WHITE-CLAWED CRAYFISH (AUSTROPOTAMOBIUS PALLIPES)

ACTION PLAN

Compiled by The Wildlife Trust

Lead Agencies Public Sector Environment Agency

Voluntary Sector The Wildlife Trust

1 INTRODUCTION

The only species of crayfish native to Britain, the White-clawed Crayfish has suffered a considerable decline in recent years through loss of habitat and the incidence of Crayfish Plague, which is carried by non-native crayfish.

2 CURRENT STATUS

2.1 International / National Status

· The distribution of the White-clawed Crayfish is widespread across the British Isles and is determined largely by geology and water quality. It is not found in soft, acid water due to its requirement for sufficient calcium to harden its exoskeleton following moulting. Neither is it found in polluted water. It is largely absent from western Wales, south-west England and Northern and Southern Ireland.

· The species is currently in decline throughout the British Isles. Until the 1980s the status of the White-clawed Crayfish was good in all regions with suitable water quality (i.e. unpolluted, alkaline water with sufficient calcium); however, since then the species has been in decline.

· Under Annexes II and V of the EC Habitats Directive, designation of protected areas for White-clawed Crayfish is required, and under Article 22, regulation of the introduction of non-native species is required. Currently, neither of these obligations is being met effectively. Although legislation is in place to provide regulation of non-native species (see above), this is not proving effective in practice. There are no protected areas for White-clawed Crayfish in the UK. As the British Isles have some of the best remaining populations of White-clawed Crayfish in Europe, despite the current decline, it is important to meet our European obligations in this respect.

· The White-clawed Crayfish is listed as an IUCN endangered species. In 1986 it was listed in Schedule 5 of the Wildlife and Countryside Act to prevent taking and sale; however, its habitat is not protected under this legislation. Schedule 9 of the same Act makes it an offence to allow non-native Crayfish to escape or to release them into the wild without a licence, but, at least up until 1995, no-one had been prosecuted under this Act and unlicensed escapes have certainly occurred.

2.2 Local Status

· The status of White-clawed Crayfish in Northamptonshire is not clear. At present there are five known populations:

· On the Whilton Arm of the Nene near Long Buckby.

· On the Cherwell in the middle of Woodford Halse.

· On the Cherwell at Trafford Bridge.

· On a tributary of the Tove.

· On various sections of the Welland, on the Northamptonshire-Leicestershire border.

· In addition, a crayfish, believed to be White-clawed, was found near Geddington in 2000, presumably from the River Ise, or a tributary. As yet there has been no confirmation that there is a population in the area.

· Recent records suggest a decline in White-clawed Crayfish in Northamptonshire. Records of outbreaks of Crayfish Plague in the Upper Nene and the River Ise have been recorded. Since this species has never showed any resistance to this disease and previous populations infected with Crayfish Plague have been wiped out in a matter of weeks, the appearance of Crayfish plague in the river systems of Northamptonshire indicates that the population in the county is in danger of serious decline. All populations downstream of areas where Crayfish plague has been confirmed are therefore in danger. Signal Crayfish (Pacifastacus leniusculus) have been found in the Nene, the Tove and the Ouse. This species can carry Crayfish Plague. However, although not all populations of Signal Crayfish carry Crayfish plague, the species appears to out-compete the White-clawed Crayfish over an extended period of time.

· There is a record of Turkish Crayfish (Astacus leptodactylus) in Dallington Lake, Northampton. It is not known whether this species could pose a threat to White-clawed Crayfish, as there is insufficient knowledge of its ecology.

