Solent & South Downs Area fish monitoring report
Results of all fish monitoring work conducted in SSD in 2013
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Foreword
The foreword to our 2012 report focused on the two starkly contrasting features of the weather that made the year so remarkable: winter drought in 2012/13 and the very wet summer that followed it, both of which undoubtedly influenced fish populations locally. This year, there is a slight sense of déjà vu but in 2013 it's the bitterly cold period that seemed to replace spring, testing the whole country's resolve in the process, followed by the kind of warm, settled summer many of us had been wishing for many years. Of course, writing in spring 2013/14, all thoughts of summer weather were washed away by the relentless rainfall and devastating flooding that gripped the country from early December until quite recently. Emergency flood management work interrupted all normal Environment Agency work, including the preparation of this report. In fact, major operations to collect tens of thousands of sandbags from Romsey and Winchester have only just been completed. The 2013 fish monitoring programme was the largest we've ever conducted and included the following principal programme elements:
– In-depth monitoring of eel populations on the Itchen and Ouse (biennial eel index surveys) – A large number of Water Framework Directive fish surveys across the area in preparation for the completion of the first River Basin Management Cycle and commencement of the second in 2014 – Six-yearly surveys of wild brown trout populations in the New Forest and on the Ouse – Three-yearly Principal Coarse Fishery monitoring of the River Arun – Biennial Principal Coarse Fishery monitoring on the Ouse – Annual Principal Coarse Fishery reference monitoring on the Western Rother – Spring and autumn Water Framework Directive Transitional and Coastal (estuarine) fish monitoring in Southampton Water and the Adur.
Acknowledgements:
We are grateful to the landowners, fishing clubs, farmers and land agents who kindly allowed us access to their land in order to conduct fish population surveys in 2013. We are especially grateful to the river keepers, whose local knowledge is invaluable in informing our work.
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Executive summary
These are the key conclusions of this report:
– Biennial eel index monitoring on the River Itchen suggested that eel abundance has reduced significantly since the first round of monitoring in 2009, with approximately 25% fewer eels caught in total in 2013 compared to 2009. Far fewer eels were caught on the Ouse in all three survey years (2009, 2011 & 2013) and the lack of any trends in terms of abundance may be largely the result of the small sample sizes. – An extensive survey of wild brown trout in the New Forest demonstrates that geographical distribution is very similar to that recorded in 2007 but that abundance was less than half. Data from routine sites monitored annually suggest that this does not indicate a consistent reduction between 2007 and 2013 but rather reflects wide natural variation between years linked to rainfall and temperature. – Fish community data from the large number of riverine Water Framework Directive surveys completed in 2013 reflect the substantial natural variation and variation in environmental quality in watercourses across the Solent & South Downs Area. This information will be used to classify individual waterbodies as being of good or less than good status for fish, which in turn prioritises waterbodies for improvement. – Coarse fish data collected in 2013 generally indicates low abundances in the area's rivers, particularly the Arun and Western Rother. Analysis of prevailing climatic conditions since the millennium strongly suggests that the principal cause is the succession of relatively cool summers since 2010, although the resilience of local fish populations to such challenging conditions is likely to be compromised by various anthropogenic pressures. – Abundance of salmon parr at survey sites on the Itchen was low compared to previous survey years and is likely to be a reflection of challenging conditions for survival in winter 2012/2013. – Wild brown trout parr abundance at the two Upper Itchen annual survey sites were higher than in the past two years but lower than the long term average. As with trends in coarse fish and salmon abundance, this is likely to be driven by prevailing flow and temperature conditions. However, there is evidence to suggest that these particular trout populations are highly dependent on adequate summer flow. – Transitional & Coastal (TrAC: estuarine) fish monitoring in both Southampton Water and the Adur estuary produced very low catches in spring but much higher ones in autumn, reflecting the long, cold spring and contrasting settled, warm summer. Twenty-eight fish species were recorded in Southampton Water, including four not caught previously, while fourteen species were recorded in the Adur estuary.
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Contents
Foreword 3 Executive summary 4 Rainfall and temperature in 2013 6 Interpreting results 9
River reports east to west: 1. East Sussex 1.1 Pevensey Levels & Coombe Haven 10 1.2 Cuckmere 15 1.3 Ouse 19
2. West Sussex 2.1 Adur 33 2.2 Arun 35 2.3 Western Rother and western streams 42
3. Isle of Wight 48
4. Hampshire 4.1 Wallington 52 4.2 Meon 55 4.3 Hamble 58 4.4 Itchen 61 4.5 Test 72 4.6 New Forest 76
5. Estuarine fish monitoring 5.1 Southampton Water 88 5.2 Adur estuary 97
6. Looking forward 100
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Rainfall and temperature in 2013
River flow and temperature influence fish spawning success and juvenile survival quite strongly, so before looking at fish survey results and considering the current abundance and distribution of fish in our area, particularly juveniles, we need to have a good grasp of what the prevailing weather conditions were like during the most recent salmonid and coarse fish spawning periods; winter 2012 / 2013 and spring and summer 2013 respectively. The two charts below clarify patterns of rainfall and temperature between October 2012 and December 2013. All fish surveys included in this report were completed by the end of October 2013, so the November and December data is included to give us a feel for how winter 2013/2014 is shaping up in terms of conditions for salmonid spawning and juvenile coarse fish over-winter survival. The first chart shows the average temperature for each month of the past fourteen months, compared with the average monthly temperature and the monthly maximum and minimums for the period 1999-2012. The data is from the Met Office's Hadley Central England Temperature dataset.
22 20 18 16 14 12 10
DegreeC 8 6 4 2 0 -2 Oct Nov Dec Jan Feb Mar Apr May Jun July Aug Sept Oct Nov Dec 2012 2012 2012 2013 2013 2013 2013 2013 2013 2013 2013 2013 2013 2013 2013
Monthly mean temp. Oct 2012 - Dec 2013 Monthly mean 1999-2012
Max 1999-2012 Min 1999-2012
Chart Temp 1: monthly mean temperature, October 2012-December 2013
The second chart covers the same period and shows total monthly rainfall measured at the Environment Agency's Romsey weather station, compared with the 1999-2012 monthly averages, maximum and minimums.
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240
220
200
180
160
140
120 MM 100
80
60
40
20
0 Oct Nov Dec Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec 2012 2012 2012 2013 2013 2013 2013 2013 2013 2013 2013 2013 2013 2013 2013
Monthly total Oct 2012-Dec 2013 1999-2012 mean monthly total Max 1999-2012 Min 1999-2012
Chart Temp 2: monthly total rainfall (Romsey), October 2012-December 2013
By comparing temperature and rainfall over the past fourteen months with the maximum and minimum values from 1999 to 2012, the charts highlight abnormally cool, warm, wet or dry months. Three months are outside of the 1999-2012 maximum / minimum ranges and indicate periods where temperature and / or flow are abnormal and therefore more likely to have stressed local fish populations. – March 2013 was, on average, 3.6c◦ cooler than the 1999-2012 average and 1.7c◦ cooler than the minimum. – Total rainfall recorded at Romsey in July 2013 was only 22% of the average and 57% of the minimum. – Total Rainfall recorded at Romsey in December 2013 was 219% of the average and 126% of the maximum. These are the extremes, or outliers. A more general summary is that winter 2012/2013 was particularly wet, spring 2013 was the coldest in more than a decade and summer 2013 was very dry, with a notable warm spell in July and August. Autumn 2013 started wet but became unusually dry in November before rapidly developing into by far the wettest December in over a decade. At the time of writing, river and coastal flooding continues to dominate the headlines and record river and groundwater levels have been broken in some local catchments.
The cold, prolonged spring is likely to have increased mortality among juvenile coarse fish, delayed the development and hatching of salmonid eggs and delayed reproduction by early spawning species, including dace, grayling and pike. The acute dry period in July was particularly stressful for salmonids in catchments susceptible to low flow, as reflected in our New Forest survey results this year.
On a more positive note, the low flows and high temperatures through mid to late summer provided excellent conditions for juvenile coarse fish growth and survival. Unfortunately, the prolonged
UNCLASSIFIED 7 of 101 UNCLASSIFIED heavy rainfall and subsequent flood conditions affecting the area throughout December and into New Year 2014 are likely to reduce juvenile coarse fish over winter survival quite significantly.
Probably the most pragmatic statement we can make regarding this quite complex information on weather patterns and its implications for fisheries management is that, because we've seen such climatic instability in recent years and because there is no way we can manage this directly in the short term, the most direct way that we can increase the resilience of fish communities is to ensure the quality of their physical habitats, with the objective of providing refuge for all life stages, as well as spawning opportunities even under abnormally high and low flows and temperatures.
An important secondary point is that fish communities are likely to be more resilient to these climatic fluctuations if the effects of other pressures are reduced, particularly poor water quality, over- abstraction, sedimentation and barriers to fish migration.
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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 circle of metal 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 are all adjusted for each specific location with the aim of capturing fish, with the minimum risk of injury. All electric fishing surveys reported involve the team wading or boating slowly upstream for approximately 100 metres until they reach a stop net placed across the channel to prevent fish escaping upstream. 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 set 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").
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 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 given area, usually 100m2.
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1. East Sussex
1.1 Pevensey Levels & Coombe Haven
Eight fish population surveys were completed on the Pevensey Levels and Coombe Haven in 2013, shown in the map below. These consisted of: one Principal Coarse Fishery survey at Boreham Bridge (Waller's Haven; brown marker), six Water Framework Directive surveys (to classify waterbodies for fish; purple markers) and a seine netting to investigate the fish community in Prince's Park lake (also known as Crumble's Pond), Eastbourne (red marker).
Map Pevensey 1: 2013 fish survey locations
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Water Framework Directive survey results Table Pevensey 1 sets out the results of the Water Framework Directive fish surveys, giving the site grid reference and numbers of all species caught. The results are listed in order of the total density of fish (number per 100m2), excluding minor species (bullhead, minnow, stone loach, brook lamprey & stickleback) - this gives a general indication of the ecological quality of the site.
Common bream Common Roach Rudd Perch Pike eel European Flounder hybrid bream common x Roach Gudgeon Dace Bullhead Minnow loach Stone lamprey Brook sp. Lampetra species of Number species) minor (excl density Total Site NGR trout sea / Brown Kentland Fleet * TQ6417908064 0 20 561 8 203 0 0 0 0 18 5 0 0 0 0 0 6 57 Watermill TQ7358211454 90 0 0 0 0 0 1 0 0 0 0 0 0 28 1 0 4 37 Ash Bourne Stream TQ6839814137 23 0 0 0 18 0 3 0 0 0 0 1 1 1 77 0 7 17.4 Churches green TQ6465117193 40 0 0 0 0 0 0 0 0 0 0 21 0 0 26 0 3 16.7 U/S Crowhurst Bridge TQ7528012307 14 0 3 3 0 0 1 0 0 0 0 0 0 1 0 1 6 9.21 Sheepwash Gates TQ7755208982 0 2 5 0 2 1 0 1 1 0 0 0 0 0 0 0 6 2.34
* Seine net survey Table Pevensey 1: Water Framework Directive survey results
Wild brown trout from the Ashbourne Stream
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Principal Coarse Fishery results Charts PL 1 and PL2 show the estimated total number and weight of each fish species caught at Boreham Bridge in 2013:
3 50 45 2.5 40
2 35 Pike Pike 30 Perch Perch 1.5 25
Rudd Rudd g./100m² No./100m² 20 1 Roach Roach 15
0.5 10 5 0 0 Density Biomass
Charts PL1 & PL2: Estimated density and biomass at Boreham Bridge, 2013
Princes Park survey results Chart PL3 below shows the total numbers of each species caught in the Princes Park lake seine net survey:
European eel, Sand goby , 5 4 Plaice, 4 Golden grey mullet, 1 Sea bass, 1
Flounder, 247
3-spined stickleback, 1627
Chart PL3: Total catch at Crumbles Pond, Princes Park
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WFD discussion Of the six surveys described in the above table, two stand out as having particularly good fish communities: Kentland Fleet and Watermill, the former being a coarse community and the latter dominated by brown trout. Brown trout were also the dominant species at three of the other sites. Only Sheepwash Gates appears to support a notably low density of fish in general, although six species were recorded. Later in 2014 this data will be used to classify the relevant waterbodies as Bad, Poor, Moderate, Good or High for fish and the results may form the basis for any necessary improvement projects.
