Crayfish Conservation in the British Isles 2009 The indigenous status of Austropotamobius pallipes (Lereboullet) in Britain David M HOLDICH1*, Margaret PALMER2 and Peter J SIBLEY3 1Crayfish Survey & Research, Peak Ecology Ltd., Lumford Mill, Riverside Business Park, Bakewell, Derbyshire DE45 1GS. 2Buglife – The Invertebrate Conservation Trust, First Floor, 90 Bridge Street, Peterborough, PE1 1DY. 3Environment Agency, South West Region, Wessex Area, Analysis & Reporting, Rivers House, East Quay, Bridgwater, Somerset, TA6 4YS, UK. *Corresponding author – [email protected] ABSTRACT In order to qualify for indigenous status in Britain, with concomitant implications for its conservation, the white-clawed crayfish, Austropotamobius pallipes, needs to have been in residence before 1500 AD. Available evidence from palaeontology, distributional, and genetic studies is examined, as well as records of crayfish in historical documents. The conclusion is that there is sufficient evidence from historical literature to indicate that A. pallipes was in residence in Britain before 1500. This has been accepted by the IUCN. Keywords: Austropotamobius pallipes, Britain, indigenous, evidence INTRODUCTION The following statement of the Live freshwater crayfish have been International Union for the Conservation of transported around Europe as a food commodity Nature and Natural Resources (IUCN) caused for centuries (Hirsch 2008) so there is a the authors to try to clarify the indigenous status possibility that A. pallipes was introduced to of the white-clawed crayfish, Austropotamobius Britain relatively recently. However, there is pallipes (Lereboullet) in Britain. currently considerable investment in the conservation of A. pallipes because it has been “To decide whether an introduced regarded as a threatened species indigenous to species is now considered naturalized to a Britain. In order to justify this effort, it is region for the purposes of a Red Data Book, important to establish the status of A. pallipes IUCN recommends that a preset year or event and this has triggered a search for evidence to may be used (IUCN 2003). For assessments of demonstrate that it was part of the British species in Europe, IUCN uses a cut-off date of freshwater fauna prior to 1500 AD. 1500 and if a species existed in a country since that date it is considered indigenous for the purposes of the Red List assessment.” DISTRIBUTION BEFORE THE INTRODUCTION OF SIGNAL CRAYFISH Austropotamobius pallipes was widely times until the early 1980s (Thomas and Ingle distributed in England and Wales from Victorian 1971, Holdich and Reeve 1991). This in itself 1 Holdich, Palmer and Sibley might suggest that it has been resident in Britain introduced in recent times (Holdich and Reeve for a long time and that it has spread both 1991, Thomas 1992, Maitland et al. 2001) and naturally and by human-mediated means as it therefore cannot be considered as indigenous. was perceived as a useful food. At the time it The origin of the introduced crayfish is not entered Britain A. pallipes would have been the known but Maitland et al. (2001) suggest they largest mobile, polytrophic invertebrate and in may have originated from stock (1100 some instances may have had a significant individuals) brought in by Lord Breadalbane impact on other freshwater biota although over 150 years ago for possible introduction to arguably less so than other more aggressive the River Tay, or from stock introduced into a introduced species (Holdich 1999a). As seen number of Scottish counties about the same time. from the introduction of the signal crayfish Thomas (1992) states that the population in Loch Pacifastacus leniusculus (Dana) into Britain in Croispol was derived from an introduction into a the late 1970s (Holdich 1999b), colonization can feeder stream in 1945 by H Campbell, Keeper of be rapid, i.e. it took less than 25 years for this the Keadal Estate, Durness, but its origin is non-indigenous species to occupy more 10 km unknown. squares than A. pallipes (Sibley 2003, Holdich et al. 2004). Its spread has been both natural and Although Ireland is not dealt with in this by human-mediated means for commercial paper, there are similar issues regarding the purposes. One wonders if A. pallipes could have indigenous status of A. pallipes (Gouin et al. spread that quickly when it re-colonized (or was 2003, Demers et al. 2005, Reynolds this re-introduced to) Britain. volume). The only two populations of A. pallipes Machino et al. (2004) provide a useful in Scotland (Loch Croispol in Durness and summary of A. pallipes introductions throughout White Moss Reservoir in the catchment of the Europe. lower Clyde) are thought to have been FOSSIL EVIDENCE AND POSSIBLE POST-GLACIAL MIGRATION The Ice Age, or Pleistocene, came to an say that “If A. pallipes reached Great Britain in a end about 10 000 years ago. Bell (1921) refers natural way, it could have reached Southern to “A. pallipes” in Pleistocene deposits: England, as there was a post-glacial stream “Potamobius pallipes Lereboullet. (Astacus connection in existence between France and fluviatilis) Fabr. Pleist. Clacton, Essex, and England. The British Isles were linked since the Stapenhall in the Lower Trent Valley”. Albrecht Tertiary until approx. 