintained on deeper pools and runs for water temperature and adult fish habitat cover. GRAVEL CLEANING: Key areas of high spawning potential have been identified, however high sediment loads impact viability and survival. Whilst continued efforts are underway to influence policy and land management practices, selective gravel cleaning should be carried out to ensure available spawning habitat for the coming season. EROSION CONTROL: Fencing and effective marginal habitat management will reduce erosion. However, where specific areas of high pressure and vulnerability are identified, erosion protection measures such as woody debris installation, environmentally sensitive revetments, and strategic tree planting would be advantageous. FISH PASSAGE ASSESSMENT: Assessment of potential fish migration barriers using the Coarse Resolution Rapid Assessment technique developed by the Scottish and Northern Irish Forum For Environmental Research (SNIFFER). A standardised survey technique to assess porosity of in-channel structures. FARM ADVICE: A key management strategy for the protection and enhancement of riverine systems. Approaching and working with local agricultural businesses to offer guidance on best environmental practice, and the use of grants for application of the recommended actions outlined. IN-CHANNEL HABITAT RESTORATION: Installation and construction of habitat enhancing features, including woody debris introduction, flow manipulation with groins and kickers, bank reprofiling for marginal zonation, strategic tree planting, gravel introduction and riffle creation, and historic channel restoration. Advanced management usually applied post success of other recommended actions. DATA LOGGERS: Install water quality data loggers at key sites. This will define the water quality indicators and produce a tracing mechanism for potential negative inputs to the river. An advanced technique for areas where specific potential issues have been identified. WALKOVER SURVEYS: Recording of habitat availability relating to ontogenetic stages of fish, including observed local land use and factors negatively impacting habitat quality. A highly important component of catchment management, essential building large scale understanding of a catchment, and engagement with local land owners. Often the starting point for work in an area.
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Table 6: Recommended actions for the River Taw sub-catchments. Action Sub catchment
Upper Taw Yeo (Lapford) Mid/Lower Taw Dalch Little Dart Little Silver Crooked Oak Yeo (Molland) Mole
Fencing
✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓
Bray Langham Lake
✓
Coppicing
✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓
Gravel Cleaning
Erosion Control
✓ ✓ ✓ ✓ ✓
✓ ✓ ✓ ✓
✓ ✓
✓ ✓ ✓
✓
Fish Passage Assessment
✓ ✓ ✓ ✓ ✓
Farm Advice
In-channel Habitat Restoration
Data Loggers
✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓
✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓
✓ ✓ ✓ ✓ ✓
Walkover Surveys
✓ ✓ ✓
✓
✓
✓
✓
Note: Given the low results and potentially large amount of work required, there could be actions in all catchments on all points in the above table. 20 | P a g e
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Figure 5: Taw Salmon Conservation Strategy map, including trends based on average scores from semiquantitative electrofishing surveys.
Figure 5 indicates the general trend for 0+ Atlantic salmon abundance across the Taw catchment, relating to the Conservation Strategy. The majority of the map displayed shows a downward or equal trend. The Yeo (Molland) catchment presents an increase from Repair/Attack to Repair, based on the finding of salmon fry at one site in 2016 where an absent score was recorded in 2015. Likewise, the Little Silver Stream catchment was upgraded from Attack to Repair/Attack, for the same reason. The severity of an average catchment scale decrease in abundance may be linked with the low river flows witnessed in 2016, and therefore continual monitoring is essential to further quantify abundance, and highlight areas in need of action from all interested parties. With the Bray historically known for good fish numbers, the declining trend should be of concern and therefore the Mole sub-catchment could consider prioritising work in the Bray and Yeo (Molland) in the short term to reverse a declining trend of potentially good habitat.
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The upper Taw area requires protection from further degradation to ensure salmon penetration through the catchment. The Yeo (Lapford) and Little Dart catchments have potential to respond well to catchment restorative works, due to their proximity to upper Taw migratory fish stocks, but a greater effort on habitat improvement or restoration is required.