Principal Coarse Fishery discussion Charts PL 1 confirms that the fish population at Boreham Bridge is very sparse, with an estimated density of just under 2.5 fish per 100m2 area. Roach is the most numerous species, followed by perch, pike and rudd, whereas biomass is dominated by pike. These results reflect the generally low productivity of such slow, wide reaches on the Pevensey Levels. However, carefully targeted angling is often more likely to attract and capture large individual fish in such reaches than an electric fishing survey of a 100m section.
Princes Park lake survey discussion This survey was conducted in order to provide a general assessment of the fish community of this artificial lake and to see if there was any evidence that fish were able to pass through an aperture in the new tidal flaps, designed to improve fish passage. The presence of estuarine species including bass, sand goby, flounder, golden grey mullet, as well as eels, which migrate into freshwater from the sea, confirms that there the tidal flaps are passable to fish to some extent. It may come as a surprise to some that 3 spined stickleback thrive in fresh, brackish and coastal waters and move between the three when passage is unobstructed. The abundance of flounder compared with other species suggests that this species are more adept at making their way upstream past tidal flaps and through artificial channels. The same has been observed on other local streams (such as the Tanners Brook in Southampton) and may be because this well-camouflaged flatfish can deal with narrow apertures and shallow, featureless, artificial channels better than "round" fish, which require more depth and some cover.
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Upstream Boreham Bridge survey site
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1.2 Cuckmere
Six fish surveys were conducted in the Cuckmere catchment in 2013: five for Water Framework Directive purposes (purple map markers) and one Principal Coarse Fishery survey, postponed from 2012 due to flood flows (Horselunges Bridge).
Map Cuckmere 1: 2013 fish survey locations
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WFD results Table Cuckmere 1 sets out the results of the five Water Framework Directive fish surveys, giving the site grid reference and numbers of all species caught. The results are listed in order of the total density of fish (number per 100m2), excluding minor species (bullhead, minnow, stone loach, brook
lamprey & stickleback) - this gives a general indication of the ecological quality of the site.
Chub Dace bream Common Gudgeon Roach Perch Pike eel European stickleback 3-spined Bullhead Minnow loach Stone lamprey Brook sp. Lampetra species of Number species) minor (excl density Total Site NGR trout sea / Brown Mill Bridge TQ5798611249 1 15 17 0 1 1 25 2 6 0 5 0 25 10 0 11 21.3 Horselunges Bridge TQ5818612135 13 4 1 0 20 0 0 0 4 8 19 104 34 19 0 10 13.1 Hamly Bridge TQ5569113626 16 1 0 0 0 0 0 0 1 1 39 32 1 1 0 8 6.9 Lea Bridge sq TQ5774513035 8 4 0 0 1 0 0 0 2 1 22 59 20 6 0 9 5.6 Sheepwash Bridge TQ6116115243 9 0 0 0 0 0 0 0 0 0 7 32 12 0 1 4 2.3
Table Cuckmere 1: Water Framework Directive survey results
Adult chub from Mill Bridge
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Boat survey in progress at Sheepwash Bridge
Principal Coarse Fishery results
The Cuckmere has five Principal Coarse Fishery sites and these were scheduled to be surveyed in 2012. However, flood flows meant that three of these had to be postponed till 2013. Unfortunately, once again high flow conditions meant that only the survey at Horselunges Bridge could be completed.
Chart Cuckmere 1 shows the estimated density of species of angling interest caught at Horselunges Bridge in all surveys we have on record (minor species are omitted):
140
120 Eel Roach 100 Gudgeon Dace 2 80 Chub Brown / sea trout
60 No./100m
40
20
0
Chart Cuckmere 1: Estimated density at Horselunges Bridge 2007-2013
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WFD discussion The WFD survey results reflect a wide range of fish communities, from the species rich, coarse fish dominated site at Mill Bridge to the brown trout dominated community at Sheepwash Bridge. No site appears to have an obviously degraded fish population. Later in 2014 this data will be used to classify the relevant waterbodies as Bad, Poor, Moderate, Good or High for fish and the results may form the basis for any necessary improvement projects.
Principal Coarse Fishery discussion Chart Cuckmere 1 shows that the most numerous fish species at Horselunges Bridge are Gudgeon, brown trout, chub and that eels and dace are also present. Roach were caught in very low numbers in each year from 2004 to 2009 but none were caught in 2013.The abundance of trout reflects the fact that this site lies in the upper reaches of the Cuckmere and that physical habitat and water quality must generally be good. Although not included in the charts, Brook lamprey, bullhead, minnow and stone loach were also abundant in most survey years, which is a further indication of good habitat and water quality. Changes in species abundance over the survey period reflect a similar pattern to that seen on other river coarse fisheries in the area, with highest densities in the warmest period around 2005, a reduction in the subsequent run of cool summers and a return to reasonable density following the relatively warm 2013 summer.
Backpack survey in progress at Horselunges Bridge
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1.3 Ouse
2013 was a major survey year for the Ouse catchment, with 5 Principal Coarse Fishery, 10 Eel Index, 11 Wild Brown Trout and 18 Water Framework Directive surveys completed. However, this didn't require 54 individual surveys, as many are multi-purpose; for example, the one survey at Sloop contributes to the Principal Coarse Fishery, Water Framework Directive and Eel Index programmes. An ad hoc investigative seine net survey was also conducted on the Glynde reach at Beddingham. Map Ouse 1 shows the locations of survey sites that are for wild brown trout only (brown), combined wild brown trout & eel (purple), combined wild brown trout & coarse fish (green) and combined coarse fish & eel (yellow). Note that most of these are also Water Framework Directive surveys. Map Ouse 2 shows the locations of surveys that were only for WFD purposes.
Map Ouse 1: fish survey locations; combined purposes
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Map Ouse 2: fish survey locations; Water Framework Directive & local investigation
WFD results Table Ouse 1 sets out the results of the eighteen Water Framework Directive fish surveys, giving the site grid reference and numbers of all species caught. The results are listed in order of the total density of fish (number per 100m2), excluding minor species (bullhead, minnow, stone loach, brook lamprey & stickleback) - this gives a general indication of the ecological quality of the site.
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Table Ouse 1: Results of 2013 Water Framework Directive surveys in the Ouse catchment
Chub Dace Gudgeon Roach Rudd Perch Pike Barbel eel European carp Common Mirrorcarp hybrid carp crucian x carp Common bream Silver Goldfish Feral Bullhead loach Stone lamprey Brook Minnow species of Number species) minor (excl density Total Site NGR trout sea / Brown Pellingford Brook TQ4015123235 7 4 12 33 26 8 2 0 0 1 0 0 0 0 0 21 6 0 58 11 34.4 Sloop TQ3845024528 7 11 40 72 5 0 1 0 1 5 0 0 0 0 0 2 0 4 21 11 22.4 Sheffield Green TQ4161525124 19 0 0 0 18 0 0 0 0 5 0 0 0 0 0 0 0 0 0 3 18.6 Great Streele TQ4977421742 33 6 1 0 0 1 0 0 0 0 0 0 0 0 0 110 0 3 3 7 15.8 North End TQ4129413846 4 19 3 2 2 0 0 0 0 9 0 0 0 0 0 10 14 0 0 8 13.9 Clappers Weir TQ4242716187 3 0 2 16 0 0 0 0 0 0 0 0 1 0 0 1 11 0 56 7 12.4 Buxted Bridge TQ4943323265 9 25 0 2 1 0 0 0 0 0 0 0 0 0 0 10 3 0 78 7 9.84 Holywell Pumping Station TQ3690427694 12 0 0 0 0 0 2 0 0 4 0 0 0 0 0 15 0 1 0 5 7.5 East Mascells Bridge TQ3638425546 0 9 15 3 2 0 4 0 1 3 0 0 0 0 0 0 1 1 9 10 7.39 Hastingsford Bridge TQ5249225747 23 0 0 0 0 0 0 0 0 0 0 0 0 0 0 56 1 3 0 4 6.5 Sheffield Bridge TQ4058723615 0 5 18 4 2 3 0 1 0 2 0 0 0 0 0 9 0 2 15 10 5.74 Maresfield TQ4530724628 0 0 0 0 1 0 3 2 0 4 3 1 0 4 0 0 0 0 0 8 5.4 Shortbridge Mill TQ4515321312 2 0 0 1 9 0 1 0 0 5 0 0 0 0 0 10-99 10-99 5 3 9 5.29 Highbridge Lane U/S Bridge TQ3790315745 15 1 3 0 0 0 0 0 0 3 0 0 0 0 1 42 8 0 34 8 4.89 Wildboar Bridge TQ3771625630 9 0 3 0 0 0 0 0 0 4 0 0 0 0 0 82 11 1 9 7 4.82 Upper Ryelands TQ3247828016 4 0 0 0 0 0 6 0 0 1 0 0 0 0 0 207 12 5 10 7 3.43 Honey Green Caravan Park TQ5028517205 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2.0 Newick TQ4276821662 0 2 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 2 0.51
Ouse Eel Index Results
Chart Ouse 1 shows the total catch (not density) of eels at each of the ten eel monitoring site in 2009, 2011 and 2013. The sites are in order from upstream to downstream, from left to right.
30
25
20 2009 2011 15 2013 10
5
0
Chart Ouse 1: Total number of eels caught in Ouse eel index surveys
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Charts Ouse 2-4 show the length frequency of all eel caught in Ouse eel index surveys in 2009, 2011 and 2013 respectively:
6 2009 (n=13)
5
4
3
Frequency 2
1
0
120 180 240 270 330 390 420 480 540 570 630 690 720 150 210 300 360 450 510 600 660 750 More Length mm
Chart Ouse 2: eel length frequency, 2009
6 2011 (n=52)
5
4
3 Frequency 2
1
0
120 180 240 270 330 390 420 480 540 570 630 690 720 150 210 300 360 450 510 600 660 750 More Length mm
Chart Ouse 3: eel length frequency, 2011
6 2013 (n=58)
5
4
3 Frequency 2
1
0
180 210 240 330 360 390 480 510 540 570 630 660 690 720 120 150 270 300 420 450 600 750 More Length mm
Chart Ouse 4: eel length frequency, 2013
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Ouse Wild Brown Trout Fishery results Eleven Wild Brown Trout fishery surveys were conducted on the Ouse in 2013: two of these, Buxted Bridge on the Uck and Highbridge Lane on the Bevern Stream are known as temporal sites and are surveyed annually to provide time-series data that should reflect variation in trout abundance over time (largely driven by annual weather patterns). The other nine are termed spatial sites and are surveyed once every six years. Their principal purpose is to reflect changes in the distribution of wild brown trout over longer periods of time. Chart Ouse 5 shows the density and age structure of brown trout caught at the two temporal survey sites in 2011, 2012 and 2013:
16
14
12 0+ 10 1+
Trout 8 Older
6
4
2
0 2011 2012 2013 2011 2012 2013 Highbridge Buxted bridge
Chart Ouse 5: Brown trout catches at Highbridge Lane & Buxted Bridge, 2011-2013
Chart Ouse 6 shows the number of trout caught at each of the 11 wild brown trout survey sites in 2013. Sites are arranged in order of distance from the tidal limit, from left to right (i.e. how far upstream they are). Numbers of young of the year (0+) and older trout are indicated. Some of the surveys only involved a single electric fishing run but where more than one run was completed, only data from the first run is used:
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35
30
25 0+ BT
20 >0+ BT Trout 15
10
5
0
Chart Ouse 6: Wild brown trout total catch
14
12
10 2 8
6 No./100m 4
2
0
Chart Ouse 7: Wild brown trout first-run density
Chart Ouse 8 is a length frequency histogram representing all 109 wild brown trout caught at the 11 survey sites in 2013. The vertical bars indicate how many trout from each 10mm length category were caught.
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18 (n=109)
16
14
12
10
8 Frequency 6
4
2
0 30 50 70 90 110 130 150 170 190 210 230 250 270 290 310 330 Length mm
Chart Ouse 8: Wild brown trout length frequency histogram
Very well-conditioned adult wild brown trout from Highbridge Lane
Ouse Principal Coarse Fishery results Charts Ouse 9 and 10 show the estimated density and biomass at each of the five principal coarse fishery sites on the Ouse for 2013. Estimates are calculated from the depletions in catch over three electric fishing runs.