3 CURRENT FACTORS CAUSING LOSS OR DECLINE

· Competition with introduced Crayfish species including, the Signal Crayfish (P. leniusculus), the Turkish or Narrow-clawed Crayfish (A. leptodactylus), the Noble Crayfish (Astacus astucus) and the Red Swamp Crayfish (Procambarus clarkii). Of these, the Signal Crayfish and the Turkish Crayfish have been found in waters in Northamptonshire. The Signal Crayfish is an aggressive and fecund species which breeds earlier than White-clawed and has similar food and habitat requirements. Evidence suggests that it tends to out-compete White-clawed, as mixed populations of these two species found in Britain during the 1980s have all become monospecific in favour of Signals. A mixed population of Crayfish studied on Boxmoor Fishery in the Thames Regions showed when Signal Crayfish populations built up, White-clawed populations declined, and then disappeared. The fact that the two species persisted over a period of time suggests the Signal Crayfish was not carrying Crayfish Plague, and competitive exclusion appears the most likely mechanism of displacement of White-clawed Crayfish. It is also possible that predation on juvenile White-clawed Crayfish could be the cause of their displacement, or could at least contribute to their disappearance from mixed populations.

· It is not known whether the Turkish Crayfish carries Crayfish Plague, and the difficulties in screening for Crayfish Plague suggest that this would be difficult to establish. However, there is no circumstantial evidence of Turkish Crayfish being associated with plague outbreaks in the native crayfish.

· Little is known about the ecology of the Turkish Crayfish, also found in Northamptonshire waters, and whether it poses a threat to native populations. The species tends to be larger and more fecund than White-clawed, giving it a competitive advantage. More study would be needed to ascertain this. No wild mixed populations have been found.

· The White-clawed Crayfish is highly susceptible to Crayfish Plague. This is a fungal disease caused by the oomycete fungus Aphanomyces astaci. It is highly virulent and has been causing mass mortalities amongst White-clawed populations in Britain since the early 1980s. It is carried by the Signal Crayfish, which is itself resistant to the disease. However, Signal Crayfish are not always found in the vicinity of plague outbreaks, and it has been shown that its spores can be transmitted in a variety of other ways, including by water, fish, effluent from fish and crayfish farms, and damp equipment, for example equipment used by anglers. It is not readily possible to screen Signal Crayfish for the disease and so identify which populations are likely to transmit the disease to native crayfish. However, this may not be important, as evidence suggests that inter-specific competition between Signals and White-clawed tends to eventually wipe out populations of native crayfish. Therefore, it is not necessarily important from a conservation perspective to know which populations of Signal Crayfish are carrying Crayfish Plague.

· Non-native Crayfish may have adverse ecological impacts on river systems. The documented impacts of Signal Crayfish out-competing White-clawed and transmitting Crayfish Plague have been discussed. Signals can also burrow into riverbanks causing weakening. If White-clawed is a keystone species in the river systems where it is found, its elimination by signal Crayfish may drastically alter the ecosystem through changing other inter-specific relationships. This is also a danger if non-native Crayfish are introduced into an area where no species of Crayfish has ever existed.

· The potential for native and non-native Crayfish to hybridise has been established in the laboratory, both between White-clawed and Signal Crayfish, and between White-clawed and Turkish Crayfish. However, more research would be required to establish whether this is likely to occur in the wild.

· White-clawed may be significantly affected by pollution and intensive river works, including dredging and its associated habitat destruction.

4 CURRENT ACTION

· The Environment Agency collates all records of crayfish, both native and non-native.

· Surveys are being undertaken where there have been recent unsubstantiated records of native crayfish.

· Planning applications are screened for potential impacts on known sites for native Crayfish in Northamptonshire.

· Research is being undertaken nationally by various bodies to broaden our knowledge both of the native Crayfish and its interactions with other species. For example the Leicestershire and Rutland Wildlife Trust and the Environment Agency have undertaken an experimental programme to remove Signal Crayfish from the River Gwash to establish the effects of removal on the population dynamics of the native species.

· In 2000 the Environment Agency commissioned a leaflet designed for display in garden centres in the county. The leaflet explained the decline of the White-clawed Crayfish in Northamptonshire, and the legislation regarding release of non-native species into the wild.

· A survey of the Whilton Arm of the Nene was carried out by the Wildlife Trust on behalf of the Environment Agency. Copies of the survey were circulated to the local planning authorities and the landowners farming adjacent the Whilton Arm of the Nene.

