Solent & South Downs Fish Monitoring Report 2014

We are the Environment Agency. We protect and improve the environment and make it a better place for people and wildlife. We operate at the place where environmental change has its greatest impact on people’s lives. We reduce the risks to people and properties from flooding; make sure there is enough water for people and wildlife; protect and improve air, land and water quality and apply the environmental standards within which industry can operate. Acting to reduce climate change and helping people and wildlife adapt to its consequences are at the heart of all that we do. We cannot do this alone. We work closely with a wide range of partners including government, business, local authorities, other agencies, civil society groups and the communities we serve.

Authors: D. Longley & P. Rudd

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

Email: [email protected]. © Environment Agency 2014 All rights reserved. This document may be reproduced with prior permission of the Environment Agency.

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Foreword

This is our eighth consecutive annual Solent and South Downs Area fish monitoring report and we hope you find it useful. Its purpose is to provide details of all the fish surveys undertaken in 2014, to present the results and, where appropriate, to set these in the context of previous years' results as well as environmental data such as for flow and temperature. It is written primarily for the angling community but also for people and organisations of all kinds with an interest in rivers, coastal waters and the fish they support. Our 2014 fish monitoring programme was dominated by Water Framework Directive (WFD) surveys, the majority of which were in West Sussex and included a high proportion that had never been visited before. As a result, surveys were less focused on specific fisheries and more on a wide range of less studied tributaries and reaches. Collectively, this yields a great deal of valuable fish data, providing us with an evidence base not only to improve ecology as part of our WFD work but also to underpin more effective fisheries management. The fish monitoring programme was undertaken as scheduled, between April and October, with only minor postponements and no cancellations. River surveys involved electric fishing, either from a boat or wading, while estuary surveys used seine and fyke netting, beam and otter trawling. Details of various survey types are given in the section titled: "Interpreting results". Readers of this report in previous years will know that we emphasise the relevance of weather data on our fish survey results and in recent years there has been no shortage of anomalous weather that has undoubtedly affected local fish populations. However, 2014 set new benchmarks on this front, with the Met Office reporting that winter 2013/14 was the stormiest in twenty years, with a succession of twelve major winter storms between December and February. It was also the wettest in their England and Wales precipitation series dataset, since 1766. In Romsey in December 2013, our rain gauge recorded just over 210% of the average rainfall for that month: in January it was 323%. With local rivers severely flooded from source to sea, it's clear that this extreme weather influenced fish communities, coarse, game and sea, and this is an important aspect of the various discussion sections throughout the report.

Acknowledgements The collection of this essential fish population data would not be possible without the support and assistance of the landowners, fishing clubs, river keepers, farmers and land agents who kindly allowed us access to their rivers in 2014 and in many cases provided valuable local knowledge and advice.

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Executive summary

• We conducted 88 fish population surveys across Solent & South Downs area in 2014: 46 for Water Framework Directive classification of freshwaters; 26 for WFD estuaries (Southampton Water & Adur); 6 for juvenile salmon (Test); 2 for juvenile wild brown trout (Meon), 5 for Principal Coarse Fisheries (Western Rother) and 3 surveys connected to specific habitat enhancement projects. • As expected, Water Framework Directive surveys reflected a broad spectrum in the quality of fish communities at contrasting survey sites, from quite severely damaged environments to those that are virtually pristine. Surveys conducted in 2014 provide evidence of pressures on fish communities resulting from, amongst other factors, barriers to migration, habitat degradation, poor water quality and the presence of non-native invasive species. • The six Principal Salmon River surveys conducted on the Test in 2014 suggested that parr abundance in 2014 was amongst the lowest recorded, probably as a result of the impacts of floods on spawning conditions and juvenile habitat during the previous winter. • Wild brown trout surveys on the Meon revealed high numbers of juveniles at Mislingford but average numbers at Titchfield (Silver Springs), suggesting that the key trout spawning grounds in the middle reaches were not adversely impacted by the previous winter's flooding. • Western Rother Principal Coarse Fishery surveys showed a continuation of very low abundance of coarse fish in general, particularly dace and roach. • Estuarine fish monitoring in Southampton Water yielded relatively large catches, with the third highest total number of fish caught in spring (out of eight survey years) and also the third highest in autumn. The dominant species in both seasons were sand smelt, common goby, juvenile bass and juvenile herring. • Estuarine fish monitoring on the Adur produced the second lowest spring catch but the highest autumn catch to date. The dominant species were juvenile bass, common goby and sand goby.

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Rivers of Solent & South Downs

East:

West:

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Contents

Foreword ...... 3 Executive summary ...... 4 Rivers of Solent & South Downs ...... 5 Contents ...... 6 Temperature and rainfall ...... 7 Interpreting results ...... 10 1. East Sussex ...... 12 1.1. Ouse and Cuckmere ...... 12 2. West Sussex ...... 16 2.1. Adur ...... 16 2.2. Arun ...... 22 2.3. Western Rother & Western Streams ...... 26 3. Isle of Wight...... 34 4. Hampshire ...... 38 4.1. East Hampshire ...... 38 4.2. Test & Itchen ...... 45 5. Estuarine Fish Monitoring ...... 56 5.1. Southampton Water ...... 56 5.2. Adur Estuary ...... 65 6. Fish monitoring in 2015 ...... 69 List of abbreviations ...... 70 Glossary ...... 70

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Temperature and rainfall

The quality of river fisheries is very dependent on weather because fish survival and growth are so strongly influenced by temperature and river flow. Graph TR1 shows the mean (average) Central England Temperature (CET) for each summer since 2000, as well as the mean temperature for the preceding winter - both of these values are highly relevant to fish survey results in each year.

Graph TR1: mean summer and winter Central England Temperature

17 14

13 16 12

11 15 10

14 9

8 Deg C C WINTER Deg

Deg C SUMMER C Deg 13 7

6 12 5

11 4

Mean temp May-Sept Mean winter temp in preceding Oct-Mar

Similarly, graph TR2 shows total summer and winter rainfall for the Solent and South Downs area, using the means of rainfall totals from gauges at Romsey and Eastbourne.

Graph TR2: total summer and winter rainfall

160

140

120

100 MM

80

60

40

20

Mean rainfall in preceding Oct-Mar Mean rainfall Apr-Sept

The first graph shows that mean summer temperature in 2014 was higher than in any of the preceding seven years and ended the succession of cool summers since 2007. This is very relevant in assessing the status of river coarse fish communities, as it is unlikely that any strong 7 of 71

coarse fish year classes (unusually large generations) were produced in this period. Although this is a positive feature, 2014's mean summer temperature was only slightly above average. Graph TR2 shows that winter 2013/14 was unusually mild, driven by the procession of storms that hit the UK from the South West. Although a lack of hard frosts may favour over-winter survival of juvenile coarse fish, severe floods do not and graph TR2 establishes the magnitude of winter rainfall in the area in winter 2013/14. It also shows that summer rainfall was roughly average in 2014, influenced particularly by a wet August. Mean, annual or seasonal values are useful for comparing long-term data for any specific year but they tend to mask briefer periods of weather that may have influenced fish communities. Graph TR3 shows mean monthly Central England Temperature for winter 2013/4 and summer 2014, compared with the monthly means, maximums and minimums for the period 2000-2013.

Graph TR3: Mean monthly Central England Temperature, 2014

20 18 16 14 12 10

8 Deg C Deg 6 4 2 0 -2 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Monthly mean temp. Oct 2013 - Dec 2014 Monthly mean 1999-2013

Max 1999-2013 Min 1999-2013

Graph TR4 shows total rainfall measured by the Romsey rainfall gauge in winter 2013/14 and summer 2014, compared to the 2000-2013 monthly mean, maximum and minimums.

Graph TR4: Romsey total monthly rainfall, 2014

300

250

200

150 MM

100

50

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

Monthly total Oct 2013-Dec 2014 Mean monthly total 2000-2013

Max. total 2000-2013 Min. total 2000-2013

Graph TR3 reveals that, with the exception of November 2013, mean monthly temperature for each month up to July lay between the long-term average and the previous maximum, i.e. 8 of 71

November to July was consistently, but not exceptionally, warm. The one anomaly in this graph is the abrupt dip in mean temperature for August; the lowest mean August temperature recorded since 2000.

Naturally, graph TR4 is dominated by the peak representing the exceptional rainfall between December and February, but it's also interesting to see how little rain fell in July and September and how much in August.

The key questions these weather observations raise are:

– Did the 2013/14 winter flooding reduce juvenile coarse fish survival and disrupt salmonid spawning by "drowning out" spawning gravels? – Did the relatively high temperatures in spring and early summer result in early salmonid fry hatching and subsequent rapid growth? – Similarly, did these temperatures favour early coarse fish spawning and result in an unusual abundance of young of the year coarse fish? – Did the exceptionally low temperatures and high rainfall in August impact fish communities?

In each of the individual catchment chapters, these questions are addressed wherever our data indicates the most likely answers.

Left: Sadlers Mil causeway in Romsey at the peak of the flooding Right: Pitton, Wiltshire, near the source of the Dun

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Interpreting results

Fish survey methods The majority of fish population surveys covered in this report were conducted using electric fishing, either from a boat or wading. Electric fishing involves the placement into the water of a pole 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) 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. 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. Captured fish are placed in a container of cool, aerated water and identified and counted before being returned to the river. Scales are sometimes taken so that fish ages can be checked. Estuarine fish surveys don't 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 sometimes also used to conduct fish surveys in very wide, slow rivers.

Types of electric fishing survey 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 Fishery and Eel Index surveys involve three successive runs ("catch depletion") - multiple run surveys require upstream and downstream stop nets to ensure the isolation of the survey reach.

Fish survey results Single-run electric fishing surveys don't 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 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 shouldn't 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.

Catch Per Unit Effort surveys (CPUE) 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 two 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 five minutes and covering approximately 75 metres.

