[Update] Byron Shark project

fish under water view
5th May 2021: Just an update with the latest on the Shark mitigation project that I keep hammering away at over many years. After 4 years and early $90k in expense, the approach of using sonar for shark detection was dumped. Not because it didn't work in general but because of a CSIRO report that explained that white sharks tend to travel up beaches in the trench between the shore and the main sand bank.
This means that our sonar system would have to work in the surf zone with all the aerated white water and this is an impossible ask of a sonar system.

New Approach Green LIDAR

After experimenting with shadow detecting photosensors running across beach trenches, I came across shallow water LIDAR scanning which is used for bathyscopy which is the mapping of shallow water zones like lakes and foreshores.
The trick is to use GREEN lasers which can penetrate the water surface and scan the beach bottom (and hopefully sharks).
The problem is that green lasers can damage your eyes so I'll be experimenting with the use of a red laser to detect the presence of a human on the surface (ie swimming or surfing) and turn of the green laser scanning until the scan line of sight moves past the person.
This is deeply technical stuff but worth the effort. If we can solve the shark problem for beach users it would be a very worthy cause.

Questions we are researching:

  • Is it true that Green LIDAR can be effectively used to scan subsurface areas up to 3-4 metres in depth?
  • What power (wattage) Green LIDAR device would we need to scan an area 100-200 metres from the viewing post and up to 3 metres underwater?
  • What would the cost of such a device be?
  • What power consumption would such a device use?
  • Could it be solar powered?
  • Could we use Red LIDAR to detect when a member of the public is on the surface of the water and momentarily turn off the Green LIDAR to ensure that we do not damage anyones eye sight?
  • Could we use Green LIDAR for subsurface scanning in a close to shore environment? Say at 1 metre below the surface?
  • What maximum range could we get?
  • We would like to set up a continuous scanning outpost which would initially detect any larger animal in the scan area and eventually using AI be able to detect sharks and even shark species.
  • The device would also contain warning capability and communications ability.
  • Also possible scan pre-processing to minimise the amount of data being sent to remote servers for processing, thus speeding up processing.
So far we have spoken to researchers in Queensland and Sydney who have been able top confirm our general hypothesis of using green LIDAR but no one as yet has had specific experience with shallow water scanning.