White-clawed crayfish in Ireland - under increasing threat. Pp. 120-128 in: Rees M, Nightingale J, Holdich DM (eds). (2011). Species Survival: Securing white-clawed crayfish in a changing environment. Proceedings of a Conference held on 16th and 17th November 2010 in Bristol, UK.

Abstract

The occurrence pattern of white-clawed crayfish, Austropotamobius pallipes (Lereboullet 1858), in Ireland is today sharply different from elsewhere in its current range, but more like that in England 50 years ago. Populations of Irish crayfish are widespread particularly in the lime-rich lowlands, north and south, and since first records in the 1700s, most populations in both jurisdictions are stable or slowly declining, for reasons not fully established. Some lake stocks have been extinguished. A single plague outbreak was recorded in the 1980s. Today there is increasing threat from non-indigenous crayfish, which are readily available through the internet trade from within and outside the EU. Legislation to prohibit their import to Ireland is in preparation. The legislation and current conservation approach in Northern Ireland is different to current British approaches, and different from that in the Irish Republic, although equally tied into EC Habitats Directive requirements. Education of customs officials and the public is a priority.

Full text

Craysh Conservation
South West
Craysh Conservation
South West
Rees M, Nightingale J, Holdich DM (eds.) (2011). Species Survival: Securing
white-clawed craysh in a changing environment. Proceedings of a conference
held on 16th and 17th November 2010 in Bristol, UK.
WHITE-CLAWED CRAYFISH IN IRELAND - UNDER INCREASING THREAT
Julian D. Reynolds.
Emeritus Fellow, Trinity College, Dublin.
Postal address: 115 Weirview Drive, Stillorgan, Co. Dublin, IRELAND.
e-mail: jreynolds@tcd.ie
ABSTRACT
The occurrence pattern of white-clawed craysh, Austropotamobius pallipes (Lereboullet 1858), in Ireland
is today sharply different from elsewhere in its current range, but more like that in England 50 years ago.
Populations of Irish craysh are widespread particularly in the lime-rich lowlands, north and south, and since
rst records in the 1700s, most populations in both jurisdictions are stable or slowly declining, for reasons not
fully established. Some lake stocks have been extinguished. A single plague outbreak was recorded in the
1980s. Today there is increasing threat from non-indigenous craysh, which are readily available through the
internet trade from within and outside the EU. Legislation to prohibit their import to Ireland is in preparation.
The legislation and current conservation approach in Northern Ireland is different to current British approaches,
and different from that in the Irish Republic, although equally tied into EC Habitats Directive requirements.
Education of customs ofcials and the public is a priority.
Keywords: Austropotamobius pallipes, bioindicator, keystone species, legislation, smuggling, threats, white-
clawed craysh
INTRODUCTION
The occurrence pattern of the white-clawed craysh, Austropotamobius pallipes (Lereboullet 1858), in Ireland
is today sharply different from elsewhere in its current range (Reynolds and Demers 2006, Reynolds 2009),
including Great Britain, although more like England of 50 years ago. Prior to the invasion of non-indigenous
signal craysh, Pacifastacus leniusculus (Dana 1852), in Britain, white-clawed craysh were widespread,
and about 15 % of all recorded sites were still-water; chiey reservoirs and water-lled quarries (Jay and
Holdich 1981, Holdich and Reeve 1991). In Ireland, while craysh occupied a comparable range of habitats,
3 2 % of records were from lakes (Reynolds 1982), but the lakes available to and occupied by this species
were up to an order of magnitude larger than in Britain. A single plague outbreak was recorded in the 1980s,
which wiped out most stocks in the Boyne catchment and in some contiguous Shannon tributaries (Matthews
and Reynolds 1992, Matthews et al. 1993). Today, most populations in Northern Ireland and the Republic
of Ireland appear to be stable, or slowly declining for reasons not fully understood (Reynolds et al. 2010a,
Gallagher 2011, pers. comm.).