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40
Pike 35 Rudd 30 Brown Trout
25 Roach
Perch 20
Gudgeon No./100m² 15 Eel
10 Dace
Chub 5 Barbel 0 East Mascalls Sloop Sheffield Fletching Mill Newick Bridge Upstream
Chart Ouse 9: Estimated density at Ouse Principal Coarse Fishery Sites, 2013
2500
Pike
2000 Rudd
Brown Trout
Roach 1500 Perch
g/100m² Gudgeon 1000 Eel
Dace
500 Chub
Barbel
0 East Mascalls Sloop Sheffield Bridge Fletching Mill Newick Upstream Chart Ouse 10: Estimated biomass at Ouse Principal Coarse Fishery Sites, 2013
Charts Ouse 11, 12 and 13 are the length frequency histograms for all Ouse dace, chub and roach caught in 2013.
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Dace, 2013 (n=127) 25
20
15
10 Frequency
5
0
0
20 40 60 80
160 180 200 220 240 260 280 360 100 120 140 300 320 340 Length mm
Chart Ouse11: Dace length frequency distribution
Chub, 2013 (n=52) 25
20
15
10 Frequency
5
0
0
20 80 40 60
100 120 180 200 220 280 300 320 360 140 160 240 260 340 Length mm
Chart Ouse12: Chub length frequency distribution
Roach, 2013 (n=16) 25
20
15
10 Frequency
5
0
0
40 60 20 80
100 120 160 180 220 240 300 320 360 140 200 260 280 340 Length mm
Chart Ouse13: Roach length frequency distribution
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60 650
50 600
40 550 2
30 500
No./100m 20 450
10 400 >12cDegree days
0 350
Dace Roach Chub 4 prev yr mean degree days>12
Chart Ouse 14: Dace, roach & chub abundance & summer temperature
60 7
50 6
5 40
2 4
30 /sec 3
3 m
No./100m 20 2
10 1
0 0
Dace Roach Chub 2 yr mean winter flow
Chart Ouse 15: Dace, roach & chub abundance & winter flow
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Beddingham seine net survey results Chart Ouse 16 shows the total catch for all species during a seine net survey at Beddingham Gate on the Glynde Reach. The survey consisted of a single sample using a 45m net.
Dace, 2 Flounder, 1 Gudgeon, 3 Silver bream, 3 Pike, 1 Roach/bream Ghost carp, 1 hybrid, 4
Rudd, 7
Perch, 13
Common bream, 44
Roach, 270
Chart Ouse 16: Beddingham seine net survey catch
WFD discussion A great deal of WFD survey work was undertaken in the Ouse catchment in 2013 and the results represent the fish communities of a wide range of watercourses types. There is a fairly good correlation between the number of species recorded in each survey and the total fish density (excluding minor species) suggesting that both of these values are useful indicators of whether or not fish communities are thriving or under pressure. However, sites such as Hastingsford Bridge may have relatively low density and number of species yet still be at good ecological status, as suggested by the prevalence of brown trout, an ecologically sensitive species. Survey results for sites such as Newick and Honey Green Caravan Park show very low total density and number of species, as well as an absence of sensitive fish species, which suggest that some factor may be restricting the fish community (most likely degraded physical habitat or water quality: there is a large sewage treatment works upstream). Later in 2014 this data will be used to classify the relevant waterbodies as Bad, Poor, Moderate, Good or High for fish and the results may form the basis for any necessary improvement projects.
Ouse Eel Index discussion The ten eel index survey sites on the Ouse are not selected because eels are particularly abundant there; they are simply a collection of well-spaced sites where fish surveys are already scheduled for other purposes and which collectively provide a good snapshot of eel distribution and abundance across the catchment.
The total number of eels caught during catch depletion surveys at these sites in 2009 was 13; in 2011 it was 52 and in 2013, 58. This is the simplest measure of overall eel abundance and suggests that there has been neither a significant decline nor increase in eel abundance since
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2009. The reason for the relatively very low number caught in 2009 is unknown but may be the result of improved conditions for eel migration (up and downstream) brought about by the removal of several impounding structures as part of an ambitious river restoration project (MORPH).
Chart Ouse 1 shows that of the thirty eel surveys conducted since 2009, all but two have caught a total of ten or fewer eels - these typically low catches suggest that much of the variation that we see in catches between sites and years may be random, rather than indicative of any real change. By contrast, the total catches for the same number of survey sites on the Itchen for the same three survey years were 321, 221 and 175.
Ouse Principal Brown Trout Fishery discussion The abundance of wild brown trout at the two annual survey sites, Highbridge Lane and Buxted Bridge was notably higher in 2013 than in the previous two years. The increase was greatest at Highbridge Lane, with more than 14 trout per 100m2 compared with approximately one in 2011 and three in 2012. Even so, at Buxted Bridge 2013 density is more than double that in 2011. The most probable reason for these increases is better flow conditions, particularly the sustained high summer flows and low temperatures of summer 2012, which remained consistent throughout the spawning and juvenile growth period in early 2013. In addition, a weir was removed from downstream of the Buxted Bridge site between the 2011 and 2013 surveys, greatly improving fish passage. Chart Ouse 6 shows wild brown trout abundance at the eleven spatial sites, which are surveyed only once every six years. There is great variation in abundance between sites, with no trout captured at Sheffield Bridge and thirty-three caught at Great Streele. Whereas Chart Ouse 6 shows the total number of trout caught in the first run at each site, the next chart shows the number of trout caught per unit area (100m2) to provide a better comparison between these sites and sites in other catchments. This chart shows that density at Great Streele is just over twelve trout per 100m2 but that density at all other sites is below six per 100m2. This generally low level of abundance reflects the clay and sandstone geology of most of the Ouse's headwaters, resulting in them being relatively unproductive and with highly variable flows, both of which restrict carrying capacity for trout to some degree. However, given that similar streams in pristine condition are capable of supporting far higher numbers of trout, this low abundance is just as likely to reflect pressures on trout populations related to human activity (anthropogenic pressures). The streams of the New Forest are a good example and their typically far higher trout densities suggest that the key physical differences between these two catchments are the most likely reasons for the differences in carrying capacity for trout. These are principally differences related to population density, agriculture and historic flood defence measures. Specific pressures include barriers to fish migration, sediment inputs, abstraction and habitat degradation caused by impoundment and canalisation.
Ouse Principal Coarse Fishery discussion Chart Ouse 14 neatly summarises where we are in 2014 with regards to coarse fish abundance in the context of the period since the start of the new millennium. Densities of dace, roach and chub were comparatively very low in 2001, almost certainly as a result of the intense flood of the previous winter. In 2013 abundance of all three species is once again relatively low, although dace are more abundant than the other two species, which has been the case throughout the study period. Charts 9 and 10 clarify which of the five annual survey sites supports the greatest and least abundance and biomass of fish, respectively, and how species compare with one another on both counts. In general, fish are most plentiful at Sloop, with gudgeon being the most numerous species, whilst East Mascalls has the highest fish biomass (greatest weight per unit area), with barbel and dace contributing most.
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In contrast, fewer than ten fish and less than a kilo of any species per 100m2 were recorded at both Sheffield Bridge and Fletching Mill. At Newick the equivalent values were fewer than five and less than 500g, making this the least productive site by far. Charts Ouse 11-13 are length frequency histograms which include the lengths of all dace, chub and roach caught at all five survey sites in 2013. Collectively, these emphasise the low average length of all three species, particularly roach, suggesting that each population is predominantly composed of young fish and/or fish that are short for their age. Charts Ouse 14 and 15 shed some light on two principal factors that appear to influence abundance of dace, roach and chub on the Ouse: winter flow and summer temperature. Both charts show the sum of the densities for these three species at the three survey sites that have been surveyed consistently since 2001: East Mascalls, Sheffield Bridge and Sloop. The first chart compares this measure of abundance with the average number of degree days above 12 Celsius in the four years prior to the survey year (the surveys are carried out in early summer, so data for the survey year itself is not included, as much of that summer has not yet happened at the time of survey). The second chart compares the same fish abundance data with the annual average winter flow recorded for the four year period up to and including the survey year (the flow data is for Oct-Mar prior to each survey and the survey year itself is included, as the fish present will have been affected by flow in the winter just past). Abundance data for all three species correlate closely with both of these environmental variables, demonstrating that Ouse coarse fish survey results in any given year reflect prevailing flow and temperature conditions over a considerable period of previous seasons. Similar observations have been made with regard to other southern coarse fishery rivers, including the Adur, Arun and Western Rother (see Arun & Western Rother sections in this report).
Beddingham seine net survey discussion Electric fishing was tried and found to be fairly ineffective in this deep, wide and weedy reach, so a seine net was used to assess the species composition of the fish community in a broad basin close to a pumping station. The total number of each species caught is shown in Chart Ouse 16 and is typical of a lake fish community, with roach and bream by far the most abundant species and very few flow-loving, gravel spawning species present.
Specimen barbel from East Mascalls
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Processing the catch at Fletching Mill
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2. West Sussex
2.1 Adur
The Adur is classed as a Principal Coarse Fishery, with five sites surveyed three-yearly; last surveyed in 2012 and to be next surveyed in 2015. In 2013 we completed four Water Framework Directive surveys, the locations of which are shown in Map Adur 1.
Map Adur 1: WFD survey locations
Adur WFD results Table Adur 1 below shows the numbers of each fish species caught at these surveys, as well as the fish density (number per 100m2), excluding minor species:
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Table Adur 1: Water Framework Directive survey results
Site NGR sea trout / Brown Chub Perch Pike Roach bream hybrid Common xRoach eel European Stoneloach Bullhead stickleback spined 3 species Numberof species) (exclminor density Total Lancing Brook- New Barn Farm Q TQ1495720503 0 0 2 4 97 2 2 0 0 0 5 36.897 Woods Mill Stream- Catslands lane TQ2354413455 29 0 0 0 0 0 1 0 65 0 3 18.75 Adur West Arm- Parsons Brook Q TQ1209824161 0 1 0 0 2 0 1 5 24 16 6 2.128 Lancing Brook- Broadoak TQ1365718995 0 0 0 2 0 0 2 8 0 0 3 1.538
Adur WFD discussion The WFD survey at New Barn Farm on the Lancing Brook revealed a remarkably high density of roach, while wild brown trout were abundant at Catslands Lane on the Woods Mill stream. In contrast, overall fish density was very low at Parson's Brook on the Adur's West arm and at Broadoak on the Lancing Brook.
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2.2 Arun
The Arun is classed as a Principal Coarse Fishery, with five sites surveyed three-yearly, including 2013. We also conducted 17 fish population surveys for Water Framework Directive purposes (either to derive a waterbody classification or to investigate a suspected issue). Map Arun 1 shows the locations of all of these surveys: WFD surveys (pink), combined WFD & coarse fish surveys (yellow) and the two coarse fish only surveys (green).
