Solent and South Downs: Fish Monitoring Report 2016

We are the Environment Agency. We protect and improve the environment. Acting to reduce the impacts of a changing climate on people and wildlife is at the heart of everything we do. We reduce the risks to people, properties and businesses from flooding and coastal erosion. We protect and improve the quality of water, making sure there is enough for people, businesses, agriculture and the environment. Our work helps to ensure people can enjoy the water environment through angling and navigation. We look after land quality, promote sustainable land management and help protect and enhance wildlife habitats. And we work closely with businesses to help them comply with environmental regulations. We can’t do this alone. We work with government, local councils, businesses, civil society groups and communities to make our environment a better place for people and wildlife.

Authors: Georgina Busst & Dom Longley Published by: Environment Agency Further copies of this report are available Horizon House, Deanery Road, from our publications catalogue: Bristol BS1 5AH www.gov.uk/government/publications Email: [email protected] or our National Customer Contact Centre: www.gov.uk/environment-agency T: 03708 506506

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Foreword

Welcome to the 2016 annual fish report for Solent and South Downs. This report covers all of the fisheries surveys carried out by the Environment Agency in Hampshire and East and West Sussex in 2016. This is the tenth annual report we have produced.

Our fisheries monitoring programme mainly focussed on spatial monitoring for salmon parr on the River Test in 2016. This work is scheduled every 6 years so we can now directly compare the data with that collected in 2010. The spatial monitoring provides information on how the distribution of salmon parr is changing over time, from 23 surveys that cover a large proportion of the Test. This is complemented by the parr temporal monitoring programme, which occurs biennially, and reveals changes in parr abundance at 6 sites. Together the spatial and temporal monitoring provide us with a fuller picture, allowing us to gain a greater understanding of the Test's salmon population and its variability over time.

We also carried out Principal Coarse Fishery (PCF) surveys on several rivers in East and West Sussex, in locations where coarse angling takes place. As well as these we surveyed various waters for the Water Framework Directive and carried out our annual Transitional and Coastal Waters (TraC) surveys in Southampton Water and the River Adur estuary. We now report all our Principal Coarse Fishery surveys in a nationally consistent way, so that anglers, fishing clubs, landowners and others can see the publication ahead of this annual report. Consequently, the PCF survey results are freely available as separate reports. However, as this is the first year of this new style of reporting, we've included the information from the PCF reports for convenience.

Weather and climate have a large influence on our fish populations and 2016 was generally warmer than usual. The average temperature over the summer months was the warmest since 2006, increasing from last year by over 1.5°C. Degree days over 12°C (a figure used to demonstrate favourable growth conditions for coarse fish) were the second highest recorded, a stark contrast to 2015 where it was the lowest figure since 1999. Winter was also warm, being the warmest since 2007.

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Executive Summary

In 2016 we carried out a total of 77 fish surveys throughout the Solent and South Downs area, which included 26 on the River Test and 12 autumn estuarine surveys.

• The salmon parr surveys on the River Test revealed that 59% fewer parr were recorded in 2016 compared to the same sites surveyed in 2010. There were 7 sites where we caught no salmon parr in 2016 where we'd previously found them. Conversely, 2 other sites yielded more parr in 2016. Low salmon parr abundance in general was noted across the UK and also in France in 2016. This was attributed to a record high average temperature in December 2015, which probably had a negative impact on spawning and egg development.

• Based on data from our salmon counters, we estimate that the number of adult salmon migrating into the River Test was 1,454 and into the River Itchen was 361 between May and December 2016. These figures represent 91% and 45%, respectively, of each river's salmon management target.

• Principal Coarse Fishery surveys were carried out on the Pevensey Levels, the Sussex Ouse and the Western Rother. This year, the Environment Agency has started producing individual reports for all PCF surveys, using a standard format - these are freely available upon request, but we've also included the information within this annual report.

• 19 Water Framework Directive surveys were carried out across the area on the Pevensey Levels, the Sussex Ouse, and rivers Arun, Hamble and Test. These surveys provide us with the opportunity to assess some stretches of river that are rarely surveyed. The results were varied and are reported in detail in this report.

• Estuarine Transitional and Coastal (TraC) surveys were carried out in the autumn of 2016 in both Southampton Water and the Adur estuary. We caught 26 species of fish in Southampton Water and 13 species in the Adur estuary. Autumn juvenile bass numbers were the highest ever recorded in Southampton Water, but bass numbers have slightly declined in the Adur estuary. Overall, the numbers of fish caught in both estuaries were higher than average for autumn, but species diversity was lower than usual.

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Rivers of Solent and South Downs

East:

West:

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Contents

Foreword ...... 3

Executive Summary ...... 4

Rivers of Solent and South Downs ...... 5

Temperature and Rainfall ...... 7

Interpreting Results ...... 9 Fish survey methods ...... 9 Electric Fishing ...... 9 Estuarine Transitional and Coastal (TraC) Surveys ...... 10 Fish Counters...... 10 Fish survey results ...... 10 Water Framework Directive surveys ...... 10

1. East Sussex ...... 11 1.1. Pevensey Levels ...... 11 1.2. Sussex Ouse ...... 21

2. West Sussex ...... 23 2.1. Arun...... 23 2.2. Western Rother ...... 31

3. Hampshire ...... 37 3.1. East Hampshire ...... 37 3.2. Test: Full Catchment Report ...... 40 3.3. Test and Itchen Fish Counters ...... 59 4.1. New Forest ...... 64

5. Estuarine Fish Monitoring ...... 66 5.1. Southampton Water ...... 66 5.2. Adur Estuary ...... 72

Looking Forward ...... 77

Acknowledgements ...... 77

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Temperature and Rainfall

Climatic conditions have a major influence on fish populations in both freshwater and marine environments. Rainfall can influence flows, with high rainfall leading to flooding and low levels leading to drought conditions. Temperature affects the rate of fish growth and also the amount of oxygen available in the water. The following graphs highlight how these 2 variables have changed over the 2016 survey year and over the course of our long term fisheries dataset.

Figure TR1 shows the mean summer and winter rainfall each year (Romsey rain gauge), and the mean temperature for the summer and preceding winter of each year. The temperature data is calculated using the Met Office’s Central England Temperature (CET) dataset. Rainfall is measured in millimetres (mm) and temperature in degrees Celsius (°C).

180 18

160 16 140 14

120 C) °

100 12

80 10

Rainfall (mm) Rainfall 60 8 ( Temperature 40 6 20

0 4 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Mean rainfall in preceding Oct-Mar Mean rainfall Apr-Sept Mean winter temp. in preceding Oct-Mar Mean temp. May-Sept Figure TR1: Mean winter and summer temperature and rainfall over the past 15 years

Figure TR2 shows the mean monthly temperature from October 2015 to December 2016. Also shown is the mean of the previous 15 years and the minimum and maximum mean for each month. The data are calculated using the CET dataset and are shown in degrees Celsius (°C). 20 18 16

14 C) ° 12 10 8 6

Temperature ( Temperature 4 2 0 -2 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Monthly mean (Oct 2015-Dec 2016) Monthly mean (2000-2014) Maximum (2000-2014) Minimum (2000-2014) Figure TR2: Monthly mean temperatures (°C) from October 2015 to December 2016

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Figure TR3 shows total monthly rainfall between October 2015 and December 2016. This is shown alongside the average monthly total between 2000 and 2015 and the maximum and minimum value for each month during this time period. All values are in millimetres (mm).

300

250

200

150 Rainfall (mm)Rainfall 100

0 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Monthly total (Oct 2015-Dec 2016) Mean monthly total (2000-2015) Maximum total (2000-2015) Minimum total (2000-2015)

Figure TR3: Monthly rainfall totals from October 2014 to December 2016

Discussion

Figure TR1 gives a general summary of temperature and rainfall conditions in 2016 in the context of the previous 15 years. Values for summer and winter rainfall were roughly average for the long term period: it was the eighth wettest winter for the period and the tenth wettest summer. However, winter and summer temperatures were both well above average: winter 2015/16 and summer 2016 were both ranked third warmest since 2001. Figure TR2 shows in detail the basis for the high average winter and summer temperatures. Probably the most striking anomaly of the whole year was the average temperature for December 2015, which was more than double the long-term average and exactly 1 and half times the previous maximum value since 2001. With December being a crucial period for spawning salmonids, but a period of relatively limited activity for coarse species, we would expect such high temperatures to impact Atlantic salmon and brown/sea trout populations and this is discussed in more detail in the River Test section of this report. Figure TR2 also shows that monthly average temperatures for May to September exceeded the long-term averages and that December 2016 (after the 2016 survey period) was warmer than average. Figure TR3 shows monthly rainfall totals from winter 2015/16 through to the end of the year. While there was a great deal of variation from the long-term monthly averages, only 2 months were outside of the long-term maximum and minimum range; these were October and December 2016, both of which had less rainfall than the previously recorded minimums in the long-term dataset. Combined with the lower than average flows in July and August, plus above average temperatures in December, climatic conditions during autumn 2016 were, like the previous year, likely to be challenging for migrating and spawning salmonids.

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Interpreting Results Fish survey methods

Electric Fishing The majority of fish population surveys covered in this report were conducted using electric fishing, either from a boat or wading. Electric fishing involves placing a pole into the water with a large metal ring at the end (the anode), which is energised with electricity from a small generator or battery. A circuit is formed through the surrounding water between the anode and a length of copper braid (cathode) that is placed in the water a few metres away. The current is carefully controlled via specialised circuitry in a control box and causes fish to swim towards the anode and become partially anaesthetised so they can easily be collected in a hand net. The type of current used is known as Pulsed Direct Current. Voltage, pulse frequency and pulse "width" (duration) are all adjusted for each specific location with the aim of capturing fish, with the minimum electrical power and therefore the minimum risk of injury to the fish.

All electric fishing surveys reported involve the team wading or boating slowly upstream, usually for 100 metres, until they reach a stop net placed across the channel to prevent fish escaping from the survey reach. All Water Framework Directive and salmonid surveys discussed in this report involve a single upstream electric fishing run or pass ("single run"), whereas Principal Coarse surveys involve 3 successive runs ("catch depletion").