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Water Framework Directive surveys Because Water Framework Directive surveys are so numerous and are not grouped into specific fisheries, we present their results in concise tables like this one for the Ouse catchment:

Waterbody name & Status

Roach Perch Pike Eel Gudgeon Dace Chub Bullhead Minnow loach Stone lampreyBrook Site name & status trout Brown Brookside Cuckmere, Warbleton to Lower Horsbridge 44 3 29 Isfield Weir Uck (Ridgewood Stream to Ishurst) 7 3 4 3 2 7 3 4 1 Stroodland Wood Uck (Ridgewood Stream to Ishurst) 3 35 1 Priors Barn Shortbridge Stream 14 103 1 Avins Bridge Ouse, Ardingly Reservoir to Lindfield 3 1 1

These tables indicate the WFD status of each individual survey site and the status of the waterbody that they represent using a colour-code, as follows: Blue=High; Green=Good; Yellow=Moderate; Orange=Poor; Red=Bad. The right hand side of the table shows the numbers of each species caught in the surveys. Cells in the species columns highlighted red indicate species that have the largest discrepancy between expected and observed abundance at that site. Cells highlighted yellow are also less abundant than expected but to a lesser degree. Where the site status is less than good, it is the absence or low abundance of these species that are causing the failure.

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1. East Sussex 1.1. Ouse and Cuckmere

Four single-run Water Framework Directive fish surveys were undertaken in the Ouse catchment in 2014, two on the River Uck and two on the Ouse itself. Only one fish survey was carried out in the Cuckmere catchment in 2014, a single run WFD survey at Brookside on the Waldron Gill.

Map E. Sussex 1 shows the location of the five WFD fish surveys carried out in 2014

Map E. Sussex 1: 2014 fish survey locations

Results Table E. Sussex 1 shows the site status, waterbody status and catch at each of the East Sussex WFD fish surveys. Status is colour coded, as follows: Blue=High; Green=Good; Yellow=Moderate; Orange=Poor; Red=Bad.

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Table E. Sussex 1: WFD survey results

Waterbody name & Status

Roach Perch Pike Eel Gudgeon Dace Chub Bullhead Minnow loach Stone lampreyBrook Site name & status trout Brown Brookside Cuckmere, Warbleton to Lower Horsbridge 44 3 29 Isfield Weir Uck (Ridgewood Stream to Ishurst) 7 3 4 3 2 7 3 4 1 Stroodland Wood Uck (Ridgewood Stream to Ishurst) 3 35 1 Priors Barn Shortbridge Stream 14 103 1 Avins Bridge Ouse, Ardingly Reservoir to Lindfield 3 1 1

Graph E. Sussex 1 shows the total density of all fish species caught at each survey site in East Sussex in 2014.

Graph E. Sussex 1: Species density at all survey sites.

80

70 Brook lamprey Minnow 60 Stoneloach

² 50 Bullhead 40 Gudgeon

No/ 100mNo/ Eel 30 Pike 20 Perch 10 Dace Chub 0 Isfield Weir Stroodland Priors Barn Avins bridge Brookside Roach wood Brown trout River Uck Shortbridge River Ouse Cuckmere Stream

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Graph E. Sussex 2 shows the biomass of fish caught, excluding minor species, at the WFD sites in East Sussex.

Graph E. Sussex 2: Species biomass

1400

1200 Gudgeon 1000

² Eel 800 Pike 600 g/100m Perch 400 Dace 200 Chub 0 Roach Isfield Weir Stroodland Priors barn Avins bridge Brookside wood Brown trout

River Uck Shortbridge River Ouse Cuckmere Stream

Discussion 2014 was a quiet year for fish surveys in East Sussex. The only surveys undertaken were five Water Framework Directive surveys, four in the Ouse catchment and one on the Cuckmere. 2014 falls between years when we carry out biennial eel index and Principal Coarse fishery surveys, which usually result in a much larger survey schedule. The catch at Brookside, on the Cuckmere, was dominated by brown trout, with the majority of the fish 1+ and older. This high catch of brown trout has resulted in a WFD classification of good for both the Brookside site and the overall waterbody it is represents. Brown trout were also caught at Avins Bridge on the Ouse and Priors barn on the Shortbridge stream (a Tributary of the Ouse) although in lower densities. Brown trout were absent from the two sites on the River Uck, with Isfield weir containing a mixture of coarse fish at low densities and Stroodland Wood producing just a small number of roach and minor species. The fish community at this site is impacted by a large weir a short distance downstream. Overall, Brookside and Priors Barn had the highest biomass (Graph E. Sussex 2), comprised entirely of brown trout. These two sites also showed the highest density of fish, although these densities were predominantly made up of bullhead at Prior's Barn and stone loach and brown trout at Brookside (Graph E. Sussex 1).

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WFD statuses for sites in the Ouse catchment ranged from moderate (Isfield Weir) to bad (Avins bridge). The species driving each failure are highlighted in table E. Sussex 1, with most of the sites showing a lack of brown trout and minor species such as bullhead.

Left: View from the survey boat at Stroodland Wood Right: The Uck at Stroodland Wood

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2. West Sussex 2.1. Adur In 2014, we carried out 11 single-run Water Framework Directive surveys across the Adur catchment. The five triennial Principal Coarse Fishery surveys are scheduled to be completed in 2015.

Map Adur 1 shows the locations of River Adur fish surveys in 2014.

Map Adur 1: Fish survey site locations

Results Table Adur 1 shows the site status, waterbody status and catch at each of the Adur WFD fish surveys. Status is colour coded, as follows: Blue=High; Green=Good; Yellow=Moderate; Orange=Poor; Red=Bad.

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Table Adur 1: WFD survey results

Waterbody name & Status

Mirror CarpMirror Carp Common bream Common breamxRoach hybrid Roach Rudd Perch Pike Eel Gudgeon Dace Chub Bullhead loach Stone lampreyBrook stickleback3-sp Site name & status trout Brown Tenchford Bridge Adur (Knepp) 1 6 11 101 8 4 5 9 3 10 2 Sheepfield Shaw Cowfold Stream 2 8 15 12 18 4 15 18 5 4 D/s Chess Bridge Chess Stream 3 74 12 82 4 7 11 21 Park Farm Chess Stream 1 12 4 16 19 5 Hookers Farm R. Adur East 49 8 1 40 53 1 4 U/s Twineham Footbridge R. Adur East 1 21 2 2 3 3 15 7 9 Shermanbury Place GS River Adur East (Sakeham) 2 28 1 3 3 2 3 7 D/s Herrings Bridge Herrings Stream 30 3 29 10 13 60 7 Wortleford Bridge R. Adur East (Goddards Green) 5 7 17 14 29 6 Capps Bridge R. Adur West 41 1 4 3 1 1 1 7 West Grinstead Adur (Lottbridge) 2 1 9 1 2 1 2 7

The backpack survey in progress (left) at Sheepfield Shaw and one of two adult wild brown trout caught there (right)

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Graphs Adur 1 - Adur 3 are length frequency histograms showing the numbers of roach, chub and eels, respectively, in different length categories based on the catches from all eleven Adur surveys combined. The roach and chub histograms are presented using identical X and Y axes to allow population structure and abundance to be compared easily.

Graph Adur 1: Roach length frequency for all Adur surveys combined

25 n=361

20

15

10

5

0

5

20 35 80 95 50 65

140 155 170 215 230 275 290 305 335 350 365 410 425 470 110 125 185 200 245 260 320 380 395 440 455 mm

Graph Adur 2: Chub length frequency for all Adur surveys combined

25 n=141 20

15

10

5

0

5

20 35 50 95 65 80

110 125 185 200 215 260 275 290 350 365 425 440 455 140 155 170 230 245 305 320 335 380 395 410 470 mm

Graph Adur 3: Eel length frequency for all Adur surveys combined

25

n=129 20

15

10

5

0

5

25 45 65 85

125 145 165 185 265 285 305 325 405 425 445 465 565 585 605 105 205 225 245 345 365 385 485 505 525 545 625 mm

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Graph Adur 4 shows fish species densities caught downstream (d/s Chess Bridge) and upstream (Park Farm) of a series of impounding structures on the Chess stream, a tributary of the Adur.

Graph Adur 4: Species density downstream and upstream of flow control structures on the Chess stream

90

80 Stone loach Bullhead 70 Gudgeon 60 European eel 50 Pike 40

Perch No/100m² 30 Dace 20 Chub 10 Roach

0 Brown / sea trout D/s Chess Bridge Park Farm

Discussion Table Adur 1 provides details of the catches at the eleven WFD surveys conducted in 2014 and shows the site and waterbody status calculated by our WFD fish classification tool (Fisheries Classification Scheme version 2: FCS2). The table clarifies the broad range in fish status amongst the surveys, with three classed as High, one as Good, three as Moderate and four as Poor. Amongst the High and Good survey results, the abundance of certain species at some sites is particularly notable: roach at Tenchford Bridge; eel and roach downstream of Chess Bridge and roach, chub and gudgeon at Hookers Farm. Amongst the surveys deemed less than Good, absence of brown trout was the main factor for five of the seven, with absence or lack of roach, eel, chub, bullhead and stone loach also problematic at various sites. West Grinstead's Poor status is attributed to a general lack of fish, across several species. Therefore, the general picture is of the majority of sites surveyed in 2014 not achieving Good status (our goal for WFD) but with a few sites supporting exceptional fish communities. Graphs Adur 1-3 show the abundance of roach, chub and eels according to length categories, which clarifies each population's age structure - the figures also give the total number of each species caught across the eleven surveys. As the WFD table shows, these species were not evenly distributed between the sites. Adur 1 shows that very few Adur roach exceed 20cm, suggesting slow growth and maturity at a relatively small size. A clear group of young of the year (0+) roach is apparent between 35-45mm but almost all of these were from Hookers Farm: roach of this size were absent from most sites. Adur 2 shows that Adur chub have a much greater size range, as you would expect for this larger species. However, even slow-growing chub of these larger sizes are likely to be much older than the largest roach in the 2014 data. As with the roach graph, these is a clear group of young of the year chub but once again, most these were caught at Hookers Farm and eight of the eleven sites produced none.

