NATIVE CRAYFISH PROJECT

EAST HAMPSHIRE RIVERS SURVEY

AND THE 1997 INTERIM REPORT ON THE PROJECT

Prepared for

The Environment Agency (Southern Region), English Nature (Species Recovery Programme) and The East Hampshire AONB Project

Adrian Hutchings, Project Manager Carol Elliott, Project Assistant

Dept. of Fish, Game and Wildlife Management, Sparsholt College, Winchester, Hampshire. SO21 2NF

February, 1998

Native Crayfish Project Hampshire

EXECUTIVE SUMMARY

This is an interim report of a long-term study of the native White-clawed or Atlantic Stream crayfish Austropotamobius pallipes Lereboullet in Hampshire. It principally details the findings of the 1997 survey and monitoring effort in selected rivers and streams in Hampshire, with particular attention to those in the north and east of the County.

The survey identified the presence of A. pallipes in the River Rother (Arun catchment) and the Lower Test, the latter being discovered in early 1998. This brings the total known native crayfish sites in Hampshire to six. The Candover Brook population is potentially the largest in Hampshire, but the native crayfish on the Rother appear to be widespread. In contrast the populations in the River Anton and possibly the Lower Test appear to be small and highly vulnerable to extinction.

In addition monitoring programmes are now in place for three of the four previously known populations of native crayfish. There appears to be little change in the Upper Candover Brook population over the year, remaining healthy and stable, whilst monitoring has only just started in the two other locations.

Signal crayfish P. leniusculus have been found in most rivers surveyed in 1997, including the rivers Anton, Southern Wey, Lyde and Whitewater, and some of these populations are substantial. At several locations both signal and native crayfish can be found in close proximity, the Rivers Anton and Rother being good examples of this. The reasons for the continued survival of native crayfish in these areas is unclear.

The Lower Test native crayfish discovery is a highly significant one, being the only lower river population in Hampshire, if not in Southern England generally, and having survived with signal crayfish directly upstream. There are many implications of this find, including giving some hope to discovering other populations of native crayfish in the main Hampshire Rivers.

Recommendations are given for conserving the recently discovered populations of native crayfish.

This survey represents the largest undertaken by the Native Crayfish Project to date and has substantially enhanced the existing information on the distribution of crayfish species in Hampshire.

Native Crayfish Project Hampshire

Confidentiality

This report contains confidential and sensitive information on the location of an endangered Red Data Book species. It is requested that the locational details of native crayfish in Hampshire remain confidential. In addition all sites where this species is found are in private ownership. Access to the sites should be strictly controlled and only permitted through consultation with the riparian owners, the Environment Agency, English Nature and the manager of the Native Crayfish Project, Sparsholt College Hampshire.

Acknowledgements

The Authors would like to thank the Environment Agency (Southern Region, Conservation Section), the Species Recovery Programme of English Nature and the East Hampshire AONB Project for their generous support of this work. The assistance in the field by Alison Strange, Susan McIntosh and Howard Colmer is especially acknowledged. Finally, but most important, the many waterkeepers and riparian owners for their help and enthusiasm towards this beleaguered species in Hampshire.

Report circulation:

Dr. Mary Gibson English Nature (Peterborough) Tim Sykes Environment Agency (Southern Region) Alison Tingley East Hants AONB Project

Clive Chatters Hampshire Wildlife Trust Jonathan Brickland Environment Agency (North East Region) Ian Davidson-Watts English Nature (Hampshire Team) Alastair Driver Environment Agency (Thames Region) Mark Elliott Environment Agency (Southern Region) Dr. J. Foster Environment Agency (Southern Region) Jim Glasspool Test and Itchen Association Dr. D. Holdich Nottingham University Shirley Medgett Environment Agency (Southern Region) John Millikin Environment Agency (Southern Region) Dr. R. Mitchell English Nature (Species Recovery Programme) Mike Mullins Environment Agency (Southern Region) Martin Noble Forestry Commission (New Forest) David Pape Hampshire County Council Planning Dept. Graham Roberts SE Region Otters Project Stuart Taylor Environment Agency (Southern Region) David Webb Environment Agency (Thames Region)

Lord Ashburton Landowner Mr. W.P Cleland Landowner Mr. M Davy Landowner Mr. R Harrison Landowner Mr. M.J Isaac Landowner Mr. K Kayser Landowner Mr P. Moncaster Water Keeper

Native Crayfish Project Hampshire

CONTENTS Page

Executive Summary 1

Confidentiality 2

Acknowledgements 2

Report circulation list 2

1.0 Introduction 1.1 Legislative background and status of A. pallipes and P. leniusculus 5 1.2 The Native Crayfish Project Hampshire 6 1.2.1 The context of this report 6

2.0 Rivers Survey 2.1 Aims 7 2.2 Extent of survey in 1997 7 2.3 Survey methodology 8 2.4 Limitations of the survey 9

3.0 Survey Results 3.1 Confirmed Native Crayfish locations 10 3.1.1 The River Rother 10 3.1.2 The Lower Test 12 3.1.3 The Lower Candover Brook (Itchen Catchment) 13

3.2 Confirmed Signal Crayfish locations 15 3.2.1 The Southern River Wey 15 3.2.2 The River Loddon (Thames Catchment) 15 3.2.3 The River Lyde (Thames Catchment) 16 3.2.4 The River Whitewater (Thames Catchment) 17 3.2.5 The Upper Basingstoke Canal 17 3.2.6 The River Rother 18 3.2.7 The Upper River Test 18 3.2.8 The River Anton (Test Catchment) 19 3.2.9 The River Dever (Test Catchment) 19 3.2.10 The Crampmoor Stream (Test Catchment) 20 3.2.11 The River Itchen at Winnal 20

3.3 Discussion 3.3.1 The distribution of native crayfish A. pallipes in Hampshire 22 3.3.2 The distribution of signal crayfish P. leniusculus in Hampshire 23

Native Crayfish Project Hampshire

Contents continued Page

4.0 Monitoring Programme 4.1 Monitoring methodology 24 4.2 Monitoring Results 4.1.1 River Anton 25 4.1.2 River Alre 26 4.1.3 Upper Candover Brook 26 4.3 Discussion 26

5.0 Other work carried out in 1997 28

6.0 Summary of the work in 1997 29

7.0 Summary of Recommendations for Future Work 30

References 32

Appendices

Annex 1: Table 1. Survey Locations and Figure 1. Map identifying rivers mentioned in the report. Annex 2: Table 2. Results from all surveyed locations Annex 3: General habitat and survey notes/survey locations Annex 4: Figure 2. Location of the River Rother native crayfish population Annex 5 : Figure 3. Location of the Lower Test native crayfish population Annex 6: Figure 4. Location of the lower Candover Brook native crayfish population Annex 7; Figure 5. The known distribution of A. pallipes in Hampshire upto January, 1998 Annex 8: Figure 6. The known distribution of P. leniusculus in Hampshire upto January 1998 Annex 9: The standard monitoring procedure (revised January, 1998) Annex 10: Figure 7 Chart showing the age structure of the native crayfish population in the Upper Candover Brook Annex 11: Figure 8. Composite map of native and signal crayfish locations in Hampshire Annex 12: Provisional Action Plan for native crayfish in Hampshire

Native Crayfish Project Hampshire

1.0 INTRODUCTION

The native crayfish Austropotamobius pallipes Lereboullet is considered to be an endangered species in Europe (Groombridge, 1993). The decline of A. pallipes is well documented and is widely attributed to the introduction of the North American signal crayfish ( Pacifasticus leniusculus Dana), which is a vector of the so called “crayfish plague” - a highly infectious disease caused by the fungus Aphanomyces astaci Schikora (Holdich and Reeve, 1991, Holdich et al, 1995). Several other causal factors may also be important in the decline of this species, including habitat modification, pollution and competitive exclusion by non-native crayfish species, where on the rare occasions mixed populations exist (Holdich and Reeve, 1991). Holdich et al (1995) suggest that 77% of British recorded sites for A pallipes have been or are under threat from crayfish plague or adverse water quality.

Hampshire is no exception to this with native crayfish now confined to a small number of sites. Whilst crayfish plague has only been confirmed locally in the Hampshire Avon (David Alderman, pers. comm.) it is still likely that this disease is the main reason for the decline of this species in the County.

Much of the information on the status and distribution of A. pallipes in Hampshire is however anecdotal and historical, but in recent years the Native Crayfish Project based at Sparsholt College has begun to fill the gaps. This report is the culmination of the 1997 survey effort and provides fresh information on the known locations of both native and signal crayfish and reports on the health of the surviving populations of native crayfish.

1.1 Legislative background and status

The native crayfish is recognised as being globally threatened and as such it is classed as endangered in the IUCN Red Data Book (Groombridge, 1993). A national action plan has been prepared for this species, which is reported in “Biodiversity, the UK Steering Group Report” (Palmer, 1995). In Britain A. pallipes is still relatively widespread, but is listed under Schedule 5 of the Wildlife and Countryside Act, 1981, providing protection against taking from the wild or sale and advertisement for sale. A. pallipes is also listed in Appendix III of the Berne Convention and Annexes II and V of the EU Habitats and Species Directive (92/43/EEC), which means that efforts should be made to conserve A.pallipes habitat, including the designation of Special Areas for Conservation (SACs).

The introduction of signal crayfish ( P. leniusculus ) is controlled in statute under Section 14 of the Wildlife Countryside Act, 1981 and under Article 22 of the EEC Habitats and Species Directive. “No go” areas for signal crayfish farms have also been set-up under the Provision for Keeping Live Crayfish Order 1996 by MAFF. In Hampshire the River Itchen and much of the New Forest is a “No go” area for farming signal and other non-indigenous crayfish.