Map Arun 1: fish survey locations
WFD survey results Table Arun 1 below shows the numbers of each fish species caught at these surveys, as well as the fish density (number per 100m2), excluding minor species:
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Table Arun 1: Water Framework Directive survey results
Site NGR trout sea / Brown Chub Dace Gudgeon Perch Pike Roach Rudd hybrid bream Common x Roach Bream Common eel European Stoneloach Bullhead Minnow stickleback spined 3 Lamprey Brook Flounder species of Number species) minor (excl density Total River Chilt- Heath Mill TQ0770716889 0 17 53 3 2 0 52 0 0 0 1 2 3 0 0 0 0 8 94.815 River Stor- Pulborough STW TQ0607918075 4 6 22 19 0 3 0 0 0 0 131 1 19 0 0 1 8 10 73.384 River Kird- Harsfold farm TQ0535424826 0 10 5 8 2 2 82 0 0 1 21 5 5 0 0 0 0 10 54.131 Boldings Brook- U/S Farthing Bridge TQ1596831035 0 2 13 7 4 1 76 1 1 3 16 3 7 2 0 0 0 13 27.252 River Stor- Hurston Place TQ0717616138 21 9 19 0 0 0 1 0 0 0 31 1 17 0 0 0 0 7 26.999 Bignor Mill Stream- Bury Mill TQ0011915225 36 0 0 0 0 0 0 0 0 0 3 0 4 0 0 2 0 4 25.658 River Kird- Kirdford SU9974726659 0 4 1 2 5 2 31 0 0 1 8 22 15 0 1 0 0 11 20.729 Loxwood Stream- Upper Ifold Farm TQ0121733742 12 0 4 13 0 0 0 0 0 0 1 24 73 71 1 2 0 9 19.355 Loxwood Stream- Frillinghurst SU9385434433 18 0 0 0 0 0 0 0 0 0 1 4 33 2 0 2 0 6 9.935 Loxwood Stream- Pockford Farm SU9823336631 21 0 0 6 0 0 0 0 0 0 0 17 71 74 0 7 0 6 7.153 Loxwood Stream- Highstreet Green SU9831635735 19 0 0 2 0 0 0 0 0 0 0 6 16 66 0 13 0 6 6.383 Loxwood Stream- Godley bridge SU9505536750 13 0 0 0 0 0 0 0 0 0 0 3 6 0 0 0 0 3 5.936 Boldings Brook- Redford Avenue TQ1660932053 0 1 0 0 0 0 0 0 0 0 7 0 0 0 4 0 0 3 3.846 Roman Station TQ1160033136 0 1 1 0 0 3 5 0 0 2 5 26 41 13 0 0 0 9 2.707 Pallingham TQ0367521204 0 5 0 0 1 3 7 0 0 0 2 0 1 0 0 0 0 6 2.5 Loxwood TQ0407331098 0 0 0 0 2 1 10 0 0 0 0 0 0 0 0 0 0 3 1.382 River Chilt- Threals Lane TQ0923016892 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0.741
Principal Coarse Fishery results: Chart Arun 1 describes the fish communities at each of the five Arun Principal Coarse Fishery sites in 2013 by indicating the number of fish of each species caught per 100m2. Similarly, Chart Arun 2 shows the biomass (grammes per 100m2):
40 Eel
35 Pike 30 Perch
² 25 Common Bream 20 Roach x Common Bream No. /100m No. 15 Hybrid 10 Rudd
5 Roach 0 Gudgeon
Dace
Chub
Chart Arun 1: Species density at Arun PCF surveys
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1800 Sea Bass 1600 Flounder 1400 Eel 1200
² Pike 1000 Perch
800 g/100m 600 Common Bream 400 Roach X Common Bream hybrid 200 Rudd 0 Roach Gudgeon Dace Chub
Chart Arun 2: species biomass at Arun PCF surveys
Chart Arun 3, below, compares the combined densities of roach caught at Horsham and Roman Station each year since 2003 (excluding 2011, when there was no survey) with the average number of degree days over 12c in the previous three years and the survey year (calculated from Central England Temperature, Hadley).
60 650
50 600
40 550 2
30 500 No/100m
20 450 Degree days >12cDegree days 10 400
0 350
Total roach est. density 4 year mean degree days>12
Chart Arun 3: Roach density at Horsham and Roman Station & 4 year mean degree days >12c.
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650 630 610 590 570 550 530 510 490 Degree days >12c: 4 yr mean yr >12c:4 Degree days 470 450 0 10 20 30 40 50 60
Total roach per 100m2, Horsham & Roman Station
Chart Arun 4: Roach density at Horsham and Roman Station scatter plot
Charts Arun 5 & 6 are length frequency histograms showing the numbers of roach in 5mm length categories recorded at Horsham and Roman Station in 2006 (when the highest abundance of roach was recorded) and in 2013, respectively.
25
20
15
Frequency 10
5
0
Length mm
Chart Arun 5: Roach length frequency, Horsham & Roman Station, 2006
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25
20
15
Frequency 10
5
0
Length mm
Chart Arun 6: Roach length frequency, Horsham & Roman Station, 2013
Arun WFD discussion Table Arun 1 sets out the results of the 17 fish surveys completed in the Arun catchment in 2013 in order to provide data to classify waterbodies for Water Framework Directive purposes. The results are very varied, indicating the diverse range of riverine habitats found in the catchment. The highest overall density (excluding minor species) was just under 95 fish per 100m2 at Heath Mill on the River Chilt, comprising mainly dace and roach. The greatest abundance of wild brown trout was recorded at Bury Mill on the Bignor Mill stream and the species was also abundant at five sites in the upper reaches of the Loxwood stream. In contrast, a survey on the lower reaches of the Loxwood recorded only a very low density of coarse fish. Among these surveys, the lowest fish abundance was recorded at Threal's Lane on the River Chilt, where the catch consisted of a single eel.
Arun Principal Coarse Fishery discussion The clearest feature of Chart Arun 1 is that fish abundance was low at all sites except for Pulborough, with fewer than 10 fish per 100m2 at Horsham, Roman Station, Loxwood and Pallingham. However, the relatively high numbers of dace and roach recorded at Pulborough are a little misleading as they were predominantly young of the year (0+) fish. This survey site is on a tidally-influenced sidestream that provides good nursery habitat for juvenile coarse fish and the small size of these fish is reflected in Chart Arun 2 which shows that they hardly register in terms of biomass (weight). Chart Arun 2 shows that, taking the Arun fish community as a whole, it is pike, chub and common bream that make up the bulk of the biomass, if not the numbers. Chart Arun 3 sheds some light on the way that roach abundance has varied on the Arun since annual surveys began in 2003. The chart uses only data from Horsham and Roman Station because these two Principal Coarse Fishery survey sites have been surveyed annually since 2003, with the exception of 2011: there are significant gaps in the datasets for the other three sites. Roach spawning and the survival of juvenile roach are known to be closely linked to prevailing water temperature and a widely accepted indicator of a good spawning year is the number of degree days above 12 Celsius (a degree day is one day at one degree, so a summer's day when the 24 hour average temperature was 18C counts as 6 degree days).
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Our electric fishing surveys are conducted in mid to late summer and tend to catch juvenile roach born in the previous few years, rather than the young of that year. Therefore, the dotted line in Chart Arun 3 shows us the average number of degree days above 12 Celsius for the three years prior to the survey and the survey year itself. This gives us a measure of the prevailing conditions for survival and growth for the majority of the fish caught in the surveys, most of which are 1-4 years old, and also reflects the cumulative nature of the effects of weather on fish populations. The other line on the graph shows the combined density of roach caught at Horsham and Roman Station in each survey year. The results are remarkably clear: roach density shows a strong association with the average number of degree days over the four year period, with a correlation value of 0.87, a relationship illustrated more clearly in the scatter plot Chart Arun 4. The low values for the four year mean number of degree days above 12C in Chart Arun 3 for the period 2010 to 2013 and the flat nature of the graph are striking and are the clearest explanation available for the relatively low roach densities recorded in that period. A serious pollution incident did occur in 2011 downstream of Horsham sewage treatment works but analysis of roach, dace and chub abundance carried out in 2012 didn't identify any clear link between the incident and variation in the abundance of these species. Chart Arun 5 shows the size distribution for roach caught at Horsham and Roman Station after the 4 year period with the highest average number of degree days above 12C and Chart Arun 6 shows the same information after the period with the lowest. This more clearly illustrates the stark difference between the Arun roach population after a run of relatively warm summers and a run of cool ones and makes it easier to appreciate the link between the cumulative effects of weather over a period of a few years and coarse fishery performance. These observations should not imply that the quality of the Arun roach fishery is entirely dependent on weather patterns - there are numerous ways in which the impacts of consistently cool summers, flood events and other weather phenomena that might reduce coarse fish survival can be mitigated for, most of which are well established principals of good fishery management. These include the enhancement of coarse fish physical habitat to provide good conditions for spawning, juvenile survival and growth under a range of climatic conditions, as well as enabling migratory access between reaches and maintaining water quality. Of course, fishing clubs and individual anglers can also contribute to the health of the Arun's coarse fish populations by employing the highest standards of fish welfare when catching, handling and returning fish.
A fine chub from the Arun at Roman Station
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Pulborough eel
Adult common bream, Roman Station
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2.3 Western Rother & Western Streams
The Western Rother is a Principal Coarse Fishery and is part of a national network of reference river coarse fisheries. This means that the same five sites are surveyed annually. Four of these sites are also used for WFD classification. Map Western Rother 1 shows the locations of these, with the coarse-only site (Woolbeding) in green and the combined WFD / coarse sites in yellow. In addition, two WFD surveys were conducted on the River Ems - the locations of these are shown in pink (triangles).
Map Western Rother 1: fish survey locations
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Western Rother WFD results Table Western Rother 1 sets out the results of the six Water Framework Directive fish surveys completed on the Western Rother & Western Streams in 2013.
Table Western Rother 1: WFD survey results
Site NGR trout sea / Brown Chub Dace Perch Pike Roach Gudgeon Grayling eel European Stoneloach Bullhead Minnow Lamprey Brook stickleback spined 10 species of Number species) minor (excl density Total Ems- Brook Meadow SU7506305987 5 0 0 0 1 0 0 0 30 0 23 0 0 4 5 7.714 Ems- Westbourne SU7567807792 13 0 0 0 0 0 0 0 9 0 91 0 0 0 3 5.058 Terwick Mill SU8314922138 10 1 4 1 2 0 3 4 1 19 91 55 3 0 12 2.832 Stanbridge SU7708123133 10 0 0 0 0 0 0 1 1 10 41 3 5 0 7 2.218 Fittleworth Bridge TQ0115018217 0 0 0 1 1 1 0 0 1 0 0 0 0 0 4 0.316 Coultershaw SU9729819058 0 0 1 1 0 1 0 0 0 1 0 1 0 0 5 0.273
Stanbridge fish survey site
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Western Rother Principal Coarse Fishery results Chart Western Rother 1 shows the density (number per 100m2) of fish species caught at each survey site in 2013. Chart Western Rother 2 shows the biomass recorded for each species.
6
Brown trout 5 Eel 4 Pike Perch 3 Roach
No./100m² Gudgeon 2 Grayling 1 Dace Chub 0 Stanbridge Terwick Woolbeding Coultershaw Fittleworth
Chart Western Rother 1: species abundance
1200 Brown trout
1000 Eel
Pike 800 Perch
600 Roach
g/100m² Gudgeon 400 Grayling
200 Dace
Chub 0 Stanbridge Terwick Woolbeding Coultershaw Fittleworth
Chart Western Rother 2: species biomass
Chart Western Rother 3 puts the 2013 fish survey data in context by presenting it in a time-series with all previous survey years, focusing on the Western Rother's principal coarse species, dace and roach. The sums of the estimated densities for roach and dace from all survey sites (except Stanbridge, where coarse fish are rarely caught) and for all survey years are plotted. Also plotted is a line representing the average number of degree days above 12 Celsius for the three years prior to the survey and the survey year itself.
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9 650
8
7 600
6
2 550 5
4
N0/100m 500 3
2
450 >12C degreedays mean 4yr 1
0 400 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Total roach est. density Total dace est. density Degree days >12C
Chart Western Rother 3: Total roach density with 4 year average degree days >12C.
A handsome adult perch from Terwick Mill
Western Rother WFD discussion Of the six WFD fish surveys conducted on the Western Rother and Western Streams in 2013, four were also Western Rother Principal Coarse Fishery surveys, while the remaining two were on the River Ems, a small chalkstream that enters Chichester Harbour at Emsworth. The fish populations at both Ems sites were typical of southern chalkstreams, featuring wild brown trout and bullhead. Eel abundance was high at both sites but particularly so at Brook Meadow.
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The four Western Rother surveys recorded low overall fish density, particularly at Fittleworth and Coultershaw - this is discissed in more detail in the next section. By far the greatest number of species was recorded at Terwick Mill: this site has characteristics of both the middle and upper reaches of the river and so supports brown trout and a range of coarse species. Stanbridge is a more typical headwater site and is dominated by trout, with coarse fish only being recorded less frequently.
