Novel technology for crayfish management

Freshwater conservation is key for the overarching health of the globe and novel technology, such as remote underwater video (RUV), provides an opportunity to advance freshwater conservation. RUVs are an underutilised tool in freshwater environments that currently lack standardised methodologies. A systematic literature review was conducted into the use of RUV in freshwater environments and a cautious set of standards are recommended, consisting of using a standard action camera, recording at ≥30fps with a resolution of 1080p for 60 minutes. I have constructed CrayCam, a specialised RUV system for surveying crayfish. Feasibility tests of CrayCam found that it could successfully observe crayfish, with diminishing returns when crayfish are further away from the RUV system and when turbidity is higher. CrayCam was used alongside traditional surveying methods to study a population of the data deficient narrow clawed crayfish (Pontastacus leptodactylus). I recommend a mixed approach of methods to successfully study this species and classified the location of this population as in the ‘Containment’ or ‘Asset Protection’ stage of the Generalised Invasion Curve. A multi-method approach was also employed to assess the extent of a signal crayfish (Pacifastacus leniusculus) invasion. This study found that over half of the barriers within the survey area had been breached by invasive crayfish and crayfish tended to be found at locations closer to upstream barriers and had higher abundances at sites with lower ORP. Field observations of native white-clawed crayfish (Austropotamobius pallipes) were also made using CrayCam. These studies found white-clawed crayfish to be more active during daylight than was initially thought, with larger individuals tending to have higher aggressive intensities. Finally, it is important to understand the threats of disease invasive crayfish can bring into their new environments and a pathological study of narrow clawed crayfish has been conducted to assess their potential risk. Overall, this thesis provides new knowledge that can be practically applied across the myriad challenges of crayfish management.