Native Crayfish Project Hampshire

1.2 The Native Crayfish Project Hampshire

1.2.1 The context of this report

The Native Crayfish Project based at Sparsholt College continues to be the focus for crayfish work in Hampshire. Distributional information on both native and non-native crayfish has been supplemented over the last three years through targeting survey work in local rivers and by following up all unconfirmed reports of crayfish in Hampshire. The Project has also been involved in a range of associated work, including river enhancement schemes, educational work, captive breeding research and various initiatives related to native crayfish conservation in the UK generally. In this respect the Project Manager sits on the recently formed National Steering Group for the native crayfish Biodiversity Action Plan, and has developed a Hampshire- based action plan for this species in association with the Environment Agency and Hampshire Wildlife Trust (Hutchings, 1997).

The following report of the survey and monitoring effort in 1997 falls directly in line with the provisional Hampshire Action Plan for native crayfish, a summary of which is given in Appendix 12.

Native Crayfish Project Hampshire

2.0 RIVERS SURVEY

2.1 Aims

Recent surveys have shown that A. pallipes survives in Hampshire in three (possibly four, see text) isolated locations in the upper tributaries of the Rivers Test and Itchen catchments (Hutchings, 1996 and 1997). Anecdotal information and unconfirmed sightings have suggested that native crayfish could also be present in other river systems within the County, particularly in the eastern and north eastern Hampshire river catchments. Similarly there have been many reports suggesting a wide distribution of signal crayfish in the Hampshire rivers.

The principal aim of this work therefore was to investigate catchments hitherto unsurveyed and to further add to the existing data base of information on the status of crayfish species in Hampshire.

2.2 Extent of Survey in 1997

The rivers systems investigated during this survey are listed below and given in more detail with grid referenced locations in Table 1 (Appendix 1).

Thames catchment River Wey and selected tributaries Loddon catchment River Loddon (upper stretches) River Lyde River Whitewater (upper stretches) Basingstoke Canal (near the Greywell Tunnel end) Ramsdell Pond Arun catchment Upper River Rother and tributaries Meon catchment River Meon (upper stretches) Hamble catchment River Hamble (upper stretch) and South Pond at Bishops Waltham Test catchment River Test (upper stretches near Overton) Anton Lakes Crampmoor Stream

In addition to the above exploratory work the following river systems were revisited in an effort to confirm recent reports of crayfish sightings:

The River Test, Little River near Nursling Mill

The New Forest The Bartley Water (upper stretches within Busketts Lawn Inclosure)

River Itchen at Winnall Moors and Kings Worthy

River Itchen at Ovington at the confluence of the Candover Brook and the main river

Native Crayfish Project Hampshire

2.3 Survey methodology

In the main rivers survey sampling was undertaken downstream from the headwaters on a systematic basis every 200 metres, or wherever the habitat appeared to be particularly favourable for crayfish. A spot check approach was also taken in some areas to enable confirmation of previous observations or to check stretches that appeared to hold adverse habitat for crayfish.

At each sampling length two methods of survey were employed:

1. Manual searching : by hand turning stones and other large substrate and placing a net downstream to catch escapees. Kick sampling was also employed where the substrate was smaller or where searching among tree roots etc.

Manual searching was standardised and undertaken for 30 minutes at each location where crayfish were found. This enabled a catch per unit effort (CPUE - expressed in catch per hour) to be calculated and provided useful comparative information.

2. Trapping: A minimum of 5 crayfish traps were placed at locations where manual sampling was not possible, for example deep water areas, or where the habitat was difficult to survey, eg, deep crevices around bridges. The traps were baited with kippers and left in place for four nights. Catch per unit effort figures are expressed in catch per four day effort.

The former of the two approaches predominated in this survey, this was mainly because of the time consuming nature of trapping and the ability to cover more ground through the manual approach.

The following standard procedures were adhered to:

a). to safeguard against the spread of disease all equipment was disinfected between sites and sampling sessions, and particularly when the team moved back upstream to cover stretches where earlier access was not possible. This procedure falls in line with that suggested by Alderman et al (1985).using a minimum 100 ppm of IOSAN iodine,

b). all visual signs of crayfish disease were noted,

c). all native and non native crayfish individuals sampled were sexed, weighed and their carapace length measured as an assessment of age, allowing an approximation of population structure,

Native Crayfish Project Hampshire

d). after recording details, all non native crayfish caught were killed humanely and disposed of by the method of dispatch recommended by the UFAW (1995),

e). observations of the habitat at the sampling points where native crayfish were found were also made using the Environment Agency’s River Habitat Survey method (EA, 1996). Full RHS information was recorded for those stretches where native crayfish were found. Additional notes on the habitat conditions at all known crayfish sites were also made.

g). notes on recommendations for the management of important stretches, i.e. those holding native crayfish, were also made in the field.

The survey was undertaken between the months of June and November 1997, primarily by a small survey team comprising the Project Manager, Project Assistant and two surveyors.

The survey also followed-up unconfirmed reports of crayfish in locations outside of the sampled points.

2.4 Limitations of the survey

Certain factors have limited the comprehensiveness of the survey. It has not been possible to thoroughly survey whole river systems for example mainly due to time constraints. Also some tributaries, such as those which are winterbournes, ephemeral streams and within urban areas were investigated in less detail with spot checks only.

Generally access has been good during the survey period, with most landowners and waterkeepers providing help as mush as possible. Some problems arose through inaccessibility due to dense vegetation, with combinations of steep banks, depth of water coupled with fast flow.

Lack of vehicular access in many cases made trapping logistically unviable, particularly considering the scale of the project in 1997 and the time constraints involved in the trapping process.

Native Crayfish Project Hampshire

3.0 SURVEY RESULTS

Details of all native and signal crayfish observations are given below in Sections 3.1 and 3.2 respectively. A general results table including grid referenced locations of all sightings are given in Table 2 (Appendix 2), whilst notes on habitats and general findings in all surveyed stretches are included in Appendix 3.

3.1 Confirmed Native Crayfish locations

The 1997 survey has confirmed two previously unknown native crayfish populations one in the upper River Rother near Petersfield and the second in the lower Test near Nursling Mill. A small population however has been rediscovered at the confluence of the Candover Brook with the main River Itchen near Ovington, but no native crayfish have been found in the other streams investigated this year.

Details of these important native crayfish findings are given below:

3.1.1 The Upper River Rother

The River Rother was surveyed from Hawkley Hurst, near Noar Hill (SU 754 306) to Wenham Manor Farm (SU 789 234) which is approximately 1.3 kilometres into the County of West Sussex.

The survey has shown native crayfish to exist in the Rother from Sheet Mill (SU 761 241) to below Penns Place (SU 772 231) encompassing approximately 3 kilometres of the River (see Figure 2, Appendix 4) The majority of this stretch was surveyed by manual methods, including stone turning, bank probing and kick sampling. Overnight trapping was undertaken at one location at Hatchmoor Farm (SU 767 301), from where there have been unconfirmed sightings of A. pallipes as recently as 2 years ago. No crayfish however were caught at this location.

Historic and Unconfirmed information:

Routine biological monitoring in 1996 of the upper reaches of the Rother by the Environment Agency revealed the presence of crayfish, but the 0+ individual found was initially believed to be a signal crayfish ( John Foster, pers. comm. 1997).

The owner of Reeds Farm, (adjacent to Hatchmoor Farm mentioned above) have also reported sightings of crayfish (SU 758 307) most recently since this survey has been completed (Alison Tingley, pers. comm.).

Habitat Characteristics

The River Rother is Hampshire’s only Greensand River flowing over this deposit for all of its length in the County. As such this system is unique and quite unlike the characteristic crayfish inhabiting chalkstreams of the Test and Itchen, both in flow regime and habitat character.

Native Crayfish Project Hampshire

The Rother has a very variable flow regime with extreme peak flows in winter and spring and characteristically stable conditions during the summer months. For much of its length in Hampshire the River meanders through the Lower Greensand beds displaying a great range of physical structure, including pool and riffle systems, runs and glides, point and mid channel bars, undercut and steep, eroding vertical banks to several metres high in places. The system appears to be a naturally developing one with little human impact in the upper reaches.

The river mainly flows through agricultural land and extensively wooded sections, in particular through the characteristic beech hangers north of Petersfield. The bank zone is generally well vegetated with open and shaded sections, the dominant tree species being alder Alnus glutinosa, and sometimes grading into wet woodland and alder carr on the flood plain. In places where steep banks prevail the well vegetated and dense margins often make access difficult.

The smooth channel bed substrate is highly characteristic of this Greensand river, and unlike any other where native crayfish are found in Hampshire. Few boulders and large blocks exist for example, with crayfish refuges mostly being provided by overhanging alder tree roots, cobble-sized gravel material, and undercut shelves between the various Greensand strata at the bank-bed interface. Sandy/silty substrate appears to be common in the Rother with several native crayfish being found within these areas at the time of survey.

Similar to other crayfish sites the marginal zones would appear to be extremely important here for A. pallipes , especially given the variable flow regime and the propensity for high water conditions.

The Upper Rother is generally an important wildlife site with notable species such as kingfishers, brown trout, and lamprey being observed during survey. Otters have also been reported on this part of the Rother. The possible coexistence of this species with native crayfish essentially elevates the conservation status of the upper Rother, since this is one of only two locations in Hampshire, if not in the Southern Region, where this still occurs.

The stretch inhabited by native crayfish appears to be unfished and relatively unmanaged.

Threats to the Population

The most significant threat to the continued existence of native crayfish in the upper Rother is the presence of signal crayfish approximately 1.5 km downstream near Wenham Manor Farm (see Section 3.2.6 for further details of this population). Despite their close proximity, signal crayfish have apparently inhabited the river for at least 10 years and do not appear to have migrated too far upstream. The reasons for this are unclear, but it could be due to the presence of two small weirs between these populations acting as barriers to upstream movement. The situation here requires further research and investigation.

Changes in landuse, in particular the loss of bankside trees, urban encroachment, agricultural improvement and increasing recreational access along the River may Native Crayfish Project Hampshire also impact upon this important native crayfish population. Further studies are essential to devise a strategy to protect the native crayfish at this locality.