Western Rother Principal Coarse Fishery discussion Charts Western Rother 1 and 2 represent a useful sample of the river's overall fish population, from the headwaters (Stanbridge) right down to near the confluence with the Arun (Fittleworth). The charts give two perspectives of the fish population: in terms of numbers and in terms of biomass (weight). A first glance at the vertical axis on the first chart tells us that we are dealing with very low values in general for fish abundance, with an estimated value of just over five individuals per 100m2 at the most densely populated site, Terwick Mill and fewer than one individual fish for the same area at Fittleworth. The biomass chart tells a similar story, with just under a kilo of fish per 100m2 at Terwick, slightly less than 300g for Stanbridge and less than 50g for Woolbeding, Coultershaw and Fittleworth. In order to make some sense of these 2013 results, we need to put them in context with previous years' data and also consider some of the environmental factors that are likely to have affected coarse fish populations in all southern rivers over this period. On the Western Rother, the only two coarse species that are caught in sufficient numbers to allow analysis are roach and dace, with dace being the more abundant - these are also two of the prime coarse fishing quarries. We have twelve years of fish survey data for the five survey sites, all based on the same electric fishing techniques at the same locations and conducted at the same time of year. However, as very few coarse fish are caught at Stanbridge, data from the other four sites is used for coarse fish analysis. Analysis of local fish data discussed in our previous annual fish monitoring reports has demonstrated that periods of unusually warm or cool weather and high and low flows can strongly influence fish abundance in rivers and it's clear that the effects may be cumulative. For example, two or three consecutive winters with heavy flood flow conditions or two or three particularly cool summers will affect coarse fish populations to a greater degree than just one such season. Conversely, a run of two or three warm summers may provide a cumulative boost to fish abundance which may be reflected in survey data and angler's catches for several years. Chart Western Rother 3 illustrates this link between coarse fish abundance and prevailing summer temperature by plotting total estimated densities of roach and dace recorded in our annual surveys and the average number of degree days over 12 degrees Celsius in the four year period up to and including the survey year: the number of degree days above 12C in a given summer is a reliable indicator of how likely that summer is to produce a strong coarse fish year class. There has been a considerable amount of variation in this figure in the 12 year period, with a peak of over 600 for the period 2003-2006 and a low of 455 in 2010 but the key feature of the data is that the last four years (2010-2013) are the lowest four values in the whole period. This defines the last four years as being unsuitable for producing strong coarse fish year classes because of the cumulative effects of successive cool conditions during the critical spawning and juvenile growth periods. Our dace and roach data reflects this, as annual abundance of the two species correlates reasonably well with the temperature data (roach=0.54; dace=0.68). As also discussed in the Arun section, it would be wrong to conclude that the status of fish stocks on the Western Rother are completely governed by climatic patterns. For example, Chart Western Rother 3 would probably show the same correlations between roach and dace abundance and prevailing temperature patterns, but with a lower degree of variation (i.e. less tendency to "boom and bust) and with higher abundance in general if other constraints on fish survival, over which we
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Looking upstream at Terwick Mill survey site, Western Rother
Jack pike from Terwick Mill
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3. Isle of Wight
Four fish surveys were conducted on the Isle of Wight in 2013, all of which used single run backpack electric fishing along 100 metre reaches. All were conducted on the 12th August.
The first survey was on the upper Medina at a site named Sheat Manor and was a Water Framework Directive classification survey, required to represent the upper river (its current classification is based only on surveys conducted on the lower river, in Newport).
Two of the other three surveys were to assess fish communities at sites that had been enhanced by habitat improvement works; one on the Medina (Shide concrete channel) and one on the Lukely Brook (Old Dairy Crest site). The final one was a pre-improvement assessment, also on the Lukely Brook (Westminster Mill - adjacent to a new housing development). Map IOW 1 shows the locations of the four survey sites.
Map IOW 1: fish survey locations
Results Chart IOW1 shows the densities (number per 100m2) of individual fish species caught at each of the four surveys:
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40
35 Stone loach 30 Bullhead
2 25 3-spined stickleback 20 European eel Dace No./100m 15 Brown / sea trout 10
5
0 Westminster Old Dairy Sheat Manor Shide Mill Crest site concrete channel
Chart IOW1: Fish density at 2013 IOW surveys
Isle of Wight discussion These four surveys were simple assessments to gauge the status of the fish communities at the respective sites. Chart IOW1 shows that the total catch at Westminster Mill consisted of bullhead (eleven were caught, the equivalent of 5 per 100m2). This survey was conducted in the concrete- lined channel immediately downstream of the mill and adjacent to a new housing development. As part of the development, it is understood that habitat improvements will be undertaken in this section of channel, so this 2013 survey provides a baseline confirming that the channel is currently in such poor condition that it supports only a few individuals of one species.
The Old Dairy Crest site is immediately downstream of the Westminster Mill site and is a reach that had channel habitat improvement works completed as part of the adjacent housing development several years ago. Bullhead was the most abundant species at this site and ten large brown trout were also caught. These trout are likely to be the descendants of brown trout fry stocked into the Lukely Brook by the Environment Agency several years ago, following a series of fish surveys that suggested the species was absent. On one hand, the presence of these trout is good news, as it proves that water and habitat quality in this reach is good enough to support large, healthy specimens of this sensitive species. On the other hand, all the fish were of approximately the same size and age, so there was no evidence of successful reproduction and therefore of a self- sustaining population.
This survey also provided an interesting opportunity to assess the river channel restoration project several years after completion, providing some very clear lessons for such projects in future. The double lines of small wooden posts in the photo below represent the route that was carefully laid out by the project designer - it appears to be a suitably narrow and meandering path that would have resulted in high quality river habitat had it survived. However, these fragile softwood posts are testament to the fact that the materials used to construct this channel were lacked the required durability and robustness, by a long chalk.
Thankfully, the project also used significant quantities of limestone cobbles and gravel to create berms, pools and riffles, which, in combination with prolific bankside vegetation, have produced excellent adult trout habitat.
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Remnant channel realignment at the Old Dairy Crest site, Lukely Brook
The survey at Sheat Manor produced a catch of an eel, a stickleback, five bullhead and seventeen stone loach: very similar to when the site was last surveyed eleven years ago. This is a poor catch and reflects the fact that the fish community of the upper Medina is seriously depleted as a result of multiple major obstructions to fish passage on the lower river, historic dredging and straightening and sedimentation from agricultural runoff. This 2013 data may reduce the Medina's current Water Framework Directive status of High in the 2014 classification process. The post-restoration survey conducted in the concrete-lined channel section at Shide was a revelation: it was certain that the new planted berms bolted to the concrete within the section would provide a range of aquatic habitats and would be a great improvement on the uninterrupted bare concrete. However, the catch made up of 32 juvenile trout, 19 bullhead, five stone loach, 2 eels and 1 dace from just a 50 metre section greatly exceeded our expectations and provided yet further proof that, given adequate water quality and quantity, well-thought out habitat improvement can result in a remarkable boost to fish abundance.
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Concrete lined channel at Shide: an unlikely haven for juvenile wild brown trout
A handful of juvenile trout is returned to the Medina at Shide
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4. Hampshire
4.1 Wallington
Two Water Framework Directive surveys were conducted in the Wallington catchment in 2013, both in the headwaters; one at a site named Newlands Farm on the Sheepwash Tributary and another at Potwell Ford, on the Potwell tributary. Both surveys were required to ensure we have up to date fish data for WFD classification at the end of the first river basin management cycle, next year. Both surveys were conducted on the 9th May, with a single run over 100m using backpack electric fishing equipment.
Map Wallington 1: fish survey locations
Wallington results: Chart Wallington 1 shows the density (number per 100m2) of each species at both sites:
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90
80
70
60 2 Stone loach 50 Minnow 40
3-spined stickleback No./100m 30 European eel 20
10
0 Potwell Ford Newlands Farm
Chart Wallington 1: WFD survey catches
Wallington discussion: The river Wallington and its tributaries have great potential to support wild brown trout, sea trout and a range of coarse and minor fish species and this potential is largely fulfilled by the river downstream of Southwick, including the Newtown / Beckford stream. However, fish surveys on the Sheepwash and Potwell tributaries that join before flowing into Southwick Park lake have all shown impoverished fish communities, with no records of brown trout and eels very scarce. This is despite there being extensive suitable physical habitat on both these streams. The chart above shows that the 2013 surveys on these two tributaries follow the same pattern as in previous years, with no brown trout or bullhead and only a single eel caught. There are thought to be two principal reasons for this: firstly, the weirs that form the lake, which are major physical obstructions to fish migration and, secondly, poor water quality caused by various discharges from the Waterlooville and Purbrook conurbations. These two 2013 fish surveys will be used to provide an accurate fish classification the upper Wallington waterbody in 2014.
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Good habitat at Potwell (left) and on the Sheepwash tributary (right), but trout & bullhead are absent and eels very scarce
Prolific growth of filamentous green algae and a concrete lined channel on the Sheepwash tributary
Do the stone loach at Potwell grow this big because there's no competition or predation from larger fish species?
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4.2 Meon
In 2013 the only fish surveys that were conducted in the Meon catchment were the two wild brown trout temporal surveys at Mislingford and Silver Springs. These two annual surveys allow us to monitor the condition of the Meon's wild brown trout fishery and are complemented by eleven spatial surveys that are conducted every six years (next due in 2017).
Map Meon 1: fish survey locations
Meon results Chart Meon 1 shows fish species density (minor species excluded) in all survey years:
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40
35 Roach 30
2 Grayling 25 Dace 20
No./100m Salmon
15 Eel
10 Chub
5 Brown trout
0
2008 2009 2012 2007 2008 2011 2012 2007 2010 2011 2013 2009 2010 2013 Mislingford Silver Springs
Chart Meon 1: Fish density in all survey years
Charts Meon 2 and 3 show the length frequencies of all wild brown trout caught at Mislingford and Silver Springs in 2013:
Mislingford (n=54) 12 10 8 6
Frequency 4 2
0
60 80
100 140 160 180 200 260 280 300 320 360 380 120 220 240 340 mm
Chart Meon 2: Mislingford wild brown trout length distribution, 2013
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Silver Springs (n=53) 12 10 8 6
Frequency 4 2
0
60 80
100 120 140 160 200 220 240 260 300 340 360 180 280 320 380 mm
Chart Meon 3: Silver springs wild brown trout length distribution, 2013
Meon discussion The data from our annual Meon surveys since 2007 shows us that brown trout reproduction success, growth and survival appears to vary quite widely according to prevailing flow and temperature conditions and that the relationships between trout of different ages and flow and temperature at different times of year are complex. Therefore, it was obvious that it would be hard to predict the effects of the cold, harsh spring and long, warm summer on Meon trout in 2013.
Chart Meon 1 shows that overall trout abundance at Mislingford was the lowest yet recorded since annual surveying started in 2007. The Mislingford length frequency histogram (Chart Meon 3) indicated that the majority of these trout were one year olds and that the 2013 year class was remarkably poor. By contrast, overall trout density at Silver Springs was the highest since 2007 and the same was true for salmon. The Silver Springs length frequency histogram (Chart Meon 3) indicates that a high proportion (just under half) of all trout caught were one year olds, suggesting a relatively strong year class at this site. 2013 is the first year that trout density at Silver Springs has exceeded that at Mislingford.
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4.3 Hamble
Four Water Framework Directive fish surveys were conducted in the Hamble catchment in 2013, two in the upper reaches, close to Bishop's Waltham, and two in the middle reaches. These results will be used to classify the three Hamble waterbodies within which these sites lie.
Map Hamble 1: fish survey locations
Hamble results: Chart Hamble 1 shows the density of each fish species caught at the four fish surveys on the Hamble in 2013. The sites are arranged in order from upstream to downstream:
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50
45 Brook lamprey 40 Minnow
35 Bullhead 3-sp. stickleback
2 30 Eel 25 Roach
No./100m 20 Dace Chub 15 Brown trout 10
5
0 Tangier Farm Brooklands Farm Durley Mill Frog Mill
Chart Hamble 1: Species densities at four Hamble WFD surveys
Hamble discussion Brown trout is the dominant fish species throughout the Hamble catchment and Chart Hamble 1 shows that this species was present at all four 2013 surveys. Actual numbers caught were much higher at Durley Mill and Frog Mill (40 & 44 respectively), but the size of the larger survey areas means a lower density value compared to small sites such as Brooklands Farm and Tangier Farm (18 & 2 trout in total).