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Adur 3 shows that a total of 129 eels were caught across the eleven surveys, ranging in length from 80-620mm. Approximately 64% of these were caught at d/s Chess Farm, which is the site closest to the tidal limit. With the exceptions of Park Farm and Sheepfield Shaw, eels were relatively scarce at most other sites and absent from the catch at Shermanbury Place, suggesting there may be problems with migratory access and / or a lack of suitable habitat with abundant food. Numbers of brown trout and bullhead are generally low in the Adur, with the former only found at two of the eleven sites surveyed. There are known problems with water quality in some reaches and areas of suitable spawning gravels and parr habitat are limited. Weirs and other structures that impound water or obstruct migration are likely to be particular constraints on trout distribution and abundance. If we look at the Chess stream in more detail, we can see the difference made by such structures (Graph Adur 4). At d/s Chess Bridge we recorded a very high abundance of eels and roach and reasonable abundances of perch, chub and dace - it was also one of only two sites on the Adur where brown trout were recorded in 2014. Several impounding structures exist between that survey site and the next one upstream: Park farm. Here, there were far fewer eels, no trout and fewer coarse fish, including bullhead and stone loach. Total fish density was 69.2 fish per 100m² downstream and 4.29 fish per 100m² upstream. The WFD site status reflects this (d/s Chess Bridge: High; Park Farm: Poor). Our South Downs Fisheries, Biodiversity and Geomorphology Team have improved conditions for coarse fish, salmonid and eel migration on the Adur with the complete removal of two obsolete weirs in 2014 and another, at Wineham, is currently being reduced.

Left: Good marginal vegetation cover at Hookers farm on the river Adur Right: A healthy chub from d/s Chess bridge on the Chess Stream

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Left: An example of one of the many elvers captured on the Adur in 2014

Right: One of a number of barriers to fish migration on the Adur. Great work is being done to reduce the number and impact of these on migratory fish species

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2.2. Arun

In 2014 on the River Arun, we surveyed four sites, two on the main river channel and two on the North River. All four sites were single run Water Framework Directive surveys.

Map Arun 1 shows the locations of fish surveys undertaken on the river Arun in 2014 for the WFD

Map Arun 1: 2014 WFD fish surveys

Results Table Arun 1 shows the site status, waterbody status and catch at each of the Arun WFD fish surveys. Status is colour coded, as follows: Blue=High; Green=Good; Yellow=Moderate; Orange=Poor; Red=Bad.

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Table Arun 1: WFD survey results

Waterbody name & Status

Roach Perch Pike Eel Bleak Gudgeon Dace Chub Bullhead Minnow loach Stone stickleback3-sp Site name & status trout Brown Theale Farm R. Arun Horsham 23 1 2 5 11 9 6 25 40 1 Oakwood Hill North River 13 1 172 37 51 1 Northlands Farm North River 2 5 14 3 58 23 Bignor Farm R. Arun (U/S Pallingham) 14 6 1 1 2 2 7 1

Graph Arun 1 shows the overall density of each survey carried out in the Arun catchment in 2014. This density includes minor species such as bullhead, minnow, stone loach and 3-spined stickleback.

Graph Arun 1: Species density

70 3-spined stickleback Stone loach 60 Minnow

50 Bullhead ² 40 Gudgeon European eel 30

No/100m Pike 20 Perch Bleak 10 Dace 0 Chub Northlands Oakwood Bignor Theale Roach Farm Hill Farm Farm Brown / sea trout North River River Arun

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Graph Arun 2 shows the species biomass, for each survey, not including minor species.

Graph Arun 2: Species biomass 1200 Gudgeon 1000 European eel

800 Pike ²

600 Perch

g/100m Bleak 400 Dace 200 Chub

0 Roach Northlands Oakwood Bignor Theale Farm Hill Farm Farm Brown / sea trout

North River River Arun

Discussion On the North River, a tributary of the Arun, which joins the main river near Slinfold, downstream of Horsham, our two surveys were carried out in very different habitats. The upstream site, at Oakwood Hill was characterised by a gravel substrate and large riffles, whereas the downstream site at Northlands Farm was generally slow flowing with a clay bed. As a consequence, the upstream site was dominated by brown trout (see Graph Arun 2) and bullhead (see Graph Arun 1), whereas the downstream site had an overall lower density and biomass, with low numbers of coarse fish including roach, dace and perch. The WFD status of the two waterbodies is Good for Oakwood hill and Poor for Northlands farm. The lower status at Northlands farm is driven by a lack of brown trout, eel and minnow. The trout at Oakwood Hill varied from 0+ (young of the year) fish through to adult fish of 30cm, indicating successful spawning in this reach. Only one eel was captured in the two surveys on the North river, most probably due to a number of impounding weirs downstream of the site at Northlands Farm, which are probably also responsible for the sluggish flows found at the site. Of the two sites on the main Arun, the upstream site at Theale Farm produced by far the greater density and biomass of fish (Graphs Arun 1 & 2) and yielded ten species. Further downstream at Bignor Farm, both fish density and biomass were low, and featured fish species more commonly found in slow flowing stretches such as bleak, roach and pike. A clay substrate and lack of habitat diversity are the likely reasons for this limited fish community, with little in the way of refuge areas for fish in high flow events. The Bignor farm survey resulted in a WFD site classification of Poor, primarily because of a lack of minnow and low numbers of other fish species in general. As with the Adur, our South Downs Fisheries, Biodiversity and Geomorphology Team are working to enhance fish habitat and remove obstructions to fish passage on the Arun, notably through the Arun and Rother Connections Heritage Lottery Project (ARC). This project saw a key obstruction removed and a fish pass installed in 2014, with another pass to be constructed in 2015. The

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project will also enhance sections of the Arun's middle reaches, particularly with the construction of backwater refuge areas designed to improve juvenile coarse fish survival.

Left: Shallow riffle areas at Oakwood Hill provided good habitat for brown trout Right: The impounded stretch at Northlands Farm contained low numbers of coarse fish

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2.3. Western Rother & Western Streams

As well as the five annual Principal Coarse Fishery surveys on the Western Rother, we also carried out five Water Framework Directive surveys in the Western Rother catchment in 2014. Two of these were on the main channel, two were on the Hammer stream and one was on the Aldingbourne Rife, a small coastal stream south of Chichester. Four of the five PCF surveys also serve a WFD purpose.

Map WR1: Western Rother survey locations

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Results:

WFD results Table WR1 shows the site status, waterbody status and catch at each of the Western Rother WFD fish surveys. Status is colour coded, as follows: Blue=High; Green=Good; Yellow=Moderate; Orange=Poor; Red=Bad.

Table WR1: 2015 WFD survey results, Western Rother & Western Streams

Waterbody name & Status

Common bream Common Roach Rudd Perch Pike Eel Flounder Gudgeon Dace Chub Bullhead Minnow loach Stone lampreyBrook stickleback3-sp Site name & status trout Brown Terwick Mill Western Rother 2 2 4 3 1 4 2 111 17 38 2 Coultershaw Western Rother 1 1 3 6 2 Fittleworth Western Rother 1 1 1 1 3 1 Milland Hammer Stream (W. Sussex) 4 2 7 45 41 1 D/s Hammer Pond Hammer Stream (W. Sussex) 1 3 5 3 1 1 45 7 14 U/s Mizzards Western Rother Durford 2 2 77 2 6 1 Durford Bridge Western Rother Durford 7 1 4 1 11 3 1 1 Stanbridge W. Rother U/S Petersfield 3 28 1 26 3 5 Felpham Way Aldingbourne Rife 1 8 1 1

Adult & juvenile American signal crayfish at Durford Bridge (left), Excellent riparian habitat downstream of the Hammer pond, Hammer Stream (right)

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Graph WR1 shows the density (number per 100m2) of fish species at the five Western Rother WFD survey sites:

Graph WR1: WFD survey fish density

40 Flounder

35 Brook lamprey Stone loach 30 Minnow

25 Bullhead ² 3-sp stickleback 20

Eel No/100m 15 Pike Perch 10 Rudd 5 Roach Common bream 0 u/s Mizzards Durford Milland d/s Hammer Felpham way Chub Bridge Pond Brown trout Western Rother Hammer Stream Aldingbourne Rife

Graph WR2 shows the biomass (grammes per 100m2) of fish species, excluding minor species, at the five Western Rother WFD survey sites:

Graph WR2: WFD survey fish biomass

900

800 Flounder

700 Eel

600 Pike

500 Perch

400 Rudd g/100m² 300 Roach Common bream 200 Chub 100 Brown trout 0 u/s Mizzards Durford Bridge Milland d/s Hammer Felpham way Pond Western Rother Hammer Stream Aldingbourne Rife

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Graph WR3 shows the density (number per 100m2) of fish species at the five Western Rother Principal Coarse Fishery survey sites:

Graph WR3: Fish density at the five annual Principal Coarse Fishery sites (minor species excluded)

6

Flounder 5 Common Carp Perch 4 Gudgeon Brown trout 3 Eel

No./100m² Pike 2 Grayling Chub 1 Roach Dace 0 Stanbridge Terwick Woolbeding Coultershaw Fittleworth

Graph WR4 shows the biomass (grammes per 100m2) of fish species at the five Western Rother Principal Coarse Fishery survey sites:

Graph WR4: Fish biomass at the five annual Principal Coarse Fishery sites (minor species excluded).

2000 Flounder 1800 Common Carp 1600 Perch 1400 Gudgeon 1200 Brown trout

1000 Eel

g/100m² Pike 800 Grayling 600 Chub 400 Roach 200 Dace 0 Stanbridge Terwick Woolbeding Coultershaw Fittleworth

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Graph WR5 is a scatter plot showing the relationship between total estimated number of dace and roach at Principal Coarse Fishery sites each year and an index of summer temperature and flow. The index represents degree days above 12C divided by summer flow (both 4-year means), where both datasets have been standardised to the same scale.

Graph WR5: dace & roach abundance and an index of flow & summer temperature: scatter plot

1.7

1.6

1.5

1.4

1.3

1.2

1.1

1.0 Summer temp. & flow index flow temp. & Summer 0.9

0.8

0.7 0 20 40 60 80 100 120 140

Total est. dace & roach

Graph WR6 is a time series based on the same data as WR5, above.

