The Fish Community of the Lower River Test

The fish community of the lower River Test

D. Longley, 11th April, 2017

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

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

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Foreword

The River Test in Hampshire is widely renowned for the quality of its water, its pastoral landscape, the wildlife it supports and the fishing it provides. Internationally, it is a byword amongst anglers for very high quality fishing in an idyllic environment, steeped in angling history. The prime quarry is the brown trout Salmo trutta but there are productive salmon Salmo salar and sea trout (also Salmo trutta) fisheries in the lower reaches and coarse (non-salmonid species) and grayling Thymallus thymallus fishing is increasingly popular in winter. Due to the high demand for trout fishing throughout the season, the majority of fisheries supplement their stock by regularly introducing farmed fish. Nonetheless, fish population surveys throughout the catchment demonstrate that wild trout are abundant wherever habitat quality is good enough, which is typically in unimpounded, less modified reaches. In common with most rivers, the number of fish species present increases farther downstream, but unusually, the Test has relatively steep, fast-flowing sections in its lower reaches, so the species that are typically representative of the upper parts of the river, especially wild brown trout and grayling, also thrive here. Several fish species found in the Test are of international conservation interest, including Atlantic salmon, European eel Anguilla anguilla, bullhead Cottus gobio, brook and sea lamprey Lampetra planeri / Petromyzon marinus. This report focuses on the fish community of the lower River Test, downstream of Romsey. Several sources of information are used, including using electric fishing survey data, fish counter data, fishery catch records and various other observations.

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Contents

Foreword ...... 3 1. Fish population surveys ...... 5 2. Additional fish records ...... 8 Other coarse species...... 8 Estuarine species ...... 8 Lamprey ...... 8 3. Salmon counter records ...... 9 4. European eel ...... 11 5. Water Framework Directive (WFD) status ...... 13

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1. Fish population surveys

Eighteen fish population surveys by electric fishing have been conducted by the Environment Agency on the lower River Test downstream of Romsey. The earliest of these was in 2004 and the most recent 2016. Seven survey sites were included, all of which are within the Broadlands Estate. Two different survey techniques were used: eleven surveys used a method known as "catch per unit effort" (CPUE), which is suited to measuring juvenile salmon (parr) abundance in wide, shallow sections of river - this involves fishing with a portable electric fishing unit worn as a back-pack and walking in a straight line upstream for a set distance and time. The specific location, distance and time are kept the same to maintain consistency between different survey years. The second method is known as a "single catch" survey and involves fishing the full width of the channel in an upstream direction, terminating at a stop-net set across the channel. Usually two electric fishing anodes are used to give broader coverage and these are connected to equipment towed along in a small dinghy. This latter method provides a better measure of species abundance across the whole fish community and invariably catches far more fish. Map 1 shows the seven lower Test fish population survey locations and Table 1 shows the years in which these were surveyed and the method used.

Map 1: Lower Test fish population survey locations

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Table 1: fish population survey methods and dates Location Type Date Upstream M27 CPUE 28/08/2007 Upstream M27 CPUE 16/09/2008 Upstream M27 CPUE 13/08/2009 Upstream M27 CPUE 29/07/2010 Upstream M27 CPUE 23/08/2012 Upstream M27 CPUE 23/09/2014 Mainstone Farm CPUE 12/08/2010 Mainstone Farm CPUE 25/08/2016 Longbridge CPUE 12/08/2010 Longbridge CPUE 25/08/2016 Moorcourt Carrier CPUE 23/08/2012 Moorcourt Carrier Single catch 25/08/2004 Moorcourt Carrier Single catch 11/08/2010 Moorcourt Carrier Single catch 25/08/2016 Moorcourt Main Single catch 25/08/2004 House Beat Single catch 02/09/2004 Broadlands trout stream Single catch 15/08/2008 Broadlands trout stream Single catch 14/06/2013

Atlantic salmon parr Excellent parr habitat at Moorcourt carrier

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Figure 1 is based on the entire, combined catch from the eighteen lower Test fish population surveys and lists species in order from most to least abundant. The horizontal bar for each species represents the percentage of the total catch.