The chart reflects the greater number of fish species encountered in the middle reaches compared with the headwaters. Bullhead were abundant at all four sites, whilst dace and chub were present at the two sites farthest downstream. Reasonable densities of eels were recorded at Durley Mill and Frog Mill, the species was absent from Brooklands Farm, whilst two were caught at Tangier Farm.
These survey results are likely to result in classification of the waterbody containing the Durley mill and Frog Mill sites as Good or High for fish but the more difficult to predict the status of the two waterbodies represented by Brooklands Farm and Tangier Farm, because of the lack of eel sin the first case and the low abundance of trout in the second.
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Brooklands Farm bluebells and a typical young of the year wild brown trout from Frog Mill
Survey in progress at Tangier Farm. Bankside fish processing station at Frog Mill
Wild garlic at Durley Mill
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4.4 Itchen
With European wide eel abundance thought to be in steep decline, the Environment Agency has established a series of Eel Index Rivers, on which eel populations are monitored closely. Along with the Ouse in East Sussex, the River Itchen is one of two eel index rivers in Solent & South Downs Area. Both monitoring programmes consist of ten three-run electric fishing surveys conducted every other year at sites throughout the catchments. These programmes commenced in 2009, so 2013 was the third year of eel index monitoring. In addition to eel index monitoring, three other fish surveys were conducted in the Itchen catchment in 2013: two post-restoration surveys on the Candover Brook and one Water Framework Directive survey on the Nun's Stream in Winchester. Two of the eel index surveys, Shawford Park and Bishopstoke also serve as our biennial juvenile salmon monitoring sites. Another two, Abbotstone and Vernal Farm, serve as annual wild brown trout monitoring sites.
Map Itchen 1: fish survey locations
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Eel Index results Chart Itchen 1 shows the estimated number of eels present at each of the ten eel index survey sites. Sites are arranged in order from upstream to downstream, with the exceptions of Abbotstone and Duck Meadow, which are on the Candover Brook and Cheriton and Vernal Farm, on the Cheriton stream (both Itchen headwaters near to Alresford).
200 180 160
140 2009
120 2011
100 2013 80
60 Estimated total Estimated 40 20 0
Chart Itchen 1: Estimated eel numbers
Charts Itchen 2, 3 and 4 are length frequency histograms showing the numbers of eels in each length category in 2009, 2011 and 2013 respectively:
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18 2009 n=321 16 14 12 10 8 Number 6 4 2
0
160 200 280 320 400 440 520 560 640 680 760 120 240 360 480 600 720 Length mm
Chart Itchen 2: Eel length frequency 2009
18 2011 n=221 16 14 12 10
8 Number 6 4 2
0
120 160 200 240 360 400 440 560 600 640 680 760 280 320 480 520 720 Length mm
Chart Itchen 3: Eel length frequency 2011
20 2013 n=175 18 16 14 12 10
Number 8 6 4 2
0
120 200 280 360 400 440 480 560 640 720 760 160 240 320 520 600 680 Length mm
Chart Itchen 4: Eel length frequency 2013
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Itchen eel index discussion Chart Itchen 1 shows that eel abundance is highest at the sites closest to the tidal limit: Ham Farm and Bishopstoke Barge (approximately 8 and 6km respectively). It's likely that eel densities are even higher downstream of Bishopstoke Barge. Given the low numbers of eels caught on the eight sites upstream of these and at all ten Ouse eel index sites, it may be that records from these sites give the most reliable indication of genuine trends in eel abundance locally.
In the 2011 report, we expressed concern that the total number of eels caught at these two sites was less than that caught in 2009. Expanding this perspective to all ten Itchen eel sites, the sum of the estimated eel populations reduced by 32% between 2009 and 2011 and 49% between 2009 and 2013. The percentage reduction between 2011 and 2013 was 25%.
The length frequency histograms on the previous page show that the "shape" or age structure of the eel population doesn't appear to have changed significantly between each of the three years (ANOVA P=0.8). However, the eel length range that has seen most reduced abundance between 2009 and 2013 is that from 270 and 290mm.
The 2015 Itchen eel index surveys will help clarify whether or not this reduction in abundance is more likely to be natural variation within the population, reflecting oceanic or climatic conditions, or a genuine indication of rapidly declining eel abundance. In the meantime, the enforcement of the Eel Regulations in SSD will continue to improve migration conditions and survival for eels in local rivers.
Itchen salmon biennial survey results
250
200
150
100 Total first run catch run first Total 50
0 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Bishopstoke Barge Shawford Park
Chart Itchen 5: Total first run salmon parr catch at annual survey sites
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16 Shawford Park n=64 14 12 10 8 6
Total 1st run catch run 1st Total 4 2 0
mm
Chart Itchen 6: Salmon parr length frequency, Shawford Park
16 Bishopstoke Barge n=93 14 12 10 8 6
Total 1st run catch run 1st Total 4 2 0
mm
Chart Itchen 7: Salmon parr length frequency, Bishopstoke Barge
250
200
150
0+ parr 0+ 100
50
0 3 4 5 6 7 8 9 10 Flow m3/s Bishopstoke Barge Shawford Park Linear (Bishopstoke Barge) Linear (Shawford Park)
Chart Itchen 8: 0+ salmon parr abundance & mean monthly flow in previous Oct-Dec
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Itchen salmon discussion Chart Itchen 5 show the total number of salmon parr caught in the first electric fishing runs at Bishopstoke Barge and Shawford Park. Recently, these surveys have also been included in the eel index monitoring programme, involving three runs. However, when looking at salmon results, we only look at the first run data so that results can be compared with previous years when only a single run was completed. The chart indicates that salmon parr abundance at both sites was relatively low in 2013 and that, for the first time in our dataset, abundance at Shawford was lower than at Bishopstoke.
To some extent, this variability in salmon parr abundance between years is likely to be the result of changes to habitat e.g. varying degrees of light & shade, bankside vegetation & woody debris between years. However, because abundance at both sites is quite well correlated, the variation is more likely to reflect differences in flow and temperature between years. Analysis of this dataset in 2011 showed that the relationships between abundance and size of 0+ and 1+ salmon parr with temperature and flow were complex and that there appeared to be clear differences between the ways the two age groups responded to conditions.
Of all the relationships investigated, the strongest was that mean monthly flow in the winter (Oct - Mar) before the survey appeared to be negatively correlated with the abundance of 0+ salmon at both sites. For the Shawford data (only four survey years), this is an almost perfect negative correlation (-0.96). Does this indicate that spawning habitat at these sites is less good in high autumn flows, or that the higher flows encourage adult salmon to migrate further upstream, or that high flows increase suspended solids and reduce egg survival, or none of these things? Each additional year of monitoring improves our chances of answering this and other crucial questions concerning Itchen salmon recruitment.
Itchen wild brown trout annual survey results
140
120
100
80
60
First run catch run First 40
20
0
2002 2004 2006 2008 2010 2012 2008 2010 2012 2001 2003 2005 2007 2009 2011 2013 2002 2007 2009 2011 2013
No survey 2001survey No 2003survey No 2005survey No 2006survey No No survey 2004survey No Abbotstone Vernal
Chart Itchen 9: First run brown trout catch at Abbotstone & Vernal.
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140 2.5
120 2.0 100
1.5
80
/sec 3
60 M 1.0
First run catch run First 40 0.5 20
0 0.0 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Abbotstone Vernal Candover Apr-Sept Candover prev. Oct-Mar Cheriton Apr-Sept Cheriton prev. Oct-Mar
Chart Itchen 10: First run brown trout catch at Abbotstone & Vernal compared with summer & previous winter flow
160
140
120
100
80
60 First run catch run First 40
20
0 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
M3/sec
Abbotstone Vernal Linear (Abbotstone) Linear (Vernal)
Chart Itchen 11: Scatter plot of trout abundance against average of Candover & Cheriton summer flow.
Itchen wild brown trout discussion Chart Itchen 9 shows that wild brown trout abundance at Abbotstone and Vernal in 2013 was slightly below average of all survey years, but greater than in the previous two. Chart Itchen 10 sheds some light on how closely linked trout abundance at these two sites is with both average
UNCLASSIFIED 67 of 101 UNCLASSIFIED flow in the summer of the surveys (they're conducted in late summer) and in the previous winter. Average summer flows in 2013 and in winter 2012/2013 were both higher than the equivalents in the previous two years.
Chart Itchen 11 illustrates the positive relationship between wild brown trout abundance and flow on the Candover Brook and Cheriton Stream by plotting the first-run catch in all survey years against the average summer flow of both streams.
Itchen whole fish community During the course of the ten eel index surveys, fish of all species are recorded, providing a comprehensive survey of the Itchen's whole fish community. The pie chart below represents the total numbers of all fish species caught during these surveys:
Brook lamprey Brown trout Stone loach Atlantic salmon Chub
Grayling Gudgeon Perch Minnow Pike Eel
3-spined stickleback
Bullhead
Chart Itchen 12: Itchen fish species relative abundance.
Candover habitat improvement monitoring results The local Environment Agency Fisheries and Biodiversity team have been working with the Wild Trout Trust to enhance wild brown trout habitat on the upper reaches of the Candover Brook since 2011. The reaches in question were particularly prone to heavy bankside poaching (trampling) by cattle and had very little vegetation cover and variation in channel form, meaning there was virtually no available cover for adult trout. The two principal enhancement techniques were bankside fencing and the pinning of large woody debris (live & dead tree trunks) into the channel. The original design for fish monitoring was to have three surveys: one on the enhanced reach, before and after works and two untreated control sites (one immediately upstream of the treatment site, one a short distance downstream), to reflect natural variation in trout abundance (long term monitoring shows that trout abundance on the Candover can vary considerably in response to flow conditions). Monitoring progressed as planned in 2011 and 2012 but in autumn 2012, after the annual fish survey had been conducted, Control site 1 was fenced and had large woody debris pinned into the channel, ceasing to be a control and becoming a second treatment site.
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Chart Itchen 13 shows wild brown trout density at each site in 2011, 2012 and 2013, based on single run electric fishing over 100m of channel.
45
40
35
30
2 Treatment site 25 Control 1: unfenced
20 Control 2 No./100m Control 1: fenced 15
10
5
0 2011 2012 2013
Chart Itchen 13: Candover habitat enhancement project trout densities
Candover habitat improvement monitoring results
Chart Itchen 13 demonstrates that In 2011, before any trout habitat enhancement had commenced, trout abundance at both control sites and at the proposed treatment site was similar at between 5 and 7 individuals per 100m2. In 2012, the effects of the enhancement works at the treatment site were apparent in that year's survey data, with approximately a halving of trout abundance at both control sites and close to a doubling at the treatment site.
The 2013 survey data indicates a more than doubling of trout abundance at the remaining control site (Control 2), between 2012 and 2013 to a value similar to that recorded in 2011. However, abundance at this site remains low compared to less impacted sites on the same stream.
Following the enhancement of Control 1 in late 2012, trout abundance increased more than 17- fold: showing a far greater response to the improvement works than to natural variation. Similarly at the original treatment site, trout abundance more than doubled between 2012 and 2013, probably reflecting further maturation and colonisation of the enhancement measures.
The remarkable increase in trout abundance at Control 1 is a typical response to the fencing of chalkstream headwaters chronically impacted by livestock poaching. The initial major change in the habitat is prolific growth of marginal watercress, producing a fast, sinuous open channel, relatively deep compared to the unfenced one. As a result, there is a rapid increase in cover available for trout, boosting the reach carrying capacity significantly. It's worth noting that even though the total number of trout caught in this newly fenced reach increased from fourteen in 2012 to forty in 2013, in the same period the encroaching watercress reduced the total area available as fish habitat from 596m2 to 93m2. This is a clear demonstration of the general principal that a narrow channel with excellent habitat quality will tend to support a greater abundance of fish than the same length of wide channel with poor habitat.
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Nun's stream WFD survey results
50
45 Stone loach 40 10 sp stickleback 35 3 sp stickleback 30 Minnow
Catch 25 Brook lamprey
20 Bullhead
15 Eel Pike 10 Brown trout 5
0
Nun's stream
Chart Itchen 14: Nun's stream fish community
River Itchen salmon datasheet Table Itchen 1 on the next page sets out key statistics for the Itchen salmon population. Returning Stock is the number of adult salmon recorded at the lower Itchen 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 immediatley returned alive; Spawning Escapement is the number of salmon estimated to be available for spawning and Egg Deposition is the total number of eggs likely to be produced by those fish.