Graph WR6: dace & roach abundance and an index of flow & summer temperature: time series

140 1.9 120 1.7 100 1.5 80 1.3 60 1.1

40

Total est. dace & roach & est. dace Total 0.9 Summer temp & flow index flow & tempSummer

20 0.7

0 0.5

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

Total est. catch dace and roach Summer temp & flow index

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Surveys in progress at Fittleworth (left) and Stanbridge (right)

Discussion

WFD surveys: Graphs WR1 and WR2 show the density and biomass of fish species caught during the five surveys in the Western Rother catchment that were for Water Framework Directive only. Graph WR1 shows that the catch on the Aldingbourne Rife was very poor, with just one rudd, one three- spined stickleback, one flounder and eight eels. This was as we expected, as the rife's fish community is constrained by poor water quality and degraded habitat. It is certain that this waterbody will continue to fail for WFD. The two sites on the main river, Durford Bridge & upstream of Mizzards, produced a typical catch for the upper Western Rother with low numbers of brown trout, a few coarse fish and relatively high numbers of minor species such as bullhead and stone loach. This low overall abundance may be partly due to recent climatic conditions, as discussed within the PCF discussion, but also reflects the geomorphology of the Rother catchment, which sees large inputs of sand and fine sediment to the river during high flow events. The Hammer stream survey sites featured some good quality habitat, with a coarser, stony substrate and as a result, fish densities were higher at both sites. There is an online lake situated between our two survey points, which was created by putting a large weir across the stream. Despite this barrier to fish migration, four brown trout were caught at the upstream survey site (Milland). These fish were probably from an isolated population, with adults remaining in this section of stream to spawn. The only site to achieve a Good or better WFD status is Terwick Mill (High). The Less than Good site classifications on the Hammer stream and Stanbridge are driven by a lack of brown trout, whereas for sites on the main river and further down the catchment the reason is absence or low abundance of coarse fish and eels.

Principal Coarse Fishery surveys: Graphs WR3 and 4 show the density and biomass, respectively, of fish species caught at the five routine Principal Coarse Fishery survey sites. Both graphs display survey sites in order from upstream to downstream (left to right on the graph). It's important to interpret these graphs in the context of the long-term datasets we have for these survey sites and what we understand about how fish abundance on the Western Rother is affected by prevailing climatic conditions in different years. Analysis of potential correlations between Western Rother fish data with weather data suggests that the two most influential aspects are average temperature and flow in summer, with higher 31 of 71

average temperatures and lower average flows resulting in greater abundance of the two key angling species, dace and roach. Winter flow is also influential, but apparently less so than summer. We analyse summer temperature expressed as the number of degree-days (one day at one degree) above 12 centigrade, which helps identify prime conditions for coarse fish reproduction, growth and survival. Summer flow is analysed as the mean flow at the most suitable gauging station (Hardham for the Western Rother) between April and September. Often, ideal temperatures for dace and roach reproduction, growth and survival in any given year are counteracted by unsuitable flows and vice versa, so a single overall value or score that reflects both is useful. In graphs WR5 and WR6 temperature and flow data have been converted to a single value for each year by first standardising the data to the same scale and then dividing the temperature value by the flow value. For example, an ideal year would have a high temperature score and a low summer flow score, resulting in a high overall value, whereas if both are high or low, the score will be reduced. However, the impacts of temperature and flow on fish communities are cumulative across periods of several years, that is, fish abundance will be higher after three or four ideal years than after just one, so the analysis described above uses four-year averages (the survey year and the previous three) for temperature and flow, rather than the values from the survey year alone. This process reveals the best correlation yet found between Western Rother coarse fish abundance and environmental conditions, with a value of 0.75 (1 being perfect positive correlation; -1 perfect negative correlation) - this is illustrated in Graph WR5 which plots, for each year, the combined temperature / flow score against the total estimated dace and roach catch. Graph WR6 uses the same data as WR5 but displays the data points along a time series from 2002 to 2014, so that dace and roach abundance in any given survey year can be picked out and compared with the temperature / flow score. The 2014 score is the third lowest since surveys began in 2002, reflecting the relatively low average summer temperatures and high summer flows in the period 2011-2014. Consequently, total estimated dace and roach abundance is also among the lowest recorded. A stark contrast is provided by the figures for 2006, where the temperature / flow score is approximately double and the combined dace and roach abundance around six times higher than 2014. Although these two species spawn at different times of year and in very different habitats (dace in early spring on gravel; roach in early summer on submerged vegetation), juveniles of both species are highly reliant on warm, shallow, slack water for survival and growth, making both vulnerable to cool, high flow conditions in summer. However, this effect can be mitigated by an abundance of high quality habitat, especially in the river margins, suggesting that the "bottlenecks" to successful recruitment on the Western Rother may be a lack of suitable spawning habitat for both species and / or lack of habitat providing ideal conditions for juveniles. Graphs WR3 and WR4 portray the low overall fish abundance on the Western Rother in 2014, with the very low abundances at Woolbeding, Coultershaw and Fittleworth particularly striking. Stanbridge is in the river's headwaters on the outskirts of Petersfield, where the dominant fish species is brown trout, a species with very different environmental requirements to dace and roach, hence its high density and biomass in comparison to coarse species at the other sites. Brown trout and a single grayling (207mm) were the only large fish species recorded on this survey. Terwick Mill is farther downstream and lies in the zone where both salmonids and coarse fish thrive, as reflected in the 2014 survey, which yielded ten species, including brown trout, grayling, chub, pike, perch, roach and eels, as well as several minor species and a common carp. The disproportionate contribution that the pike, carp and chub make to the site's overall biomass can be seen in graph WR4. Despite this diversity, overall density at Terwick was estimated to be less than three fish per 100m2. At Coultershaw density was estimated to be just over one fish per 100m2 and at Woolbeding and Fittleworth it was less than one. These are very low coarse fish abundances, reflecting the fish community's sensitivity to adverse environmental conditions and demonstrating a

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lack of resilience to normal climatic variability. This is probably symptomatic of the significant constraints suspected of impacting the river's fish populations, notably, sedimentation, impoundment, barriers to migration and channel modification. Our South Downs Fisheries, Biodiversity and Geomorphology Team are working to mitigate these constraints and have constructed three backwater juvenile fish refuges on the Western Rother in the past eighteen months. Of course, some of these stretches and others nearby occasionally produce large specimen barbel, pike, bream and other species but these cautious, long-lived survivors are scarce and are only rarely captured in surveys.

Good quality habitat on the Hammer stream resulted in a greater density of fish than sites on the main Western Rother

A well conditioned chub from Coultershaw (left) , where the catch consisted of a low number of large fish A grayling from Terwick Mill (right), a species which was once much more common on the Western Rother.

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3. Isle of Wight

The 2014 survey season was particularly interesting on the Isle of Wight, as we conducted fish surveys on the Caul Bourne for the first time since the late 1990's and on the upper Eastern Yar for the first time since 2002. We also conducted surveys for the first time ever on the Brighstone stream. Seven surveys were completed in total; all were single run and were required in order to classify the relevant waterbodies for fish for the Water Framework Directive. Map IOW1 shows the survey site locations.

Map IOW1: 2014 fish survey sites

Results Table IOW1 shows the site status, waterbody status and catch at each of the Isle of Wight WFD fish surveys. Status is colour coded, as follows: Blue=High; Green=Good; Yellow=Moderate; Orange=Poor; Red=Bad.

Table IOW1: WFD survey results

Dace Roach Perch Eel Bullhead loach Stone lamprey Brook Site name & status Waterbody name & status trout Brown Roud E. Yar upper 51 6 1 13 Godshill E.Yar upper 14 6 27 6 2 Horringford E. Yar lower 14 28 2 1 13 22 2 Shalfleet Caul Bourne 36 23 7 Calbourne Mill Caul Bourne 8 6 133 Grange Chine Brighstone streams 26 35 22 Thorncross Brighstone streams 1 2

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Graph IOW1 shows which fish species were recorded at each site and how many individuals per 100m2 were caught (density).

Graph IOW1: Species density

60

50

40

2 Brook lamprey

30 Stone loach Bullhead No/100m 20 Eel

10 Perch Roach 0 Dace

Roud Brown trout

Godshill

Shalfleet

Thorncross

Horringford

Grange Chine Grange Calbourne Mill Calbourne Caul Bourne Brighstone Stream Eastern Yar

Graph IOW2: Species biomass

3500 3000

2500 2 2000 Eel

1500 Perch g/100m 1000 Roach

500 Dace 0

Brown trout

Roud

Godshill

Shalfleet

Thorncross

Horringford

Grange Chine Grange Calbourne Mill Calbourne Caul Bourne Grange Chine Eastern Yar

Discussion This series of seven surveys provides vital information on the fish communities of three Isle of Wight streams that have not been surveyed for many years. With the exception of the Thorncross survey, all the results are positive. Thriving populations of healthy, wild brown trout were recorded at all other sites, with densities at Roud, Shalfleet and Grange Chine surprisingly high. Trout density at Godshill, Horringford and Calbourne Mill was lower but this is no cause for concern: at Horringford the fish community is typical of a river's middle reaches, with a mixture of trout and coarse fish, while at Calbourne Mill, trout abundance is likely to be constrained to some extent by 35 of 71

the effects of milling on flow. Milling requires the mill pond to be refilled, resulting in regular periods of low flow in the reach immediately downstream, a process that has been routine here for many centuries. Godshill is a site that had been heavily modified (dredged and straightened) a long time ago but has recovered and naturalised to a great extent, with dense, varied woodland lining the banks and plentiful woody debris in the channel - a great example of a river reach thriving on neglect and lack of disturbance. However, it would certainly be beneficial to cut back the canopy in places, in order to let light into the channel and promote herbaceous plant growth both underwater and on the banks. Eel abundance was generally high, too, especially at the two sites closest to their streams' tidal limits: Grange Chine and Shalfleet. Eel abundance at Grange Chine was particularly surprising, as the stream flows over a concrete weir beneath the road viaduct, which was suspected of being an obstruction to upstream elver migration. With 35 eels of varying age caught on this survey, elvers can certainly pass this structure, probably by climbing up the wet vegetation to the sides of the main flume of water. A single eel and two bullhead were caught at Thorncross, all three taken from the one pool, beneath the only tree along the survey reach. The reason for this lack of fish is obvious to anyone who walks the public footpath along the reach: the stream has, at some point in the past few decades, been straightened and deepened so that it resembles an agricultural drainage ditch almost entirely devoid of bankside trees and heavily overgrown with Norfolk reed. This leaves very little open water and virtually no suitable fish habitat. The good news is that this stream does have the key ingredient to give it the potential to support a thriving fish community: a constant flow of clean spring water. In addition, the work required to rectify the damage to the channel is relatively simple, requiring basic remeandering, tree planting and the installation of large woody debris. However, there is some concern that fish passage through Brighstone is constrained by an online millpond and various flow control structures.