Some electric fishing surveys for juvenile salmon and trout (parr) take place in sections of river that are too wide, shallow and weedy for stop nets to be used and for 2 anodes to fish the whole width effectively. Under these circumstances a reasonable measurement of parr abundance can be made by fishing with an electric fishing backpack unit and wading in a straight line upstream, through suitable parr habitat, for a set distance and period of time. If the time fished and the distance covered is kept consistent, then data can be compared between sites and between years. We use this method for several of our salmon parr surveys on the Test and Itchen, fishing for exactly 5 minutes and covering approximately 75 metres.

Captured fish are placed in a container of cool, aerated water and identified and measured before being returned to the river. Scales are sometimes taken so that fish ages can be estimated. 9 of 78

Estuarine Transitional and Coastal (TraC) Surveys Estuarine fish surveys do not use electric fishing, because of the very high conductivity of salt water. Instead, a combination of beach seine netting, small beam trawling and fyke netting (a type of static fish trap) is used. Seine netting is also sometimes used to conduct fish surveys in very wide, slow rivers.

Fish Counters To monitor adult returning salmon, we have 2 fish counters; 1 at Nursling on the River Test and 1 at Gaters Mill on the Itchen. These counters work by detecting a change in resistance when a fish swims over a set of electrodes in the channel. By having 3 electrodes, we can tell whether the fish is moving upstream or downstream, according to the pair that were triggered first. As the electrodes detect a change in resistivity, a count is made and a photograph is taken either from above (at Nursling) or through a glass screen to the side (at Gaters Mill). These fish counters do not provide an exact count of fish as they only cover 1 possible route of ascent. However, through previous monitoring, we can estimate the proportion of fish using the monitored route compared to others and we apply a calculation to our count to correct this. Our counts therefore are an estimate of the total number of salmon ascending our rivers each year.

Fish survey results Single-run electric fishing surveys cannot catch every fish in the reach they cover, so the catch is a minimum estimate and gives a general idea of the species present and their abundance. Catch depletion surveys (3 runs) catch the majority, but usually not all of the fish in the survey reach. However, the difference in catch in each successive run allows a reliable estimate of the total population of each species to be calculated. Catch depletion results should not be compared directly with single run results, although sometimes single run results are compared to the first run of a catch depletion survey. The results from both types of survey are expressed as the number or weight of fish per 100m² of river (i.e. within a 10m by 10m area).

Water Framework Directive surveys Water Framework Directive (WFD) surveys consist of 1 single run, either between stop nets, or with 1 upstream stop net. The results are collated each year and classified using FCS2 (the Fisheries Classification Scheme, Version 2). This produces the formal classification we use for WFD, from High to Bad. These surveys are only carried out once in every 6 years, and so are best represented in tabular form (see below). This example WFD table shows the number of each fish species caught, the total number of species and the total density of each (number of fish per 100m²), excluding minor species such as minnow, bullhead, stone loach, brook lamprey and 3- spined stickleback. The sites are ordered within the table according to their total density.

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1. East Sussex

1.1. Pevensey Levels 7 fish population surveys were conducted in the Pevensey Levels catchment in 2016. These were all Water Framework Directive (WFD) surveys (used to classify waterbodies for fish) and 2 of these were also Principal Coarse Fishery (PCF) survey sites.

The locations of the survey sites are shown on the map below. The orange markers indicate the sites that were solely used to produce WFD classifications and the red markers indicate the WFD sites that were also PCF surveys sites. To avoid performing multiple surveys at dual purpose sites, a single catch depletion surveys was performed, therefore fulfilling the requirements for PCF surveys and allowing the data collected from the first run to be used for WFD classification.

1.1.1. Water Framework Directive Surveys

Table Pevensey 1 sets out the results of the Water Framework Directive fish surveys. Each site is listed along with its grid reference, the number of each species caught, the total number of species and the total density of fish, excluding minor species (i.e., minnow, stone loach, bullhead, 3-spined stickleback and lamprey). The results are listed in order of the total density of fish, measured as the number of fish per 100m².

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Table Pevensey 1: WFD summary table, Pevensey Levels WFD sites, 2016. *Seine net surveys

Site NGR Bleak lamprey Brook Common bream eel European Gudgeon Perch Pike Roach Rudd Ruffe loach Stone Tench Number of species Total density minor (excluding species) Horse Bridge* TQ6690708965 366 1 110 3 5508 132 1 7 588.56 Middle Bridge* TQ6679906818 131 1 10 858 7 1742 8 18 8 370.00 Pevensey Haven* TQ6400605786 3 11 5 477 3 99 11 1 8 127.08 D/S Tilley Bridge TQ6620112865 1 11 2 35 3 98 1 1 8 93.75 New Bridge TQ6262409760 3 2 1 3 72 10 6 9.10 U/S Boreham Bridge TQ6757812075 2 8 27 3 4.99 Horse Eye Sewer TQ6031208461 2 2 5 3 4.09

Figure Pevensey 1 shows the actual fish population densities for the major fish species recorded during the WFD surveys. Sites are ordered according to their total fish density and species are ranked according to their densities across all WFD sites.

600 Roach

500 Perch

Common bream 400 Ruffe

Pike 300

Rudd Density (No/100m²) Density 200 Gudgeon

European eel 100 Tench

0 Bleak Horse Bridge Middle Bridge Pevensey D/S Tilley New Bridge U/S Boreham Horse Eye Haven Bridge Bridge Sewer Figure Pevensey 1: Fish population densities (number of fish per 100m²), excluding minor species, Pevensey Levels WFD sites, 2016

Figures Pevensey 2, 3 and 4 below are length frequency histograms showing the numbers of roach, perch and common bream, respectively, in 5mm length classes caught across all the WFD surveys on the Pevensey Levels in 2016. Please note that the fish length and frequency axes differ on the graphs between the species.

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500 450 400 350 300 250

Frequency 200 150 100 50

60 25 30 35 40 45 50 55 65 70 75 80 85 90 95

175 100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 180 185 190 195 200 205 210 215 220 225 230 Length (mm) Figure Pevensey 2: Length frequency of roach (n=1694), WFD surveys, 2016

500 450 400 350 300 250

Frequency 200 150 100 50

25 35 45 55 65 75 85 95

175 185 105 115 125 135 145 155 165 195 205 215 225 235 245 255 265 275 285 295 305 315 325 335 345 355 365 Length (mm) Figure Pevensey 3: Length frequency of perch (n=1259), WFD surveys, 2016

50 45 40 35 30 25

Frequency 20 15 10 5

30 40 50 60 70 80 90

140 160 100 110 120 130 150 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 Length (mm) Figure Pevensey 4: Length frequency of common bream (n=256), WFD surveys, 2016

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Discussion

Fish populations varied across the 6 WFD sites in the Pevensey Levels catchment. The survey results reflect a wide range of fish communities, from the species rich, coarse fish dominated sites at Horse Bridge and Middle Bridge to the extremely low density, species poor sites at Boreham Bridge and Horse Eye Sewer. Population size structures from length frequency histograms indicate that the populations of perch and bream in the Pevensey Levels are dominated by very small and/or young individuals. Length frequency histograms of roach and common bream show the presence of a number of age classes within the catchment. This data will be used to classify the relevant waterbodies under the Water Framework Directive as Bad, Poor, Moderate, Good or High for fish and the results can be used to form the basis for any necessary improvement projects.

1.1.2. Principal Coarse Fishery (PCF) Surveys

Summary

• 2 Principal Coarse Fishery sites on the Pevensey Levels were surveyed between August and September 2016; 1 by seine netting (single catch) and the other by catch-depletion electric fishing (3 catches); • 8 species of fish were recorded, including 7 of angling interest. A total of 6,168 fish were captured (47 at Boreham Bridge and 6,121 at Horse Bridge); • Roach were the most abundant species and were recorded at both sites; • A total density estimate of 6.3 fish per 100m² and biomass estimate of 786 grams per 100m² was recorded at Boreham Bridge; • A total density estimate of 588.7 fish per 100m² and biomass estimate of 2,566 grams per 100m² was recorded at Horse Bridge.

Fish population surveys at Horse Bridge have previously been completed using electric fishing, however, due to the wide deep channel (around 25m wide, 2m deep and usually quite murky), this was considered as an ineffective method. Consequently, in 2016 seine netting was trialled and proved to be an ideal technique for this site.

Results

The seine net survey was a single-catch (one sweep with the net) and the electric fishing survey involved 3 catches, therefore the data produced is slightly different. The former produces minimum abundance and density values, whereas total fish abundance and density estimates can be calculated from the latter. However, given the very high efficiency of deploying a seine net between 2 stop nets (i.e. very little chance of avoiding capture), these minimum values are likely to be at least as accurate as the calculated estimates. Please note that the site at Boreham Bridge had been dredged earlier in the year which may have impacted the range of species and number of fish that were caught. Table Pevensey 2 shows estimated density values per species for Boreham Bridge and actual density values per species for Horse Bridge, for the major fish species recorded during the surveys (number of fish per 100m², i.e. in a 10m by 10m section of river). The table also gives the length ranges for each species. 14 of 78

Table Pevensey 2: Population density estimates (number of fish per 100m²) or number of fish caught and size ranges (min – max, mm) for the key species recorded Boreham Bridge Horse Bridge (Electric fishing) (Seine netting) Common bream Density 0.27 35.40 Size range 121 30 – 190 Eel Density 0.14 Size range 315 Gudgeon Density 0.10 Size range 46 Perch Density 0.27 10.60 Size range 50 - 149 37 - 365 Pike Density 1.75 0.30 Size range 116 - 624 140 - 516 Roach Density 3.91 529.50 Size range 58 - 221 30 - 150 Ruffe Density 12.70 Size range 39 - 100 Tench Density 0.10 Size range 464

Figure Pevensey 5 shows the fish population densities (number of fish per 100m²) for the major fish species recorded at both 2016 survey sites (actual for Horse Bridge: estimated for Boreham Bridge).