Recommendations for further work

1. Further investigate the distribution and status of both native and signal crayfish in the upper and middle Rother.

2. Implement a monitoring programme for both the native and signal crayfish populations.

3. Examine the options for site protection measures in the upper Rother, eg. designation as a Site of Special Scientific Interest.

4. Devise an action plan and strategy to protect the native crayfish population in the upper Rother.

5. Liaise with riparian owners, managers, local authority and Environment Agency staff to inform and educate about the importance of this site and to devise appropriate measures to ensure the protection of native crayfish in the short term.

3.1.2 The Lower Test - the Little River near Nursling Mill

In late January, 1998 a report was received about a crayfish capture in the lower Test near to Nursling Mill (SU 356 157) (Paul Moncaster (Waterkeeper), pers. comm.) (see Figure 3, Annex 5 for the location of this find). On examination the specimen was confirmed as a native crayfish - a healthy 4 + female in berry. This is a somewhat surprising find given the known presence of signal crayfish upstream on the Broadlands Estate fishery and at Romsey.

The individual was found in the Little River - a large carrier stream which is directly fed from the main River via a system of weirs and salmon ladders. The carrier is sympathetically managed primarily for salmon and sea trout fishing. This find is close to the mouth of the River Test, the estuary being approximately 3 km away.

This important discovery was made in early February too late to undertake any further investigations.

Historic and Unconfirmed Records

Few records of native crayfish exist for the lower Test. Crayfish were apparently abundant in the Testwood and Nursling Mill sections some 10 - 15 years ago, but no recent sightings have been recorded (Vic Foote (retired Waterkeeper) pers. comm.). It can be assumed that these early records are of native rather than signal crayfish.

Native Crayfish Project Hampshire

Habitat Characteristics

The carrier stream where the crayfish was located, comprises a variety of aquatic and bank zone habitats, including riffles and runs, large deep pools, shallow gravel margins and a variety of wooden bank revetment and deflector features. The stream initially flows through a deep contained pool before plunging down through the weir and salmon ladder into a largely open section and a wooded plantation beyond.

Along the whole stretch the potential as crayfish habitat is considerable including overhanging tree roots, good emergent vegetation, and large boulder and block material in the margins. A small bypass ditch enters the stretch beyond the weir and this appears to be an exceptional habitat and refuge area out of the main current.

The wild stock management policy for the stream has probably benefited crayfish here with the waterkeeper’s emphasis on maintaining a diverse stream system.

Threats to the population

It is unclear how this population has survived in the lower Test. Its position in the catchment and the relatively short distance upstream to the nearest signal crayfish (approximately 3 km) would lead one to believe that the population here is highly vulnerable, and perhaps only surviving by chance.

With such a major connection with the main River Test it is difficult to understand how this population escaped the initial outbreak of crayfish plague. This presumably hit the River in the early 1970s, when the first signal crayfish farm was set up, although this has never been confirmed.

Recommendations for future work

1. Implement a monitoring programme for the native crayfish population in the Little River.

2. Implement a crayfish survey of the main River Test to ascertain the distribution of signal and native crayfish.

3. Liaise with CEFAS (MAFF) and National BAP Committee regarding the possible funding of research into disease transfer mechanisms etc.

3.1.3 The River Itchen - the Lower Candover Brook

The lower Candover Brook near to the old railway bridge (SU 569 324) was revisited during the survey to check on a previously recorded population of native crayfish which had subsequently disappeared in 1996 (Hutchings, 1996). During the summer of 1996 this site was visited twice in June and September to monitor a small population of native crayfish first discovered in 1995. The population was thought to be contiguous with that of the Itchenstoke Mill native crayfish downstream (SU 563 317). This latter population was also thought to have been lost, after an extensive Native Crayfish Project Hampshire trapping programme and manual search over a period of two weeks produced a nil return (Hutchings, 1996).

It was with some surprise therefore that the lower Candover population was rediscovered during this survey. A number of native crayfish, including one large female, were found directly downstream of the railway bridge, but above the gauging station weir (SU 569 323) a short length of stream comprising approximately 50 metres (see Figure 4, Appendix 6 for the location of this population).

Habitat Characteristics

This short section is mostly shaded by overhanging trees and as such is poor in macrophytic and emergent vegetation. The channel bed comprises a mosaic of large blocks and boulders, and gravel and silt, the former predominating near to the old railway bridge where most of the crayfish are found. The bank structures also vary from old steel piling along the eastern bank to undercuts and overhanging tree roots on the western bank, before entering the canalised section of the gauging station weir itself.

The section is totally unmanaged and undisturbed with no footpath access along either bank, apart from the mown entrance to the gauging station.

Threats to this Population

The reasons for the temporary disappearance of this small colony are unclear. It was initially feared that crayfish plague ( Aphanomyces astaci ) had struck and that this disease was active in the upper Itchen. The apparent loss of the Itchenstoke Mill population appeared to bolster this view.

It seems likely now that this small population was merely overlooked last year, perhaps due to some synchronised event such as a moulting phase. For this to coincide with two separate visits however is hard to believe. More than anything this probably highlights the difficulties associated with surveying for this species, especially when they are only found in small, fragmented populations.

The threats to this population appear therefore to be minimal and the existence of a barrier, in this case the gauging station weir, may once again be significant in the continued presence of a native crayfish population.

Recommendations for further work

1. Implement a monitoring programme for the native crayfish population at this location.

2. Revisit the Itchenstoke Mill site and undertake an intensive search and trapping programme to confirm the status of native crayfish at this location.

3. Examine the options for habitat enhancement work in the lower Candover Brook. Native Crayfish Project Hampshire

3.2 Confirmed Signal Crayfish Locations

The main aim of this survey was native crayfish-orientated, but some notes were made on signal crayfish, their populations and habitats. The following notes refer to all sites where this survey confirmed their presence.

3.2.1 The Southern River Wey

Survey and habitat notes

The southern River Wey rises near Liphook flowing north-east to Frensham Ponds and converging with the northern Wey at Tilford.

A substantial colony of signal crayfish being found at Passfield, north of Liphook (SU 823 342). It is a healthy population with clear evidence of recruitment. Mature individuals were active during the day in some sections being found in mid-channel and the margins. Juveniles however tended to be confined to the bank edges. Gastroliths littered the river bed possibly indicating the high density of this colony. No further native crayfish investigations were deemed necessary below this point.

Spot checks along this stream have shown the river to provide favourable conditions for crayfish with plenty of refuges created by large cobbles/boulders, with deciduous woodland on both banks and fast flowing well-oxygenated water. Generally the channel is wide, with predominantly sand/gravel substrate and large numbers of boulders. The flow appears chaotic with standing waves, riffles and point bars evident.

This stretch is worthy of further investigation for signal crayfish.

Unconfirmed and/or Historic information:

A signal crayfish farm has existed at Bramshott Mill (in region of SU 840 330) but whether it still exists is uncertain. Downstream an unconfirmed sighting of a native crayfish juvenile was made at Passfield during the summer of 1997 (Adrian Bird, (River Wey Trust) pers. comm.), a doubtful record given the density of signal crayfish at this location.

3.2.2 The River Loddon

Survey and habitat notes:

The river was surveyed from Barton’s Mill at Old Basing (SU 662 531) to Wildmoor Farm (SU 692 554). The Loddon valley lies almost entirely on clay although the River Loddon (upper reaches), Lyde and Whitewater are on the chalk of the Hampshire Downs. The water is of good quality, Class 1B.

Native Crayfish Project Hampshire

No crayfish were found in the upper River Loddon, despite the apparent favourable habitat conditions. The stretch surveyed for the most part consists of coarse gravel substrate with occasional cobbles and areas of silt. Aquatic vegetation and the emergent zone along the stretch are diverse and complex. Downstream the banks are mostly vertical eroding cliffs, with undercuts, and too deep to manually search by stone turning.

Kick sampling and bank probing revealed no crayfish here. Further downstream surveying proved difficult with deep water, strong currents and dense vegetative growth along bank-tops.

Unconfirmed and/or Historic information:

At Bridge Farm fish hatchery (SU 665 532) a lecturer from Reading University had studied signal crayfish in the Loddon in 1996 (J. Domaniewski), but despite extensive searching in this survey none were found here. However since the survey in the summer two signal crayfish have been found in one of the ponds on the farm in December 1997 (Ian Duckels, and Julie Bywater (EA Thames) pers. comm.).

Signal crayfish were introduced to Stratfield Saye lake (SU 701 610) in 1976 and subsequently native crayfish disappeared from the adjacent River Loddon in 1977 (Steve Penny, pers. comm.). In the summer of 1982 however the river at SU 682 583 which is upstream of the lake, contained a healthy native crayfish population, but by the autumn of 1983 it had also disappeared, the cause of which was never confirmed (Lowery et al, 1984).

Holdich et al (1995) have suggested that native crayfish exist in the upper Loddon, but this survey has not proved this to be the case.

3.2.3 River Lyde

Survey and habitat notes:

The survey on the Lyde commenced near to the perennial head, which is approximately 0.5 km upstream from Andwell Priory Farm (SU 682 526). Here water flow is slow over predominantly silt, but becomes faster flowing with occasional areas of coarse gravel downstream. The water quality is exceptional along its length (Class 1A).

A manual search below the fish farm at Andwell Mill (SU 692 527) identified a signal crayfish. An unconfirmed sighting at Hartley Mill (SU 697 573) during July 1997 prompted further investigation but with no further crayfish found.

The proximity of the Loddon to the Lyde (which is connected via small ditches initially, and then at Hartley Wespall, has perhaps allowed for easy migration across these watercourses.

The Loddon is worthy of a further investigation by trapping.

Native Crayfish Project Hampshire

Unconfirmed and/or Historic information:

A landowner has reported crayfish near Andwell Mill Fish Farm (SU 692 527), but the species was unknown.