Figure 1: Fish species abundance in lower Test fish population surveys

Minnow Atlantic salmon Eel Bullhead Stone loach Chub Brown trout Dace Gudgeon Grayling Roach Perch Pike 3 sp stickleback 0 5 10 15 20 25 30 35 %

Figure 2 lists the fish species caught in the eighteen fish population surveys in order according to total weight of catch. The horizontal bar for each species represents the percentage of the total weight of catch. Note that very small species (bullhead, minnow, brook lamprey, stickleback & stone loach) are not measured or weighed during surveys so are excluded from this graph.

Figure 2: Fish species percentage of total weight in lower Test fish population surveys

Eel Chub Brown trout Pike Atlantic salmon Dace Roach Grayling Gudgeon Perch

0 10 20 30 40 50 60 %

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2. Additional fish records

Because the fish surveys discussed in this report have been targeted at suitable salmon parr habitat, they are unlikely, inevitably, to encounter the fish species that reside in deeper, slower sections of the river - the majority of this habitat type lies downstream of the M27, where no formal surveys have been conducted. Therefore, it's important to take into account other sources of information on the fish community in these reaches.

Other coarse species Anglers fishing for salmon and sea trout on the lower Test occasionally catch coarse fish species; most frequently perch Perca fluviatilis, pike Esox lucius and chub Leusicus cephalus, but carp Cyprinus carpio, common bream Abramis brama, roach Rutilus rutilus and eel Anguilla anguilla have also been recorded in the catch records. Environment Agency staff routinely spend time on a range of different tasks at Testwood water works and large chub, carp and common bream are often observed.

Estuarine species Flounder, Platichthys flesus and sea bass Dicentrarchus labrax are marine fish species that are estuary-dependent for part of their life cycle and frequently venture quite significant distances into freshwater; both species are caught surprisingly frequently in Testwood and Nursling fisheries by anglers fishing for salmon and sea trout. A thin-lipped grey mullet Liza ramada was filmed underwater immediately downstream of the Nursling fish counter in December 2016. Like flounder and bass, this species is often found in the lower reaches of rivers and can tolerate freshwater.

Lamprey Sea lamprey Petromyzon marinus are occasionally seen in spring and summer, as they ascend the river to spawn on gravel riffles and they have been photographed ascending the Nursling salmon counter. During an operation to capture adult salmon broodstock in the little River Test at Conegar in the early 2000's, the water level was reduced by closing the set of hatches upstream, exposing several beds of deep sediment - these were found to be densely populated with juvenile brook lamprey Lampetra planeri ; several hundred were observed. In order to sample this species effectively by electric fishing, effort needs to be focussed specifically at silt beds and for a longer duration than for other species - this is why the species is absent from the lower Test fish population survey record.

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3. Salmon counter records

Since 1990, the numbers of Atlantic salmon migrating upstream into the River Test each year have been monitored using a resistivity fish counter at Nursling Mill. Counter data and photographic images are used to estimate the total number of upstream migrating salmon each year. Calculations are made in order to account for days that the counters are out of operation and to account for the estimated proportion of salmon migrating via the Little River Test (and thus bypassing the counter). Map 2 shows the location of Nursling salmon counter. The alternative migration route, via the Little River Test, is on the easternmost channel, which leaves the main Test a few hundred metres upstream of Nursling Mill and rejoins a short distance upstream of Redbridge.

Map 2: Location of Nursling salmon counter

Figure 3 shows the estimated annual salmon runs for the River Test between 1990 and 2016, along with the five year moving average. Also shown is a horizontal line set at 1,395 returning adults: this is the number required to meet the egg conservation limit of 3.4 million eggs, which is the theoretical target number of salmon required to ensure long-term sustainability of the population.

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Figure 3: Estimated annual salmon runs, Test & Itchen, 1990-2016

2200 2000 1800 1600 1400 1200 1000 800 600 Est. upstream salmon Est. 400 200

1990

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2015 2016

Estimated run Egg conservation limit 5 per. Mov. Avg. (Estimated run)

Figure 3 emphasises that, while the trend on the Test is towards an Atlantic salmon population that is increasing in size, by far the majority of estimated runs since 1990 fall well below the threshold for population sustainability. This figure also demonstrates the high degree of variability in salmon run sizes between successive years.

