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The Hairy Marron An Integral Part of the Ecosystem in Western Australia

Hairy Marron

Discover the Critically Endangered Hairy Marron: A Species Worth Protecting

As a kid I loved to go ‘yabbying’ – will my grandkids still be able to do the same? Exhibit A: The hairy marron, a species of freshwater crayfish only found in Western Australia – now critically endangered and at risk of complete extinction. These animals, scientifically known as Cherax tenuimanus, are an integral part of the ecosystem in the rivers and streams of their native habitat.

Marron Postage stamp

Marron are the largest freshwater crayfish in Western Australia – and the third largest in the world growing up to 38cm. The hairy marron is named for the distinctive tufts of hair that adorn its claws and body which are not obvious on juveniles. The head and sometimes tail (of larger marron) are covered the short hairs. These hairs, known as setae, help the crayfish to sense their surroundings and defend themselves from predators. The marron’s body is typically a dark olive brown or black color, with a pale underside.

Habitat

The hairy marron is found in a variety of freshwater habitats, including rivers, streams, and swamps. They are native in the south-western region of Western Australia an area known globally for wine and surf breaks but not this endangered species. Specifically, it lives in the only found in the upper reaches of the Margaret River and is currently listed as critically endangered on the IUCN Red List because of the threat from the wider ranged smooth marron, Cherax cainii, which was introduced into its habitat. The hairy marron is an important source of food for a variety of other species. Marron grow mostly in summer, when water temperature is warmest. They grow by moulting (shedding their shell, exposing a larger shell, which had been forming underneath). During the short time the new shell takes to harden, marron are especially vulnerable to attack by predators. 

Diet

The diet of the hairy marron is varied and opportunistic. Marron play a critical role as recyclers, breaking down animal and plant debris. Marron eat living, dead and decaying plant and animals found on the river or dam bed, including small invertebrates, fish eggs, fish larvae and algae. In addition to foraging for food, the marron is also capable of using its powerful claws to dig for roots and tubers to supplement its diet.

Reproduction

When it comes to reproduction, the hairy marron is a fascinating species. They reach sexual maturity at two to three years and spawn in early spring producing between 200 and 400 eggs, but large females may produce up to 800. The gestational period for the eggs take nearly six months to develop inside the females. During mating, the males pass on a sperm packet that the females use to fertilise their eggs after laying.

Once the eggs are fertilised, the females carry them in a large mass under the tail until they hatch in late spring. The hatched larvae then hang under the mother’s tail, clinging to fine hairs. They stay there for many weeks, feeding on nutrients from the yolk sac and moulting several times.

By summer, these tiny juveniles are ready to actively feed. They drop away from their mother and remain in waterways close to where they were hatched.

Behavior

In terms of behavior, the hairy marron is a solitary creature that is mostly active at night. These crayfish are known for their territorial behavior, and will fiercely defend their territory from intruders. They are also capable of producing a loud, clicking noise by snapping their claws together, which is thought to be a way of communicating with other marron in the area.

Distribution

They are preyed upon by native water rats, tortoises, birds, fish and introduced species such as redfin perch and trout. Small juveniles are vulnerable to cannibalism by larger marron. The hairy marron does face some threats to its survival. Habitat destruction and pollution are both potential dangers to these crayfish, is over-fishing by humans. In order to ensure the long-term survival of the hairy marron, it is important that we work to protect and preserve their natural habitat and adopt sustainable fishing practices are restore habitat.

Conservation Status

Farmers stocking dams with smooth marron, destruction of riverbank vegetation, increasing salinity, climate change and reduced river flow are affecting all of south-west WA’s freshwater systems. Efforts are being made to protect the hairy marron and its habitat. In Western Australia, the government has implemented regulations on the fishing of marron in order to prevent over-fishing and ensure the sustainability of the population. In addition, conservation organizations are working to restore and protect the natural habitats of these crayfish, including efforts to clean up pollution and restore damaged rivers and streams.

There is always more to learn about the amazing world of the hairy marron. Here are a few additional points of interest:

  • In addition to being an important food source for other species, the hairy marron also plays a role in the ecosystem as a predator. These crayfish are known to prey on a variety of small animals, including insects, snails, and even other crayfish.
  • The hairs on the marron’s claws and body serve more than just a sensory function. These hairs are also thought to help the crayfish to regulate its body temperature, as well as to defend itself from predators.
  • The marron is an extremely hardy species, able to withstand long periods of drought by burrowing into the mud and entering a state of torpor. This allows them to conserve energy and survive until conditions improve.
  • The marron species is a popular animal for aquaculture and is often farmed for food. In addition to being a delicious and sustainable source of protein, the marron is also considered a delicacy in some parts of the world.
  • While the hairy marron is not currently considered critically endangered, it is still important to monitor the population and ensure that their habitat is protected. Conservation efforts, such as habitat restoration and sustainable fishing practices, can help to ensure the long-term survival of this species.

The hairy marron is a truly amazing and fascinating species, with a rich cultural history and an important role in the ecosystem of Western Australia. As we continue to learn more about these creatures, it is our responsibility to ensure that they are protected and conserved for future generations.

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