Further down at the point where the Lyde enters the Loddon, the river keeper has recently identified a signal crayfish during weed cutting at Hartley Mill (SU 697 573), but interestingly had not until that time seen crayfish in either river (Dr Alan Gibberd, pers. comm.). A local farmer remembers people fishing for crayfish in the river at least 30 years ago, though he had not seen one himself for 40 years (John Self, pers. comm.).- it must be assumed that these were native crayfish.

3.2.4 The River Whitewater

Survey and habitat notes:

During the survey a signal crayfish (a 1+ juvenile) was found in a ditch (approximately 30 metres in length) between the Basingstoke Canal and the River Whitewater (SU 727 518). Local children had also been finding crayfish during the summer of 1997, species unknown.

A spot check was made on the Bidden Water (SU 713 498). This stretch comprises a very shallow, narrow choked channel with silt substrate and was therefore not investigated further.

Unconfirmed and/or Historic information:

Historical records suggest that signal crayfish were present in the Whitewater at least 3-4 years ago. Dying native crayfish were observed in August 1982 in the upper Whitewater (SU 735 525) but the cause of this mortality has never been confirmed (Lowery et al, 1984).

A landowner at Warnborough Green (SU 728 520) has frequently seen large (130 mm + total length) crayfish in amongst tussock sedges and occasionally during the day (John Fleming, pers. comm.). At the time of survey this could not be confirmed due to access problems.

3.2.5 Basingstoke Canal (vicinity of Greywell Tunnel)

Survey and habitat notes:

The Basingstoke Canal is known to contain a population of signal crayfish, but their presence was not confirmed by this survey. The discovery of signal crayfish in the connecting ditch adjoining the Canal however (as noted in Section 3.2.4) certainly would suggest that this waterway does indeed hold this species.

The most recent confirmed sighting was at Ash Lock (SU 890 530 vicinity) in July 1997 (Jon Curtis (Basingstoke Canal Centre), pers. comm.) Native Crayfish Project Hampshire

The combination of silt and deep water made manual searching difficult along the canal, although targeted searches were attempted. It was considered generally unfeasible to trap at the time of survey due to ongoing canal management work and the easily accessible towpath which may have resulted in trap disturbance.

Unconfirmed and/or Historic information:

Unconfirmed sightings of signal crayfish have suggested their presence near the Greywell Tunnel. (Andrew Branson, pers. comm.).. Signal crayfish have been reported further downstream near the Hampshire/Surrey border (Colin Ryall (Farnborough College), pers. comm.).

3.2.6 The River Rother

Survey and habitat notes:

During this survey signal crayfish were found at Wenham Manor Farm (SU 789 233). This population is approximately 1.5 km downstream from the native crayfish reported in Section 3.1.1. As such it is essential to undertake a more detailed investigation of this population and to ascertain the actual threat that this species poses for the native crayfish population.

The signal crayfish were found in a section where the channel bed consists primarily of boulders, many too large to move, and gravel and sand. The flow here is fast, chaotic with occasional standing waves. Scattered trees and shrubs along the bank zone provide little shading and shelter along this stretch. The adjacent land use here is mostly open farmland and with the unfenced banks poaching by cattle is evident.

Unconfirmed and/or Historic information:

It is well known that signal crayfish were introduced into ponds 10-15 years ago 0.5 kilometres north of the Rother at Durleighmarsh Farm (SU 785 237) close to the Hampshire boundary in West Sussex. It is undoubtedly stock from these ponds which have now colonised this section of the Rother, A drain links the ponds to the main River and signal crayfish have even been observed crossing the A272 towards the river! (Martin Henslow, pers. comm.).

3.2.7 The Upper River Test (source to Whitchurch)

Survey and habitat notes:

Following an unconfirmed sighting of a native crayfish at Quidhampton, the river was surveyed at specific locations from Polhampton (SU 527 503) below the source to Native Crayfish Project Hampshire

Bere Mill above Whitchurch (SU 478 481). Spot checks only were made from Polhampton to Southington (SU 505 497) due to access difficulties. The Laverstoke Park to Bere Mill section was manually searched in more detail. No crayfish were found during the survey of these locations, however they been observed within the last 4 years at Bere Mill fish farm , Southington Mill and Polhampton. Photographs taken at the time by the river keeper (Neville Wiltshire, pers. comm.) have shown them to be signal crayfish (confirmed by Author).

From Polhampton to Southington the river appears unmanaged with the Portals Company (paper mill) owning a long stretch. The habitat here for the most part is gravel/cobble mosaic with substantial shading. From Laverstoke Park downstream the substrate becomes increasingly silted and the river is managed for fishing. No crayfish were found at any point along this river.

Unconfirmed and/or Historic information:

The most recent known sighting of native crayfish was 6 years ago at Laverstoke Park (Neville Wiltshire, pers. comm.), and the general consensus from owners, keepers and fishermen is that signal crayfish now inhabit the upper reaches of the Test.

3.2.8 The River Anton: Westover Farm, Goodworth Clatford

Survey and habitat notes:

This stretch was manually searched in June with negative results. Traps were then set over a period of 14 days in carrier streams and the main river. This effort resulted in just one large male signal crayfish (carapace length of 64 mm) from a carrier stream at Westover Farm (SU 373 406). A gastrolith was also found approximately 50 metres further downstream, which indicates the likelihood of further individuals being present.

The importance of this find is its proximity to the native crayfish population at Goodworth Clatford 1.5 km upstream. It is interesting to note the lack of physical and/or natural barriers between these two populations, and it would appear that the signal crayfish have not migrated very far upstream over the last 13 years.

Unconfirmed and/or Historic information:

In 1994 ditches were dug in the watermeadows adjacent to the Anton with 200 signal crayfish being introduced in March 1985 (Sean Wilson, pers. comm.). These ditches subsequently dried up in 1989 and the crayfish disappeared. No crayfish had been seen again until the spring of 1997, when an individual was found at the point where a silted ditch entered the carrier stream (SU 373 406).

3.2.9 The River Dever

Survey and habitat notes: Native Crayfish Project Hampshire

Signal crayfish were found to be present in the River Dever at Hunton (SU 485 396) in November 1996 (confirmed by Author). A manual search in June 1997 resulted in 2 small individuals being caught; one was found by kick sampling and the other appeared at the entrance to a burrow. Trapping during the summer of 1997 revealed a dense population with a good range of age classes and with some exceptionally large individuals.

Unconfirmed and/or Historic information:

The lower Dever is a well known signal crayfish location having been introduced to various ponds and escaped into the River some yeas ago (Sally Merrison, pers. comm.). The stretch at Hunton would appear to have held signals for a similar length of time. The previous landowner here has trapped this species from the River and from several of the ponds in the locality (Mr Mayward, pers. comm.)

3.2.10 The Crampmoor Stream

Survey and habitat notes:

The two sources of the Crampmoor Stream - at Two Lakes Fishery (SU 383229) and the Crampmoor Farm fishery (SU 388224) converge at Halterworth before flowing through Romsey to the main River at Mainstone (SU 353204). For much of its lower length the stream is canalised, but the upper reaches are diverse and natural, albeit impenetrable in places. The stream holds a good range of channel characteristics, including pool and riffle systems and bankside trees offering substantial shading in places.

Manual searching revealed signal crayfish to be present along the middle and upper stretches of the Crampmoor Stream but in apparent low densities - only two individuals being found (SU 378221 and SU 383221 respectively).

Unconfirmed and/or Historic information:

Both the Two Lakes and Crampmoor Lake Fisheries are known to hold substantial populations of signal crayfish. The Two Lakes Fishery has held signal crayfish since the early 1970s, when they were reared intensively and introduced into the lakes intentionally (John Fields, pers. comm.). Surprisingly these populations appear to have a restricted range in the locality and without achieving similarly high densities in the Crampmoor Stream.

A single signal crayfish carapace was found during a routine biological survey by Environment Agency staff in 1996 in the middle section of the Crampmoor Stream at Tadburn Lake (SU 3846 2223 John Foster, pers. comm.).

Signal crayfish are known to exist on the main River Test near to the mouth of the Crampmoor Stream at Saddlers Mill (SU 348208) and further downstream on the Broadlands Estate at Skidmore (SU 355 178) (confirmed by Author). These Native Crayfish Project Hampshire individuals are presumed to have originated from the upper Crampmoor Stream populations.

3.2.11 River Itchen at Winnall

Survey and habitat notes:

This location was initially surveyed in 1995 with negative results (Hutchings, 1996). Unconfirmed sightings have suggested signal crayfish to be present in the general area of Winnall (SU 486 298) and in the River Itchen close to the road bridge at Kings Worthy (SU 493 318 and SU 494 315). An extensive trapping exercise was undertaken during the 1997 survey at all 3 locations but no crayfish were found. A manual search also failed to locate any crayfish at the above locations and downstream to the City Mill (SU 486 293).

Unconfirmed and/or Historic information:

Sightings early on in the year by the Hampshire Wildlife Trust Warden have suggested the presence of crayfish at Winnall Moors Nature Reserve (SU 490 306) (Jess Payne, pers. comm.) and it is likely that these are signal crayfish given the size and colour of individuals observed.

During the 1995 survey what were thought to be signal crayfish burrows were found in the ditches of the northern-most meadows of Winnal Moors Nature Reserve, but again no individuals were located at the time (Hutchings, 1996).

These observations deserve further investigation in summer 1998 given the possible implications of signal crayfish being confirmed in the Itchen catchment.

Recommendations for future work on signal crayfish

1. Investigate the possible presence of signal crayfish at Winnal Moors again during summer 1998.

2. Investigate the signal crayfish populations near to existing native crayfish sites, i.e. the Rivers Anton, Rother and Lower Test.