600 Common bream 500 Eel

2 Gudgeon 400 Perch 300

No/100m Pike

200 Roach Ruffe 100 Tench 0 Horse Bridge Boreham Bridge Figure Pevensey 5: Population density (number of fish per 100m2), excluding minor species, PCF survey sites, 2016

Figure Pevensey 6 shows the fish biomass for the major fish species recorded at both 2016 survey sites (actual for Horse Bridge: estimated for Boreham Bridge). 15 of 78

2500 Common bream Eel 2000

Gudgeon 2 Perch 1500

Pike g/100m 1000 Roach

Ruffe 500 Tench

0 Horse Bridge Boreham Bridge Figure Pevensey 6: Population biomass (grams of fish per 100m²), excluding minor species, PCF survey sites, 2016

Figure Pevensey 7 shows the total number of roach caught at Boreham Bridge in every survey year and the number of degree days above 12 degrees centigrade in each year. A degree day is a theoretical unit of 1 day at 1 degree, so a 24 hour period where the average temperature was 13°C equals 1 degree day above 12°C. This unit is a useful indicator of coarse fish reproductive success and juvenile survival and is calculated from the Central England Temperature (CET) dataset.

180 700 160 650 140 600 550 120 500 100 450 80 Total roach Total 400

60 >12c Degree days 350 40 300 20 250

0 200

1999 2002 2003 2004 2005 2006 2007 2008 2009 2013 2016

2011no survey 2001no survey 2010no survey 2012no survey 2014no survey 2015no survey 2000no survey Figure Pevensey 7: Total number of roach and degree days above 12°C, Boreham Bridge

Figures Pevensey 8 to 11 are length frequency histograms showing the numbers of roach, common bream, and perch, respectively, in 5mm length categories recorded at Horse Bridge in 2016. As so many fish were captured a representative sub-sample of around 100 individuals of each species were measured. The length structures reveal that across all 4 species the majority captured were young and/or short. Figure 8 is the length frequency histogram for roach caught at Boreham Bridge. Identical axes have been used to allow direct comparison.

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50 40 30 20 n=100 Frequency 10

35 20 50 65 80 95

155 275 110 125 140 170 185 200 215 230 245 260 290 305 320 335 350 365 Length (mm)

Figure Pevensey 8: Length frequency of roach, Horse Bridge, 2016 50 40 30 n=100 20 Frequency 10

35 20 50 65 80 95

155 275 110 125 140 170 185 200 215 230 245 260 290 305 320 335 350 365 Length (mm)

Figure Pevensey 9: Length frequency of common bream, Horse Bridge, 2016

50 40 30

20 n=105 Frequency 10

35 20 50 65 80 95

155 275 110 125 140 170 185 200 215 230 245 260 290 305 320 335 350 365 Length(mm) Figure Pevensey 10: Length frequency of perch, Horse Bridge, 2016 50 40 30

20 n=29 Frequency 10

20 35 50 65 80 95

110 230 365 125 140 155 170 185 200 215 245 260 275 290 305 320 335 350 Length (mm)

Figure Pevensey 11: Length frequency of roach, Boreham Bridge, 2016

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1.1.3. WFD Classification of PCF sites

The Boreham Bridge survey site lies within the “Ashbourne and Hugletts streams” waterbody and is the only site use to classify the waterbody for fish. Horse Bridge lies within the “Waller Haven between Windmill Hill and the coast” waterbody and is 1 of 2 sites used to classify it for fish, the other being Middle Bridge. Table Pevensey 3 shows the most recent WFD classification for each waterbody (official status from 2015) as well as the fish element that contributes to the overall status. Note that these classifications are NOT based on the 2016 surveys covered by this report but on the most recent ones previous to this – FCS2 analysis of 2016 data has not yet been published.

Table Pevensey 3: Water Framework Directive (WFD) classification status for the overall waterbody and for the fish element for the Pevensey Levels

Waterbody name 2015 Overall status 2016 Fish status

Pevensey Levels - Ashbourne Poor Poor and Hugletts Streams, GB107041012521

Pevensey Levels - Waller Poor Poor Haven between Windmill Hill and A259, GB107041012460

Discussion

The fish community of the Pevensey Levels is typical of a lowland lake, with roach by far the most abundant species and a lack of flow-loving, gravel-spawning species. Length frequency distributions of the most abundant species suggest that few juveniles survive to adulthood and that the numbers of large adult fish is relatively low.

Boreham Bridge The current classification of the Boreham Bridge site as Poor is based on a survey conducted in 2013: the failure is caused primarily by the absence of eels from the catch and, to a lesser extent, the low abundance of pike and roach. The 2016 survey does not show an increased abundance of these species, so the classification is unlikely to change. Low eel abundance may indicate lack of food and/or obstructions to migration but may also reflect the general decline in the species across its range in recent years. The survey site had been dredged earlier in the year. Given the low abundance of these species over many years, dredging is likely to have a chronic, as well as an immediate impact on the local fish community, especially for eels. Although the width of the channel at this site is ideal for electric fishing, the depth raises some concerns that this technique might be inefficient. Therefore, a comparison with seine netting will be undertaken at the time of the next scheduled survey in 2019. The total number of roach caught in all survey years at Boreham Bridge, compared with the number of degree days above 12°C recorded in that year indicates that there is a fairly strong positive correlation between the 2 factors, with an r value of 0.5 (where 1 = perfect positive correlation). Degree days above 12°C are a useful predictor of coarse fish reproductive success. This correlation indicates that water temperature is probably the most important environmental factor controlling roach recruitment.

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Horse Bridge The survey site at Horse Bridge is almost 4 times the width of Boreham Bridge, making electric fishing very inefficient. Therefore, in 2016 we surveyed by seine netting, which proved to be vastly more effective, yielding 6,000 fish comprising 7 species, compared to 9 fish of 2 species in the 2012 survey. This change is likely to result in an improvement in WFD classification, as the 2 species driving the current failure, roach and pike, were both recorded, with roach being extremely abundant. The roach population was dominated by young of the year and 1 year old juveniles, with far fewer adults and the largest individual measuring only 150mm in length. This suggests that a small proportion of juveniles survive to adulthood, and those that do, tend to grow slowly and reproduce at a small size, which is common for low-productivity, slow flowing waterbodies.

Planned actions • In order to improve fish passage into the Pevensey Levels, fish friendly tidal flap valves have been purchased and will be installed over the 2017/ 2018 period. The fish flaps work by remaining open for a longer period than the existing flap valves, giving fish more time to pass through the structure.

• The Pevensey Invasive Species Project will continue to map the extent of invasive non-native New Zealand pigmyweed on the Levels. The goal is to eventually develop a control programme and trial a new control measure in partnership with Natural England and the Centre for Agriculture and Bioscience International (CABI) in order to better protect the UK from non- native invasive species. In the long term, this project is likely to have a beneficial effect on fish habitat on the Levels.

Next survey The 2 Pevensey Levels coarse fish surveys will next be completed in summer 2019.

Ruffe from Horse Bridge Common bream from Boreham Bridge

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Setting the seine at Horse Bridge on the Pevensey Levels, 2016

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1.2. Sussex Ouse

3 fish population surveys were conducted in the Sussex Ouse catchment in 2016. These were all Water Framework Directive (WFD) surveys (used to classify waterbodies for fish).

1.2.1. Water Framework Directive Surveys

The locations of the 3 WFD sites are shown on the map below.

Table Ouse 1 sets out the results of the Water Framework Directive fish surveys. Each site is listed along with its grid reference, the number of each species caught, the total number of species and the total density of fish, excluding minor species (i.e., minnow, stone loach, bullhead, 3-spined stickleback and lamprey). The results are listed in order of the total density of fish, measured as the number of fish per 100m².

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Table Ouse 1: WFD summary table, Ouse WFD sites, 2016. *D/S Old Ship Gauging Station

Site NGR stickeback 3-spined Dace eel European Gudgeon Perch Pike Roach Rudd loach Stone species of Number density Total minor (excluding species) Iron River* TQ4471315423 1 4 1 1 4 6 19 2 8 10.57 Isfield Church TQ4439517641 3 2 2 1 5 1 6 0.91 Anchor Weir TQ4425916171 3 1 3 2 7 5 0.88

Discussion

Both WFD fish population surveys on the main Ouse yielded extremely low numbers of fish. This was also the case when these sites were last surveyed in 2011. The most significant pressures on the fish communities at these locations are the various impoundments both upstream and downstream, which reduce water velocity and obstruct fish passage. This data will be used to classify the relevant waterbodies as Bad, Poor, Moderate, Good or High for fish and the results can be used to form the basis for any necessary improvement projects.

Survey site A juvenile pike and a roach

Unexpected finds: A raft spider and a newt found during the Sussex Ouse surveys

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2. West Sussex

2.1. Arun 5 fish population surveys were conducted in the Arun catchment in 2016. These were all Principal Coarse Fishery (PCF) surveys and 4 of these were also used for classification under the Water Framework Directive (WFD).

The locations of the survey sites are shown on the map below. The blue marker indicates the PCF only site and the red markers indicate the PCF sites that were also used for WFD surveys. To avoid performing multiple surveys at dual purpose sites, a single catch depletion surveys was performed, therefore fulfilling the requirements for PCF surveys and allowing the data collected from the first run to be used for WFD classification.

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2.1.1. Water Framework Directive Surveys

Table Arun 1 sets out the results of the Water Framework Directive fish surveys. Each site is listed along with its grid reference, the number of each species caught, the total number of species and the total density of fish, excluding minor species (i.e., minnow, stone loach, bullhead, 3-spined stickleback and lamprey). The results are listed in order of the total density of fish, measured as the number of fish per 100m².

Table Arun 1: WFD summary table, Arun WFD sites, 2016

Site NGR stickeback 3-spined Bleak lamprey Brook Bullhead Chub Dace eel European Gudgeon Minnow Perch Pike Roach Rudd loach Stone species of Number density Total minor (excluding species) Pallingham TQ0367521204 21 3 2 2 4 23 6 7.77 Horsham STW TQ1450829816 1 2 2 2 3 2 5 9 8 3.45 Loxwood TQ0407331098 1 1 1 4 12 2 6 2.71 Roman Station TQ1160033136 11 1 4 1 95 2 2 5 3 9 2.57

Discussion

All 4 WFD sites in the Arun catchment have a very low total density and few non-minor species. Roach were the most abundant and widespread species. There is a distinct absence of sensitive fish species across the sites, which suggests that some factor may be restricting the fish community. This is most likely due to degraded physical habitat or issues with water quality. The sewage treatment works at Horsham discharges to the Arun and is known to impact on the water quality of the river. This data will be used to classify the relevant waterbodies as Bad, Poor, Moderate, Good or High for fish and the results can be used to form the basis for any necessary improvement projects.