Apart from geology (lowland Ireland, where craysh are widespread, is Paleozoic, underlain by Carboniferous
limestone) there are several historical reasons that may explain differences between the craysh stocks of
the islands of Ireland and Britain:
1) Craysh have not been a popular food in Ireland, even apparently during famine years, and they do not
gure in Irish folklore (Reynolds 1992, pers. comm., Lucey 2009, pers. comm.). In the 1970s and 1980s a
few people, including some Swedish crayshermen, periodically caught craysh at Pollaphuca (Blessington
Lakes) Reservoir and White Lake, as did others in the country, e.g. a sherman in the Erne and a farmer near
Lough Owel (Matthews 1992, pers. comm.).
120
Irish craysh under increasing threat (Reynolds)

Craysh Conservation
South West
Craysh Conservation
South West
Rees M, Nightingale J, Holdich DM (eds.) (2011). Species Survival: Securing
white-clawed craysh in a changing environment. Proceedings of a conference
held on 16th and 17th November 2010 in Bristol, UK.
2) As a measure to safeguard salmonid stocks, importation of craysh has been prohibited under the Live
Fish (restriction of importation) Order 1972 of the Irish Fisheries (Consolidation) Act 1959. However, the
original 1959 Act appears only to apply to marine crustaceans and so this legislation may not in practice
be enforceable over this issue (http://www.irishstatutebook.ie/1959/en/act/pub/0014/index.html). Despite
differences in legislation between the two jurisdictions on the island, they have cooperated in discouraging
the importation of non-indigenous craysh species (NICS).
3) There was no encouragement from the Irish Government to import signal craysh in the 1970s and 1980s,
at a time when this was happening in Britain and elsewhere in Europe. The author was lobbied at that time
by two farmers who had sought to import signals to County Louth, but were refused licences.
Historical records
The origins of Irish craysh stocks are still unclear. Mitochondrial DNA and microsatellite genetic studies
indicate that Irish craysh are rather uniform and were probably derived from western French stocks; it has
been suggested that they may have been brought in by 12th Century Cistercian monks (Reynolds et al.
2002, Gouin et al. 2003). A possible separate origin of Northern Ireland stocks has not yet been established
(Souty-Grosset 2011, pers. comm., Wilson 2011, pers. comm.). Holdich et al. (2009) produced documentary
evidence that craysh were present in Great Britain before 1500 AD and are thus considered indigenous
under IUCN rules. Lucey (1999) cites the rst reference to craysh in Ireland in a 1680 MS that said they
were introduced from England. Two early observers, Rutty (1772) of craysh near Finglas, outside Dublin,
and Thompson (1843) of craysh from the Royal Canal about 12 miles W of Dublin, both attributed their
ndings to introductions. The earliest specimens in the National Museum NMI are 19th century specimens
from three locations around Dublin and there are early 20th century records in the British Museum BMNH from
R. Dodder (1905), again in the vicinity of Dublin.
Most Irish records of craysh are 20th century, generally published either in the Irish Naturalist or The Irish
Naturalists’ Journal (summarized in Reynolds 1982, Lucey and McGarrigle 1987, Reynolds 1997 and Reynolds
et al. 2010a). The rst scientic studies on Irish craysh were by Moriarty (1973) on craysh in White Lake,
Co. Westmeath, and an unpublished report by Watson (1971) on Co. Fermanagh craysh lakes. Moriarty
was interested in the interactions of craysh and eels, and noted that thriving lake populations appeared to
be mostly in eel-free waters.
THE PRESENT SITUATION
Craysh in Irish freshwater ecosystems
Whether indigenous or a medieval or later introduction, white-clawed craysh are now in balance in Irish
freshwater ecosystems, both lakes and rivers. Along with some sh, they act as keystone species, as
detritivores altering the relative proportions of ne and coarse particulate organic matter (FPOM and CPOM)
and selectively feeding on aquatic plants, epibionts, invertebrates and vertebrates (frogs and sh) (Matthews
and Reynolds 1992, Matthews et al. 1993, Reynolds and O’Keeffe 2004, Füreder et al. 2006). They may
further alter the ecosystem by mechanical means – controlling aquatic weed-beds (Reynolds et al. 2002)
and burrowing into banks.
