November 2102 Expedition - Checking out the big blue

Our on-going monitoring efforts of the mid-water realm of the Chagos MPA have been partly centred on the development and implementation of mid-water cameras, a Stereo Imagery System for Shark and Tuna Analysis (SISSTA). The SISSTAs have been developed in close collaboration with the Zoological Society of London (ZSL), and present a novel technique for the non-destructive study of temporal and spatial patterns in the distribution of mid-water fauna. Simply put, the SISSTAs constitute of two fixed cameras pointing at a bait canister, and are deployed on moorings for three hours at a time, at a fixed depth.

The SISSTAs currently deployed in Chagos represent the culmination of a year of concerted efforts to establish this technique as a Indo-Pacific mid-water monitoring tool. The journey started on Dirk Hartog Island in Western Australia, where the camera rigs were initially trialled. The kit was then modified based upon our experience, and subsequently deployed in the Timor Sea, in collaboration with the Australian Institute for Marine Science, and in Le Grand Lagon Nord in New Caledonia, in collaboration with the Institut de recherche pour le developpement.

During the expedition so far, we have conducted 30 deployments, and have already collected some exciting footage of animals from the mid-water realm (but more on this later from Lloyd Groves, our chief video analyst!). We have been deploying the SISSTAs on the 100m contour line on features known to cause aggregations of pelagic species. The resulting footage will be analysed back in the lab, generating data on species distribution, relative abundance, and size. Here in Chagos, the information will be used to corroborate seabird observations by our resident ornithologists, Pete Carr, and acoustic measurements made by our onsite acousticians, Martin Cox and Philipp Boersch-Supan.
 
Watch this space for information on our results!
 
Tom Bech Letessier, Expedition scientist