3. Undertake small-scale research on the behaviour and in particular the movements and dispersion of signal crayfish.

Native Crayfish Project Hampshire

3.3 Discussion

3.3.1 The distribution of native crayfish A. pallipes in Hampshire

The known distribution of native crayfish in Hampshire is given in Figure 5 of Appendix 7. The present survey has highlighted two previously unknown populations in the River Rother and the Lower Test, bringing the total known native crayfish sites to six in the County. These are:

Upper Candover Brook at Fobdown (SU 571 338) Lower Candover Brook near Ovington (SU 569 324) Middle Alre above Drove Lane (SU 577 327) Upper Rother near Penns Place (SU 761 241) River Anton (Test tributary) near Goodworth Clatford (SU 361426) Lower Test, Little River near Nursling Mill (SU 356 157)

The two recent finds are significant for several reasons. The River Rother population is the first non-calcareous river find in Hampshire. The hydrological and habitat conditions in this system are unique and quite unlike the other native crayfish sites in the County. Indeed this may also be a significant find for the Arun catchment and West Sussex generally with only one other known native crayfish site in East Sussex at Pippingford Park, near Nutley (Holdich et al, 1995, and John Foster, pers. comm.).

The Rother population certainly requires further investigation and is the subject of a separate Environment Agency contract report. Catch per unit effort results in this survey, from both trapping and manual searching (3.7 and 7.6 respectively)., suggest a low density population along an approximate 3 km length of stream These results may reflect the difficulties encountered in surveying deep stretches and the different habitat conditions, eg undercut Greensand strata. In terms of their local range however this population would appear to inhabit the longest section of all the known native crayfish rivers in Hampshire.

The Lower Test discovery is also a highly significant find for Hampshire. It is for example, the first native crayfish population to be found in a lower section of a Hampshire river and in this case one which is extremely close to the upper tidal limit. Most of the other populations are found in small stream upper tributaries where the conditions are obviously very different. The opportunity to investigate the ecology and habitat requirements of A. pallipes in these conditions is a rare one in the South.

This find has also given some hope to discovering other fragmented populations in the middle and lower sections of the Hampshire rivers. The main River Test has always been regarded as a low priority site for native crayfish because of the known signal population, but this discovery suggests that perhaps a main River survey could be fruitful.

Native Crayfish Project Hampshire

The question remains how this population has survived. A number of factors may apply to this population:

• it could be immune to crayfish plague, but this is highly unlikely, • it may be co-existing with a disease-free signal population ( a feature of some of the Thames crayfish populations), • the apparent decline of native crayfish in the Test may be due to factors other than crayfish plague, again highly unlikely given the varying sources and time periods of signal crayfish entering the River. • it may have escaped the initial disease outbreak (?) and has subsequently recolonised this stretch,

It would appear that the latter is the most likely explanation for the continued presence of native crayfish in the Lower Test. Further research here may reveal some answers.

The rediscovery of the native crayfish near Ovington makes the Candover Brook , alongside the upper Rother, one of the most important stream systems in Hampshire for this species. This has been recognised, alongside other factors, with the full length of the Candover Brook being designated an SSSI. Further investigations need to be made here, both up and downstream, to firmly establish the presence or otherwise of native crayfish in the locality.

It is interesting to note that the continued survival of four of the six known populations may be due to the presence of a barrier feature - the Rother native crayfish exist upstream of two small weirs, and both the Candover and Alre populations are found above gauging station weirs. The remaining two populations in the Anton and Lower Test however appear to be unprotected in this respect.

Finally, an extensive trapping programme in the Bartley Water once again revealed no crayfish in 1997. A disappointing result given the relatively recent sightings in this system. This natural stream has definite similarities with the upper Rother and given its isolation from the Test, has great potential as a restocking/reintroduction site for native crayfish.

3.3.2 The distribution of signal crayfish P. leniusculus in Hampshire

The known distribution of signal crayfish in Hampshire is given in Figure 6 of Appendix 8. The majority of rivers surveyed during 1997 have contained signal crayfish and this species would appear to be widespread throughout the county.

It is of interest to note here that whilst this species is present in most rivers their local distribution would appear to be highly clustered and fragmented. For the most part very few individuals were found, apart from one notable location (see Section 3.2.1 above), and indeed in some well known signal crayfish streams this species appeared to be highly elusive.

Native Crayfish Project Hampshire

Anecdotal information suggests that signal crayfish in Hampshire are numerous with some reports of very dense populations, including:

River Whitewater 1994-5, upper River Loddon 1995, River Lyde 1997 River Meon at Warnford 1994, upper River Test 1994 and the Dever tributary 1997, middle Test at Crampmoor.

A large question mark hangs over the presence of signal crayfish in the main Itchen near Winchester. Anecdotal information and some evidence of burrowing activity certainly suggests this species to be present at Winnal Moors and immediately upstream, but this survey has failed to reveal any individuals. Their presence is therefore very likely at this location and the whole area needs to be investigated in more detail.

Considerably more information is required on the distribution and habitat requirements of this signal crayfish in Hampshire, and something which is a prerequisite to any catchment-based strategy for protecting native crayfish.

Native Crayfish Project Hampshire

4.0 MONITORING PROGRAMME

Monitoring programmes have been established for three of the known native crayfish populations in Hampshire. These are:

River Anton at Green Meadows (SU 361 426) River Arle above Drove Lane (SU 577 327) Candover Brook at Fobdown Farm (SU 571 338)

Signal crayfish monitoring work has also begun on the upper River Dever.

4.1 Monitoring Methodology

A standard monitoring methodology has been devised for the remnant native crayfish populations in Hampshire (see Appendix 9). The monitoring effort in 1997 represents a baseline year, except the for Upper Candover population which has been the subject of detailed analysis in previous years.

The following results therefore are only briefly discussed.

4.2 Monitoring Results

4.1.1 The River Anton at Green Meadow, Goodworth Clatford

This population was discovered during the Test tributaries survey of 1996 (Hutchings, 1996). This survey found the main population to inhabit a stretch approximately 150 metres in length, with a further two juveniles being located approximately 350 metres downstream (apparently drifted down from the main colony). After the initial find in 1996 this population appeared to disappear from the stretch in the Autumn despite extensive manual searching, trapping and night survey work.

It was therefore important to re-establish their presence in the Anton this year and to investigate their distribution at this location. Subsequently the monitoring programme was set up in this stretch during summer 1997.

The population is indeed still present here but in this monitoring effort only being found in one small section, rather than over the range noted last year. It is without doubt a very small population confined on present evidence to a carrier sidestream. In the 1996 survey crayfish were found in the main River as well. Monitoring revealed an average CPUE of 10 crayfish in this single section.

It is too early to suggest a decline in this population, yet it would appear that the native crayfish are restricted in their distribution here and as such are vulnerable to extinction at this location. Further monitoring in 1998 should provide more information on this population and their status in the Anton.

Native Crayfish Project Hampshire

4.1.2 The River Alre above Drove Lane, Alresford.

This population was discovered in January 1997 and a monitoring programme was initiated in the summer of the same year. Initially the population was found to be dispersed over a stretch of approximately 50 metres, but during summer 1997 a survey to establish the extent of native crayfish found them to be widely distributed over a length approximating 150 metres of the main channel and a side ditch. Four sections were established on which to base the monitoring effort and several visits were made during late summer.

The results from monitoring suggest a thinly spread population along the stretch and throughout the four sections, with relatively low numbers of crayfish being found by both manual search and trapping in deeper water (average CPUE of 3.2 and 10 respectively). These low figures may reflect a wider spread distribution over the 150 metres stretch, rather than a small, clustered and fragile population. Evidence of recruitment and the range of age classes found suggests a relatively healthy population here despite the low numbers recovered.

Similar to the Anton site further monitoring should provide a clearer picture of the size and extent of the population here.

4.1.3 Upper Candover Brook at Fobdown Farm.

The monitoring programme was formally established at this location also in 1997. 10 sections were identified along the 300 metre stretch of the Upper Candover Brook on which to base the monitoring effort.

Work at this site in 1997 revealed an average CPUE of 18.4 crayfish, a relatively high figure reflecting the size of the population at Fobdown Farm. All 10 sections monitored contain crayfish with maximum CPUE figures of 30 and 38 being recorded in the southern sections. This population therefore appears healthy with a diverse age structure (see Figure 7 Appendix 10). The extent of the crayfish population at this site has remained static over the year, with no apparent colonisation of the section where habitat enhancement work was undertaken in early 1997, nor downstream of this locality.

This population continues to be the main stronghold for A. pallipes in the central Hampshire rivers .

4.3 Discussion of monitoring results and methodology

1997 was the first year of this monitoring method and as such it has proved generally workable and relatively easy to apply.

One aspect of the method has been reviewed due principally to time constraints. The requirement to visit each population three times over the months from April to October was regarded necessary to avoid behavioural events, eg moulting phases Native Crayfish Project Hampshire and to ensure a representative assessment of the population. This has now been modified to take in only one monitoring visit during late July or August. This change should ensure useful results with minimum effort and disturbance to the stream.

It is inevitable that this method will evolve, as it is a novel approach and relatively untested. There are inherent difficulties in surveying and monitoring for crayfish, the dynamic nature of the aquatic environment and natural fluctuations in population levels possibly being the most important. Native and signal crayfish can be quite simply very difficult to find at certain times of the year, as well as during the moulting cycle, and experience has shown these small remnant populations can disappear, yet reappear in a matter of days or months at the same location.

The problems of monitoring invertebrates generally have been discussed in detail elsewhere (Fowles, 1996 and Eyre, 1996), and the issues identified above are by no means just confined to crayfish.

There is a need to standardise and replicate sampling for monitoring purposes, but these must be weighed against the constraints of time and effort in gaining useful results. In some situations a surveillance approach rather than monitoring could be more appropriate, especially when dealing with wide ranging signal crayfish populations (Eyre, 1996).

Native Crayfish Project Hampshire

5.0 Other work carried out in 1997

Two other projects were undertaken in 1997:

• a stream habitat enhancement project, • production of display panels on the Hampshire Project

A stream habitat enhancement project was undertaken on the Upper Candover in March 1997. The primary aim of this work is to facilitate the upstream colonisation of native crayfish from the Fobdown watercress area. A largely uniform, silted section appears to inhibit upstream movement of this species, so several deflector features were placed in the stream to redistribute the silt and recreate a gravel bed. In addition a substantial amount of large chalk flints were imported and distributed along the banks of the stretch.

