The world’s large silvery predators such as tunas, billfish and sharks have suffered tremendous declines due to targeted fishing effort by an ever-expanding global industrial fishery fleet. As part of the NERP supported voyage of discovery on the AIMS RV Solander, we have a tremendous opportunity to deploy our newly developed Stereo Imagery System for Shark and Tuna Analysis (SISSTAs), designed to assess the status of these ecologically important, open ocean species. Initially derived from camera rigs deployed on the seafloor, SISSTAs are suspended mid water to specifically sample pelagic species. Our SISSTAs were previously trialled prior to this expedition at Shark Bay WA in April 2012 - view footage.

On this expedition, we have now conducted over 50 SISSTA deployments off the RV Solander, thanks to the diligence and hard work of the vessel’s Master and crew. As a result, we have collected excellent footage of the kind of fauna typical of the Timor Sea’s mid water ecosystems. The deployment and recovery is a rather delicate and sophisticated procedure that requires all the manoeuvring skills of the vessel’s Master, whereby 250 meters of anchor, chain, and mooring line are deployed off the stern of the vessel, while an array of buoys and finally the cameras rigs are attached to the line. Quite a feat, considering that the process has to also be done in reverse when we retrieve our kit.

From our initial field-overview of the footage collected to date, we have observed Australian oceanic black tip sharks and Scalloped hammerheads as well as a range of pelagic fishes. Observing scalloped hammerheads was particularly exciting as this species is listed as vulnerable in Western Australian waters. Another interesting aspect has been the staggering amount of baitfish caught on the cameras. This is something we have not previously observed – it appears they congregate around the cameras not to feed on our bait, but as a place of interaction.

Anyways, that’s all from the University of Western Autralia team this time, stay tuned for the next contribution, from our very own marine mammal expert, Phil Bouchet.

Dr Tom Bech Letessier
University of Western Australia – Centre for Marine Futures

Image 1 - Stereo Imagery System for Shark and Tuna Analysis (SISSTAs)

Image 2 - A shoal of bait-fish investigating the bait dispenser, but not to feed apparently...

Image 3 - An Australian Oceanic Blacktip shark, coming in for a closer look of the SISSTA

Image 4 - A school of leatherjackets

Image 5 - SISSTAs getting ready for launch at dawn

Imgae credits:  Jamie Colquhoun, AIMS; Tom Bech Letessier and Phil Bouchet, UWA