2.1.2. Principal Coarse Fishery Surveys

Summary

• 5 sites on the River Arun were surveyed by electric fishing, using a three-run, catch-depletion method between July and September 2016; • A total of 586 fish were captured, representing 16 species, including 9 of angling interest; • Roach, pike, perch and gudgeon were the most widespread species, being recorded at all 5 sites; • An average total density estimate of 12.72 fish per 100m² and biomass estimate of 1,006.22 grammes per 100m² were recorded across all sites, excluding minor species (i.e., minnow, bullhead, stone loach, brook lamprey and three-spined stickleback); • Roach were the most numerous species, whilst pike had the highest biomass.

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Results

Table Arun 2 shows population density estimates (number of fish per 100m², i.e. in a 10m by 10m section of river) in tabular form for the major fish species recorded during the surveys.

Table Arun 2: Population density estimates (number of fish per 100m2) and size ranges (min – max, mm) for the key species recorded during the surveys Horsham Roman Loxwood Pallingham Pulborough STW Station Cut Bleak Density 0.14 10.45 Size range 51 48 - 90 Chub Density 2.10 0.34 1.70 3.31 Size range 97 - 259 359 - 397 64 - 428 30 - 160 Common Density 0.15 bream Size range 98 Dace Density 1.80 1.37 2.26 Size range 112 - 184 73 - 136 50 - 166 Eel Density 0.90 1.20 0.14 0.30 Size range 410 - 585 120 - 295 345 365 - 380 Gudgeon Density 2.85 0.51 0.14 0.57 1.36 Size range 70 - 133 104 - 114 85 73 - 110 41 - 120 Perch Density 0.30 1.88 0.27 0.71 0.15 Size range 50 - 86 85 - 224 54 - 60 68 - 129 130 Pike Density 0.75 0.51 0.68 0.99 0.30 Size range 405 - 735 411 - 587 113 - 317 182 - 512 177 - 583 Roach Density 4.05 2.91 4.89 7.91 16.57 Size range 20 - 170 82 - 168 63 - 222 37 - 208 32 - 170 Rudd Density 0.30 0.41 0.14 Size range 57 - 84 51 - 70 165

Figure Arun 1 shows the fish population density estimates for the major fish species recorded during the surveys. Roach, pike, perch and gudgeon were the most widespread species, being recorded at all 5 sites. Horsham STW and Pulborough Cut were the most species-rich sites and the highest total density estimate was also recorded at Pulborough Cut, where the catch was dominated by roach.

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Figure Arun 1: Population density estimates (number of fish per 100m2), excluding minor species, PCF survey sites, 2016

Figure Arun 2 shows population biomass estimates for the major fish species recorded during the surveys. Across the 5 sites, pike had the greatest biomass, with the largest individuals caught at Horsham STW, while chub dominated the biomass at Pallingham.

Figure Arun 2: Population biomass estimates (grams of fish per 100m2), excluding minor species, PCF survey sites, 2016

Figures Arun 3 and 4 are length frequency histograms showing the numbers of roach in 5mm length categories recorded at all 5 surveys sites in 2013 and 2016, respectively.

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Figure Arun 3: Length frequency of roach, PCF surveys, 2013

Figure Arun 4: Length frequency of roach, PCF surveys, 2016

Figure Arun 5 shows the total number of roach and gudgeon caught at Horsham STW and Roman Station in all survey years. Also shown is the 4-year moving average of the number of degree days above 12 degrees centigrade in each year: a degree day is a theoretical unit of 1 day at 1 degree, so a 24 hour period where the average temperature was 13°C equals 1 degree day above 12°C. This unit is a useful indicator of coarse fish reproductive success and juvenile survival and is calculated from the Central England Temperature (CET) dataset. Other sites are excluded because they were added to the programme at a later date.

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250 600 200

550 150

Total catch Total 500

100 4 yr mean deg.days >12c mean yr 4 deg.days 50 450

0 400

2002 2003 2004 2005 2006 2007 2008 2009 2010 2012 2013 2016

No surveys 2011 Nosurveys 2014 Nosurveys 2015 Nosurveys

Roach Gudgeon 4 yr mean degree days >12°c

Figure Arun 5: Total estimated number of roach and gudgeon caught at Horsham STW and Roman Station and the 4-year moving average number of degree days above 12°C, 2002 - 2016

2.1.3. WFD Classification of PCF sites

Water Framework Directive (WFD) survey results are collated each year and classified using FCS2 (the Fisheries Classification Scheme, Version 2). FCS2 uses a range of complex statistical models and geographical data to predict the fish community at any given location under natural conditions. The system then compares this with the actual survey catch at individual sites and provides a score (EQR) that reflects whether or not the 2 are similar. Scores determine formal classifications and may be Bad, Moderate, Good or High: Bad or Moderate constitute failures. Waterbodies tend to have between 1 and 3 WFD classification survey sites within them (surveyed once every 6 years) and the overall waterbody classification for fish is determined by the average EQR score of those constituent surveys. FCS2 is the most objective, evidence-based method available for assessing whether or not fish communities have been impacted by human activity but the process depends on high-quality survey data. The lack of particular species at a site can indicate the nature of the constraints on the fish community. Of the Arun coarse fishery survey sites, only Pulborough is not used to classify the waterbody that it lies within. The Horsham survey site lies within the “Arun: Horsham” waterbody; Roman Station and Pallingham survey sites lie within the “Arun (upstream of Pallingham)” waterbody and Loxwood lies within the “Loxwood stream” waterbody. Table Arun 3 shows the most recent WFD classification for each waterbody (official status from 2015) as well as the fish element that contributes to the overall status. Note that these classifications are NOT based on the 2016 surveys covered by this report but on the most recent ones previous to this – FCS2 analysis of 2016 data has not yet been published.

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Table Arun 3: Water Framework Directive (WFD) classification status for the overall waterbody and for the fish element for the River Arun Waterbody name 2015 Overall status 2016 Fish status River Arun – Horsham Poor Good GB107041012310 River Arun – upstream of Moderate Moderate Pallingham GB107041017950 River Arun - Loxwood Poor Good stream GB107041017970

Discussion

Fish population density estimates for all species combined were higher in 2016 than in 2013 at almost all sites, however, roach and gudgeon (typically the most numerous species overall), both yielded low catches relative to previous years. A strong relationship between roach and gudgeon abundance and summer temperature is apparent, with the abundance of both species correlating remarkably closely with summer temperature over time (r = 0.94: where 1 = perfect positive correlation). Additionally, both species are individually closely correlated to the average number of degree days above 12°C in the 4 years leading up to (and including) the survey year (for roach r = 0.82; gudgeon r = 0.69). This suggests that in this river, not only is summer temperature a key factor in determining variation in roach and gudgeon abundance, but also that there is a cumulative positive effect of a succession of warm summers. The length frequency histograms demonstrate the low average length of roach in 2013, indicating that the population was predominantly composed of young of the year fish in the 30-60mm range. In contrast, in 2016, fish in the 90-130mm range dominated. This peak almost certainly represents the 2013 year class, in their fourth year of growth, which suggests poor recruitment since then.

Arun: Horsham The Horsham STW site is 1 of 2 used to classify this waterbody for fish; the other is at Theale Farm. The 2013 survey at Horsham was classed as Poor because of the absence of trout, bullhead and stone loach. However, the waterbody as a whole was classed as Good for fish because the Theale Farm survey (2014) was categorised as High. Although trout were also absent from Theale Farm, bullhead were fairly abundant, stone loach were present and the total number of fish species was 10, as opposed to 6 at Horsham (9 species were expected at both sites). The most likely cause of the difference in fish community between the 2 sites is proximity to the sewage treatment works outfall. Theale Farm is approximately 3.5km downstream, whilst Horsham STW is only 350m downstream. Although a few bullhead were recorded in the 2016 Horsham STW catch, trout and stone loach were absent, so the classification is unlikely improve.

Arun (upstream of Pallingham) 3 sites are used to classify this waterbody for fish: Roman Station, Bignor Farm and Pallingham, which were classed as Good, Moderate and Moderate respectively, in 2016. Bignor and Pallingham fell short of Good status for 2 reasons; low fish abundance in general and the absence of minnows. Minnows were recorded in the majority of surveys at both sites prior to 2013 and may have been affected by a serious pollution incident in 2011. The results show that the 2016 catch at Pallingham remained relatively low and minnows were also still absent. Therefore, the WFD classification is unlikely to change on the basis of this survey.

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Loxwood stream The Loxwood stream waterbody is classed as Good for fish, based on surveys at Loxwood and Upper Ifold Farm (both in 2013). However, at site level, the former is classed as Bad and the latter High. The reason for the Loxwood failure was that 9 species were expected and only 3 were observed: the key missing species were minnow, bullhead, chub, eel and stone loach. The results from 2016 show that the catch was similarly low, with the underlying reason likely to be the impounded nature of this reach.

Completed improvements: To increase the connectivity of the river and ease fish passage, 2 fish passes were installed on the River Arun in 2016. An eel pass was installed at Alfoldean, near the site at Roman Station and a baffle fish pass was installed at Tanyards, near Wisborough Green.

Eel pass at Alfoldean Baffle fish pass at Tanyards

Next survey The River Arun Principal Coarse Fishery will next be surveyed in summer 2019.

A pike from the Arun caught during the WFD surveys, 2016

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2.2. Western Rother

5 fish population surveys were conducted in the Western Rother catchment in 2016. These were all Principal Coarse Fishery (PCF) surveys.

2.2.1. Principal Coarse Fishery Surveys

Summary

• 5 sites on the Western Rother were surveyed by catch-depletion electric fishing in July 2016. The river is classed as a national Principal Coarse Reference river and these 5 sites are surveyed annually; • A total of 571 fish were captured, comprising 17 species, including 9 of angling interest; • Between the 5 sites, the average estimated total density was 16.3 fish per 100m²; • The average estimated total biomass was 580.1 grammes per 100m²; • Eels, stone loach and minnows were recorded at all 5 sites; • Of the species of angling interest, brown trout were the most numerous, whilst pike had the highest biomass.

The locations of the PCF sites are shown on the map below.

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Results

Table Rother 1 shows population density estimates (number of fish per 100m², i.e. in a 10m by 10m section of river) and size ranges caught, for fish species recorded during the surveys. Minor species (minnow, bullhead, stone loach and brook lamprey) are not included.