Survey in progress at Roud A perfect Grange Chine brown trout

Viaduct flume at Grange Chine Heavily modified reach at Thorncross

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Fine perch and dace from Horringford

Bootlace eels and a close up of an adult yellow eel, all from Grange Chine

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4. Hampshire 4.1. East Hampshire

Two Water Framework surveys were conducted in East Hampshire in 2014: one on the Hampshire Lavant, at Langstone Technology Park and one on the River Alver at Apple Dumpling Bridge, in Gosport. The two annual wild brown trout surveys on the Meon were also completed at the usual sites, Mislingford and Silver springs.

No surveys were carried out in the Wallington or Hamble catchments this year. Map EH1 shows the locations of all East Hampshire fish surveys in 2014.

Map EH1

Results Table EH1 shows the site status, waterbody status and catch at each of the East Hampshire WFD fish surveys. Status is colour coded, as follows: Blue=High; Green=Good; Yellow=Moderate; Orange=Poor; Red=Bad.

Table EH1

Roach trout Brown stickleback 3-sp Bullhead carp Common Site Waterbody name Eel Langstone Technology Park Lavant (Hants) 13 4 85 Apple Dumpling Bridge R. Alver 1 38 of 71

Meon Graph Meon 1 shows fish density (number per 100m2), excluding minor species, recorded at Mislingford and Silver Springs since annual wild brown trout surveying commenced in 2007.

Graph Meon 1: Fish density at Mislingford and Silver springs

40

35 Roach 30

2 Grayling 25 Dace 20

No./100m Salmon 15 Eel

10 Chub

5 Brown trout

0

2010 2011 2012 2013 2014 2013 2014 2007 2008 2009 2007 2008 2009 2010 2011 2012 Mislingford Silver Springs

Graphs Meon 2 and 3 show the number of brown trout in each 5mm length category recorded in 2014 at Mislingford and Silver Springs respectively.

Graph Meon 2: Brown trout length-frequency histogram; Mislingford

18 16 14 12 10

8 Frequency 6 4 2

0

50 95 65 80

110 125 170 185 230 245 260 305 320 140 155 200 215 275 290 335 mm

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Graph Meon 3: Brown trout length-frequency histogram; Silver Springs

18 16 14 12 10

8 Frequency 6 4 2

0

65 80 50 95

110 140 155 185 200 230 245 275 305 320 125 170 215 260 290 335 mm

Graph Meon 4 is a scatter plot showing the relationships between 0+ (young of the year) and 1+ trout (parr in their second year) abundance and mean summer flow at Mislingford.

Graph Meon 4: Mislingford 0+ and 1+ abundance and mean summer flow

140

120

100

80 Catch 60

40

20

0 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 M3/sec

0+ catch 1+ catch Linear (0+ catch) Linear (1+ catch)

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Graph Meon 5 shows the relationship between the mean lengths of 0+ and 1+ trout caught at Mislingford in each survey year and mean summer flow that year.

Graph Meon 5: Mislingford 0+ and 1+ mean length and mean summer flow

200 190 180 170 160 150 140

MM 130 120 110 100 90 80 70 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 M3/sec

0+ mean length 1+ mean length Linear (1+ mean length) Linear (1+ mean length)

Discussion

WFD surveys: Alver and Lavant Despite there being only two Water Framework Directive fish surveys in East Hampshire in 2014, the results and observations made during the surveys give us plenty of useful ecological evidence of pressures constraining fish communities in the two watercourses. The first attempt to conduct an electric fishing survey on the Alver had to be abandoned when it was found that there was very high salinity even at Apple Dumpling Bridge, two kilometres upstream of the stream mouth at Browndown - electric fishing with normal gear is not possible in saline conditions due to the very high conductivity of the water. An investigation was necessary to work out how far upstream we would have to venture to find salinity low enough to enable electric fishing. The answer was surprising: salinity dropped quickly only a few metres upstream of Apple Dumpling Bridge, as the source of very high conductivity water appeared to be a small woodland pond whose outlet stream joined the main Alver just downstream of the bridge - this is now the subject of a separate investigation. An electric fishing survey from a small boat was completed in late September and covered 700 metres of the Alver, from Apple Dumpling Bridge upstream. A single common carp was caught and no other fish were observed, despite excellent fishing conditions. More surprisingly, large numbers of eels are often seen by workers clearing beach gravel from the outlet grills at the stream mouth and shoals of small silver fish (rudd or roach) are often seen where people feed bread to ducks at Apple Dumpling Bridge (where salinity is too high for electric fishing). Whatever the specific reasons for the absence of fish upstream of the bridge, the root cause is almost certainly the combined impact of contaminated water leaching from several historic landfill sites and military dumps in the area, as well as the canalised nature of the watercourse. 41 of 71

By contrast, the number of bullhead and eels recorded by the fish survey on the Hampshire Lavant at Langstone indicated good water quality - certainly good enough to sustain the brown trout that are typically the dominant species in spring fed streams of this type. However, their absence reflects two pressures: heavily modified habitat and obstructions to migration, particularly to sea trout trying to ascend the stream from Langstone Harbour. The failure of this waterbody for fish under the Water Framework Directive will provide evidence and a driver to address these problems.

Left: East Hampshire's hidden chalkstream; the Hampshire Lavant Right: The Alver in the Wild Grounds nature reserve

Meon principal brown trout fishery Graph Meon 1 shows that the density of wild brown trout recorded at Mislingford was the second highest since 2007: 153 were caught in a single electric fishing run, equating to 22.4 per 100m2 (in 2010 it was 174 & 26.9 respectively). Graph Meon 2 shows that the majority of these (just over 82%) are young of the year (0+; hatched in spring 2014), ranging in length from 68 to 136mm. Just over 17% of the catch comprised older, longer fish, the majority of which were one year olds, between 166 and 224mm. Only five fish were >224mm). A single salmon parr was caught at Silver springs - the lowest catch to date: 48 were caught in the 2013 survey. The graph demonstrates that the pattern of trout abundance at Silver Springs is not similar to that at Mislingford and that the number of trout recorded in 2014 was less than half that in the previous year. This difference between the two sites is one indication of the complexity of our Meon trout data. The relationships between juvenile trout (growth and abundance) and environmental conditions (flow and temperature) are unclear, with differences between young of the year parr and one year olds, as well as differences between the two survey sites. A thorough analysis of annual abundance and average length of 0+ and 1+ trout shows a surprising lack of any consistent relationship between these factors and flow or temperature at key periods of the year. For example, we would expect the varying abundance of 0+ trout at Mislingford to be correlated to some extent with average flows in summer, but this is not the case. This is illustrated by Graph Meon 4, which shows annual abundance of 0+ and 1+ parr at Mislingford, set against the annual average summer flow. On a scale from -1 to +1, the correlation coefficient for 0+ trout abundance with summer flow is 0.33 and for 1+ parr it's -0.43, suggesting that increasing summer flows tend to increase young of the year abundance but reduce one year old parr abundance but neither relationship is strong. There are probably two main reasons for this difficulty in identifying the drivers of good and poor recruitment years on the Meon: firstly, this trout population is largely migratory, meaning that there

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are likely to be other important environmental factors affecting marine survival and fecundity, such as sea temperature, predation and food availability, with knock-on effects on patterns in parr abundance. However, without long term data from a fish counter monitoring returning adult sea trout, this is impossible to quantify. Secondly, the dataset seems to suggest that the environmental factors that have exerted the most influence on Mislingford trout abundance and growth have been different in various years between 2007 and 2014, which is why strong correlations are evident over briefer periods but not for the whole period. This implies that it's less important to look at consistent patterns throughout the whole dataset than to appreciate the effects of specific periods of abnormal flows or temperatures, which have been relatively frequent in recent years. The most consistent correlation evident throughout the whole period is that between average flow measured at Mislingford gauging station between April and September and annual average length of Mislingford 0+ and 1+ parr. Graph Meon 4 shows this relationship and emphasises the general tendency for chalkstream flow to be linked to carrying capacity for trout. For both 0+ and 1+ trout (coincidentally) the correlation coefficients between mean length and summer flow are both 0.63.

Our first grayling (left) and an adult chub from Mislingford

Infected wound on a sea trout head Silver springs backpack survey

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Silver Springs salmon parr Yellow eel close up

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4.2. Test & Itchen

Test: Three types of fish survey were conducted in the Test catchment in 2014: eight Water Framework Directive (WFD) waterbody classification surveys, six biennial salmon parr surveys and a single "local investigative" survey. Five of the salmon parr surveys sites are so wide, fast flowing and shallow that the five-minute, Catch Per Unit Effort (CPUE) survey method is used (see "Interpreting results" section for details).

Itchen: Only three fish surveys were required in the Itchen catchment in 2014, all of which were for WFD waterbody classification purposes.

Map T&I 1 shows the site names and locations of all fish surveys undertaken in the Test and Itchen catchments in 2014. Purple triangles are WFD surveys, green circles are salmon parr surveys and the yellow circle is the local investigative survey. WFD waterbody boundaries are shown in black.