6000 years ago with the (1983) comments on this as follows, although he mainland through a bridge of land. The rivers of gives Bell’s paper as 1920: “In Bell (1920) we southern England met with the original Rhine, find two statements about Pleistocene findings of the Seine, Somme, Authie and Cauche. The first A. pallipes in Mid-England. Unfortunately these immigrants (whether A. pallipes or not) stood no two statements are problematic. Bell only gives chance to survive the Ice Age in England, as the a list of different findings without any British Isles were partly ice-over or belonged description. It is impossible to know how many partly to the area of permafrost.” parts of the animals existed nor which criteria were applied to classify them. There is also no Spitzy (1979) has speculated that statement where these pieces were stored. Even prehistoric man would have recognised crayfish if they were really A. pallipes these findings as a valuable food source and, due to the ease by must come from anteglacial migration, which which they can be transported in damp baskets, were deposited in the Pleistocene. The English may well have seeded lakes in new areas with populations of today are only to be understood as them. However, he, as the current authors have postglacial new immigrations.” He goes on to found, could find no reference to crayfish in 2 Status of Austropotamobius pallipes European literature in or before the Middle Ages native are a result of recolonization from the (1066-1485 AD), or references to their remains latter part of the Lateglacial (c. 14 000 years being found in middens. Their absence from ago) and that by the early to middle Holocene middens, unlike the shells of bivalve molluscs (7500-5000 years ago) the “native” freshwater such as those of swan mussels, he speculated bivalve fauna was complete. One has to wonder could be put down to the fact that their remains whether crayfish would have been equally may have been carried away by birds and capable of such recolonization, especially as they rodents, thrown in a fire, or just not survived in are much more mobile as adults than bivalve the soil conditions round encampments. molluscs, although they do lack larvae, i.e. what hatches out from the egg is an almost fully Much more is known about the formed crayfish (Holdich 1992). The production recolonization of Britain by freshwater bivalve of free-swimming larvae is probably the means molluscs after the last Ice Age. Killeen et al. by which the larger bivalve molluscs recolonized (2004) state that most species now regarded as British waters. GENETIC EVIDENCE There is, therefore, speculation as to how zones. The latter observation is probably due to some of the current marginal populations habitat fragmentation and subsequent subsequently came about in Europe. For example recolonizations from refugial areas during the are the populations of A. pallipes in Britain Pleistocene. Souty-Grosset et al. (1997) have natural or introduced by man in relatively recent suggested that at least three refugia were formed times? Grandjean et al. (1997a) found a lack of during the last ice age: the first in the Iberian genetic diversity in A. pallipes from Britain Peninsula, the second the Balkans, and the third in suggesting a recent origin. Grandjean et al. the south of France; north-western Europe being (1997b) found a strong genetic similarity to some colonized from this latter refuge after the last ice populations in northern France, suggesting that period. Grandjean et al. (2001a, b) have British A. pallipes may have originated from elaborated further on this matter and, based on there. Whether this was by tribes moving north RFLP analysis from mDNA, have suggested at with the melting ice when the British Isles were least four main refugia for A. pallipes during the connected to mainland Europe some 6000 years Pleistocene, which could have been located in the ago, or much more recently, i.e. in the last 1000 Balkans, Carpathians, Italy and France. Three years, is not known. One also has to consider the clusters with specific haplotypes have been found fact (as mentioned above) that as the ice melted in north-western France and Britain, southern some of the rivers between mainland Europe and France and northern Italy. Each had low genetic the British Isles were joined, so colonisation of differentiation, thus indicating recent divergence the British Isles by A. pallipes may also have been during the last periods of glaciation with three natural, as has occurred with some fish species refugia located in the Atlantic French region, (George 1962, Maitland and Campbell 1992).