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Table Itchen 1: River Itchen salmon datasheet, 1990-2013
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 444 154 100 444 1.08 +
Salmon egg conservation limit 1.63 M Salmon egg management target 1.97 M
Notes ** Likely to be a slight underestimate due to sensitivity fault in May and June + Provisional count awaiting verification
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4.5 Test
In 2013 eight Water Framework Directive fish surveys were conducted, either to replace old data or to provide data from new, more suitable locations for classifying waterbodies. Two of these were on the Anton, two on the Bourne Rivulet, two on Romsey Barge Canal and one on a carrier on the Broadlands Estate.
Map Test 1: fish survey locations
Results
Chart Test 1 shows the densities of fish species caught at all of these surveys:
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70 Brook lamprey
Stone loach 60 Minnow
50 Bullhead
3-spined
2 40 stickleback Gudgeon
30 Pike No./100m Perch
20 Roach
European eel 10 Chub
0 Dace Artist's Way Cottonworth The Island Hurstbourne Landford Red River Romsey Romsey Carrier, Canal Canal railway Grayling Broadlands bridge Brown / sea Anton Bourne Rivulet Blackwater Main Test Romsey Barge Canal trout
Chart Test 1: WFD survey results
Discussion The obvious highlight of Chart Test 1 is the survey result for "The Island", a site in the middle reaches of the Bourne Rivulet. This survey produced a truly exceptional quantity of wild brown trout and included numerous fish from all life stages; young of the year through to large adults. This result is a strong endorsement of effective habitat management, lack of disturbance and no stocking. Far fewer trout were caught at Hurstbourne, further downstream on the same watercourse, which is probably attributable to the survey site lying between two manmade features that may hinder fish passage: a flow gauging weir and an historic stone impoundment. Wild brown trout were also fairly abundant at Artist's Way and Cottonworth on the River Anton and at Landford on the River Blackwater. Trout were notable by their absence from the Red River Carrier on the Broadlands Estate but eels were plentiful, reflecting the site's proximity to the head of tide and the good fish passage conditions downstream. The site at Romsey Canal is the formal WFD sampling point for this Waterbody (Fairbourne stream & Fishlake meadows) but was impounded by a set of removable boards, put in place to hold up the water level for aesthetic reasons. The boards were considered to be damaging to the stream ecology and were removed permanently in spring 2013, immediately after the fish surveys. In order to record any change to the fish community, a control site downstream of the boards (unaffected by their removal) was also surveyed; Romsey Canal railway bridge. Both surveys were scheduled for repeat in 2014. The contrasting results from these two sites in 2013 reflects the effects of the boards on the fish community in the impounded reach, with roach being the most numerous species, no trout and few bullhead. The effect on the physical habitat was even more clear-cut, with a thick deposit of silt and leaf litter throughout the impounded reach, compared with stretches of clean gravel riffle in the downstream control site.
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River Test salmon datasheet Table Test 1 on the next page 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 immediatley returned alive; Spawning Escapement is the number of salmon estimated to be available for spawning and Egg Deposition is the total number of eggs likely to be produced by those fish.
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Table Test 1: River Test salmon datasheet, 1990-2013
River Test Adult Catch and Spawning Return Returning Release Escapeme Egg Year Stock Rod Catch Rate nt 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 +
Salmon egg conservation limit 3.40 M Salmon egg management target 3.88 M
Notes * Returning stock estimate based on historic relationship with rod catch due to fish counter faults + Provisional count awaiting verification
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4.6 New Forest
In July and August 2013, fish population surveys were conducted at sixteen sites on the Lymington River and at fifteen sites on the Beaulieu River. Both rivers support modest wild brown trout fisheries in their lower reaches and there is also a small coarse fishery on the Lymington River: the survey programme is aimed at informing the management of these fisheries as well as the broader management of Forest streams. Our fish population monitoring programme consists of two sites on each river that are sampled annually and a further twelve sites on each that are sampled once every six years. A small number of additional sites are sampled for Water Framework Directive purposes in some years: two of these, Ivy Wood (Lymington) and North Lane (Beaulieu), were sampled in 2013 and the results included in this report. All surveys were conducted using a battery-powered backpack electric fishing unit, sampling 100m of channel. The twelve 6-yearly sites on each catchment were first sampled in 2007 and the same sites were sampled for the second time, in 2013.
Please note that as this data was presented as a separate report in late 2013, the format is slightly different from the rest of this document.
Map New Forest 1 shows the locations of all Lymington River wild brown trout surveys (brown), all New Forest WFD surveys (pink) and the single combined trout / WFD site (Upstream of Puttle's Bridge: yellow). Map New Forest 2 shows the locations of all Beaulieu River wild brown trout surveys.
Map New Forest 1: Lymington wild trout & New Forest WFD survey locations
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Map New Forest 2: Beaulieu wild trout survey locations
How the results are set out
The results of over fifty surveys are summarised in this section, so it is restricted to presenting individual survey results and addressing the most fundamental questions about the fish communities: Has fish abundance changed since 2007? Has the geographical distribution of fish species changed? The report focuses on brown trout and leaves a great deal of scope for further analysis, particularly regarding coarse fish, eels and minor fish species.
Pie charts are used to illustrate the overall species composition of each river's fish community. Length-frequency charts for trout are given to illustrate abundance in each survey year and the size of fish making up the population (age structure). Individual survey results are presented in the form of "stacked" bar charts, each representing a group of survey sites relating to a tributary or channel section. These charts give the number of fish of each species caught at each survey site, with one bar for the 2007 survey and one for 2013. Sites are generally set out in upstream to downstream order, from left to right. Results for trout are given as "0+", meaning young of the year, and ">0+", meaning all older trout. Minor fish species (bullhead, minnow, brook lamprey, 3 spined stickleback & stone loach) are omitted from these charts, as they obscure the trout data and were recorded differently in 2007 and 2013. Minor species data for 2007 and 2013 is set out in separate tables.
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Results
Fish community pie-charts These two charts are based on the combined catch from all survey sites in each catchment - they indicate which species are present and the total number caught in 2013:
Lymington River fish species relative abundance, 2013
Stone loach, 97 Roach, 2 3 spined stickleback, 1 Pike, 6
Brown trout, 510 Minnow, 360
Brook lamprey, 38 Gudgeon, 1 Bullhead, 206 Eel, 5 Chub, 13
Chart NF 1: Lymington River relative abundance
Chart NF 2: Beaulieu River relative abundance
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Lymington River, 2007 (n=562)
120
100
80
60
Number of trout of Number 40
20
0
30 45 75 60 90
105 120 150 165 195 210 240 270 285 315 330 135 180 225 255 300 Length category mm
Chart NF 3: Lymington trout length frequency, 2007
Lymington River, 2013 (n=255)
120
100
80
60
Number of trout of Number 40
20
0
45 60 75 90 30
105 120 195 210 225 240 255 270 285 135 150 165 180 300 315 330 Length category mm
Chart NF 4: Lymington trout length frequency, 2013
Beaulieu River, 2007 (n=235)
120
100
80
60
Number of trout of Number 40
20
0
30 60 90 45 75
120 135 150 165 195 225 255 270 285 300 330 105 180 210 240 315 Length category mm
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Chart NF 5: Beaulieu trout length frequency, 2007
Beaulieu River, 2013 (n=146)
120
100
80
60
40 Number of trout of Number 20
0
60 75 90 30 45
105 120 135 210 225 240 255 270 285 300 150 165 180 195 315 330 Length category mm
Chart NF 6: Beaulieu trout length frequency, 2013
Individual site results
Note that the vertical axis maximum varies between graphs, so that the results of surveys with relatively low catches can be seen more clearly.
Lymington River:
Highland / main Lymington
180 Roach
160 Pike 140 Gudgeon 120
100 Eel
Number by species by Number 80 Chub 60 >0+ BT 40
20 0+ BT
0
2007 2013 2007 2007 2013 2007 2013 2013 2007 2013 2007 2013 2006 2013 Ocknell Lucas Withybed Long Brook Forest Gate Bolderford Ivy wood Inclosure Castle Bottom Bridge
Chart NF 7: Highland Water & main Lymington catches, 2007 & 2013
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Blackwater 90 80 Pike 70 Eel 60 50 Chub 40 30 >0+BT
Number caught by species by caught Number 20 0+ BT 10
0
2013 2007 2007 2007 2007 2007 2007 2013 2013 2013 2013 2013 Slufter's Bratley Arch Bratley Blackensford u/s Fletchers Inclosure Wood Lawn Blackensford Water / Bratley confluence
Chart NF 8: Blackwater catches, 2007 & 2013
Ober Water
70 Roach 60 Pike 50 Gudgeon 40 30 Eel
20 Chub Number caught by species by caught Number 10 >0+ BT 0
0+ BT
2013 2007 2013 2007
2013 no survey 2013no survey 2007no Turfcroft Puttles Bridge U/S Puttles Bridge
Chart NF 9: Ober Water catches, 2007 & 2013
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Beaulieu River:
Main Beaulieu 35 Eel 30
25 >0+ BT 20 0+ BT 15
10 Number by species by Number
5
0
2007 2013 2007 2013 2007 2013 2007 2013 2007 2013 2008 2013 Dunce's Arch Mallard Longwater u/s Ashurst Withycombe North Lane Wood lawn Lodge Shade
Chart NF 10: Main Beaulieu catches, 2007 & 2013
Longdown / Deerleap 70
60
50 0+ BT 40
30
Number by species by Number 20
10
0
2013 2007 2013 2007 Deerleap Inclosure Longdown Inclosure Tributary
Chart NF 11: Longdown tributary & Deerleap Inclosure catches, 2007 & 2013
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Matley trib. 35 30 25 Eel 20
15 >0+ BT
Number by species by Number 10 5 0+ BT
0
2007 2013 2007 2013 Holmhill Passage Matley Passage
Chart NF 12: Matley tributary catches, 2007 & 2013
Shepton 30
25 Eel
20 >0+ 15
Number by species by Number 10 0+
5
0
2007 2013 2007 2013 Upper Shepton Water Shepton Water
Chart NF 13: Shepton Water catches, 2007 & 2013
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Penerley 60 Eel 50 >0+ BT 40 0+ BT 30
Number by species by Number 20
10
0
2013 2013 2007 2007 2007 2013 Wort's Gutter Penerley Bridge Penerley Water - u/s Shepton confluence
Chart NF 14: Penerley Water catches, 2007 & 2013
Table NF1: Lymington River minor species catches
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Table NF2: Beaulieu River minor species catches
Discussion
Broader fish community: The New Forest fish survey programme is specifically designed to monitor juvenile trout, so the sites are generally in the headwater tributaries - as a result very little coarse fish and eel habitat is sampled and numbers recorded are subsequently very low: the Lymington pie charts on page 2 may look quite different if a few survey sites were located well downstream of Lyndhurst. Despite this, the bar charts for the individual Lymington survey sites show that certain sites on this catchment do support low numbers of roach, pike and gudgeon. No coarse fish have been recorded on any of our Beaulieu surveys, although some escaped carp have been seen in the tidal reaches. Another contrast between the catchments is that the Beaulieu appears to support a greater proportion of 3 spined sticklebacks than the Lymington.
Brown trout: The length frequency charts on page 3 go a long way to describing the status of the Lymington and Beaulieu brown trout populations in late summer, 2013: on the Lymington, fewer than half the total number of trout was caught in 2013 compared to 2007, whilst on the Beaulieu the number was a
UNCLASSIFIED 85 of 101 UNCLASSIFIED little more than half. The shapes of the length frequency graphs indicate that 2007 produced a strong year class of trout (many young of the year), whilst 2013 produced a remarkably weak one, comprising fish of a shorter average length. By contrast, the relatively strong year class of 2012 is evident as one year old fish in the 2013 graphs.
So why so many young of the year trout in 2007 and so few in 2013; why are the 2013 trout shorter on average and is this indicative of a downward trend?