Map T&I 1: survey site locations

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Results

Water Framework Directive Tables Test 1 and Itchen 1 show the site status, waterbody status and catch at each of the Test and Itchen catchment WFD fish surveys respectively. Status is colour coded, as follows: Blue=High; Green=Good; Yellow=Moderate; Orange=Poor; Red=Bad.

Table Test 1: River WFD survey results

Brown trout Brown Chub Dac Grayling Gudgeon Roach Rudd Perch Pike Eel Flounder stickleback 3-sp Bullhead Minnow loach Stone lamprey Brook trout Rainbow Site name & status Waterbody name & status Salmon Dunbridge Station Dun 19 5 84 Park Farm Dun 6 2 123 4 Old Vicarage Dun 32 3 169 6 Romsey Canal F'bourne stream & f'lake meadows 1 9 24 7 3 6 15 25 10 Fairbourne Stream, Brook Farm F'bourne stream & f'lake meadows 3 2 1 35 19 1 46 56 11 Timsbury Mayfly Carrier R. Test 3 10 4 15 4 Romsey Memorial Park R. Test 6 2 1 2 2 3 58 67 Fish Lake R. Test 2 1 2 18 Coxford Road Tanners Brook 1 10 2 252

Table Itchen 1: Itchen WFD survey results

Chub Gudgeon Roach Eel stickleback 3-sp Bullhead Minnow loach Stone orfe Golden Site name & status Waterbody name & status trout Brown Stoneham Monks Brook 10 1 11 2 7 2 35 261 63 Bow Lake Fish Farm Bow Lake 7 33 39 1 8 2 2 Upstream of Leyland's Farm Bow Lake 1 15 3 21

Test salmon parr surveys: Graph Test 1 shows the average number of salmon parr recorded in our five Catch Per Unit Effort surveys (red dotted line) in each survey year. Also shown is parr abundance (density: number per 100m2) in the first run of Romsey War Memorial Park surveys (solid grey line) and the average flow in the winter preceding the survey (Oct-Mar) recorded at the Broadlands gauging station. Note that there were no CPUE surveys before 2007 and that both types of survey switched from annual to biennial in 2011.

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Graph Test 1: Salmon parr abundance and winter flow

14 26

24 12 22

10 20

18

8 /sec

/mean catch catch /mean 16

3 2

6 M 14

No/100m 4 12 10 2 8

0 6

2005 2006 2009 2012 2003 2004 2007 2008 2010 2014

No survey 2011survey No No survey 2013survey No Mean catch CPUE sites 1st run density Memorial park Mean flow Oct-Mar

Graph Test 2 is a scatter plot based on the same data as Test 1 and is aimed at clarifying the relationship between salmon parr abundance and winter flow.

Graph Test 2: Salmon parr abundance and winter flow scatter plot

22 20 18 16 14 12 10

Salmon parr Salmon 8 6 4 2 0 5 7 9 11 13 15 17 19 21 M3/sec

Total catch CPUE sites 1st run density War Memorial Park

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Table Test 2: salmon data summary sheet

Table Test 2 sets out key statistics for the Test salmon population.

– Returning Stock is the number of adult salmon recorded at the Nursling salmon counter – Rod Catch is the total number of salmon caught by rod and line fisheries on the river – Catch and Release rate is the percentage of those salmon immediately returned alive – Spawning Escapement is the number of salmon estimated to be available for spawning – Egg Deposition is the total number of eggs likely to be produced by those fish

River Test Adult Catch and Return Returning Release Spawning Egg Year Stock Rod Catch Rate Escapement Deposition (%) (millions) 1990 790 288 - 505 1.23 1991 538 139 - 405 0.99 1992 614 151 - 471 1.15 1993 1155 335 - 870 2.12 1994 775 247 14 560 1.37 1995 647 167 0 465 1.13 1996 623 146 13 496 1.21 1997 361 49 14 319 0.78 1998 898 204 44 784 1.91 1999 867 159 46 781 1.91 2000 595 147 66 545 1.33 2001 410 215 99 398 0.97 2002 1046 342 99 1044 2.55 2003 367 164 100 367 0.90 2004 1129 449 100 1129 2.75 2005 1150 357 100 1150 2.81 2006 1058 210 100 1058 2.58 2007 664 258 100 664 1.62 2008 1487 424 100 1487 3.63 2009 903 185 100 903 2.20 2010 833 225 99 831 2.03 2011 980 312 100 979 2.39 * 2012 949 293 100 949 2.32 * 2013 1020 323 100 1020 2.49 *** 2014 1001 235 100 1001 2.44

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 *** Provisional count awaiting verification

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Table Itchen 2: salmon data summary sheet

Table Itchen 2 sets out key statistics for the Itchen salmon population.

– Returning Stock is the number of adult salmon recorded at the Gaters Mill salmon counter – Rod Catch is the total number of salmon caught by rod and line fisheries on the river – Catch and Release rate is the percentage of those salmon immediately returned alive – Spawning Escapement is the number of salmon estimated to be available for spawning – Egg Deposition is the total number of eggs likely to be produced by those fish

River Itchen Adult Catch and Return Returning Release Spawning Egg Year Stock Rod Catch Rate Escapement Deposition (%) (millions) 1990 367 187 - 106 0.26 1991 152 69 - 37 0.09 1992 357 95 - 230 0.56 1993 852 357 - 495 1.21 1994 378 183 14 219 0.53 1995 880 241 0 664 1.62 1996 433 261 13 275 0.67 1997 246 95 14 204 0.50 1998 453 161 44 414 1.01 1999 213 92 46 176 0.43 2000 208 168 66 189 0.46 2001 217 190 99 214 0.52 2002 239 188 99 202 0.49 2003 222 78 100 204 0.50 2004 410 149 100 393 0.96 2005 411 87 100 411 1.00 2006 419 121 100 419 1.02 2007 302 224 100 301 0.73 2008 609 282 100 584 1.42 2009 276 205 100 276 0.67 2010 757 361 100 749 1.83 2011 697 295 100 697 1.70 ** 2012 622 373 100 622 1.52 2013 478 154 100 478 1.17 *** 2014 779 269 100 779 1.90 **

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 *** Provisional count awaiting verification

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Graph Test & Itchen 1: returning adult salmon stock Graph Test & Itchen 1 shows the numbers of returning adult salmon counted migrating upstream at Nursling (Test) and Gaters mill (Itchen) each year. The six-year moving average is given for each river.

1600

1400

1200

1000

800

600

400

200

0

1990 1991 1993 1994 1997 2000 2001 2003 2004 2006 2007 2009 2010 2012 2013 1992 1995 1996 1998 1999 2002 2005 2008 2011 2014

Test returning stock Test 6 year moving average Itchen returning stock Itchen 6 year moving average

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Discussion

Water Framework Directive surveys As we approach the end of the first six year cycle of the Water Framework Directive, the fish monitoring component has been revised so that we only survey waterbodies that are failing for fish, at risk from pressures likely to impact fish or are "surveillance" waterbodies, in which every ecological element is monitored. All of the sites listed in Tables Test 1 and Itchen 1 are in waterbodies already classed as less than Good for fish before 2014, except for Coxford Road, which is on the Tanners Brook, a waterbody classed as at risk from pressures linked to fish and sampled for the first time in 2014. All waterbodies monitored for fish are sampled once every six years.

Test WFD The WFD fish surveys conducted on the Test in 2014 are clustered around Romsey and the Dun. In the second six year cycle of WFD the Dun becomes a single waterbody, when it was previously two: upper and lower. The failure of both these waterbodies for fish was driven primarily by the low abundance of eels. As table Test 1 shows, the three surveys conducted on the Dun in 2014 (Park Farm, Old Vicarage and Dunbridge Station) yielded no eels, which is the primary reason they and the new waterbody are classed as less than Good in 2015. This doesn't mean eels are entirely absent from the river, only that they are absent or at very low abundance at these three spaced-out samples of the fish community and are therefore likely to be relatively scarce throughout the catchment. The area Fisheries, Biodiversity and Geomorphology (F, B&G) Team have developed a project to improve eel passage into the Dun from the main Test: one obstructive weir has already been removed and another crucial one is expected to be taken out in 2015. A lack of trout at Park Farm and salmon (parr) at Old Vicarage also contributed to the less than Good status. The Fairbourne Stream and Romsey Canal survey sites lie in the same waterbody but are physically very different - the former is a natural rain-fed stream that feeds into the latter, a manmade Test carrier. Only three minor species and a single eel were caught at Fairbourne Stream when it was last surveyed in 2011. The increased catch and number of species caught in 2014 was probably linked to the high flow conditions earlier in the year, which may have encouraged coarse species to move into side channels. However, the site still failed as a result of the lack of eels and brown trout. A fairly wide range of species was caught at Romsey Canal but the results still led to a WFD failure on the basis of low salmon, trout and grayling abundance. The survey at Coxford Road, on Southampton's Tanner's Brook was of particular interest as it revealed that this section of the middle reaches features some good quality physical habitat, which contrasts with the heavily modified and urbanised character of the majority of the watercourse. On the basis of this habitat alone, we would expect to find wild brown trout, so their absence indicates that other factors such as water quality and barriers to migration may be preventing recolonisation by sea trout. Their absence and the low abundance of eels also led to the site and waterbody being classed as Bad for fish in 2015. Also of particular interest at Coxford Road was the abundance of flounder in this wholly freshwater, urban watercourse at a site approximately 3.5km from the sea. This suggests that, whereas some factor or factors prevent sea trout from ascending this stream, the same is not true for flounder. The length of flounder caught ranged from 98 to 160mm meaning they were likely to be juveniles in their second year (see length frequency histogram SW6 in the Southampton Water section). This flounder data demonstrates that there is probably a great deal to learn about the role of freshwater habitats in the life cycle of Southampton Water's flounder population. The surveys at Timsbury Mayfly Carrier, Romsey Memorial Park and Fish Lake are used to classify the major River Test waterbody between Romsey and Kimbridge. These sites represent the relatively modified nature of the river in this waterbody, which has undergone a high degree of dredging and canalisation (over several centuries) and also features numerous flow control structures. Table Test 1 shows that the 2014 survey data resulted in the first two of these sites

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being classed as Poor and the last Bad, with the waterbody status Poor. The main reason for this is that, quite remarkably, no brown trout were caught in any of the three surveys in 2014. Lack of eels and grayling in Fish Lake also contributed to this failure. These results reflect the impact that extensive channel modification typically has on wild salmonid populations.