River stocks today
Irish lowland rivers are often characterized by unclear catchment boundaries and articial drainage or canal
links (Reynolds 2009). Recent surveys indicate that craysh remain widespread in many rivers (Demers and
Species Survival: Securing white-clawed craysh in a changing environment
121

Craysh Conservation
South West
Craysh Conservation
South West
Rees M, Nightingale J, Holdich DM (eds.) (2011). Species Survival: Securing
white-clawed craysh in a changing environment. Proceedings of a conference
held on 16th and 17th November 2010 in Bristol, UK.
Reynolds 2003). Craysh are routinely encountered during sh and macroinvertebrate surveys by agencies
such as Inland Fisheries Ireland (IFI) (King 2011, pers. comm.) and in water quality investigations by
Environmental Protection Agency (EPA) staff (Lucey 2011, pers. comm.) and by environmental consultants,
and thus are well known. Byrne et al. (1999) published a sampling methodology for streams, since modied
by other workers: monitoring today generally follows Peay (2003). The current picture for the Republic of
Ireland (ROI) indicates that craysh are still widespread (Demers et al. 2005, NPWS 2008, Reynolds et al.
2010a), with some recoveries from the plague outbreak, a range extension in the south (Lucey 2010) and
some declines (e.g. Lyons and Kelly-Quinn 2003), while in Northern Ireland (NI), Gallagher et al. (2006)
describe the environmental requirements for river craysh. Craysh are known from the Erne, Blackwater
and Ballinderry systems (Gallagher 2002), and there have been more recent unpublished surveys (Early
2011, pers. comm., Gallagher 2011, pers. comm.) including the Ballinderry catchment (Wilson and Horton
2008).
Lake stocks today
A number of individual lake stocks of white-clawed craysh have been studied, e.g. in White Lake (Moriarty
1973, O’Keeffe, 1986), L. Lene (Matthews 1992, Matthews et al. 1993, Reynolds and Matthews 1993, 1997),
Blessington Lakes (Pollaphuca Reservoir) (Matthews and Reynolds 1995), and there have been several
studies in NI lakes (e.g. Watson 1971, Gallagher 2002) including the Magheraveely Marl Lakes SAC (Bradley
2008). Sampling methods are described by O’Connor et al. (2009) and Reynolds et al. (2010b, 2010c).
Lake stocks, being more or less isolated, are vulnerable to extinction, and deserve closer study. Plague is
believed to have wiped out several lake stocks in 1985-88 (White Lake, Lough Bane, Lough Glore, Lough
Lene in the Irish midlands). There is anecdotal information about other midlands lake stocks in trouble or lost,
e.g. from L. Owel, L. Ennell, L. Sheelin and Pallas L. Of 26 ROI lakes where craysh had been recorded,
stocks are still present in 15 (O’Connor et al. 2009, Reynolds et al. 2010c), and there are also declines and
stock losses in NI lakes (Bradley 2008, Early 2011, pers. comm.).
Lough Owel provides an example of recent craysh mortalities. Craysh population expansions and
contractions have been periodically noted in this clear water lime-rich midlands lake since the 1970s (Champ
2010, pers. comm.), including a major incident in the 1980s linked to the plague outbreak (Reynolds and
Matthews 1996). In 2007 a snorkeler observed abundant craysh in Lough Owel, but in May 2010 when he
returned to take photos of craysh, he found low visibility and lamentous algae covering the bottom. He
reported seeing hundreds of dead craysh, and very few living. His video may be seen at http//underwater-
ireland.com/article.htm.
This evidence was conicting, however. It was suggested that given the time of year of the occurrence, some
of these ‘dead craysh’ could be exuviae that had accumulated in one area. However, others were clearly
egg-bearing dead females. A survey commissioned by the NPWS found plentiful craysh in Lough Owel in
June and again in September 2007, and a further video in October 2010 showed healthy craysh and stands
of Chara, so if this was a kill, it appeared to be localized (Reynolds et al. 2010c). Clearly, closer study is
needed to understand the lake and its craysh stocks.
