CRUSTACEAN RESEARCH, SPECIAL NUMBER 7: 1–4, 2012 Further translocation of the Redclaw, Cherax quadricarinatus (Decapoda: Parastacidae), to Lake Ainsworth in northeastern New South Wales, Australia Jesse C. Leland, Jason Coughran and James M. Furse Abstract.—The native Australian crayfish its tolerance of extreme environmental Cherax quadricarinatus (or Redclaw) is a large, conditions (e.g. water temperatures up to highly fecund and fast growing species that 34°C and poor water quality, including has been widely translocated both interstate brackish water), these intrinsic qualities have and internationally. This paper describes a facilitated the worldwide translocation of C. translocated population of the species in Lake quadricarinatus for aquaculture research, Ainsworth, an acidic coastal window lake in New commercial farming, recreational fishing South Wales. This population now represents (Horwitz, 1990; Kailola et al., 1993) and the the southern–most extent of its translocated aquarium trade (Peay et al., 2010). Recipient range within Australia, and coincides with regions include the Americas, Europe, Asia two native crayfishes, Cherax cuspidatus and a and the Middle East (Lawrence & Jones highly imperilled species of Tenuibranchiurus. 2002) and, more recently, areas within Consistently high trap catches and collection of Australia beyond its natural range (Coughran berried females indicates that the population in Lake Ainsworth is large, well established and self– & Leckie, 2007; Doupé, 2007; Doupé et al., sustaining. The probable pathway of introduction 2007; Wingfield, 2008). to the lake was by human action (deliberate or Translocation of crayfish species accidental), rather than natural dispersal from of commercial aquaculture potential previous sites of introduction. Native crayfish (e.g. Procambarus clarkii (Girard) and were not captured in the lake, but their presence Pacifastacus leniusculus (Dana)) (Anastacio was confirmed in ephemerally connected habitats et al., 1999; Gherardi et al., 2002; Peay ~2–3 km away. There are serious concerns about et al., 2010) have been replicated in the the further spread of the highly invasive C. Australian state of New South Wales (NSW), quadricarinatus and its potential to displace native where both C. quadricarinatus and Cherax species. destructor Clark have been introduced (Coughran & Leckie 2007; Coughran et al., 2009; Coughran & Daly, 2012). Coughran INTRODUCTION & Leckie (2007) described the first invasion The Redclaw crayfish Cherax of a NSW waterway (Emigrant Creek) by quadricarinatus (von Martens) is native to C. quadricarinatus and discussed the need Queensland, the Northern Territory and New for monitoring the translocation of this Guinea (Kailola et al., 1993; Lawrence & species. However, it appears that no funding Jones 2002; Wingfield, 2008) and is listed or effort has been allocated to this objective, as Least Concern on the IUCN Red List and no further reports of C. quadricarinatus (Austin et al., 2009). This tropical species translocation have been made since that time. is highly fecund, grows rapidly (harvestable The presence of C. quadricarinatus in size of 50–90 g in 8–12 months), matures Lake Ainsworth, NSW was brought to the quickly (between ~30–70 g in 6–9 months), authors’ attention in April 2011, when a and can reach substantial weights of up to recreational fisher was observed removing 590 g (Wingfield, 2002). Combined with large adult crayfish from his traps. Lake 2 J. C. LELAND ET AL. Ainsworth (28.78327°S 153.591936°E) is movement through local waterways and a relatively uncommon lake–type (perched overland migration is possible. However, freshwater window lake) that occurs along more probable pathways include inadvertent the east coast of central Australia (Timms, “bait–bucket” transfer, aquarium discards, 1982). The geology of the area is dominated and intentional (and illegal) translocation/ by basaltic and rhyolitic bedrock and soils stocking by recreational fishers. from the former Tweed Volcano (Willmott, Extensive trapping surveys and 1986). Lake Ainsworth was formed by opportunistic observations of recreational coastal siliceous sand deposits overlaying fishers, indicate that large numbers of the bedrock, and has a surface area of ~0.12 mature C. quadricarinatus can be captured km2 with a maximum depth of ~10 m. As irrespective of season and suggest that is typical in perched window lakes, pH is the population is well established (Leland usually acidic (~pH 5.0) and salinity is low unpublished data). Reproduction is occurring (70–115 ppm) (Timms, 1982). within the population as evidenced by Riparian vegetation includes various the capture of berried females, which are grasses and macrophytes, and the northern extremely rare in