The Hairy Marron (Cherax tenuimanus) also known as the Margaret River Hairy Marron, is a large freshwater crayfish that grow to more than 38cm in length. They are one of the largest freshwater crayfish species in the world. The hairy marron has tufts of hairlike setae on the carapace and other body surfaces, giving it its name.
The Hairy Marron is listed as critically endangered due to its very restricted geographical distribution with an estimated extent of occurrence of 50km of the Margaret River.
Habitat and Life Cycle
It is mainly found in the upper reaches of the Margaret River which are found in state forest. It is absent from the heavily degraded middle reaches and extremely rare in the lower reaches of the river (or now possibly extinct from these lower reaches). Long term studies of the marron show a decline in the range and abundance of this species. The hairy marron prefers sandy areas, particularly where detritus (organic matter) accumulates, and requires in-stream structural diversity for protection.
The main identified threats to the hairy marron are competition from smooth marron and changes to the middle and lower reaches of the Margaret River. The smooth marron was introduced to the Margaret River in the early to mid-1980s and rapidly displaced the hairy marron. The river has been greatly modified with reduced water quality and changed flow regimes. The main potential threats to the hairy marron are fishing and hydrological changes due to local anthropological impacts.
SWCC Strategic Priority
The Hairy Marron is identified as a first order priority asset within SWCC’s NRM Strategy under the Aquatic Biodiversity theme.
The Cape to Cape Catchments Group are currently undertaking a project for the Hairy Marron to try and reduce numbers of the Smooth Marron in the areas where the Hairy Marron are found as well as looking at the sustainability of this action into the future. They are also doing surveys to confirm the current distribution and are working with private landholders to undertake fencing and protection of riparian areas in areas where they still may be located.