Two sites on each catchment are surveyed annually and the time-series data from these suggests that the differences between the 2007 and 2013 datasets indicate natural variability rather trends and should not be a cause for concern. The chart below shows the total number of trout (predominantly young of the year) caught at the two most variable annual survey sites: Withybed Bottom on the Lymington and Penerley Bridge on the Beaulieu, both of which are prone to drying out in some years and supporting remarkable numbers of juvenile trout in others. This data is compared with the minimum flow recorded between April and September at Brockenhurst gauging station and a strong positive correlation can be seen:
180 0.09 160 0.08 140 0.07 120 0.06
100 0.05
/sec 3
80 0.04 m 60 0.03
Number of trout of Number 40 0.02 20 0.01 0 0.00 2007 2008 2009 2010 2011 2012 2013
Penerley Bridge Withybed Bottom Min flow Apr-Sept
Chart NF 15: Trout numbers at Lymington annual sites and minimum summer flow at Brockenhurst gauging station
The chart illustrates the highly variable, "boom or bust" nature of brown / sea trout spawning success in the New Forest headwaters and how dependent this is on summer flow. In contrast, the relationship between juvenile trout abundance and low flows appears to be different at sites that are not prone to complete drying out. The chart below compares minimum summer flow with trout abundance at the annual survey sites upstream of the Blackensford / Bratley confluence on the Lymington and Matley Passage on the Beaulieu. The chart suggests a degree of negative correlation between low flow and trout abundance at these sites (i.e. low flows are associated with abundant trout), with the exception of 2013, where low flow is coupled with low trout abundance:
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90 0.09
80 0.08
70 0.07
60 0.06
50 0.05
/sec 3
40 0.04 m
30 0.03 Number of trout of Number 20 0.02
10 0.01
0 0.00 2007 2008 2009 2010 2011 2012 2013
Matley Passage u/s Blackensford / Bratley confluence Min flow Apr-Sept
Chart NF 16: Trout numbers at annual Beaulieu sites and minimum summer flow at Brockenhurst gauging station
There are likely to be many factors contributing to this pattern, particularly flow conditions during autumnal upstream adult migration, the impact of flows on the availability of spawning and juvenile habitat and possibly even downstream drift of parr. However, the most likely explanation for the low flow/low trout abundance situation at these sites in 2013 is the combination of prolonged low temperatures in spring and high temperatures in summer. The unusual cold snap in spring 2013 is likely to have reduced survival and growth rates in juvenile trout, both directly and as a result of reduced food availability. In stark contrast, notable features of the 2013 survey programme were the unusually high air and water temperatures and the recurrent observation of asphyxiated trout (back arched, gills flared) at the edges of isolated pools in drying stream sections. Wherever, possible, trout caught in such pools were moved to larger nearby pools with more shade and offering higher chance of survival.
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5. Estuarine fish monitoring
5.1 Southampton Water
In 2013 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 comprising two 15 minute trawls, carried out by the coastal survey vessel "Solent Guardian" in relatively deeper water around 600m east of Hythe.
Map SW1 shows the locations of all Southampton Water TrAC survey sites:
Map SW1: Southampton Water TrAC fish survey locations
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Fyke nets in place at Bury Marsh
Measuring the catch at Bury Marsh
Juvenile starry smooth hound caught in the Hythe Pier otter trawl
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Results Chart SW1 shows the numbers of each fish species caught in 2013 in all the surveys that are repeated in spring and autumn (beach seines, beam trawls & fyke nets). Note that where there is a species name but no bar is visible, only a small number of individuals were caught (or possibly just one):
2000 1800 1600 1400 1200 Spring
1000 Autumn 800 600 400 200 0
Chart SW1: Species caught in spring & autumn 2013
1.5m beam trawl about to be towed from Weston Shore
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Chart SW3 shows the catch for the 2013 Hythe Pier otter trawl survey, which is only conducted in autumn:
80
70
60
50
40
30
20
10
0
Chart SW3: Hythe Pier otter trawl catch, autumn 2013
Dover sole from the Fawley fyke in spring
An adult cuttlefish: by-catch from the Fawley fyke net in spring
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Chart SW3 compares the numbers of bass caught in spring surveys with average sea surface temperature in the preceding winter:
1000 10.5
900 10
800 9.5 700 9 600
8.5 C) 500 °
Catch 8 400 7.5 300
200 7 Temperature ( 100 6.5 0 6 2007 2008 2009 2010 2011 2012 2013
Bass Winter sea surface temp.
Chart SW3: Bass caught in spring surveys & winter sea surface temperature
Chart SW4 compares the numbers of bass caught in autumn surveys with average sea surface temperature in the summer of the same year:
2000
1800 16.5
1600 16.3 1400
1200
C)
Catch 16.1 1000
800 15.9
600 Temperature ( Temperature 400 15.7 200
0 15.5 2007 2008 2009 2010 2011 2012 2013
Bass Summer sea surface temp.
Chart SW4: Bass caught in autumn surveys & summer sea surface temperature
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Juvenile bass from the Bury Marsh fyke net
Charts SW5 and SW6 show the proportion of bass caught at each survey site in spring and autumn respectively, based on data from all survey years:
Chart SW5: Proportion of bass caught at each seine net site in spring (all years combined)
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Chart SW6: Proportion of bass caught at each seine net site in autumn (all years combined)
Setting the seine net at Swanwick
Southampton Water TrAC discussion We have been monitoring Southampton Water's fish community for Water Framework Directive purposes since 2007 and in that time, 61 species have been captured. The greatest number of species recorded in any one year is 58 (2009); the lowest is 12 (2008). Eight species have been recorded in every one of the seven survey years; these are: common goby, sand goby, flounder, golden grey mullet, thick lipped grey mullet, greater pipefish, sand smelt and bass. Five species have been recorded in only one survey year; these are: brill, Nilsson's pipefish, Lozano's goby, scad (horse mackerel) and scaldfish. Thirty five species were recorded in 2013, all of which had been recorded in previous years.
Overall catches were low in our spring surveys, probably due to the very cold conditions in March and April: numbers of gobies and sand smelt were particularly low. The much more favourable conditions over the summer months ensured that the catches in autumn were more typical.
Although our monitoring of fish populations in Southampton Water yields a great deal of valuable ecological information, its primary purpose is to provide data for the classification of the estuary for
UNCLASSIFIED 94 of 101 UNCLASSIFIED the Water Framework Directive. The 2014 status for the estuary for fish is "moderate", but with a low degree of confidence, which stems from the fact that there is so much variation in the dataset (data from a six year period is included in the calculation). However, despite the current lack of statistical confidence, it is clear that it is the data derived from beam trawling that is the main reason that the overall classification is less than "Good" (the order of classes is: Bad, Poor, Moderate, Good or High; less than Good is a failure).
Multiple methods are used for TrAC fish sampling because each one is more effective at sampling certain types of habitat and is biased towards certain types of fish. For example, fyke nets can be set in places where a seine net or beam trawl sample would be impossible (for example, adjacent to salt marsh: Bury Marsh, or on very soft sediments: Fawley). The fish community in these places is often very different from suitable seine and beam trawl sites. Beam trawling samples benthic (bottom dwelling) fish species, usually from just beyond the intertidal zone at sites fished at low tide and within it at those fished at high tide. Since beam trawling was introduced as a sampling method in Southampton Water it has yielded remarkably few fish and only a small range of species, despite careful checks that the gear is fishing correctly and the fact that four contrasting and widespread sites are sampled (Goatee Beach, Calshot, Weston Shore & Manor Farm).
One explanation for these consistently poor beam trawl catches over many years is that the particular habitat sampled by beam trawl in Southampton Water is in poor condition and, as a result, supports a depleted fish community. If this is the case, it's important to understand what pressures might be affecting these benthic fish communities. A likely candidate is physical damage and disturbance, possibly as a result of regular shellfish dredging and / or dredging for navigational purposes. Alternatively, this may be a natural feature of the estuary that we currently understand little about. Further investigation and analysis is currently underway.
Bass Charts SW3 and 4 compare bass abundance in spring and autumn with average sea surface temperatures in winter and autumn respectively. The close correlations between winter sea temperature and spring abundance and between summer temperature and autumn abundance are reflected in the 2013 data, emphasising the generally detrimental impact of low sea temperatures on juvenile bass in Southampton Water.
Charts SW5 and 6 illustrate the relative proportion of bass caught at our various survey sites, indicating that Itchen Bridge, Manor Farm and Swanwick yield the majority of our bass captures. This information is useful in showing that juvenile bass stocks don't appear to be spread evenly throughout the estuary, with the Hamble in particular likely to be an important bass nursery area.
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Above: deep-snouted (a.k.a. broad-nosed) pipefish and, below, Greater pipefish, both caught at on the Hamble at Manor Farm in spring
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5.2 Adur estuary
In 2013 we surveyed the three routine sites on the Adur estuary; Ladywell, 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 1: Adur estuary TrAC fish survey locations
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Results: Chart Adur 1 shows the total number of fish of all species caught in spring and autumn respectively, from 2010 to 2013:
1200
1000
800
600 Spring autumn
Total no. of Total fish caught 400
200
0 2010 2011 2012 2013 Chart Adur 1: Total catch, spring & autumn, 2007-2013
Chart Adur 2 shows the numbers of each species caught in spring and autumn in 2013:
350
300
250
200
150
Spring No. fish caught No.fish 100 autumn
50
0
Chart Adur 2: Spring & autumn catches in 2013
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Discussion The two different survey periods on the Adur estuary showed very different results in 2013, reflected in Charts Adur 1 and 2, with the spring catch being the lowest on record, almost certainly as a result of the prolonged cold snap that persisted into March (see page 6). In contrast, autumn 2013 produced nearly double our previous highest catch for all sites combined. Fourteen species of fish were caught in 2013, with the most numerous being sand goby, sand smelt and thin-lipped grey mullet. Like Southampton Water, the Adur estuary is currently classified as Moderate for the Water Framework Directive, but with a high degree of statistical confidence. The principal pressure on the estuary's fish community is probably the degree to which it has been physically modified for navigation, flood defence and land drainage purposes over a period of several centuries: the river is largely disconnected from its floodplain by massive embankments throughout its tidally influenced course (around 9 miles).
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6. Looking forward
The 2014 fish survey season will have a relatively lighter workload compared with 2013 as it falls between biennial eel index years. However, teams will still be out conducting fish surveys twice or three times a week in order to complete our annual round of estuarine Water Framework Directive surveys in spring and autumn as well as a large number of riverine WFD surveys that need to be completed to provide waterbody classifications.
2014 is the first year of the ecology sampling period for the second round of WFD management, known as River Basin Management Cycle 2 and it brings changes with regard to fish monitoring. We have carried out a comprehensive risk assessment of all UK waterbodies in order to identify the environmental "pressures" that each is most at risk from. The impacts of each pressure are best measured by monitoring different biological elements: the three pressures best reflected by fish data are morphology (physical habitat quality), sedimentation (primarily from agricultural erosion) and hydrology (low flow). As such, we will cease WFD monitoring in waterbodies not at risk from these pressures (unless they are currently monitored and are failing). Conversely, we will start monitoring fish in waterbodies that are at risk from these pressures, unless they are already monitored and classed as good.
A major factor that will undoubtedly feature in our fish survey results in 2014 is the impact of the flooding in winter 2013/2014, which resulted in record river levels for most southern chalkstreams and almost certainly affected the geographical distribution of salmonid spawning and the survival and distribution of overwintering juvenile coarse fish. At the time of writing, the spring 2014 estuarine fish surveys have been completed and catches suggest that these communities may have been impacted by the wild winter, probably as a result of decreased salinity due to freshwater inputs and possibly persistent stormy conditions over a prolonged period.
One final factor likely to affect the 2014 fish survey season and probably subsequent seasons, is the major reorganisation of the Environment Agency that is currently underway, aimed at reducing the size of the organisation and cutting operating costs. To date, this has resulted in two changes to fish monitoring programmes. Firstly, it is unlikely that any fish surveys will be undertaken in future that do not have specific, nationally recognised purposes, such as WFD, Principal Fishery or Eel Index monitoring. Secondly, Principal Brown Trout fishery temporal (wild brown trout) surveys will reduce in frequency from annual to biennial. In SSD, this affects two sites each on the rivers Ouse, Meon, upper Itchen, Beaulieu and Lymington.
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