Redclaw Crayfish

Historical Background

C. quadricarinatus is an aquatic crayfish, naturally distributed in a wide variety of habitats in its native range of distribution (Queensland and Northern Territory in Australia and southeastern Papua New Guinea). Due to the harsh physical conditions it has adapted to in its native range, C. quadricarinatus has a robust nature with broad tolerances to environmental extremes. Such environmental tolerance, combined with its rapid growth rate and relatively large dimensions, makes it an ideal species for aquaculture and aquarium trade.

In Australia, the commercial interest in this species began in the late 1980s, when it was introduced to Western Australia and New South Wales. Starting from the 1990s, many countries in southern Asia (including China), North and South America, New Caledonia, Africa, Israel and parts of Europe obtained permits to import broodstock and juveniles. Established, feral populations are reported in Ecuador, Israel, Mexico, Jamaica, Paraguay, Puerto Rico, Singapore, South Africa, Thailand, and Zambia.


Introduction

C. quadricarinatus was introduced to Israel from the USA in the early 1990s by the Department of Fisheries, Ministry of Agriculture, for aquaculture purposes (FAO-DIAS, 2011). Experimental stocking and growout studies were carried out at the Agricultural Research Organization at Bet Dagan and the Aquacultural Research Station, Ministry of Agriculture, Dor (Karplus et al., 1995, 1998; Sagi et al., 1998). In the latter location, in 1994, individuals were discovered to have overwintered in open earthen ponds. Moreover, it was recorded that “in the absence of fences” individuals wandered into adjacent ponds and drainage canals. Karplus et al. (1998) opined that the species is able to survive, disperse and establish in Israel. He considered that “introduction of C. quadricarinatus into Israel’s southern part, in which the introduction sites are isolated from natural water sources by the desert, seems safer” and cautioned against introducing it into the temperate areas. As noted by Snovsky and Galil (2011), Karplus’ advice went unheeded, the species is now raised in Kfar Monash, on the central coastal plain, where intensive farming is able to provide up to 100,000,000 juveniles to distributors and ornamental shop chains in Israel and Europe. On January 2011, a large specimen was captured in shallow waters (2-3 m depth) at the Sea of Galilee (Lake Tiberias), opposite Tiberias promenade and bathing beach (Snovsky and Galil, 2011).

In Mexico, the redclaw crayfish have been introduced a number of times to establish commercial cultures and several ventures have been producing moderate amounts for the local markets in at least the states of Colima, Distrito Federal, Morelos, Jalisco, Tamaulipas, and Yucatan (Bortolini et al., 2007). The first importation of redclaw crayfish into Mexico occurred in 1995 when the Experimental Aquaculture Plant of the Universidad Autónoma Metropolitana, in Mexico City, brought a small stock to initiate a research program to determine its suitability to be cultured in Mexico (Ponce-Palafox et al., 1999). In 1998, organisms were transferred to several research centers in Ensenada, Baja California; La Paz, Baja California Sur; and Mérida, Yucatan, plus to an aquaculture center in the state of Morelos; since then several other research centers and universities around Mexico have started research projects using this species. Feral established populations of C. quadricarinatus were reported in the states of Morelos and Tamaulipas in 2005. In Morelos, C. quadricarinatus is apparently contained inside an aquatic park reaching very high densities, probably taking advantage of food remains left by park visitors and a controlled environment where no fishing is allowed (Bortolini et al., 2007). In Tamaulipas, the population is widely spread over an area 65-km long within a network of irrigation canals connected to the Guayalejo and Sabinas rivers (Bortolini et al., 2007).

Spread

In Singapore, since 2000 sampling and observations in several water catchment reservoirs have revealed the presence of C. quadricarinatus. Crayfish were recorded from at least three of Singapore’s major reservoirs, namely Kranji, Lower Peirce and Upper Seletar (Ahyong and Yeo, 2007). C. quadricarinatus is likely to be a recent introduction, probably becoming feral some time between late 1990s and early 2000s. It is not presently cultured for human consumption, but in the last decade it has become popular in the aquarium trade. As such, feral populations probably derive from accidental or deliberate releases. Multiple independent releases or escapes of C. quadricarinatus have probably occurred.

In Europe, it has been generally considered that this tropical species would not become established if it escaped into the wild. For this reason, it is the only crayfish from outside Europe that can be imported alive into Britain (Holdich et al., 1999). On the contrary, since it has the potential to survive low winter temperatures, there is the risk that it will become established, particularly in southern European countries. Its introduction and its culture in England and Spain are mainly purposed to the aquarist trade. Currently, only Italy is involved in culturing redclaws for food. Recently, Koutrakis et al. (2007) reported the presence of C. quadricarinatus in restaurant’s aquaria in the city of Igoumenitsa, Epirus, Greece, and the availability of the species to the aquarium hobbyists (Perdikaris et al., 2005).

C. quadricarinatus has been assessed by IUCN (2010) as Least Concern. There are no major threats impacting this species or its habitat, and it is unlikely to be experiencing significant population declines.