Table Rother 1: Population density estimates (number of fish per 100m2) and size ranges (min – max, mm) Stanbridge Terwick Woolbeding Coultershaw Fittleworth Mill Bridge Brown Density 3.69 0.63 0.09 trout Size range 120 - 299 58 - 295 251 Chub Density 0.10 0.37 Size range 441 162 - 440 Dace Density 0.10 0.82 1.09 0.29 Size range 213 71 - 259 122 - 214 35 - 80 Eel Density 0.15 0.21 0.27 0.49 0.29 Size range 520 235 - 595 210 - 505 165 - 530 270 - 425 Grayling Density 1.67 0.09 Size range 184 - 272 198 Gudgeon Density 0.36 0.07 Size range 99 - 124 104 Perch Density 0.52 0.55 0.24 0.07 Size range 156 - 309 100 - 350 170 - 231 110 Pike Density 0.42 0.64 0.79 Size range 453 - 629 75 - 672 97 - 450 Roach Density 0.18 0.21 Size range 104 - 210 86 - 115 Tench Density 0.15 Size range 125

Figure Rother 1 shows fish population density estimates for the major fish species recorded during the surveys. Along the Western Rother there is a distinct change in species composition from the headwaters down towards the coast, with brown trout and grayling dominant at Stanbridge and Terwick Mill, respectively, and coarse fish becoming more prevalent as the sites move downstream.

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5 Brown trout Chub 4 Dace Eel 2 3 Grayling Gudgeon

No/100m 2 Perch Pike

1 Roach Tench

0 Stanbridge Terwick Woolbeding Coultershaw Fittleworth

Figure Rother 1: Population density estimates (number of fish per 100m2), excluding minor species, PCF survey sites, 2016

Figure Rother 2 shows biomass estimates for the major fish species recorded during the surveys.

1400 Brown trout 1200 Chub Dace 1000 Eel

2 800 Grayling

600 Gudgeon

g/100m Perch 400 Pike

200 Roach Tench 0 Stanbridge Terwick Woolbeding Coultershaw Fittleworth

Figure Rother 2: Population biomass estimates (grams of fish per 100m2), excluding minor species, PCF survey sites, 2016

Figure Rother 3 shows the estimated total numbers of dace and roach recorded from all 5 survey sites in every survey year. Also shown is the 4-year moving average of the number of degree days above 12 degrees centigrade in each year: a degree day is a theoretical unit of 1 day at 1 degree, so a 24 hour period where the average temperature was 13°C equals 1 degree day above 12°C. This unit is a useful indicator of coarse fish reproductive success and juvenile survival and is calculated from the Central England Temperature (CET) dataset.

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80 650

70 600

60 550 50 500 40 450 30

Total est.Total number 400

20 degree mean >12C days 4yr

10 350

0 300

2010 2002 2003 2004 2005 2006 2007 2008 2009 2011 2012 2013 2014 2015 2016

Total dace est. number Total roach est. number 4 yr mean degree days >12C

Figure Rother 3: Total estimated number of dace and roach on the Western Rother and the 4-year moving average of number of degree days above 12°C, 2002 - 2016

2.2.2. WFD Classification of PCF sites

The Stanbridge survey site lies within the “Western Rother (upstream Petersfield)” waterbody and is 1 of 2 sites use to classify it for fish, the other being Liss. The remaining 4 Principal Coarse Fishery survey sites lie within the “Western Rother” waterbody and all except Woolbeding are used for WFD classification. Table Rother 2 shows the most recent WFD classification for each waterbody (official status from 2015) as well as the fish element that contributes to the overall status. Note that these classifications are NOT based on the 2016 surveys covered by this report but on the most recent ones previous to this – FCS2 analysis of 2016 data has not yet been published.

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Table 2. Water Framework Directive (WFD) classification status for the overall waterbody and for the fish element for the Western Rother Waterbody name 2015 Overall status 2016 Fish status Western Rother - (upstream Poor Moderate of Petersfield) GB107041012840 Western Rother - Moderate Moderate GB107041012810

Discussion

The results suggest a progressive reduction in both fish density and biomass between Terwick Mill and Fittleworth, which was particularly distinct in the 2016 catch. The 2 main differences between the river in the region of Terwick and the sites further downstream, are channel gradient, where the upper river is steeper, faster flowing and less silty and the degree of channel engineering and impoundment, which is greater in the lower reaches. Dace and roach are typically the most abundant fish species of angling interest in the Western Rother. Analysis of the total estimated catch of both species (i.e. the sum of all 5 site estimates) in each year since surveys began in 2002 shows a strong correlation with various environmental factors, especially prevailing temperature and average flow in both summer and winter. The strongest correlation identified is with average number of degree days above 12° centigrade in the 4 years leading up to (and including) the survey year. This suggests that in this river, not only is summer temperature a key factor in determining variation in dace and roach abundance, but also that there is a cumulative positive effect of a succession of warm summers. Although variation in dace and roach abundance is linked with temperature and flow, at no time in the past 15 years has dace or roach abundance been particularly high. This, in combination with the Water Framework Directive failures described below, strongly suggests that the Western Rother’s fish community appears to be under pressure, particularly in the lower reaches. The primary pressures are considered to be siltation, impoundment and historic channel modification.

Western Rother (upstream of Petersfield) The “Moderate” fish classification of the Stanbridge site in the current WFD assessment is primarily the result of the absence of eel and roach from the 2015 survey catch and, secondarily, the absence of chub and gudgeon. All 4 species were absent from the 2016 catch, with the exception of a single eel, so a change in WFD status is possible, but unlikely. The lack of eels may reflect obstructions to upstream elver migration, particularly weirs, but also the general decline in the species across its entire range.

Western Rother Of the 3 survey sites used to classify the main Western Rother waterbody, only Fittleworth is classed as not achieving Good and it is this failure that causes the waterbody as a whole to be Moderate. The Fittleworth failure is driven largely by the absence of roach, but also pike and chub. Low numbers of roach and pike were caught in 2016, which may influence the WFD results at the next interim assessment.

Completed improvements: • To increase the connectivity of the river, a new fish easement was installed at Fittleworth Mill in the lower reaches. This was delivered through partnership between the Environment Agency, the Arun and Rother Rivers Trust and the land owner.

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• A new gravel riffle was also constructed to improve the river habitat, increase flow diversity and create a spawning habitat for brown trout above Coultershaw near Petworth. The work was undertaken by Leconfield Sporting Services with support from the Environment Agency.

Fish easement at Fittleworth Mill New gravel riffle above Coultershaw

Planned actions Plans for a fish bypass channel at North Mill near Midhurst are currently being finalised: this is likely to be constructed after 2017.

Next survey The 5 Western Rother coarse fish surveys will next be completed in summer 2017.

Stanbridge, a Principal Coarse Fishery survey site on the Western Rother, 2016

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3. Hampshire

3.1. East Hampshire

4 coarse fish population surveys were conducted in the East Hampshire catchment in 2016. These were all Water Framework Directive (WFD) surveys (used to classify waterbodies for fish).

3.1.1. Water Framework Directive Surveys

The locations of these sites are shown on the map below. All 4 sites were located on the River Hamble.

Table Hampshire 1 sets out the results of the Water Framework Directive fish surveys. Each site is listed along with its grid reference, the number of each species caught, the total number of species and the total density of fish, excluding minor species (i.e., minnow, stone loach, bullhead, 3-spined stickleback and lamprey). The results are listed in order of the total density of fish, measured as the number of fish per 100m².

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Table Hampshire 1: WFD summary table, Hamble WFD sites, 2016

Site NGR lamprey Brook trout sea / Brown Bullhead Chub eel European Minnow species of Number density Total minor (excluding species) Thickets Farm SU5489017040 10 10 1 3 18.33 Treefield SU5406515896 3 36 59 8 4 8.92 Chancellor's Lane SU5107115419 2 23 65 1 2 5 8.60 Holme Farm SU5005617179 8 39 1 40 4 3.86

Figure Hampshire 1 below is a length frequency histogram showing numbers of wild brown trout in 5mm length classes caught across the WFD surveys on the Hamble in 2016. The graph describes the age structure of all wild brown trout captured.

Frequency 2

55 40 45 50 60 65 70 75 80 85 90 95

110 165 280 100 105 115 120 125 130 135 140 145 150 155 160 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240 245 250 255 260 265 270 275 285 290 295 300 305 Length (mm) Figure Hampshire 1: Length frequency of wild brown trout (n=77), WFD surveys, Hamble, 2016

Discussion

The results demonstrate that this small, often overlooked, Hampshire river supports a thriving fish community typical of chalk streams; dominated by brown trout and featuring high densities of bullhead, with other minor species present. Length frequency of brown trout shows the presence of a number of age classes within the catchment. Eels were only abundant at Treefield, with only 1 individual recorded on the Ford Lake tributary (also known as Horton Heath stream). While this demonstrates that elvers are able to pass the several weirs between the sea and Treefield, it also suggests that it will be worth investigating whether or not there are any obstructions to upstream migration in the downstream reaches of Ford Lake.

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Above: an adult wild brown trout; below: a brown trout parr and an eel

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3.2. Test: Full Catchment Report In 2016 we conducted the 6-yearly Salmon Action Plan (SAP) spatial surveys as well as the biennial SAP temporal surveys, covering 26 sites spread across the Test catchment, last completed in 2010.

The spatial surveys are completed in order to record the distribution of juvenile salmon and how this compares with previous records. The temporal surveys are undertaken much more regularly in order to reveal any trends in the numbers of juvenile salmon present over time.

3.2.1. Distribution of juvenile salmon

Map Test 1 shows the key results of the exercise: the green markers indicate surveys where salmon parr where present and the red markers where they were absent from survey sites in 2016.

Map Test 1: Presence and absence of salmon parr at all Test survey sites, 2016 40 of 78

The same sites were surveyed at the same time of year and using the same methods as in 2010. In Map Test 2 the distribution of salmon parr in both years is compared; green triangles indicate where salmon parr where recorded in 2010 only, yellow circles in 2010 and 2016, pink squares in 2016 only.