The enhanced stretch has been monitored during the summer of 1997, but no crayfish have colonised this area yet. Native crayfish would appear to be very sensitive to habitat change so the colonisation of this area will probably be slow initially. Additional work is still required at this site and it is hoped that the Fobdown project will be continued in 1998.

A series of display panels have also been produced giving information on the identification of crayfish species, the issues involved and a summary of the Hampshire Project. This was a joint venture between Sparsholt College and the Environment Agency. It is hoped that these panels will be widely used at events and country shows and interpret the issues surrounding native crayfish conservation to as wide a public as possible.

Education and information is seen as an important objective locally and as such a leaflet to accompany the panels should be available by mid 1998.

Native Crayfish Project Hampshire

6.0 Summary of the work in 1997

This report is the culmination of a substantial effort in surveying a large number of streams and rivers in Hampshire during the period May to December 1997. As a result two populations of native crayfish have been found, on the upper River Rother and the Lower Test, bringing the total of known sites for this species to six in the County. The River Rother and the Candover Brook populations are potentially the largest, whilst others such as the River Anton and in the Lower Test appear to be small and highly vulnerable to extinction. In addition monitoring programmes are now in place for three of the remaining four populations of native crayfish. There appears to be little change in the Upper Candover Brook population over the year, remaining healthy and stable, whilst monitoring has only just started in the two other locations.

Signal crayfish have been found in most rivers surveyed in 1997, but a substantial population has been located in the Southern River Wey. Other rivers hold signal crayfish but they appear at lower densities and probably clustered in their distribution locally. At several locations signal crayfish have been found close to known native crayfish populations albeit downstream, the Rother and Anton sites are good examples of this (see Figure 8, Appendix 11). The Lower Test native crayfish population is an astonishing find, given the known presence of signal crayfish approximately 3 - 4 km upstream. The reasons for their continued survival is unclear.

The Native Crayfish Project based at Sparsholt College continues to provide a focus for crayfish work in the County, and the 1997 survey has been the largest effort to date in improving distributional information on both A. pallipes and P. leniusculus .

Native Crayfish Project Hampshire

7.0 Summary of Recommendations for future work

Site specific recommendations for native crayfish work:

The River Rother population:

1. Further investigate the distribution and status of both native and signal crayfish in the upper and middle Rother.

2. Implement a monitoring programme for both the native and signal crayfish populations.

3. Examine the options for site protection measures in the upper Rother, eg. designation as a Site of Special Scientific Interest.

4. Devise an action plan and strategy to protect the native crayfish population in the upper Rother.

5. Liaise with riparian owners, managers, local authority and Environment Agency staff to inform and educate about the importance of this site and to devise appropriate measures to ensure the protection of native crayfish in the short and long terms.

The Lower Test, the Little River population

1. Implement a monitoring programme for the native crayfish population in the Little River.

2. Implement a crayfish survey of the main River Test to ascertain the distribution of signal and native crayfish.

3. Liaise with CEFAS (MAFF) and National BAP Committee regarding the possible funding of research into disease transfer mechanisms etc.

The Lower Candover population:

1. Implement a monitoring programme for the native crayfish population at this location.

2. Revisit the Itchenstoke Mill site and undertake an intensive search and trapping programme to confirm the status of native crayfish at this location.

Native Crayfish Project Hampshire

3. Examine the options for habitat enhancement work in the lower Candover Brook

Native Crayfish Project Hampshire

Recommendations for future work on signal crayfish

1. Investigate the possible presence of signal crayfish at Winnal Moors again during summer 1998.

2. Investigate the signal crayfish populations near to existing native crayfish sites, i.e. the Rivers Anton, Rother and Lower Test.

3. Undertake small-scale research on the behaviour and in particular the movements and dispersion of signal crayfish.

Native Crayfish Project Hampshire

REFERENCES

Alderman and Polglase (1985) Disinfection for crayfish plague Aquaculture and Fisheries Management, 16, 203- 205

Environment Agency (1996) River Habitat Survey - field survey guidance manual 1996

Eyre, M.D (1996) Observations on invertebrate monitoring, surveillance and conservation in Eyre, M.D (1996) Environmental monitoring, surveillance and conservation using invertebrates. EMS pub.

Foster, J (1993) The status of native crayfish in the southern region of the NRA. Internal report to English Nature. June 1993

Fowles, A.P (1996) Experiences of invertebrate monitoring in Wales in Eyre, M.D (1996) Environmental monitoring, surveillance and conservation using invertebrates. EMS pub.

Gledhill, T, Sutcliffe,D.W and British Freshwater Crustacea Malacostraca - a key Williams, W.D (1993) with ecological notes. FBA Scientific Publication No.52

Groombridge, B (Ed)(1993) IUCN Red List of Threatened Animals. IUCN, Gland, Switzerland and Cambridge, UK

Holdich, D.M and Distribution of freshwater crayfish in the British Reeve,I.D (1991) Isles, with particular reference to crayfish plague, alien introductions and water quality Aquatic Conservation 1: 139 - 158

Holdich, D.M, Rogers, W. D Crayfish Conservation and Reader, J.P (1995) NRA Project Record 378/10/N and Y

Hutchings A R (1996): Interim report on the Native Crayfish Project, Hampshire - native crayfish survey of the River Itchen 1995 Internal EA/EN contract report

Hutchings A R (1997): Interim report on the Native Crayfish Project, Hampshire - native crayfish survey of the River Test Tributaries 1996 Internal EA/EN contract report

Native Crayfish Project Hampshire

Ingle, R.W (1995) The UFAW Handbook on the Care and Management of Decapod Crustaceans in Captivity. UFAW pub.

Lowery R S, Hogger J, Crayfish Mortalities in UK ) Rivers Polglase J L, Alderman D J (1984) Freshwater Crayfish VI, IAA

NRA : Fact File - River Loddon

NRA (1991) River Test Catchment Management Plan Phase 1

Palmer, M (1995) Action plan for the conservation of the native crayfish, Austropotamobius pallipes in the UK. JNCC report No. 193 Peterborough and “Biodiversity: the UK Steering Group Report” London, HMSO

Native Crayfish Project Hampshire

Appendix 3.

General Survey Notes

1.0 Thames Catchment

1.1 Northern River Wey and selected tributaries

Native Crayfish: nil Signal Crayfish: nil

Survey and habitat notes

The northern Wey rises at Alton and Selbourne (River Lavant), flowing east to Tilford where it converges with the southern Wey before continuing its course towards Godalming and north to the Thames. It was surveyed with spot checks made in Alton, and thereafter a more thorough survey down to Bentley near the County border.

A largely eutrophic meandering river system, and with the exception of Alton, flows mostly through improved farmland. It is not managed for fishing purposes, and although in places has good bank structure, suitable substrate and shading, there was no evidence of crayfish.

Unconfirmed and/or Historic information:

Landowners have not seen native crayfish here for over 10 years. Similarly no signal crayfish have been observed. In August 1983 dead and dying crayfish were observed at Bentley (SU 796 438), and on examination showed evidence of Aphanomyces astaci spores (Lowery et al, 1984). Further investigations at that time revealed, dead and dying crayfish as far downstream as Godalming (30 km), but failed to find any native crayfish upstream.

1.2 River Lavant

Native Crayfish: nil Signal Crayfish: nil

Survey and habitat notes:

Maps show the Lavant to rise at Chawton, but on investigation flowing water is only present near Alton. Here it comprises a slow, silted, generally choked channel. The lack of gravel, boulders and associated flow would appear to make this stretch an unlikely location for native crayfish.

Native Crayfish Project Hampshire

Unconfirmed and/or Historic information:

No historic records are thought to exist for the River Lavant.

1.3 Caker Stream

Native Crayfish: nil Signal Crayfish: nil

Survey and habitat notes:

The Lavant flows into the Caker Stream at Alton which then joins the Wey. Similar to the Lavant the Caker Stream is generally slow flowing and choked with silt.

Unconfirmed and/or Historic information:

No historic records appear to exist for the Caker Stream.

1.4 Southern River Wey and Tributaries

Native Crayfish: nil Signal Crayfish: present

Details on this confirmed signal crayfish site are found in Section 3.2.1 above

1.5 Hollywater and Hollywater Pond

Native Crayfish: nil Signal Crayfish: probably

Survey and habitat notes:

The sections surveyed showed a narrow, meandering stream flowing through deciduous woodland on acid soils. The substrate was of sand with good flow and a few debris dams. The swan mussel Anodonta cygnea was present as were Gammarus . Hollywater Pond was too deep for manual searching and although it appeared to have good bank structure and a wealth of emergent reeds and sedges, a trapping session was not implemented due to the known occurrence of signal crayfish in the locality. However further investigation would be worthwhile here to ascertain the distribution of signal crayfish.

Unconfirmed and/or Historic information:

Signal crayfish have been found at Hollywater Pond in the past (Chris Webb (National Trust) pers. comm.), but none were found during the survey.

Native Crayfish Project Hampshire

1.6 River Slea and its tributaries Oakhanger, Kingsley and Oxney Streams

Native Crayfish: nil Signal Crayfish: nil

Survey and habitat notes:

Spot checks were made along these streams where access was possible. The tributaries generally were found to be narrow, slow flowing with overgrown densely shaded sections. The Oakhanger Stream had dried up at Selbourne by 24th July with an almost imperceptible flow at both Priory Farm (SU 755 344) and Shortheath Common (SU 781 369). The River Slea at the sampled section was shallow with coarse gravel/cobble substrate, and fast flow

Unconfirmed and/or Historic information:

No historic information on crayfish appear to exist for this river and it’s tributaries.