trap catches, probably and southern landward extents of the lake because of trap avoidance (Brown & Brewis, are bordered by extensive coastal swamp 1978). Compared with males, females are and floodplain. The bordering Melaleuca disproportionally common and low numbers swamps are inhabited by the native of juveniles in catches probably indicate crayfish species Cherax cuspidatus Riek similar behaviour, due to the presence of and Tenuibranchiurus sp. Riek (authors larger adult crayfish in or around the traps unpublished data and Coughran 2006a, (i.e. trap size–selectivity Mitchell et al., 2006b). The former is classified as Least 1994; Rabeni et al., 1997). Further studies Concern, while the latter is considered an to quantify the population characteristics are “Evolutionarily Significant Unit” (ESU, needed, with a view towards identifying best Moritz, 1994) by Dawkins et al. (2010) and practises for controlling C. quadricarinatus therefore a very high conservation priority. in Lake Ainsworth. To our knowledge there have been no The absence of native crayfish in catches initiatives in funding, education, or field is of some concern. It may be that C. effort to reduce the spread of this exotic quadricarinatus has displaced the smaller, species since it was first reported in NSW. native C. cuspidatus, which is otherwise Of particular concern regarding this new ubiquitous in the area. However, it is also population in Lake Ainsworth is that the possible that native crayfish are present in the species is now in immediate proximity lake, and were simply avoiding the traps in to the only known site inhabited by the the presence of the larger C. quadricarinatus. previously outlined Tenuibranchiurus sp., a During 2010 and 2011, trapping and sweep– highly imperilled native crayfish (Dawkins netting surveys of the adjacent Melaleuca et al., 2010). In this paper, our aim was to (i) swamp habitat (~2–3 km north of Lake formally report the presence of the species Ainsworth) confirmed the presence of the and (ii) briefly discuss the implications for native C. cuspidatus and Tenuibranchiurus native crayfish in Lake Ainsworth. sp. in the area (Furse unpublished data). During that time, C. cuspidatus were captured with the same bait traps in the DISCUSSION Melaleuca swamp, which establishes the To our knowledge, this is the first formal species was not generally ‘trap shy’ at that record of a C. quadricarinatus population time. To date C. quadricarinatus have not in an acidic coastal window lake. The been captured in any adjacent habitat by the pathway of the species’ introduction to authors or our colleagues. Lake Ainsworth is unknown, but the lake Freshwater crayfish (including C. is in the same catchment as the Emigrant quadricarinatus) are well known for their Creek population, so a combination of ability to move overland (Riek, 1951; Translocation OF C. QUADRICARINATUS IN Australia 3 Olszewski, 1980; Furse et al., 2004; International Union for Conservation of Nature Coughran & Leckie, 2007), and we are and Natural Resources. Gland, Switzerland. concerned about the further spread of this Brown, D. J. & Brewis, J. M., 1978. A critical look species. In particular, there is a serious at trapping as a method of sampling a population of Austropotamobius pallipes (Lereboullet) in a concern regarding the potential of this mark and recapture study. Freshwater Crayfish, 4: species to disperse into adjacent, ephemerally 159–163. interconnected swamps and waterways, Coughran, J., 2006a. Field guide to the freshwater especially to the north where the only crayfishes of Northeastern New South Wales known locality of the ESU Tenuibranchiurus (Compact Disk Format). Natureview Publishing, sp. is situated, ~2–3 km away from Lake Bangalow, NSW, Australia. ISBN: 0 9581149 3 5. Ainsworth. At a broader level, it also appears Coughran, J., 2006b. Biology of the freshwater crayfishes of Northeastern New South Wales, that the species may be being deliberately Australia, Ph. D Thesis. School of Environmental translocated in the northeastern NSW region, Science and Management, Southern Cross where it appears capable of establishing feral University, Lismore, Australia. populations. This region supports several Coughran, J. & Daly, G., 2012. Potential threats rare and endangered crayfish, fish and other posed by a translocated crayfish: the case of aquatic species (e.g. amphibians): and Cherax destructor in coastal drainages of New introduced crayfish are well known for their South Wales, Australia. Crustacean Research, capacity to displace native crayfish, fish and Special Number 7: 5–13. Coughran, J. & Leckie, S. R., 2007. Invasion of amphibian species (Horwitz, 1990; Harlioğlu a New South Wales stream by the Tropical & Harlioğlu, 2006). Crayfish, Cherax