Map Test 2: Presence of salmon parr on the Test; surveys conducted in 2010 and 2016

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3.2.2. Abundance of juvenile salmon

Maps Test 3 and Test 4 show the abundance of salmon parr recorded at each site in 2016 and indicate the principal spawning areas that are vital for the sustainability of the stock. Separate maps are necessary; 1 for full channel width surveys (i.e., standard single-run or catch depletion surveys where only the first run data is used, so that results can be compared with single run surveys) and 1 for part channel width surveys: timed 5 minute catch per unit effort (CPUE) surveys) conducted at survey sites too wide for the standard electric fishing techniques, hence the generally lower catches.

Map Test 3: Total number of salmon parr caught in 2016: full channel width surveys (markers are sized proportionally)

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Map Test 4: Total number of salmon parr caught in 2016: part channel width CPUE surveys sites (markers are sized proportionally)

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Figures Test 1 and Test 2 compare the total number of salmon parr caught at each site on the River Test between 2010 and 2016 for full and part channel width surveys, respectively. In both figures, survey sites are listed in order from upstream to downstream.

Tufton Carrier Tufton Main Rooksbury Mill Beat 6 Carrier Stockbridge, Marsh Court Compton Carrier Kimbridge, New stream Mottisfont Abbey, Oakley Carrier Timsbury Mayfly Carrier Romsey War Memorial Park Moorcourt Carrier

0 10 20 30 40 50 60 70

2010 2016

Figure Test 1: Total number of salmon parr caught in 2010 and 2016: full channel width surveys

Freelands House, Wherwell Mayfly Bunnies Longstock Mill Sheepbridge Horsebridge Compton Mottisfont, Oakley Farm Kimbridge Mill Cottage Grayling Island Greatbridge Railway Burnt Mill Mainstone Farm Longbridge Upstream M27 0 5 10 15 20 25 30 35 40

2010 2016

Figure Test 2: Total number of salmon parr caught in 2010 and 2016: part channel width CPUE surveys

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The Mottisfont Abbey, Oakley Carrier site had the highest salmon abundance in 2016

3.2.3. Temporal patterns

Of the survey sites shown in the maps above, 6 are known as temporal sites and are surveyed biennially in order to monitor salmon parr abundance over time. The sites, from upstream to downstream are: Bunnies (Leckford), Longstock Mill, Horsebridge, Sheepbridge, Romsey War Memorial Park and Upstream M27 (a site on the Broadlands Estate). 5 of the salmon parr surveys sites are so wide, fast flowing, weedy and shallow that the 5-minute CPUE survey method is used. At the remaining site, Romsey War Memorial Park, a standard full channel width method is used. Figure Test 3 shows the mean temperature in December (spawning period) before the following summer survey, against the total number of young of the year parr caught (parr born that year) at all 5 CPUE survey sites between 2007 and 2016, along with a trendline.

22 20 2007 18 16 2008 14 2009 12 2010 10 2012 8 2014

Totalnumber parr of0+ 6 2016 4 2 0 2 3 4 5 6 7 8 9 10 Mean temperature, previous December (°C) Figure Test 3: CPUE total catch and mean temperature in the previous December (Central England Temperature)

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3.2.4. Length-frequency of juvenile salmon

A total of 129 salmon parr were caught on the 2016 surveys on the River Test. Figures Test 4 and 5 are length frequency histograms showing the numbers of fish in 5mm length classes for 2016 and 2010, respectively. The same axes have been used to allow for direct comparison.

Frequency 20

50 55 60 65 70 75 80 85 90 95

140 165 100 105 110 115 120 125 130 135 145 150 155 160 170 175 180 185 190 195 200 Length (mm)

Figure Test 4: Length frequency histogram of salmon parr from all surveys, 2016 (n=129)

Frequency 20

50 55 60 65 70 75 80 85 90 95

140 165 100 105 110 115 120 125 130 135 145 150 155 160 170 175 180 185 190 195 200 Length (mm)

Figure Test 5: Length frequency histogram of salmon parr from all surveys, 2010 (n=386)

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Discussion

The salmon parr surveys on the Test in 2016 recorded 59% fewer salmon parr in total than in 2010. Of the 26 surveys, only 2 yielded more salmon parr in 2016 than in 2010; Mottisfont Abbey, Oakley Carrier and Mayfly Inn.

During the course of summer 2016, reports were received from areas throughout the UK that juvenile salmonid monitoring was indicating very low salmon and trout parr abundance. A report from Natural Resources Wales stated that salmon parr were largely absent from some Welsh salmon catchments and had reduced by as much as 90% in others, compared with 2015 survey data. The report also suggested that similar observations had been made in France and that the most likely cause appeared to be record high temperatures during the spawning period, especially November and December 2015. This suggestion is consistent with the findings of this report, (see figure TR2 in the temperature and rainfall section).

A strong negative correlation is demonstrated between the mean air temperature in December and the total number of young of the year (0+) salmon parr captured in the following summer CPUE surveys (r = -0.8). This suggests that the warmer the previous December, the fewer salmon parr present the following summer. The 2016 data shows the mean December (2015) temperature was 9.7°C and the total number of 0+ salmon parr recorded was 2.

It is worth noting that the salmon parr recorded during summer 2016 were predominantly young of the year; the progeny of the largest run of adult salmon recorded on the Test in 25 years. The parr recorded in 2010 were largely derived from the 2009 run, which was less than half the size of the 2015 run (according to our counters). This highlights the very significant effects of environmental conditions (especially flow, temperature and physical habitat) on salmon abundance at different life stages (from egg, to alevin, fry, parr, smolt and finally adult) and demonstrates how such effects can override the significance of abundance at the preceding life stage.

These results emphasise the importance of increasing salmon parr population resilience by improving habitat quality and protecting flows. Of particular importance are features such as patches of shade, sufficient water velocity and pool and riffle sequences, which are likely to mitigate against high air temperatures.

Examples of salmon parr caught on the Test, 2016

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3.2.5. Wild brown trout

The juvenile salmon survey programme also provides a good opportunity to assess the distribution of wild brown trout in the River Test.

Maps Test 5 and 6 show the abundance of wild brown trout recorded at each site in 2016. As with the juvenile salmon, separate maps are necessary; 1 for full channel width surveys (i.e., standard single-run or catch depletion surveys where only the first run data is used, so that results can be compared with single run surveys) and 1 for part channel width surveys (timed 5 minute catch per unit effort (CPUE) surveys) conducted at survey sites too wide for the standard electric fishing techniques.

Map Test 5: Total number of wild brown trout caught in 2016: full channel width surveys (markers are sized proportionally)

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Map Test 6: Total number of wild brown trout caught in 2016: part channel width CPUE surveys sites (markers are sized proportionally)

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Figures Test 6 and 7 compare the total number of wild brown trout caught at each site on the River Test between 2010 and 2016 for full and part channel width surveys, respectively. In both figures, survey sites are listed in order from upstream to downstream.

0 50 100 150 200 250 300 350 400

2010 2016 Figure Test 6: Total number of wild brown trout caught in 2010 and 2016: Full channel width surveys

2010 2016 Figure Test 7: Total number of wild brown trout caught in 2010 and 2016: Part channel width CPUE surveys

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A total of 401 wild brown trout were caught on the 2016 juvenile salmon surveys on the River Test in 2016. Figures Test 8 and 9 below are length frequency histograms showing the numbers of fish in 10mm length classes for 2016 and 2010, respectively. The graphs describe the age structure of all wild brown trout captured. The same axes have been used to allow for direct comparison.

225

200

175

150

125

100

Frequency 75

60 70 80 90

100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400 410 420 Length (mm)

Figure Test 8: Length frequency histogram of wild brown trout from all surveys, 2016 (n=401)

225

200

175

150

125

100

Frequency 75

60 70 80 90

100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400 410 420 Length (mm)

Figure Test 9: Length frequency histogram of wild brown trout from all surveys, 2010 (n=979)

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Ideal salmonid habitat: Ranunculus macrophyte. clean gravel and fast flowing, well oxygenated water

Discussion

The distribution of wild brown trout recorded during the salmon parr surveys shows that the species is present at most survey sites and is generally more abundant in the headwaters.

Comparison between the data from 2010 and 2016 reveals that there has been a reduction in the number of parr caught at most sites. However, at 3 CPUE sites; Longstock Mill, Compton and Grayling Island, trout were recorded where they were absent in 2010 and significantly more fish were caught at Tufton Carrier (full channel width) and Kimbridge Mill Cottage (CPUE) than in 2010.

The density of brown trout parr recorded at Beat 6 on the River Anton was an exceptional result in 2010. In 2016 however, the density was much reduced, but the site still contained the highest density of wild brown trout recorded across all the sites surveyed.

The length frequency histograms show that the catch in 2010 was much greater than in 2016 and the population was predominantly parr. Once again in 2016, although fewer individuals were caught, the catch was dominated by parr. This is as expected due to the selection of the survey sites for their suitability as salmon parr habitat.

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3.2.6. European eel

The dramatic decline in abundance of the European eel across its range has caused widespread concern because of the species' immense value both economically and ecologically.

The Test's neighbour, the River Itchen was designated as an Eel Index river in 2009, which involved the commencement of specific eel population surveys at 10 sites every 2 years. The data collected strongly suggests a rapid and steady decline in eel abundance between 2009 and the most recent surveys in 2015. Naturally, there is concern that a similar decline might be in progress on the Test, but there is no equivalent programme of detailed eel population monitoring. However, as with wild brown trout, the juvenile salmon survey programme provides a good opportunity to assess the distribution and abundance of eels. Maps Test 7 and 8 below show the abundance of eels recorded at each site in 2016. As previously, separate maps are necessary; 1 for full channel width surveys and 1 for part channel width surveys.

Map Test 7: Total number of eels caught in 2016: full channel width surveys (markers are sized proportionally) 53 of 78

Map Test 8: Total number of eels caught in 2016: part channel width CPUE surveys sites (markers are sized proportionally)

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Figures Test 10 and 11 compare the total number of eels caught at the same survey sites, using the same electric fishing techniques, between 2010 and 2016. Figure Test 10 shows single run, full channel width electric fishing surveys, whilst Figure Test 11 shows 5 minute, timed CPUE survey results. In both figures, survey sites are listed in order from upstream to downstream.

