The importance of baseline a monitoring?

Baseline monitoring was undertaken in all six priority areas before any project works were implemented This, combined with monitoring undertaken at the end of the project, helped identify any changes or improvements that may have occurred in this stretch of river over the life of the project Many of the project works, such as revegetation, will take many years to become established and should provide longer term benefits such as re-introduction of timber into the river and moderating the impacts of heat waves This will require longer term monitoring, beyond the life of the project End of project monitoring was undertaken in Spring 2022 and Autumn 2023

As part of the baseline and end of project monitoring, both juvenile and adult crayfish were captured in the priority areas, with the larger specimens tagged The presence or absence of juveniles and adults was noted at each site Giant Freshwater Crayfish can be found in low numbers in many poor-quality sites; however, the densities increase rapidly in sites with excellent habitat Adults were measured, weighed, and tagged before being released back into the same spot they were trapped Sampling information was collected and is recorded in a state-wide database

Left: Same male trapped again in 2022. He had moulted and grown an additional 11 mm and was 300 g heavier than in 2020. Photo credit: Todd Walsh

Far left: Todd Walsh checking for a tag in an adult crayfish.

Future monitoring will involve trying to use in-stream microchip readers to monitor the movement of these tagged adults or to recapture tagged animals and measure growth rates over time. Due to the different habitat requirements of juvenile versus adult Giant Freshwater Crayfish, a number of sites along a reach might have been sampled. For example, juveniles prefer the faster flowing and shallower areas of the stream, whereas adults prefer well-shaded, flowing parts of the stream with deep pools, decaying logs and undercut banks.

The AUSRIVAS sampling that was also undertaken as part of the baseline and end of project monitoring, uses aquatic macroinvertebrates (animals without backbones that can be seen with the naked eye such as mayfly, caddisfly, dragonfly larvae and shrimps) as biological indicators of river health, and will also provide the means to measure changes in water quality over time.

Prior to the finalisation of the six priority areas at the beginning of the project, a social survey was undertaken by external provider Myriad Research, to provide an independent assessment of community attitudes in relation to the management of threatened species, and in particular the Giant Freshwater Crayfish. Respondents were selected at random across the region and owned or leased land of more than two hectares. The majority of respondents (92%) knew that the crayfish was a threatened species, but time and age and to a lesser extent cost were identified as major influences on getting involved in conservation activities