The threat from NICS and recent sightings of NICS in Ireland
Not all reports of craysh in Ireland have been accepted as indigenous (ICS). Lucey and McGarrigle (1987)
note a personal communication from C. Moriarty that reports of the European noble craysh, Astacus astacus
(Linnaeus 1758), have not been authenticated for Ireland. When interest in farming exotic craysh was rst
high in Great Britain, Reynolds (1979) advised against their importation to Ireland, fearing the displacement
of white-clawed craysh through competition as well as the possibility of plague introduction. However, while
the legislation has been effective so far, it needs to prohibit all exotic craysh if the risk of plague, north and
122
Irish craysh under increasing threat (Reynolds)

Craysh Conservation
South West
Craysh Conservation
South West
Rees M, Nightingale J, Holdich DM (eds.) (2011). Species Survival: Securing
white-clawed craysh in a changing environment. Proceedings of a conference
held on 16th and 17th November 2010 in Bristol, UK.
south, is to be averted. Only ve craysh species are listed on the draft NI legislation (Early 2011, pers.
comm.). However, there are already six NICS inhabiting waters in Britain (Holdich and Sibley 2009), and
despite stringent legislation this has not stopped them spreading. Recent risk assessments have shown that
most have the capability to be highly invasive (Peay et al. 2010).
Some of the currently high levels of activity and interest in NICS being shown in Britain (Holdich and Sibley
2009) have engendered a correspondingly heightened awareness about the potential threat to white-clawed
craysh of NICS importation into Ireland. In 2009 a TV Chef came to Belfast to publicize craysh cooking,
saying that his raw material was local signals from Lough Neagh (Early 2011, pers. comm.). It is feared
that tightening legislation in Britain may lead to activity of trapping and smuggling signals being directed into
Ireland (Peay 2010, pers. comm.). Government-funded projects such as such as Invasive Species Ireland,
www.invasivespeciesireland.com, have been working to increase knowledge and awareness of established
and potential invasives.
Recently, there have been several reported sightings of NICS in Ireland, North and South. Northern Ireland
has had at least two false alarms since 2007, both from the Ulster Blackwater River. Both sightings were
from anglers who claimed to be familiar with signal craysh. On each occasion baited traps were shed over
several weeks at the report sites, but only white-clawed craysh of all age ranges and sexes were trapped.
(Early 2010, pers. comm.).
In ROI there was a NICS alarm in 2010 from the R. Barrow, accompanied by a photo of the dorsal side of
a craysh claw found in a tributary of the R. Barrow. Responders commented on the large claw teeth and
extreme rugosity. One suggested identication, based on a photograph in a British ID sheet, was that it
looked like the spiny-cheek craysh, Orconectes limosus (Ranesque 1817), adding ‘It could just be shing
bait - do we know if that sort of bait would be used to sh in that area?’ Another response said that it
looked like stone craysh, Austropotamobius torrentium (Schrank 1803). However, David Holdich and Julian
Reynolds considered that it was most probably A. pallipes, and Catherine Souty-Grosset arrived at the same
conclusion, having eliminated the most likely non-indigenous species. Again, subsequent searches only
found white-clawed craysh. These events underline the interest in craysh, the dangers of introductions,
and the problems of unfamiliarity with craysh material for professionals likely to be tasked with identication.
A website with many photographs of exotic craysh is in preparation (O’Neill 2011, pers. comm.) and
permanent collections of preserved craysh of the species currently present in Europe should be a priority.
In August 2010 the author received an e-mail from a sh fancier concerned that there are numbers of craysh
being brought into the country. He suggested that customs and/or the Department of Agriculture are not
systematically checking deliveries from inside the EU for non-indigenous species, although the multitude
of species introduced into EU countries over the years is well known and it is therefore as likely that non-
indigenous species may be introduced to Ireland from within the EU as from their country of origin. He noted
that red swamp craysh, Procambarus clarkii (Girard 1852), is widely available from aquarists in Ireland; ‘they
come in from the Czech Republic, and Customs does not check anything trans-shipped from within the EU’.