Tanners Brook - surprisingly good flounder The Dun at Dunbridge Station habitat

A large chub from the Fairbourne Stream Juvenile brown trout, Dunbridge Station

Perfect perch from Fish Lake Backpack survey at Park Farm

View from the survey boat at Timsbury

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Itchen WFD Although the total fish density at both Bow Lake WFD survey sites exceed that recorded at Stoneham on the Monks Brook, the key difference is that wild brown trout were abundant at Stoneham and absent from Bow Lake. This has resulted in the continued failure of the Bow Lake waterbody for fish, with the Bow Lake Fish Farm site classed as Poor, Leylands Farm as Bad and the waterbody as whole as Poor, driven primarily by the absence of brown trout. A great deal of positive work has been undertaken by the area Fisheries, Biodiversity & Geomorphology team and the Land and Water team to improve water quality on the Bow Lake, by reviewing the permits and water management practices of various local businesses. The Monks Brook waterbody is classified as Good for fish in 2015, on the basis of the 2014 Stoneham survey and also 2013 surveys at Fleming Park (High) and in Chandlers Ford (Poor). The absence of trout from the one watercourse and their abundance in the other is a clear reflection of the contrasting conditions: trout are probably unable to thrive in the Bow Lake as a result of unsuitable water quality, barriers to migration, sedimentation and low flows. On the Monks Brook, despite there being some very heavily modified sections in urban reaches, water quality, flow and migratory passage are clearly sufficiently good for trout to thrive in most reaches. The Stoneham survey is a particularly good example of this potential, in that it is actually a channelised, concrete-lined reach, where the habitat has recovered enough to provide complex fish habitat.

Straightened channel in the upper Bow Lake Concrete bed and banks on the Monks Brook at Stoneham

Test salmon parr surveys: Graph Test 1 shows that the average catch at the five Test salmon parr CPUE surveys in 2014 was the lowest recorded since these surveys began in 2007. The number of salmon parr caught in a single electric fishing run at the survey site in Romsey War Memorial Park was the second lowest recorded since these surveys began in 2003: the only lower catch was in 2005. Analysis of our salmon parr survey dataset suggests that possibly the most influential factor in determining salmon parr abundance in most years is mean flow between October and March in the winter preceding the surveys, although flow at other periods of the year is certainly also of greater or lesser importance in different years. Graph Test 2 shows that, despite a high degree of variability in the data points, there appears to be a weak, positive correlation between salmon parr abundance and flow in the previous winter, with the highest parr abundances recorded following winters where the average flow was roughly between 13 and 15m3/sec at Broadlands gauging station. However, both graphs suggest that this relationship is probably curved rather than linear and that winters where the average flow exceeds an optimum (seemingly somewhere between 15 and 19 m3/sec) appear to result in fewer salmon parr in the following summer, indicating that such flow

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may be detrimental to salmon parr production. There are several potential explanations for this observation, including the reduction in the total area of ideal spawning habitat under high flow conditions and an increase in suspended sediment load, which may promote salmon egg mortality. Whatever the actual cause, it would appear that the very low salmon parr abundance recorded in 2014 may be linked to the phenomenal and relatively sudden high flows experienced in winter 2013/14 (see the "Temperature and rainfall" section at the start of the report for rainfall data). Of course, these observations beg the question that if salmon parr abundance is largely dependent on a factor outside of our immediate influence, is there anything that can be done to increase the size of the parr population? The answer is actually very clear: in discussing the link between salmon parr abundance and environmental factors such as flow and temperature, we're only investigating the causes of variation in abundance between years and not the underlying factors that determine the overall size of the population. Factors such as habitat quality, water quality, abstraction, ease of fish passage, disease and predation are what largely determine the river's parr carrying capacity. Therefore, the removal or major mitigation of these constraints would result in a larger, more resilient parr population that would still vary in size according to prevailing climatic conditions from year to year but would do so around a greater average size and would be far less likely to experience profound reductions, such as that recorded in 2014.

Test & Itchen salmon data summary sheets Tables Test 2 and Itchen 2 provide comprehensive summaries of data for the returning adult salmon stock on both rivers. Graph Test & Itchen 1 puts the counted returning stock data into a time-series format. Analyses of these annual counts with flow, temperature and salmon parr abundance data indicate a lack of any consistent correlation. This reflects the significance of mortality in the parr to smolt and smolt to returning adult phases of the lifecycle, the first of these in the river over winter and the second at sea, from spring through to the following summer for the majority of fish (i.e. grilse). Graph Test & Itchen 1 also includes six-year moving averages for each river and these suggest a gradual increase in the average size of the returning adult stock since the early years of this millennium. However, the six year average has declined slightly on the Test since a peak in 2009. The largest number of returning adult salmon counted since records began (in 1990) was 1,487 in 2008 on the Test and 880 in 1995 on the Itchen. One of the most striking aspects of graph Test & Itchen 1 is the typical magnitude of the difference in numbers of returning adults in consecutive years: on average, the returning stock in any given year differs from that in the previous year by just under 47% on the Test and just over 55% on the Itchen.

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Salmon parr survey at Leckford The view upstream from Sheepbridge

Sheepbridge on the Test

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5. Estuarine Fish Monitoring 5.1. Southampton Water

In 2014 the Southampton Water Transitional and Coastal (TrAC) fish monitoring programme included the routine spring and autumn beach seine and beam trawl surveys at four sites, beach seine only surveys at three sites (where beam trawling would be hazardous) and fyke net surveys at a further two sites. Seine net surveys consist of two semi-circular samples in the same location, with a 45m net set from a boat. The beam trawl is 1.5m wide and is towed for exactly 200m, parallel to the shore, at the seine net site. Each fyke survey consists of two double ended fykes, set close to shore in one metre of water at low tide and left for 24 hours. All the sampling described above is carried out by the local area team. The programme also includes an autumn otter trawl survey which in 2014 comprised of three 10 minute trawls, carried out by the coastal survey vessel "Solent Guardian" near to the edge of the maintained shipping channel, around 600m east of Hythe.

Map SW1 shows the TrAC monitoring sites in Southampton water, coloured according to the types of survey carried out at each location.

Map SW1: TrAC survey locations

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Left: Sparsholt College marine conservation students haul the seine net at Manor Farm Right: The otter trawl being retrieved aboard the coastal survey vessel Solent Guardian

Table SW1 summarises the 2014 classification results for Southampton Water. For each of the four sampling methods, a score between 1 and 5 is calculated for the ten metrics that make up the classification tool. Overall scores (Ecological Quality Ratios: EQR) are given for each method at the bottom of each column, with the overall estuary score in the bottom right cell. NB the "boot" column refers to "bootstrapping, a statistical method for taking variance in the whole dataset into account.

Table SW1: 2015 WFD classification results

Southampton Water Method Number of samples 37 12 14 161 Total: 224 Metric description Beam trawl Fyke Otter trawl Beach seine boot 1. Species composition 2 4 3 1 1.94 Species diversity & composition 2. Presence of indicator species 5 3 3 3 3.53 3. Species relative abundance 5 2 2 3 3.27 Species abundance 4. Number of taxa that make up 90% of abundance 5 4 4 3 3.78 5. Number of estuarine resident taxa 3 4 4 4 3.74 6. Number of estuarine dependent marine taxa 2 5 5 3 3.25 Nursery function 7. Functional guild composition 3 5 5 5 4.47 8. Number of benthic invertebrate feeding taxa 2 5 4 4 3.64 9. Number of piscivorous taxa 3 3 4 3 3.09 Trophic inegrity 10. Feeding guild composition 5 5 5 5 5.00 EQR 0.63 0.75 0.73 0.60 0.64

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Graph SW1 shows the total number of fish of each species caught at all sites for the spring and autumn survey seasons in 2014. Fish are ordered from highest to lowest catch in spring.

Graph SW1: Fish abundance by species in spring and autumn, 2014

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Spring Autumn

Graph SW2 shows the total spring and autumn catches for the seine nets & beam trawls combined for Southampton water for all survey years.

Graph SW2: combined seine & beam trawl catch, spring and autumn

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Graph SW3 shows the catch in the autumn CSV otter trawl, carried out in deeper water near to Hythe Pier

Graph SW3: Species caught in the Autumn Otter trawl near Hythe 300

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Graph SW4 shows the total number of bass caught in the spring and autumn surveys in each survey year.

Graph SW4: Bass catch in spring and autumn

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Spring Autumn

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Graph SW5 shows the catches of six flatfish species in the CSV otter trawl near to Hythe Pier in each survey year. Catch is expressed in the number caught per minute of trawling (NB the line for brill appears to show zero for all years but, in fact, one specimen was caught in 2009).

Graph SW5: Flatfish caught per minute in the CSV trawl off of Hythe pier

8 Solenette 7

6 Sole

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3 Flounder

2 Dab 1 Brill 0 2009 2010 2011 2012 2013 2014

A large plaice (left) and a dab (right)

Brill Dover sole

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Graph SW6 is a length frequency distributions of flounder captured in spring and autumn for all of our survey years combined in Southampton Water.

Graph SW 6: Flounder frequency histogram

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Graph SW7 shows the relationship between the number of flounder caught in our spring surveys and the average Hayling Island sea surface temperature in spring.

Graph SW7: Flounder catch and spring sea surface temperature

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20 C Deg

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Total spring catch Mean spring Hayling sea surface temp. C

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Graph SW8 shows the same data as a scatter plot, illustrating the negative correlation between mean spring sea surface temperature and total flounder abundance in the spring survey catch (correlation coefficient, r = -0.9).