Figure 6: Taw Trout Conservation Strategy map, including trends based on average scores from semiquantitative electrofishing surveys.
Figure 6 indicates the general trends for 0+ Brown trout abundance across the Taw catchment, relating to the Conservation Strategy. The Brown trout map contrasts with the Atlantic salmon map by displaying more areas of increase in 0+ abundance. However, in most cases this is an increase from Attack based on Absent scores, to Attack/Repair based on very low abundance. Although a more positive result, abundance is still very low and requires long term investment to witness further sustainable status increase. 22 | P a g e
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The River Bray is a key area to defend and protect, receiving the highest Conservation Strategy status. Likewise, an increase from Attack/Repair to Repair for the Mole catchment is encouraging, and therefore further protection from degradation is important here. Adult trout were observed in the Yeo (Lapford) catchment, suggesting concentration on spawning and fry habitat improvement here would benefit the trout populations.
Recommendations Tree and bank management to protect against erosion and stabilise river banks is largely necessary across the whole catchment, whilst improving and enhancing in-river fish habitat through woody debris introduction. Livestock access is a problem in areas of high stocking densities as the cumulative impact of many hooves poaching and eroding the river banks (as well as direct defecation input) contributes widely to reduced habitat and water quality. Areas of highest impact can be identified through walkover surveys for prioritisation, but all areas will benefit from selective coppicing, natural revetment, and the exclusion or formalised drinking of stock. The concept of walkover surveys to detail fish habitat is highly recommended as the surveys qualify and quantify available habitat whilst at the same time provide direct observations throughout the catchment which help identify river protection aspects. This will help increase the accuracy of resource prioritisation. Gravel cleaning would be beneficial in areas where we know fish can get to, either recently or historically. In areas important for spawning and areas with good gravel matrices but degraded by siltation, this technique will benefit the short term recruitment effort whilst longer term activity tackles the source of the degradation. The main priority for 2017 would appear to be the Upper Taw, Yeo (Molland), the Yeo (Lapford), Dalch, Knowle and Mole. The Holewater, Yeo (Barnstaple) and Hacche may also be considered to help maximise the survival of salmonid stocks. Fish migration access is extremely important in the Taw and a lot of work has taken place since 2010 to improve the migration of fish in the main river routes. This is one way of ensuring a higher proportion of salmonids are reaching suitable spawning habitat during times when the returning stocks appear lower. It is recommended that a SNIFFER rapid coarse migration assessment be conducted on known downstream weirs to incorporate a scientific evidence base with observed migration, and to qualify if expenditure is justified in improving the migration for all fish species across the catchment/s. Important side tributaries should now be investigated to improve access to habitat in areas such as the Little Silver Stream and the Wickington Stream. Whole rivers in the wider Taw catchment (those running directly into the estuary) should be assessed in this regard as the entire reason a river is failing for fish under the Water Framework Directive may be a migration barrier at the base. It is highly recommended the Bradiford Water, Knowle, Caen and the Yeo (Barnstaple) are individually assessed for suitable habitat (walkover surveys) and fish access. Continuous water quality monitoring is a very powerful tool whereby the river is monitored at strategic points for indicative water quality and the data can show if and when any patterns emerge. This baseline data gives an insight into diurnal patterns in low flows as well as ‘first flush’ events after prolonged dry periods. The placement of sensors or loggers also gives a starting point from 23 | P a g e