In this context Chucholl (2010) has shown that in Germany at present, over 100 NICS originating from North
America are available as ornamental aquarium species, each one probably capable of transmitting craysh
plague. Holdich et al. (2009) have reviewed the threat to ICS in Europe from NICS and have shown that ICS
in most countries are affected.
A discussion thread on the website www.irishshforum.com also deals with the ease of bringing in craysh
from within the EU. The people on the forum are for the most part not only concerned about their sh but are
also keenly interested in preserving wildlife in this country. The desire for education is clearly demonstrated
and, following this, the author posted a thread on the website with some details about the current legal and
conservation situation with regard to importation of craysh. Similar postings have also been placed on other
websites.
Species Survival: Securing white-clawed craysh in a changing environment
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Craysh Conservation
South West
Craysh Conservation
South West
Rees M, Nightingale J, Holdich DM (eds.) (2011). Species Survival: Securing
white-clawed craysh in a changing environment. Proceedings of a conference
held on 16th and 17th November 2010 in Bristol, UK.
DISCUSSION
The threat from NICS
NICS are increasingly likely to be introduced to Ireland, by accidental or intentional means, wherever the
media message has not hit home. The main threats come from the general public, unaware that UK law is
different in NI from that in Britain; from aquarists importing through the internet (see above); from soft-hearted
citizens who might dispose of ailing craysh or multiplying pets (e.g. the parthenogenetic marbled craysh
or marmorkrebs, Procambarus sp.) or those that get too large (e.g. Cherax spp.) into the wild; from Foodies
keen to ‘eat to beat’ (one chef even cooking signal craysh for TV in Belfast with the statement that they came
from Lough Neagh); and from shermen, of whom an increasing foreign component is less aware of local
regulations and more convinced of what they think ‘should be’ in water. Another threat is the introduction of
plague by various possible means, such as damp shing gear, water with farmed sh, or movement of birds.
Education and conservation
The Craynet project has emphasized the importance of education in several publications. For example, Puky
et al. (2002) showed great variability in knowledge about craysh across European countries. At that time
Ireland and Croatia had the lowest levels of knowledge. The evidence shows that even in groups dedicated
to protection of indigenous stocks, the ability to identify NICS and ICS may be insufcient. There is a clear
need for education, especially for those with statutory responsibility for craysh to be able to identify them,
and awareness campaigns for other stakeholders and the general public.
Relevant actions
Conservation activities, and priorities for action, are different in NI and ROI, and the current Irish conservation
approach therefore differs from current British approaches, though each is equally tied into EC Habitats
Directive requirements.
In NI, current emphases include the development of ark sites (Horton 2009), while in ROI there is an
emphasis on population monitoring. A recommendation for NI would be renewed vigilance to curb smugglers
who may seek alternative markets for UK signals. In both NI and ROI, emphases should be on controlling
internet aquarium trade and the movement and sale of live materials from within the EU, the education of
professionals and ofcials, and an alert public. A modern hatchery in NI has the potential to rear juveniles
from different strains (Policar et al. 2010), which could be the basis of a restocking programme for SACs
depleted or lacking craysh stocks.
Of the two main threats, an outbreak of craysh plague would certainly devastate many stocks, but slow
recovery has been shown to be possible. However, an invasion of NICS, either North or South, would mean
the rapid and irreparable extinction of nearly all Irish white-clawed craysh stocks. The message is clear
and strong – never introduce living craysh, for whatever reasons. It remains to be seen how we make this
message stick, and how best to train people to implement current legislation.
ACKNOWLEDGEMENTS
My thanks to present and former co-workers and to all those who answered my queries, most of whom are
indicated as ‘personal communication’. I am particularly grateful to Mary Gallagher, for providing information
for NI and to John Early, Christopher Moriarty and Brian Nelson for commenting on a draft of this paper.
124
Irish craysh under increasing threat (Reynolds)

Craysh Conservation
South West
Craysh Conservation
South West
Rees M, Nightingale J, Holdich DM (eds.) (2011). Species Survival: Securing
white-clawed craysh in a changing environment. Proceedings of a conference
held on 16th and 17th November 2010 in Bristol, UK.
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Craysh Conservation
South West
Craysh Conservation
South West
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