Flecker's spiny crayfish  (Euastacus fleckeri)

Flecker’s spiny crayfish is classified as Endangered (EN) on the IUCN Red List (1).

Flecker’s spiny crayfish (Euastacus fleckeri) is a large freshwater crayfish found only in Queensland, Australia (1) (3) (4) (5). It is a particularly large Euastacus species (2), with a blue to brown body and bright red tips to its large, pincer-like claws (6).

Like other Euastacus species, Flecker’s spiny crayfish is characterised by its spiny appearance (2) (4) (5). However, it is considered to be quite distinct from most other members of the genus (2) (4), and the spines on its abdomen are somewhat reduced (4) (5).

As in other crayfish, the abdomen of Flecker’s spiny crayfish is divided into six segments, and ends in a tail fin composed of a central tail flap (telson) and surrounding flaps called uropods. In addition to the large claws, crayfish have four more pairs of appendages attached to the thorax. These are known as ‘pereiopods’ and are modified for feeding and walking. The abdomen bears further appendages, which are known as ‘pleopods’ or ‘swimmerets’ and are involved in swimming and in the brooding of eggs by the female (7) (8).

On its head, a crayfish has a pair of compound eyes, as well as several feeding appendages, a pair of antennae and a second pair of smaller, central antennae known as ‘antennules’. The body of a crayfish is encased in a hard, protective carapace (7) (8). In Flecker’s spiny crayfish, the front part of the carapace which projects in front of the eyes (the ‘rostrum’) is quite short, broad and U-shaped (4) (5).

Flecker’s spiny crayfish is endemic to northern Queensland, Australia, where it occurs in a small highland area west of Mossman, on Mount Lewis, Mount Spurgeon, and in areas in between (1) (3) (4) (5). The distribution of this species is highly fragmented (1) (3).

This freshwater species inhabits cool, clear, fast-flowing headwater streams in rainforest (1) (2) (3), at elevations above 900 metres (1) (3) (4) (5). Like most other Euastacus species, Flecker’s spiny crayfish prefers well-oxygenated, shaded locations (1) (3).

Little specific information is available on the biology of Flecker’s spiny crayfish. However, like other freshwater crayfish it builds burrows around the streams it inhabits (7), usually under rocks or logs (1) (3). The diet is likely to include a variety of plant and animal matter, as well as detritus (7).

Freshwater crayfish do not have long, planktonic larval stages, instead producing large eggs which hatch into miniature versions of the adult. The eggs are incubated on the pleopods of the female before hatching (7) (8). The female Flecker’s spiny crayfish reaches maturity at an occipital carapace length of about four to six centimetres (2).

Although Flecker’s spiny crayfish is thought to be relatively common within its range, it has a rather restricted and severely fragmented distribution. It also has quite specialised habitat requirements, and any decline in the extent or quality of its habitat will therefore significantly affect its populations (1). The slow reproductive rate of Flecker’s spiny crayfish makes it harder for the species to recover from any declines (1).

One of the main threats to Flecker’s spiny crayfish is the loss and degradation of its habitat, due to the destruction of streamside vegetation, rooting by feral pigs (1) (3), and agricultural activities, which can reduce water quality through factors such as siltation (3). Climate change is also a potentially significant threat, as it may lead to increased temperatures, altered water regimes, more severe weather events, more frequent bushfires, and the loss of cool highland forest habitats (1) (3).

In addition to the threats to its habitat, Flecker’s spiny crayfish may be under threat from introduced species such as cats and foxes. It may also be affected by the non-native cane toad (Bufo marinus), although the exact impact of this species is not yet known (1) (3). Although there is a catch size limit for spiny crayfish of over nine centimetres occipital carapace length, meaning that individuals below this should not be caught, Flecker’s spiny crayfish is a particularly large species that often exceeds this size. It may therefore be at risk of over-exploitation by recreational fishing (1) (3).

There are no specific conservation measures currently in place for Flecker’s spiny crayfish (1) (3). However, its range coincides with the Northern Queensland World Heritage Area, which may offer this species some protection (1) (3).

Further research is needed into the threats to Flecker’s spiny crayfish, as well as into its populations, biology, habitat requirements, and the effects of illegal recreational fishing (1) (3). In Queensland, all Euastacus crayfish are officially ‘no take’ species under the Fisheries Act 1994 and should be released if captured. However, illegal poaching does occur, and this species may also be confused with unprotected Cherax species and so taken by mistake (1) (3).

In 2005, a project was started with the aim of surveying, identifying and documenting all of Australia’s freshwater crayfish species, including Flecker’s spiny crayfish. It is hoped that the information gathered by the Australian Crayfish Project (ACP) will help in the conservation of freshwater crayfish species and their habitats (9).

Find out more about freshwater crayfish conservation in Australia:

• Australian Aquatic Biological Pty Limited - Australian Crayfish Project:
  http://www.aabio.com.au/crayfish.html