Tufton Carrier Tufton Main Rooksbury Mill Beat 6 Carrier Stockbridge, Marsh Court Compton Carrier Kimbridge, New stream Mottisfont Abbey, Oakley carrier Timsbury Mayfly carrier Romsey War Memorial Park Moorcourt Carrier

0 5 10 15 20 25 30

2010 2016 Figure Test 10: Total number of eels caught in 2010 and 2016: Full channel width surveys

2010 2016 Figure Test 11: Total number of eels caught in 2010 and 2016: Part channel width CPUE surveys

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Eel from SAP survey on the Test, 2016

Discussion

The distribution of eels recorded during the salmon parr surveys shows that the species is present at most survey sites, albeit in generally low numbers.

Comparison between the data from 2010 and 2016 reveals that there has been a reduction in the total number of eels caught in all River Test salmon parr surveys, reducing from 151 in 2010 to 61 in the repeat surveys in 2016. This is a decline of just under 60% which is similar to the decline in survey catches recorded on the River Itchen. At 1 site, Horsebrige, eels were present in 2016 where they were absent in 2010, however, at 7 other sites, eels were absent in 2016 where they were present in 2010.

In all rivers, European eel abundance tends to increase with reduced distance from the sea. Therefore, the highest densities recorded are typically in the most suitable habitat in the lowest reaches, while the lowest densities are in the upper headwaters. This is partly due to the availability of food and territory and partly a natural effect of the fact that all European eels found in inland freshwaters have migrated from the Sargasso Sea into coastal waters, before ascending river systems.

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3.2.7. Coarse fish and minor species

As with brown trout and eels, the 2016 salmon parr surveys provide a useful illustration of the Test’s non-salmonid fish community.

The pie charts below show the average density (number per 100m²) of all fish species caught in single run surveys in 2016 and 2010 providing a general indication of the composition of the river’s fish community. Please note that different colours have been assigned to each species on the graphs.

Bullhead Brown / sea trout Minnow Atlantic salmon Stone loach Grayling European eel Roach 3-spined stickleback Chub Pike

Figure Test 12: Average species density, River Test, 2016: Single run surveys. Species are ordered from the highest to lowest mean density

Bullhead Brown / sea trout Atlantic salmon Minnow Grayling Stone loach European eel Roach Dace Chub 3-spined stickleback Gudgeon Pike Common bream

Figure Test 13: Average species density, River Test, 2010: Single run surveys. Species are ordered from the highest to lowest mean density

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Releasing a grayling on the Test, 2016

Discussion

The composition of the coarse fish and minor species is similar between 2010 and 2016, however in 2016 no common bream, gudgeon or dace were caught in the single run surveys completed on the Test where they were caught, all be it in very low densities, in 2010. Additionally, the relative ordering of the average densities of the species has changed over the 6 years; most notably, there were higher densities of Atlantic salmon than minnow in 2010 but more minnow than salmon in 2016.

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3.3. Test and Itchen Fish Counters

Since 1990, the numbers of Atlantic salmon migrating upstream into the rivers Test and Itchen each year have been monitored using resistivity fish counters at Nursling Mill and Gaters Mill, respectively.

Counter data and photographic images are used to estimate the total number of upstream migrating salmon each year. Calculations are made in order to account for days that the counters are out of operation and to estimate the numbers of salmon migrating via routes that by pass the counters. The counts that are recorded between 1st May and 31st December are reported to the International Council for the Exploration of the Seas (ICES) as the formal salmon run estimates, as counting has been conducted consistently over this period since 1990. However, as far as possible, counting is now maintained year round and Figures T&I 2 and 3 cover the whole of 2016. The estimated total salmon runs for the Test and Itchen for 1st May to 31st December 2016 are 1,454 and 361, respectively. The Test estimate is the third highest and the Itchen estimate the fourteenth highest since 1990.

3.3.1. Total estimated runs, 1990-2016

Figure T&I 1 shows the total estimated numbers of salmon migrating upstream into the rivers Test and Itchen each year, between 1st May and 31st December, since 1990; the dashed lines represent 5 -year moving averages for each river.

Figure T&I 1: Test and Itchen estimated number of upstream salmon, 1st May to 31st December 1990-2016

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3.3.2. Estimated run per month, 2016

Figure T&I 2 shows the total estimated numbers of salmon migrating upstream into the rivers Test and Itchen in each month, from January to December in 2016.

Figure T&I 2: Estimated number of upstream salmon per month, 2016

3.3.3. Estimated daily run and mean daily flow, 2016

Figure T&I 3 shows the estimated numbers of salmon migrating upstream into the rivers Test and Itchen daily in 2016. Mean daily flow is also given, measured in cubic metres per second, gauged at Broadlands gauging station on the Test and Allbrook / Highbridge combined on the Itchen.

Figure T&I 3: Estimated number of upstream salmon per day, 2016

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The new roof over the Nursling Mill fish counter, completed in December 2016, will protect the counter electrodes and improve photographic imaging for decades to come.

This new flow control sluice, located at the head of the fish counter channel at Gaters Mill, will make cleaning and maintaining the electrodes and lighting equipment much safer and easier.

The Environment Agency Field Operations Team installing new GRP electrode panels into 1 of the 2 counter channels at the Nursling Mill fish counter on the River Test.

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3.3.4. Salmon counter data sheets

Table T&I 1: Salmon data sheet for the River Test, 2016 River Test Adult Catch and Spawning Egg % egg % egg Return Returning Release Escapeme Depositio conservati managem Year Stock Rod Catch Rate nt n on limit ent target (%) (millions) 1990 790 288 - 505 1.23 36 32 1991 538 139 - 405 0.99 29 25 1992 614 151 - 471 1.15 34 30 1993 1155 335 - 870 2.12 62 55 1994 775 247 14 560 1.37 40 35 1995 647 167 0 465 1.13 33 29 1996 623 146 13 496 1.21 36 31 1997 361 49 14 319 0.78 23 20 1998 898 204 44 784 1.91 56 49 1999 867 159 46 781 1.91 56 49 2000 595 147 66 545 1.33 39 34 2001 410 215 99 398 0.97 29 25 2002 1046 342 99 1044 2.55 75 66 2003 367 164 100 367 0.90 26 23 2004 1129 449 100 1129 2.75 81 71 2005 1150 357 100 1150 2.81 83 72 2006 1058 210 100 1058 2.58 76 67 2007 664 258 100 664 1.62 48 42 2008 1487 424 100 1487 3.63 107 94 2009 903 185 100 903 2.20 65 57 2010 833 225 99 831 2.03 60 52 2011 980 312 100 979 2.39* 70 62 2012 949 293 100 949 2.32* 68 60 2013 1020 323 100 1020 2.49 73 64 2014 1001 235 100 1001 2.44 72 63 2015 2007 499 100 2007 4.90 144 126 2016 1454 352 100 1454 3.55 104 91

Salmon egg conservation limit 3.4 Million Salmon egg management target 3.88 Million

Notes * Returning stock estimate based on historic relationship with rod catch due to fish counter faults 62 of 78

Table T&I 2: Salmon data sheet for the River Itchen, 2016 River Itchen Adult Catch and Spawning Egg % egg % egg Return Returning Release Escapeme Depositio conservati managem Year Stock Rod Catch Rate nt n on limit ent target (%) (millions) 1990 367 187 - 106 0.26 16 13 1991 152 69 - 37 0.09 6 5 1992 357 95 - 230 0.56 34 28 1993 852 357 - 495 1.21 74 61 1994 378 183 14 219 0.53 33 27 1995 880 241 0 664 1.62 99 82 1996 433 261 13 275 0.67 41 34 1997 246 95 14 204 0.50 31 25 1998 453 161 44 414 1.01 62 51 1999 213 92 46 176 0.43 26 22 2000 208 168 66 189 0.46 28 23 2001 217 190 99 214 0.52 32 27 2002 239 188 99 202 0.49 30 25 2003 222 78 100 204 0.50 31 25 2004 410 149 100 393 0.96 59 49 2005 411 87 100 411 1.00 62 51 2006 419 121 100 419 1.02 63 52 2007 302 224 100 301 0.73 45 37 2008 609 282 100 584 1.42 87 72 2009 276 205 100 276 0.67 41 34 2010 757 361 100 749 1.83 112 93 2011 697 295 100 697 1.7** 104 86 2012 622 373 100 622 1.52 93 77 2013 478 154 100 478 1.17 72 59 2014 779 269 100 779 1.9** 117 96 2015 903 341 100 903 2.20 135 112 2016 361 313 100 361 0.88 54 45

Salmon egg conservation limit 1.63 Million Salmon egg management target 1.97 Million

Notes ** Likely to be a slight underestimate due to fault in May and June

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4.1. New Forest

In the New Forest 2 "local investigative" surveys were completed in 2016. Both surveys required fish to be removed to allow habitat improvement work to take place and provided additional opportunity to assess the fish populations in the New Forest streams.

Both surveys were single run electric fishing surveys. The locations of these sites are shown on the map below.

4.1.1. Avon Water: Wootton Bridge

Wootton Bridge site is undergoing habitat restoration work by the Forestry Commission. Fish were captured, removed and relocated in order for the canalised reach to be re-meandered during autumn 2016 and 2017. A total of 298 wild brown trout were caught on the survey. Figure New Forest 1 is a length frequency histogram showing the numbers of brown trout in 5mm length classes. The graph describes the age structure of all wild brown trout captured.

10 Frequency

40 45 50 55 60 65 70 75 80 85 90 95

115 200 100 105 110 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 205 210 215 220 225 230 235 240 245 250 Length (mm) Figure New Forest 1: Length frequency histogram of all wild brown trout (n=298)

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4.1.2. Danes Stream: Milford Bridge

Similarly, at Milford Bridge fish were captured, removed and relocated to just a few hundred yards upstream. This was to ensure their safety prior to work being carried out to remove silt deposits under a road bridge.

4.1.3. Fish Densities

Figure New Forest 2 below shows the density of each fish species caught at Wootton Bridge and Milford Bridge, including minor species, (number of fish per 100m²).

60 Brown / sea trout

50 Bullhead

Minnow 40 Stone loach 30 Brook lamprey

20 3-spined stickleback Density Density (No100m²) / European eel 10 Dace 0 Wootton Bridge Milford Bridge Flounder

Figure New Forest 2: Density of fish caught (number per 100m²), New Forest, 2016

Discussion

In total, 706 fish were caught and relocated from Wootton Bridge. 7 species were found and brown trout dominated the catch. Carrying out a fish population survey here, prior to restoration work, is beneficial in order to allow for comparisons to be made once the habitat improvements have been completed.