5. WHITE-CLAWED CRAYFISH OBJECTIVES AND ACTIONS

	Objective	Action	Lead Agency	Partners	Targets
5.1	Policy and Legislation
	Objective One: Ensure the protection of the species under the instrumentation of the Countryside and Wildlife Act 1981 and other relevant Acts and Conventions	Implement and enforce relevant legislation and policy	English Nature	Environment Agency	Throughout Plan Period
	Objective Two: Introduce and improve control measures to prevent introduction of non-native species into watercourses	Establish effective methods to prevent escapes and advise crayfish farmers	English Nature	Environment Agency	2004
	Objective Three: Ensure that BAP species and their habitats are given an appropriate level of protection in local plans	Include species protection policies in local plans and/or supplementary guidance	Local Authorities	BAP Partners	By 2003
		Do not permit the development of crayfish farms in the vicinity of waterways where there are good populations of White-clawed Crayfish	Local Authorities	Environment Agency	By 2003
5.2	Site Safeguard and Management (including Species Management and Protection)
	Objective Four: Maintain and enhance the range and numbers of White-clawed Crayfish in Northamptonshire (This may first be achieved with some intervention with a view to future natural re-colonisation	Ensure that all known sites are appropriately managed	Environment Agency	Wildlife Trust	By 2002
		Undertake an intensive programme of trapping and removal of non-native crayfish from all river systems in Northamptonshire	Environment Agency	Wildlife Trust	By 2010.
		Conduct experiments to identify selective chemicals which may be used to control non-native species of Crayfish	Environment Agency	Wildlife Trust	By 2010.
	Objective Five: Prevent invasions of river systems by non-native Crayfish species	Locate all crayfish farms in Northamptonshire	Environment Agency	Local Authorities	By 2002
		Monitor waters in the vicinity of crayfish farms for the presence of non-native species and Crayfish Plague	Environment Agency	Wildlife Trust	Throughout Plan Period
		Establishing methods of preventing colonisation by Signal and Turkish Crayfish of areas which currently free from introduced crayfish species, but hold good White-clawed populations	Environment Agency	English Nature, Wildlife Trust	2005
5.3	Advisory
	Objective Six: Provide advice, guidance and training in White-clawed Crayfish conservation	Provide information and guidance for waterway managers to ensure that watercourses are managed appropriately	Environment Agency	Wildlife Trust, Farming and Wildlife Advisory Group, English Nature, Local Authorities	By 2003
		Advise anglers and other users of important rivers of the importance of properly drying and disinfecting equipment after use to minimise the risk of transmission of Crayfish Plague to plague-free waters	English Nature	Wildlife Trust, Environment Agency	2003
		Produce and disseminate literature on White-clawed Crayfish conservation aimed at crayfish farmers and other keepers	Environment Agency	English Nature, Wildlife Trust	By 2003
		Develop a training programme for potential volunteer surveyors	Wildlife Trust	Environment Agency, English Nature	Commencing 2002
5.4	Future Monitoring and Research
	Objective Seven: Establish the status of introduced Crayfish species within the Northamptonshire	Undertake a countywide survey to determine the size and location of all crayfish (native and non-native) populations, prioritising rivers with current and historical records of the species	Environment Agency	Wildlife Trust	By 2003
		Develop targets for the county’s White-clawed Crayfish population following initial survey	Wildlife Trust	BAP partners	2003
		Continue to send information gathered to national monitoring scheme	Environment Agency	Wildlife Trust, English Nature	Throughout Plan Period
	Objective Eight: Improve knowledge of the local habitat and other requirements of the White-clawed Crayfish, their numbers and locations	Establish a research project focussing on at least one site with a strong White-clawed population	Environment Agency	English Nature, Wildlife Trust, University College Northampton	By 2004
5.5	Communications and Publicity
	Objective Nine: Raise the profile of the White-clawed Crayfish	Promote the importance of the White-clawed Crayfish as an indicator of good water quality	Environment Agency	BAP Partners	Throughout Plan Period
5.6	Review
	Objective Ten: Review the White-clawed Crayfish action plan to assess progress and, where necessary, update and amend		Environment Agency	BAP Partners	2005
	Objective Eleven: Publicise the progress made in delivering this Action Plan in a BAP Annual Report			BAP Partners	Annually

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