2.0 The Loddon Catchment

2.1 River Loddon

Native Crayfish: nil Signal Crayfish: present

Details on this confirmed signal crayfish site are found in Section 3.2.2 above

2.2 River Lyde

Native Crayfish: nil Signal Crayfish: present

Details on this confirmed signal crayfish site are found in Section 3.2.3 above

2.3 River Whitewater

Native Crayfish: nil Signal Crayfish: present

Details on this confirmed signal crayfish site are found in Section 3.2.4 above

Native Crayfish Project Hampshire

2.4 Basingstoke Canal (Greywell Tunnel to the swing bridge at Tunnel Lane North Warnborough )

Native Crayfish: nil Signal Crayfish: present

Details on this confirmed signal crayfish site are found in Section 3.2.5 above

2.5 Ramsdell Pond

Native Crayfish: nil Signal Crayfish: nil

Survey and habitat notes:

The north section of the pond is of largely gravel/cobble substrate with areas of silt. The pond bed profile gently slopes away forming a shelf of approximately 1-2 metres wide, after which it becomes progressively deeper. This made manual searching hazardous. Exposed submerged tree roots are abundant in the emergent zone. The remainder of the pond comprises mostly silt. A thorough manual search of the top end of the pond showed no evidence of crayfish.

Unconfirmed and/or Historic information:

Native crayfish were last seen in this pond during 1990/1991 and although the waterkeeper set traps in 1994, none were caught or have been seen since (Michael Moore, pers. comm.).

3.0 The Arun Catchment - the River Rother and it’s Tributaries

3.1 River Rother

Details of the results from the main River Rother survey are given in Sections 3.1.1 and 3.2.6 . Both native and signal crayfish were found in the main river, but the following information applies to the Hampshire tributaries only.

3.2 Ashford Stream

Native Crayfish: nil Signal Crayfish: nil

Survey and habitat notes:

Initially the stream meanders through semi-continuous deciduous woodland, with good cobble/gravel substrate, mostly fronting gardens. The stream then flows through improved pasture/arable land, with good pool and riffle systems evident, becoming slower and deeper in places bordered by steep earth banks. Despite a thorough manual search from Ashford Chase (SU 741 262) to the new A3 (SU 753 250) no evidence of crayfish could be found. Native Crayfish Project Hampshire

Access difficulties (owner unknown) left the remaining short section unchecked (SU 755 249 - SU 761 247).

Unconfirmed and/or Historic information:

The only historic sighting of native crayfish on the Ashford Stream was at least 20 years ago near the confluence with the Rother. (David Ball, pers. comm.).

A number of landowners further upstream have never seen crayfish, and one landowner in particular has considered starting his own signal crayfish farm as a result.

3.3 Stanbridge Stream/Criddell Stream

Native Crayfish: nil Signal Crayfish: nil

Survey and habitat notes:

The confluence of this stream with the main River Rother provides exceptional habitat for native crayfish and should be the subject of a more detailed investigation.

A sewage treatment works 0.35 kilometres upstream from the confluence discharges approximately >5000m 3/d but is probably of little significance in the absence of crayfish at this location. Spot checks further upstream showed the stream to be slow with deep silt and very little aquatic vegetation.

Unconfirmed and/or Historic information:

No historic records are thought to exist for the Stanbridge stream.

3.4 The Blackwater (Moor Park)

Native Crayfish: nil Signal Crayfish: nil

Survey and habitat notes:

This flows into the Rother near Greatham (SU 779 288). The Blackwater is recognised as a stream draining the acidic Surrey heaths and as such was a low priority for this survey.

This stream is worthy of a more detailed investigation.

Native Crayfish Project Hampshire

Unconfirmed and/or Historic information:

No historic records are thought to exist for the Blackwater.

3.5 Tilmore Brook (Petersfield Stream)

Native Crayfish: nil Signal Crayfish: nil

Survey and habitat notes:

The majority of the Tilmore Brook flows through Petersfield and the surrounding semi-urban areas. For much of its length in this area the stream has undergone extensive canalisation and bank revetment work, obviously handling considerable flows at times. Spot checks only were made here with the stream generally being narrow, of silty substrate and slow flowing.

Unconfirmed and/or Historic information:

No historic records are thought to exist for the Tilmore Brook.

3.6 Oakshott Stream/Batt’s Brook

Native Crayfish: nil Signal Crayfish: nil

Survey and habitat notes:

At the time of survey the stream was dry near its source and close to where Doscomb Pond once existed, a reservoir has now been built. Similarly further downstream the channel was almost dry, with occasional standing water, but after this some flow was evident, albeit very slow.

Unconfirmed and/or Historic information:

No historic records are thought to exist for the Oakshott Stream.

Native Crayfish Project Hampshire

4.0 The Meon Catchment

4.1 River Meon : East Meon to Droxford

Native Crayfish: nil Signal Crayfish: probably

Survey and habitat notes:

The Meon above Warnford (SU 637 238 )is shallow, sometimes drying-up by August, and meanders through improved meadows with occasional bankside trees. Open unfenced sections has led to considerable poaching from dairy cattle along much of this stretch. Mink are apparently widespread along the Meon. The river at Warnford Park is spring fed resulting in a perennial flow at this point.

Thorough searching during this survey revealed no crayfish. The habitat throughout this stream would appear to be favourable for crayfish with the river flowing through semi-continuous woodland, with a diverse substrate and physical structure of the bed and banks. Gravel/cobbles, riffles/runs systems with occasional chaotic flow patterns are common along the stretch.

The Meon is worthy of a more detailed further investigation to ascertain the distribution of signal crayfish here.

Unconfirmed and/or Historic information:

Signal crayfish were identified 2 years ago and confirmed below Paper Mill Cottage (SU 620 212) at Warnford (Author). Moorhen Pond above Warnford once held a colony of signal crayfish but the owner had not seen any for several years. A side stream showed evidence of burrowing in the banks. It is likely that this population is still extant at this location.

5.0 The Hamble Catchment

5.1 Upper River Hamble at Bishops Waltham including South Pond

Native Crayfish: nil Signal Crayfish: nil

Survey and habitat notes:

The River Hamble is fed from two sources at Bishops Waltham - the Moors and that above South Pond nearer the town. The spring feeding South Pond (SU 551 174) dries up for at least 9 months during the year, and the pond itself, at the time of survey in July comprised largely of silt with a few cobbles. The banks hold a semi- continuous cover of willow scrub and larger trees. The pond is small and intensively fished.

Native Crayfish Project Hampshire

The stream rising at The Moors (SU 562 168) was surveyed through Locks Farm to the Botley Road. This stretch appeared favourable for crayfish having coarse/fine gravel, boulders, debris dams, good bank structure and shading from overhanging trees and shrubs. Sections of bank are unfenced allowing poaching by cattle.

Unconfirmed and/or Historic information:

There are some historic reports of crayfish at or near Chase Mill below the Moors some 15 - 20 years ago (Peter Milbourne, pers. comm.)

6.0 The Test Catchment

6.1 River Test : Source to Whitchurch

Native Crayfish: nil Signal Crayfish: present

Details on this confirmed signal crayfish site are found in Section 3.2.7 above

6.2 The Anton Lakes

Native Crayfish: nil Signal Crayfish: nil

Survey & Habitat notes:

The Hampshire Wildlife Trust Reserve at Anton Lakes near the northern outskirts of Andover comprises a series vegetated gravel pits with a wide range of surrounding wetland and scrub habitats. An upper section of the River Anton feeds the Lakes and flows alongside the largest water body at the south western end.

Most of the upper lakes are heavily silted and hold little potential as crayfish habitat, but the larger lake at the bottom of the series appears less silted and has good bank structure with gravel to cobble substrate. The occasional overhanging willows in this lake enhance the bank zone considerably and much of the trapping programme undertaken concentrated upon this area. Trapping over a period of four days however revealed no crayfish. The stream was also manually searched, and whilst the stream bed and bank zone look favourable for crayfish, again none were found.

Unconfirmed and/or Historic information:

No historic records are thought to exist for crayfish at this site.

Native Crayfish Project Hampshire

6.3 Crampmoor Stream

Native Crayfish: nil Signal Crayfish: present

Details on this confirmed signal crayfish site are found in Section 3.2.10 above

7.0 The Itchen Catchment

7.1 River Itchen at Winnall

Native Crayfish: nil Signal Crayfish: probably

Details on this confirmed signal crayfish site are found in Section 3.2.11 above

7.2 Candover Brook South

Native Crayfish: nil Signal Crayfish:

Survey and habitat notes:

The southern part of the Candover Brook was resurveyed after the apparent loss of the native crayfish population previously observed at this point. A small number of native crayfish were rediscovered here in the 1998 survey (SU 569 324). Detailed notes on this stretch are given in Section 3.1.3.

8.0 The New Forest

8.1 Bartley Water Catchment

Native Crayfish: nil Signal Crayfish: nil

Survey and habitat notes:

The Bartley Water is an exceptional natural stream system found within the New Forest SSSI. It comprises a great diversity of habitat and physical structure including extensive pool and riffle systems, undercut banks, massive earth cliffs and debris dams. For much of its length it flows through ancient broad-leaved and mixed woodland and finally through farmland and the urban-fringe of Totton before entering Southampton Water. As such the Bartley Water is isolated from the River Test and the signal crayfish population therein.

The prospect of finding native crayfish within this natural system is an exciting one, but unfortunately no recent records for native crayfish exist. An extensive programme of trapping and manual searching over a period of a month was undertaken on the Native Crayfish Project Hampshire middle and upper Bartley Water during September and October 1998, but with a nil return.

Given the complexity of the system and the possible different behavioural characteristics of the Bartley Water crayfish in comparison with chalkstream populations, this small catchment is still worthy of further research.

Unconfirmed and/or Historic information:

Native crayfish have been found in the Bartley Water as recently as 1995 (John Gulliver, pers. comm.) and the stream is well known amongst locals as a site for crayfish.

Native Crayfish Project Hampshire

Appendix 1

Figure 1. Locations of rivers, streams and ponds mentioned in the text

Native Crayfish Project Hampshire

Figure 1 Map identifying rivers mentioned in the text

Native Crayfish Project Hampshire

Appendix 4

Figure 2. Location of the River Rother native crayfish population

Appendix 5

Figure 3. Location of the Lower Test native crayfish population

Appendix 6

Figure 4. Location of the Lower Candover Brook native crayfish population

Native Crayfish Project Hampshire

Appendix 7

Figure 5. The known distribution of native crayfish in Hampshire upto January 1998.

