Habitat requirements for the Giant Freshwater Crayfish

As mentioned, the habitat requirements for Giant Freshwater Crayfish vary depending on it's age. Juvenile crayfish prefer shallow, fast-flowing streams with bed materials such as cobbles and boulders that they use for shelter. Adults often move to slower-flowing reaches where they like undercut banks to burrow in or logs and boulders to seek shelter under.

Crayfish prefer well-vegetated streams with clear water and even, cool temperatures. In addition to providing shelter, in-stream logs and dead wood are critical for providing food. Vegetation along both banks of the waterway moderates temperature extremes and filters sediments from soil and effluent which would otherwise muddy the water and degrade crayfish habitat Without a ‘messy’ layer of fallen leaves, logs, stones, and branches, the Giant Freshwater Crayfish will be without an environment to live and breed

The land alongside your waterways is probably your property’s most productive, thanks to its deeper soils and higher moisture content, but it is also the most vulnerable to damage from stock impacts and flooding impacts Riparian areas are easily damaged by stock that eat and trample the vegetation, destroy soil structure and release effluent in and around the waterway Without vegetation on the batters of the waterway and on top of the high bank, the riparian land is susceptible to bank erosion and slumping in times of high flow or flooding

Sedimentation in the waterway from erosion and animal access can cover the crayfish habitat in silt, sand or gravel and the lack of vegetation on the banks reduces the shading impact and increases the temperature of the water, which doesn’t suit the crayfish

A good mixture of native vegetation – trees, shrubs and groundcover - is essential to provide stability to the waterway banks as well as providing habitat for the animals (large and very small) that rely on our waterways too Diverse riparian vegetation with density and structure can slow the flow of the water and armour the banks Riparian vegetation also helps filter out the nutrients and sediment contained in runoff, which reduces pollution of the waterway leading to excess algae growth and water weeds

Good riparian vegetation has a number of layers and goes from the edge and across a buffer area on the high bank.

Naturalregenerationmay occuroncestockandgrazing areexcludedfromthe waterwaybutinsome instances,revegetationor replantingofparticularspecies mayberequiredtoo For example,maturetreesmaybe presentbutnoshrublayer,so infillplantingmaybe recommended,particularlyif seedbankshavedisappeared asaresultofprevious management.

Excludingstockisagreatfirst stepinprotectingyourriparian area,butyoucannot“lockitup andleaveit”.

Just like other productive areas of your property the riparian land needs ongoing management. Weed issues are probably the most common ongoing management issue, as well as things like pest animals, stabilising erosion areas, or slowing the flow of water. It is essential to keep on top of the weeds as soon as they emerge so that they don’t outcompete your plantings or your natural regeneration. The first two or three years after fencing are probably the most critical, after which your native vegetation should be able to out-compete the weeds. The Giant Freshwater Crayfish Project has worked with adjoining neighbours in particular sub-catchments to try and ensure a coordinated response.

Finally, improved riparian management provides public as well as private benefits, and can impact landholders and water users both upstream and downstream of the area improved