Several studies have analysed the Nursling salmon counter dataset, alongside a variety of environmental data including flow, temperature, tides and turbidity, with the aim of better understanding factors governing salmon migration into the lower Test. The ultimate objective is to develop a model accurate enough to reliably predict salmon migratory behaviour across the spectra of environmental conditions, which would, among other things, allow the forecasting of any potential effects on salmon migration of different degrees of water abstraction for public supply. However, the sheer number of environmental variables involved, as well as the highly variable (and always unknown) number of returning adults in different years means that such a model does not yet exist and may continue to elude fisheries scientists indefinitely. Another important level of complexity is the probability that salmon behaviour itself varies depending on a rage of factors, including age, size, health and time spent in fresh or brackish water.

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4. European eel

The dramatic decline in abundance of the European eel across its range has caused widespread concern because of the species' immense value both economically and ecologically. The Test's neighbour, the River Itchen was designated as an Eel Index river in 2009, which involved the commencement of specific eel population surveys; ten sites spread throughout the catchment are sampled by catch-depletion (three-run) electric fishing every two years. The data collected strongly suggests a rapid and steady decline in eel abundance between 2009 and the most recent surveys in 2015. Naturally, there is concern that a similar decline might be in progress on the Test, but there is no equivalent programme of detailed eel population monitoring. Nevertheless, there is a programme of detailed salmon parr monitoring on the Test in which all eels are recorded. This programme involves single-run, full channel-width electric fishing surveys at eleven sites and 5 minute, timed catch per unit effort surveys at a further fifteen sites: all 26 surveys are conducted every six years. Figures 4 and 5 compare the total number of eels caught at the same survey sites, using the same electric fishing techniques, between 2010 and 2016. Figure 4 shows 5 minute, timed catch per unit effort survey results, hence the lower catches, while Figure 5 shows single run, full channel width electric fishing surveys. In both figures, survey sites are listed in upstream to downstream order from left to right.

Figure 4: Total eel catches in 2010 & 2016 in R. Test CPUE salmon parr surveys

5 2010 4

Total eels Total 2016 3

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Figure 5: Total eel catches in 2010 & 2016 in single-run R. Test salmon parr surveys

20 2010 2016

Totaleels 15

The total number of eels caught in all River Test salmon parr surveys in 2010 was 151, compared with 61 in the repeat surveys in 2016: this is a decline of just under 60% and very similar to the decline in survey catches on the River Itchen. In all rivers, European eel abundance tends to increase with reduced distance from the sea. Therefore, the highest densities recorded are typically in the most suitable habitat in the lowest reaches, while the lowest densities are in the upper headwaters. This is partly due to the availability of food and territory and partly a natural effect of the fact that all European eels found in inland freshwaters have migrated from the Sargasso Sea into coastal waters, before ascending river systems.

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5. Water Framework Directive (WFD) status

5.1. General situation WFD fish population survey results are classified using FCS2 (the Fisheries Classification Scheme, Version 2). FCS2 uses a range of complex statistical models and geographical data to predict the fish community at any given location under natural conditions. The system then compares this with the actual survey catch at individual sites and provides a score (Environmental Quality Ratio: EQR) that reflects whether or not the two are similar. Scores determine formal classifications and may be Bad, Moderate, Good or High: Bad or Moderate constitute failures. The overall waterbody classification for fish is determined by the average EQR score of the constituent surveys. The River Test waterbody above the tidal limit is named Test (lower), with the code GB107042016840. This waterbody as a whole was classed as being at Good status for fish in the most recent (interim) 2016 round of classification; this is based on two site-level classifications, both of which were also classed as Good. The first was the 2010 survey on Moorcourt carrier, the second the 2013 Broadlands trout stream survey. The next waterbody upstream commences at approximately Broadlands House and is named Test (confluence Dun to Tadburn Lake, GB107042016460) - this waterbody is currently at Poor for fish, the failure being driven predominantly by lack off brown trout and eels.

5.2. Analysis of fish samples and EQR Figures 6 and 7 below show detailed results of the classification analysis for Moorcourt carrier and Broadlands trout stream respectively. In both figures, the first column shows the catch in the fish population survey; the second shows the probability that more of each would be caught under pristine / reference conditions and the third column shows the probability of each species being present under pristine / reference conditions (i.e. the predicted fish community).