Native Crayfish Project Hampshire

Appendix 8

Figure 6. The known distribution of signal crayfish in Hampshire upto January 1998.

Native Crayfish Project Hampshire

Appendix 11

Figure 8. Composite map of the known native and signal crayfish locations in Hampshire. Native Crayfish Project Hampshire

Appendix 9

Monitoring of remnant native crayfish populations in Hampshire.

Guidelines for participants:

The method described below has been devised to enable a person, with relatively little experience, to help in the assessment of changes in abundance of native crayfish in small fragmented populations in the rivers and streams of southern England.

This transect method has been adapted from that first devised by Pollard, (1977) and utilised extensively in the monitoring of other groups. a). Introduction:

The transect is a fixed route along which monitoring will take place. Once chosen the route should not be altered. Annual comparisons are dependent on continuity from year to year and standardising the approach as much as possible. The dynamic nature of aquatic ecosystems however will make the monitoring approach somewhat different to terrestrial areas, but nonetheless standardising the approach is important.

The transect should only be as long as is easily manageable and has been devised to take into account the following:

- it must be undertaken at least once between the months of July (end) and August

- during July and August there may be many juveniles and 0+ individuals and monitoring can be very time-consuming.

- someone else may take over the monitoring in the absence of the regular recorder. b). Safety of recorders

This should be upper most in your mind when undertaking monitoring work. Ideally work in pairs or at least implement some form of reporting procedure, letting someone know where you are working and when you will return. Many of the native crayfish sites in Hampshire are in small, shallow stream systems, but even these can be dangerous - keep to the banks and shallow areas where crayfish are most likely to be found during summer. Do not walk into water if you can not see the bottom! c).Starting:

Before you begin monitoring as far as possible assess the extent of the native crayfish population in the stretch. This is best done by manually searching at the Native Crayfish Project Hampshire water line amongst the bank and underneath larger stones and boulders. In some situations crayfish may be found in debris dams and other in-channel material.

Restrict your searching to the edges or bank zones of the stretch and this will mean walking in the stream, that is if water depth allows. You will need to examine both banks starting in upstream sections first, then working downstream.

Mark the upstream and downstream extents of the population with small marker posts. This is the extent of the monitoring transect. d). Sections:

Once the extents of the population have been marked the stretch should then be divided into sections. A maximum of ten sections is recommended, but the stretch may only be large enough for one or two. The start and end points of each section could be marked with similar posts as mentioned above or existing river bank features could be utilised.

These sections could be designated in a purely systematic manner, ie every 100 metre stretch, or identified through changes in in-channel or bank zone habitat. Once these sections have been defined they should not be changed. e). Map

Produce an accurate map of the stretch, noting the length of each section and also any natural and/or man-made features, eg pool and riffles, weirs, bridges, bank works etc. It is recommended that the Environment Agency’s River Corridor Survey approach is adopted in the production of this map. The Project can help in the production of this map. f) Habitat and management

A short description of the habitat and any signs of management activities in each section is useful for the transect records. Particular attention should be given to the nature of the substrate on the stream bed and within the bank, and the vegetation in the emergent and bank zones. The presence of trees and shrubs for example is especially important for crayfish. g). Photography

Keeping photographic records of each section is also useful. These can be taken on an annual basis rather than at every visit. h). Identification

It is essential to identify the various species which could be encountered in Hampshire rivers and streams. There are two likely species: the native crayfish, Austropotamobius pallipes , and the non-native signal crayfish, Pacifastacus leniusculus . An ID leaflet is attached to help with separating these species. As adults there is generally little difficulty, but the juveniles of both species are very similar, so beware. Ensure that adequate ID training is obtained before monitoring begins, but Native Crayfish Project Hampshire there is very little likelihood that the two species will be found together in a single stretch. The Manager of the Native Crayfish Project Hampshire will help with this training if required.

i). Recording

A standard recording form has been devised for use in monitoring native crayfish populations.

Before you start monitoring a transect or section complete the top of the form up to the box on recording method. It is useful to take a recording of the water temperature, but not essential. If you find more than 32 individuals continue on another sheet.

The identified section should then be walked in-channel down the right bank first then up the left bank. Once completed move to the next section and repeat the procedure.

There are three possible methods of recording in the section as noted on the form:

- manual searching - kick sampling - trapping

Manual searching is the standard approach in this monitoring protocol, but this could be backed-up with overnight trapping and kick sampling of finer substrate or deeper water areas (upto 50 cm depth).

It is not recommended that night survey is utilised for monitoring purposes until research has shown the validity of this approach.

Manually search along both banks of the section for 30 minutes (15 minutes per bank). Ideally time yourself with a stop watch or similar. Keeping to this time period is important as this “catch per unit effort” or CPUE approach is fundamental to the monitoring procedure and to its success.

Carefully turn the larger stones and boulders to systematically search for crayfish. Sometimes a net downstream will help catch escapees. Usually crayfish will remain still if the refuge is slowly turned over, and once the silt has settled they can be picked off the bottom or directed into a net.

During July and August first year juveniles or 0+ individuals can be observed in the warm shallow margins. In this situation a small, fine fry or minnow net can be useful.

Use a sturdier net, preferably with a metal rim, to investigate over-hanging bank material and tree roots.

Kick sampling is not recommended as a standard approach in the small Hampshire streams, but may be an option in deeper sections. If you use this method ensure that Native Crayfish Project Hampshire it is also standardised, ie 6 kicks per sample or kicking for 15 seconds, for each section or bank of a section.

Similarly trapping may also be used, but standardise this as well, eg 5 traps per bank, or all the sections along the transect trapped at the same time. It has been found that trapping is more effective if undertaken over a period of at least three nights rather than one. Trapping and kick sampling should only be used to back-up the standard manual searching technique. If trapping and kick sampling are applied ensure that this is noted on the record card, indicating the kick method and how many traps used and for how long.

Processing individuals

On catching an individual two possible processing methods can be adopted:

- process immediately and stop the watch to ensure you get the full 15 minutes of searching time or,

- place the crayfish in a container or bucket with a lid and process when the search has finished.

It is recommended that the former approach is taken and crayfish are replaced immediately after processing into their original refuge. Minimising impact and stress is vital for these invertebrates, particularly as monitoring requires repeated visits and many native crayfish in the southern streams exist in small vulnerable populations.

The methods of sexing, weighing and measuring crayfish will be given during the initial training session. These operations should be undertaken as quickly and methodically as possible, ensuring that all details are recorded.

If you encounter a good population it is important to note that these operations can take a substantial amount of time. Ensure that you allow enough time and don’t hurry the procedure.

Moulting stages

Crayfish undergo several moults during the main growing period, the number of which depends on age and environmental conditions in the stream. It is useful to note the stage of moulting in the comments section of the record card. These can be identified with practice:

Intermoult - a very rigid carapace, the norm

Pre-moult - animal dark in appearance (darker than post- moult phase), noticeable separation of the epidermis from the exoskeleton.

Native Crayfish Project Hampshire

Moult - animal feels like gelatin, only lasts a few hours

Post-moult - animal light coloured appearance, post- orbital ridge and cervical groove easily bent. Carapace often feels leathery.

Females with young

During June and possibly July females with young may be encountered. It is more important than ever to minimise stress for these individuals. Hold these females always by the carapace and with one finger stop the tail from flicking - an instinctive response to release and save their young - and process as quickly as possible. Placing the female in a bucket or other container will avoid juveniles being flicked off into bank vegetation. Approximate the number of young (recording this in the appropriate comments section on the form) and place back into the same refuge.

Disease identification

During the initial training session surveyors will be shown how to identify the various crayfish diseases, especially porcelain disease, Thelohania contejeani , and the fungal crayfish plague, Aphanomyces astaci. j) When not to monitor

Do not monitor when the river or stream is in flood. Apart from the danger to yourself most crayfish will be difficult to find anyway at such times.

Do not monitor between end of November and the start of April. Crayfish are difficult to find in winter, some may even burrow into the stream bed or banks. In addition females will be berried (carrying eggs) during this period and extra handling can be stressful to these individuals. Give your stretch a break from the impact of monitoring. k) Data collation and analysis

The Native Crayfish Project will collate the information at the end of the annual monitoring period. Please send your results to the address on the record card as soon as possible after November. The project will analyse the findings and disseminate the information in due course to all participants.

Thank you for your help.

References:

Pollard (1977) A method of assessing changes in the abundance of butterflies. Biol. Conserv. 12, 115 - 134

Native Crayfish Project Hampshire

Adrian Hutchings Native Crayfish Project Hampshire January, 1998 Native Crayfish Project Hampshire

Appendix 10.

Figure 7.(a) Numbers of crayfish (CPUE) per monitored Section

Figure 7 (b) Age structure of the native crayfish population

Native Crayfish Project Hampshire

Appendices

Annex 1: Table 1. Survey Locations and Figure 1. Map identifying rivers mentioned in the report. Annex 2: Table 2. Results from all surveyed locations Annex 3: General habitat and survey notes/survey locations Annex 4: Figure 2. Location of the River Rother native crayfish population Annex 5 : Figure 3. Location of the Lower Test native crayfish population Annex 6: Figure 4. Location of the lower Candover Brook native crayfish population Annex 7; Figure 5. The known distribution of A. pallipes in Hampshire upto January, 1998 Annex 8: Figure 6. The known distribution of P. leniusculus in Hampshire upto January 1998 Annex 9: The standard monitoring procedure (revised January, 1998) Annex 10: Figure 7 Chart showing the age structure of the native crayfish population in the Upper Candover Brook Annex 11: Figure 8. Composite map of native and signal crayfish locations in Hampshire Annex 12: Provisional Action Plan for native crayfish in Hampshire