Graph SW8: Flounder catch and spring sea surface temperature

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Flounder 15 10 5 0 6 7 8 9 10 11 12 Deg C

Emptying a fyke net end at Bury Marsh

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Discussion Southampton Water WFD status Table SW1 shows the results of the 2014 classification analysis by the Transitional and Coastal Fish Index tool (TFCI) for Southampton Water and indicates that the individual scores (EQR's) for each sampling method, and also the overall score, were in the Good range (i.e. > 0.58 & <0.81). It's essential to take into account the "confidence in class" statistic that's also calculated and this is 92.4% meaning that the we can be "Quite Certain" That the Southampton Water's fish community is at "Good" status in 2015 (>95% = "Certain"; <75% = "Uncertain"). This represents a change from the 2013 status, which was "Moderate", with a confidence in class of "Uncertain". An informal investigation into what aspects of the fish data have changed will be undertaken in spring 2015.

General observations 2014 was the eighth consecutive year in which we have monitored the fish population in Southampton Water. This year we caught 33 species in total, with one new addition to our all-time species list in the shape of a three-spined stickleback (caught at Calshot - although capable of surviving at sea, this was probably washed out of a river by flood flows). This brings the total number of fish species we have captured in Southampton Water up to 62. Overall, catches in the spring were relatively high and comparable with the largest catches that we have had in spring in the estuary (Graph SW1). It is likely that the mild water temperatures that we had throughout the winter of 2013/14 helped the survival of small estuarine species and overwintering juveniles. Impacts of the severe storms that damaged structures along the South coast and beyond appear not to have impacted the fish population in the estuary. Throughout the summer, warm, settled weather ensured high inshore water temperatures and the autumn catch was again relatively high in comparison to previous years (Graph SW2). We carried out our annual otter trawl in October and caught a variety of deeper water fish species that we tend not to see in the catches using other methods, including thornback ray, starry smooth hound and tub gurnard, as shown in Graph SW3. Graph SW4 shows that numbers of bass caught in spring and autumn were relatively high and we know from analysis in previous reports that bass abundance is closely linked to prevailing sea temperature. Bass caught in spring are predominantly overwintered juveniles entering their second year of life, whose abundance is largely dependent on winter sea temperature: those caught in autumn are predominantly young of the year whose abundance is closely linked to summer sea temperature. This year we have seen an increase in the number of flatfish caught in both our fyke nets and the otter trawl, with the otter trawl in particular showing a positive trend in flatfish catches (Graph SW5). Solenette, Dover sole and plaice all show upward trends in abundance over the past five years but flounder continue to be captured in very low numbers. Flounder spawn in spring, with juveniles of around 30mm length drifting into estuaries from May to July - these grow to approximately 80mm by the end of their first year. It is likely that the majority of the juvenile flounder we catch in our spring surveys are migrating upstream through the estuary to less saline environments (streams such as the Tanner’s Brook, for example), where a WFD survey captured a number of juvenile flounder (see page 51). Graph SW6 shows that the 0+ year class flounder are almost exclusively caught in the spring and are present in much lower numbers in our autumn surveys. Flounder can penetrate far into freshwater and these habitats are probably essential to maintain a large, resilient population. When looking at the Southampton water flounder population over time, there is a strong link between the numbers of juveniles we catch in the spring and the average temperature spring sea surface temperature: cooler spring seas result in more juvenile flounder and vice versa.

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Juvenile golden, thick and thin lipped grey mullet are not easy to tell apart

Tub gurnard, left, and thornback ray, right, both from the Hythe otter trawl

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5.2. Adur Estuary

In 2014 we surveyed the three routine sites on the Adur estuary; Ladywell Stream, Old Toll Bridge and Kingston Beach. We carried out seine net and beam trawl samples at each site, using the same techniques as in Southampton Water. Map Adur 1 shows the locations of these sites.

Map Adur TrAC 1 shows the location of surveys carried out in the Adur estuary in 2014

Map Adur TrAC 1: survey locations 2014

A juvenile Dover sole from Kingston Beach Towing the Kingston beam trawl

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Results Table Adur TrAC 1 summarises the 2014 classification results for the Adur estuary. For each of the two sampling methods, a score between 1 and 5 is calculated for the ten metrics that make up the classification tool. Overall scores (environmental quality ratios: EQR) are given for each method at the bottom of each column, with the overall estuary score in the bottom right cell. NB the "boot" column refers to "bootstrapping, a statistical method for taking variance in the whole dataset into account.

Table Adur TrAC 1: 2015 WFD classification results

Adur Method Number of samples 29 71 Total: 100 Metric description Beam trawl Beach seine boot 1. Species composition 3 1 1.33 Species diversity & composition 2. Presence of indicator species 5 1 1.66 3. Species relative abundance 5 4 4.16 Species abundance 4. Number of taxa that make up 90% of abundance 5 5 5.00 5. Number of estuarine resident taxa 2 3 2.84 6. Number of estuarine dependent marine taxa 4 3 3.16 Nursery function 7. Functional guild composition 4 5 4.84 8. Number of benthic invertebrate feeding taxa 3 2 2.16 9. Number of piscivorous taxa 3 2 2.16 Trophic inegrity 10. Feeding guild composition 5 5 5.00 EQR 0.73 0.53 0.56

Graph Adur TrAC 1 shows the number and species of fish caught in all surveys combined in the 2014 spring and autumn survey.

Graph Adur TrAC 1: Number & species of fish caught 2014

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Spring Autumn

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Graph Adur TrAC 2 shows the 2014 spring and autumn catches compared to those in previous survey years.

Graph Adur TrAC 2: Total catches 2010-2014

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Spring Autumn

Graph Adur TrAC 3 shows the relationship between the number of bass caught in autumn on the Adur estuary and the average summer sea temperature.

Graph Adur TrAC 3: Bass catch and average summer temperature

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Discussion WFD status Table Adur 1 shows the results of the 2014 classification analysis by the Transitional and Coastal Fish Index tool (TFCI) for the Adur Estuary. This indicates that the overall score (EQR) for the beam trawl data was in the "Good" range (>0.58 & <0.81) but that the beach seine score was in the "Moderate" range (<0.58 & >0.4). Combined, these resulted in an overall estuary score of 0.56, so the formal 2014 classification for the estuary is "Moderate". The "confidence in class" statistic is 83.4% meaning that we can be "Quite Certain" that this is the correct status for the Adur estuary's fish community in 2015 (>95% = "Certain"; <75% = "Uncertain"). This is the same classification as in 2013. By checking the ten individual metric scores in the beach seine net column in the table we can see that metric 1 and 2, "species composition" and "presence of indicator species" both score only 1 out of 5 and are therefore the primary reasons for the overall EQR being below the threshold for Good status. A formal investigation into the validity of this apparent WFD failure will completed in spring 2015.

General observations Graph Adur TrAC 1 shows that spring surveys on the Adur estuary resulted in a very low overall catch of just 238 fish, only one individual of which was a bass. This is probably due to the very high rainfall and subsequent river flows experienced in winter of 2013/14: the Adur estuary is far narrower than Southampton Water and water velocities can be very high as a result of river discharge and tide. This effect is exacerbated by the massive earth and chalk embankments that keep water within the channel and prevent flooding of the wider valley. This means that there is very little "off-channel" habitat for juvenile and small fish to use as refuge from high water velocity, so there is an increased risk of a proportion of the fish community to be "washed out" during very wet winters such as 2013/14. A very settled warm summer, with little in the way of high flow periods, appears to have resulted in excellent survival and growth conditions in the estuary, producing our highest ever autumn catch for the Adur (Graph Adur TrAC 2). We saw a 400% increase in the juvenile bass abundance compared to our highest previous catch and goby numbers, both sand and common, were the highest recorded. The warm summer sea temperature and the link between sea temperature and the number of bass caught in our autumn surveys can clearly be seen in graph Adur TrAC 3. The Beam trawl carried out at Kingston beach turned up some interesting species, with a brill in the spring and a lesser weever fish in the autumn catch. This highlights the importance of carrying out surveys across a wide range of habitats and salinities within the estuary as these fish wouldn't be found in the higher, more riverine locations further inland.

Two interesting specimens from the Kingston Beach surveys: a large thick lipped grey mullet (left) and the first lesser weever we've captured in the Adur estuary

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6. Fish monitoring in 2015

The Solent and South Downs fish monitoring programme for 2015 is relatively large and includes the following elements:

• Biennial Eel Index monitoring on the Ouse and Itchen (10 sites each) • Six-yearly Principal Brown Trout spatial monitoring on the upper Itchen (14 sites) • Six-yearly salmon parr spatial monitoring on the Itchen (14 sites) • Principal Coarse Fishery monitoring on the Cuckmere, Ouse, Adur, Western Rother, Wallington and Hamble (5 sites each except for Wallington & Hamble; 2 sites each) • Estuarine fish surveys in spring and autumn on the Adur at Shoreham and throughout Southampton Water (24 surveys in total) • Annual Principal Brown Trout temporal monitoring on the Meon, Lymington and Beaulieu (2 sites each) • 28 Water Framework Directive surveys, covering various catchments across Hampshire, West and East Sussex

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List of abbreviations

EQR: Ecological Quality Ratio F, B & G: Fisheries, Biodiversity & Geomorphology Team TFCI: Transitional and Coastal Fish Index TrAC: Transitional and Coastal, the term used for our estuarine fish survey programme. WFD: Water Framework Directive.

Glossary

Biomass: a measure of the weight of fish per unit area. In this report, density means the weight of fish in grammes per 100m2. Canalise / channelise: to straighten and widen a natural, varied watercourse Density: a measure of fish abundance per unit area. In this report, density means the number of fish per 100m2. Length-frequency histogram: a graph that shows the number of fish in each incremental length category (usually 5mm) that helps clarify the size and age structure of a fish population. Waterbody: a sub-catchment of a river, or a coastal water or lake that is a discrete management unit for the Water Framework Directive. For rivers, these divisions are usually based on natural hydrological units, such as tributaries. Water Framework Directive: a European Union Directive that sets out a common approach to the monitoring, management and improvement of fresh and coastal waters, with the aim of all waterbodies achieving at least "Good" status by 2027.

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www.gov.uk/environment-agency

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