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Figure 6: WFD classification results for Moorcourt carrier

Figure 7: WFD classification results for Broadlands trout stream

The two bar charts on the right hand side of each figure show that, for both survey locations, brown trout, salmon and eel have the highest calculated probability of being present, so the WFD status of the waterbody for fish rests predominantly on the abundance of these three species. Figures 6 and 7 indicate that the greatest discrepancy between expected and observed abundance at both sites was for brown trout; the second greatest discrepancy at Moorcourt was for eel and on the Broadlands trout stream it was for salmon. Despite this, the presence of more species than were expected (albeit at low abundances) resulted in the surveys meeting the threshold score for Good

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status, although the waterbody EQR of 0.49 is closer to the Moderate / Good boundary (0.4) than the Good / High boundary (0.7), as shown in the figure 8, below. This reflects the lack of the most expected species and indicates that the Good status of this waterbody should be interpreted as vulnerable to deterioration, particularly if there are known pressures that are likely to have had an impact since classification or which are likely to increase in future.

Figure 8: Waterbody EQR position within class boundaries

5.3. Relevance of migratory species With waterbody status resting largely on three species, it is important to understand the implications of their ecology: salmon and eel are exclusively migratory species; eels are "catadromous", reproducing at sea and entering freshwaters to feed and grow. Salmon are the opposite; "anadromous", feeding and growing at sea and only entering freshwaters to reproduce - both species migrate enormous distances. Therefore, every salmon and eel in the Test that survives to complete its lifecycle must travel between the sea and the freshwater reaches at least twice as they migrate between their feeding and spawning areas. A major component of the brown trout population of the lower Test is migratory: a proportion of juvenile trout migrate to sea to feed and grow, before returning to the Test to spawn - these fish are known as "sea trout". In general, the physical form and migratory behaviour of sea trout is superficially similar to salmon, with the important exceptions that sea trout migrate less far in the sea compared to salmon and that it is usual for sea trout to spawn several times in their lives (moving between sea and river each time), whereas the majority of salmon die shortly after their first spawning. Therefore, the WFD status for fish of the lower Test waterbody is closely associated with migratory conditions between the estuary and the river for sea trout, salmon and eels and additional pressures constraining the success of one or more of these species can be expected to increase the probability of waterbody status deterioration. It is also important to note that brown trout, eel and salmon are also highly influential in the status of the next waterbody upstream, Test (confluence Dun to Tadburn Lake, GB107042016460) which is currently at Poor for fish.

5.4. Pressures on key species Anthropogenic pressures likely to constrain salmon, sea trout and eel populations and therefore affect WFD status on the Test, include abstraction, entrainment of juveniles at abstraction points, barriers to migration, sedimentation and deterioration in water quality - which are inter-related. Another pressure, which may have a less direct anthropogenic basis, is a higher frequency of stressful climatic conditions, especially high water temperature and low flow. For example, juvenile

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salmonid abundance across the UK and France in 2016 was exceptionally low, most probably as the result of record-breaking high temperatures in the previous December (the spawning period) - there is some evidence of the same phenomenon the following year. For salmon and eels, pressures on the marine phases of their lives play an extremely important role in population size, particularly changing ocean currents, water quality, prey availability and exploitation. The sharp decline in eel abundance across its range and reflected in River Test catch data comparing 2010 with 2016 (figure 5) suggests that the WFD status of the lower Test waterbodies may deteriorate if recalculated using contemporary fish population data. If not, then deterioration can be expected in future if the decline continues. Although the dynamics of eel populations in the lower reaches of rivers and their estuaries are not well understood, it's clear that these reaches provide the most important feeding and growing habitat and support the highest population densities, rather than solely being migration routes. Therefore, the vulnerability of eel status within the WFD classification should be viewed in terms of potential impacts on growth and survival, as wells as constraints to migration. In conclusion, the WFD fish classifications of both of the River Test's two lowest waterbodies are largely dependent on wholly or largely migratory species, whose populations are evidently under considerable pressure and are at sub-optimal levels. The combined evidence strongly suggests that, in order to reduce the risk of WFD class deterioration in the lower waterbody and to improve the chance of the next waterbody achieving Good status, it is necessary to take active steps to increase population resilience as far as possible. This will be best achieved by reducing pressure on the freshwater life stages, particularly migration and reproduction.

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