In comparison, only 20 fish belonging to 4 species were captured and relocated from Milford Bridge. The stark difference between the density and diversity of fish species found at the New Forest surveys is likely to relate to the locations and surroundings of the sites. Milford Bridge is located in an urban, highly populated area close to the coast whereas Wootton Bridge is much more rural and situated within the main New Forest National Park area. The influence of the coast at Milford Bridge is exemplified by the presence of flounder, which were not found at Wootton Bridge.

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5. Estuarine Fish Monitoring

5.1. Southampton Water

In 2016 the Southampton Water Transitional and Coastal (TraC) fish monitoring programme included routine beach seine and beam trawl surveys at 4 sites, beach seine only surveys at 3 sites (where beam trawling would be hazardous) and fyke net surveys at a further 2 sites. Unlike in previous years where this work has been completed in the spring and in the autumn, in 2016 only autumn surveys were undertaken.

Seine net surveys consist of 2 semi-circular samples in the same location, with a 45 metre net set from a boat. The beam trawl is 1.5 metres wide and is towed for exactly 200 metres parallel to the shore, at the seine net site. Each fyke survey consists of 2 double ended fyke nets, set close to the shore, in 1 metre of water, at low tide and left for 24 hours. The programme also includes an autumn otter trawl survey which in 2016 comprised of 2 15 minute trawls, carried out by the Coastal Survey Vessel (CSV) "Solent Guardian" near to the edge of the maintained shipping channel, around 600 metres east of Hythe. Map Soton Water 1 shows the TraC monitoring sites in Southampton Water, coloured according to the types of survey carried out at each location.

Map Southampton Water 1: Fish monitoring sites, Southampton Water, 2016

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Summary

• 26 species of fish were caught in Southampton Water in 2016;

• A total of over 8,520 individual fish were caught;

• The total catch in autumn was the second largest we have recorded, capturing more than double the total number of fish from spring and autumn surveys in 2015;

• Autumn juvenile bass numbers were the highest ever recorded.

Towing the beam trawl at Calshot

Hauling the seine at Itchen Bridge

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Figure Soton Water 1 and 2 show the abundance of each species of fish caught in all surveys in Southampton Water in 2016, and in the CSV trawl in autumn 2016, respectively. Where the bar appears absent, this is where only very few or single individuals were caught.

4000 3500 3000 2500 2000 1500 1000 500 0

Autumn

Figure Soton Water 1: Total number of fish caught in seine, fyke and beam trawls, Southampton Water, autumn 2016

250

200

150

100

Autumn

Figure Soton Water 2: Fish abundance, otter trawl, Southampton Water, autumn 2016

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From the top: A tub gurnard, a dragonet, a thornback ray and a plaice from the otter trawl on Southampton Water, autumn 2016

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Figure Soton Water 3 shows the total autumn catch for seine net, beam trawl and fyke net surveys for each year from 2007 to 2016.

14000

12000

10000

8000

6000

4000

2000

0 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016

Spring Autumn

Figure Soton Water 3: Total catch for seine, fyke and beam trawls, Southampton Water, spring and autumn, 2007-2016

Figure Soton Water 4 compares autumn juvenile bass catches to average summer sea surface temperature. Average sea surface temperature is gained by taking an average of the mean monthly sea surface temperature for the summer months as recorded at the Hayling Island data buoy.

4000 18.0

3500 17.5 3000 17.0 2500

2000 16.5

1500 16.0 1000 15.5 500

0 15.0 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016

Sea bass numbers Summer sea surface temp. (°C)

Figure Soton Water 4: Juvenile bass abundance in autumn compared to summer sea surface temperature, Southampton Water, 2007-2016

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Discussion

In 2016 the autumn catch was less diverse than in previous years, however the species that were caught were present in higher numbers than average. We caught a total of 8,520 fish from Southampton Water in the autumn, which is over 2000 more than in 2015, 538 of which were from the annual CSV otter trawl. We caught 26 species of fish in total and lesser sandeel were identified for the first time.

19 of the 26 species were caught from the seine, fyke and beam trawl surveys, which is less than in 2015, where 30 species were identified. Although a less diverse number of species were caught in 2016, fish numbers were greatly increased. For example, we caught over 3,500 sea bass in 2016 compared to just over 1000 in the previous year. Similarly, in the CSV trawl, we caught 14 species of fish, which is again less than in 2015, where 20 species were found. However, fish numbers were greater. For instance, sand goby and transparent goby dominated the catch in 2016 with over 200 individuals of each caught, compared to in 2015 where less than 100 of each were caught.

As the spring surveys were not completed in 2016, no comparison between spring and autumn catches can be made. However, the autumn catch was the second highest we have recorded and juvenile bass numbers were the highest ever recorded. Numbers of juvenile sea bass tend to correlate with summer sea surface temperature and the increase in abundance of this species is likely to be in response to the increase in summer temperatures seen in 2016.

A spiny seahorse and the otter trawl in action on the Coastal Survey Vessel (CSV), "Solent Guardian", Southampton Water, autumn 2016

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5.2. Adur Estuary

In 2016 we carried out the 3 routine surveys on the Adur estuary at Ladywell Stream, Old Toll Bridge and Kingston Beach. At each site we completed a seine net survey followed by a beam trawl.

As with Southampton Water, unlike in previous years where these Transitional and Coastal (TraC) surveys have been completed in the spring as well as in the autumn, in 2016, only autumn surveys were undertaken. These locations of the sites are shown on the map below.

Map Adur TraC 1: Fish monitoring sites, River Adur estuary, 2016. All sites are both beam trawl and seine net surveys

Summary

• We caught 13 species of fish in the Adur estuary in 2016;

• Overall the numbers of fish caught were higher than average in autumn;

• Bass numbers have slightly declined since 2015;

• Pelagic fish numbers are the highest ever recorded and numbers of gobies are at their lowest.

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Figure Adur TraC 1 shows the numbers of each species caught in 2016. Where the bar appears absent this is where only very few or single individuals were caught.

4500 4000 3500 3000 2500 2000 1500 1000 500 0

Autumn Figure Adur TraC 1: Total number of fish caught in seine, fyke and beam trawls, Adur estuary, autumn 2016

Figure Adur TraC 2 shows the size of the catch in 2016 and how this relates to the total catch in previous years.

6000

5000

4000

3000

2000

1000

0 2010 2011 2012 2013 2014 2015 2016

Spring Autumn Figure Adur TraC 2: Total catch for seine, fyke and beam trawls, Adur estuary, spring and autumn, 2010-2016

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Hauling the seine net: a large catch at Ladywell stream

An unexpected anchovy found amongst the herring

A shanny from Ladywell stream

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Figure Adur TraC 3 illustrates the correlation between total catches of juvenile bass in autumn and the mean summer sea surface temperature. Average sea surface temperature is gained by taking an average of the mean monthly sea surface temperature for the summer or winter months as recorded at the Hayling Island data buoy.

500 18.0 450 17.5 400 350 17.0 300 250 16.5 200 16.0 150 100 15.5 50 0 15.0 2010 2011 2012 2013 2014 2015 2016

Sea bass numbers Summer sea surface temp. (°C)

Figure Adur TraC 3: Juvenile bass numbers compared to mean summer sea surface temperature, Adur estuary, 2010-2016

Figure Adur TraC 4 describes the total catch of different fish types in autumn surveys from 2010 to 2016. Please note that 4173 herring have been removed from the numbers of pelagic fish for presentation purposes.

900

800

700

600

500

400

300

200

100

0 2010 2011 2012 2013 2014 2015 2016

Gobies Mullet spp. Flatfish Pelagic fish* Sea bass

Figure Adur TraC 4: Abundance of different fish types, Adur estuary, autumn 2010-2016. *4173 herring have been removed for presentation purposes 75 of 78

Discussion

Similarly to Southampton Water, in 2016, the autumn catch in the Adur estuary was less diverse than in previous years. However, the total number of fish caught was higher than average. In total, we caught 13 different species of fish over the autumn surveys, 2 less than in 2015, and more than twice the number of fish were caught than in any previous year. The most prevalent species by far was herring, which dominated the autumn catch in terms of numbers caught. Previous catches of herring have not exceeded more than 160 individuals, so the catch of over 4000 in 2016 was an exceptional anomaly and unlikely to occur again. The total number of fish caught, even disregarding herring, was more than in 2015, but still less than on average.

The reduced catch from 2015 was thought to relate to the low summer temperatures of that year coupled with occasional high rainfall events influencing the salinity in the Adur estuary. Juvenile sea bass numbers tend to show a clear correlation with mean sea surface temperatures, however in 2016, mean summer sea surface temperatures increased but sea bass numbers have slightly declined compared to 2015. Although, numbers are still higher than those recorded between 2010 and 2013.

The survey site at Ladywell Stream on the Adur estuary, 2016

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Looking Forward

In 2017 we have a varied and interesting programme with a particular emphasis on Eel Index surveys, which are completed biennially, as well as focussing on spatial and temporal monitoring of wild brown trout on the River Meon.

New to the programme in 2017 is a requirement to survey particular sites for the National Drought Monitoring Network. These will involve carrying out fully quantitative catch depletion fish population surveys as well as completing HABSCORE habitat assessments at each designated site.

In summary, the programme in 2017 will include:

• Biennial Eel Index surveys on the Itchen;

• National Drought Monitoring Network surveys on the Test and the Itchen;

• Principal Coarse Fishery annual surveys on the Western Rother;

• Salmon Action Plan biennial surveys on the Itchen;

• Wild Brown Trout biennial temporal monitoring on the Meon, the Itchen and in the New Forest and 6-yearly spatial monitoring on the Meon;

• Various WFD surveys across the catchment;

• TraC surveys in the spring and autumn in Southampton Water and the Adur estuaries.

Acknowledgements

As always, we would like to express our gratitude to all the landowners, keepers, fishing clubs and stakeholders who have allowed us riverbank access in 2016. It would be impossible for us to carry out these important surveys without your cooperation, assistance and local knowledge and it is greatly appreciated - thank you.

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78 of 78 SSD Fish Monitoring Report 2016

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