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which the catchment can be investigated or traced to detect particular areas or tributaries having a significant effect on the system. If significant input is identified, expertise within the WRT can be employed to work with the affecting industry and reduce impacts on the rivers. With the poor state of recruitment in 2016, a longer-term strategy may be considered alongside the immediate habitat improvements. Salmonid stocks in larger catchments may be genetically unique and it would be beneficial to understand if there is genetic distinction between catchments in the Taw. The information would help identify if certain populations are more threatened than others, but it would also help inform a conservation strategy that can factor if the Taw population is interriverine and interbreeding or if the populations need to be treated separately; highlighting more urgency in particular areas. There are still gaps in the data despite a 69 site survey in 2016. It is recommended that the river users and angling associations/clubs be engaged in the North of the Taw catchment and that all areas currently not surveyed be considered in the future to present a holistic picture of fishery management throughout the Taw. Although not particularly mentioned so far there is the need to tackle NNIS (Non-Native and Invasive Species) along the river corridor. This is an expansive problem along the rivers and needs to be tackled in a co-ordinated way. There has been a survey of the Upper Taw waterbody which gives an idea of the scale of Himalayan Balsam along the upper Taw, but most importantly defines the upstream extents. Project/s will be worked up within the catchment partnership, but as a baseinitiative it is recommended that the angling community (as well as other river users) instigate and promote a “Pull 10� strategy whereby if every time a person visits the river they pull up and hang 10 Himalayan Balsam plants where they cannot re-root then the problem will reduce in its exponential spread. Concurrently, the North Devon Catchment Partnership will continue to tackle longer term issues and wider land management solutions through the statutory CSF (Catchment Sensitive Farming) initiatives as well as project specific solutions such as Sustainable Intensification and better land management of soils and waste.
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6. Acknowledgements This work could not have taken place without the financial support of the River Taw Fisheries Association for which Westcountry Rivers Trust and the wider North Devon catchment partnership are very grateful. Local knowledge and voluntary input from the Taw fisheries group who meet quarterly is also very appreciated as this helps bring a lot if information together in one room on a regular timetable and co-ordinates the fisheries activity in the catchment. Westcountry Rivers Trust could not perform this valuable work without the co-operation and kind permission of the multitude of land owners, river owners and tenants looking after the area. We thank you for working with us and supporting us in our work and hope to build an ever increasingly positive relationship for your businesses and the river. If land owners and tenants would like advice on how to improve their river habitat and potentially how to attract an alternative revenue stream from the river to assist in its conservation or development then the Westcountry Rivers Trust will be happy to provide further information.
7. References Armstrong, J.D., Kemp, P.S., Kennedy, G.J.A., Ladle, M. and Milner, N.J. (2003). Habitat requirements of Atlantic salmon and brown trout in rivers and streams. Fisheries Research. 62(2): 143-170 Crozier, W.W. and Kennedy, G.J.A. (1994). Application of semi-quantitative electrofishing to juvenile salmonid stock surveys. Journal of fish biology. 45(1): 159-164 Jonsson, B. and Jonsson, N. (2011). Ecology of Atlantic salmon and brown trout: Habitat as a template for life histories. London: Springer Kemp, P., Sear, D., Collins, A., Naden, P. and Jones, I. (2011). The impacts of fine sediment on riverine fish. Hydrological processes. 25: 1800-1821 King, M. (2007). Fisheries biology, assessment and management (2nd ed.). Oxford: Blackwell Publishing Klemetsen, A., Amundsen, P.A., Dempson, J.B., Jonsson, B., Jonsson, N., O’Connell, M.F. and Mortensen, E. (2003). Atlantic salmon Salmo salar L., brown trout Salmo trutta L. and Arctic charr Salvelinus alpinus (L.): A review of aspects of their life histories. Ecology of freshwater fish. 12: 1-59 Nislow, K.H. and Armstrong, J.D. (2012). Towards a life-history-based management framework for the effects of flow on juvenile salmonids in streams and rivers. Fisheries management and ecology. 19: 451-463
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8. Appendix Taw Catchment Salmon Classification Map 2016
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Taw Catchment Salmon Classification Maps 2013-16
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Taw Catchment Trout Classification Map 2016
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Taw Catchment Trout Classification Maps 2013-16
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Taw Catchment Salmon Conservation Strategy Map 2016/17
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Taw Catchment Trout Conservation Strategy Map 2016/17
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