November 2102 Expedition - Going to sea - The first open water expedition in the Chagos
The entire scientific team has now arrived in Diego Garcia, travelling from Australia and the UK. We have arrived on our expedition vessel, the MV Pacific Marlin, the expedition medical officer, Dr. Jasjot Singhota, is establishing her infirmary, and scientific equipment is being sorted, checked and stowed.
The latter is a big task as we have three main types of research activities occurring on the Marlin, all around the question of how do we understand the benefits of the Chagos no-take marine protected area (MPA) to open water species such as oceanic sharks and tunas.
Understanding shark movements and residency in a large no-take MPA: Our tagging team, Matt Gollock and Gabe Vianna, are planning to tag ten oceanic sharks, with a focus on blue sharks. This species was historically the highest proportion of bycaught sharks in the tuna longline fishery. Using pop-up satellite tags which will release from the sharks in 90 days we can monitor movement patterns and increase our understanding of their residency in the Chagos MPA.
Developing a method to monitor open ocean sharks, tunas and other large fish: Our fish ecologists, Tom Letessier, Lloyd Groves and Dave Tickler, are trialling the use of Stereo In-water Systems for Shark and Tuna Assessment (SISSTAs). These stereo video systems are baited and record the sharks and fishes that approach the camera out to a distance of about 10m. The team will later analyse these videos, determining the species and abundance of the observed sharks and fishes, and the sizes of all the individuals. Paired with the SISSTAs team are our acousticians, Martin Cox and Philipp Boersch-Supan, using sonar (sound waves) to “see” the fish as they school and move through the areas where SISSTAs are filming. Providing basic environmental data to understand the conditions where we are deploying SISSTAs and acoustics is our oceanographer, Lewis Fasolo. If this pilot study is successful, we will have a much needed non-destructive method, based on videos and acoustics, to determine the status of open ocean species, and the benefits of protection not only in Chagos but in the ocean generally.
Seabirds as an aid to fish monitoring: Our ornithologist, Pete Carr, is building on the close relationship between seabirds and tunas, whereby tunas drive balls of small baitfish to the surface, providing a relatively easy meal for hunting seabirds. By documenting the seabird activity over areas where video cameras and acoustics are being deployed, we can further explore this relationship as an aid to identifying appropriate monitoring locations. As we are going to areas of the MPA where no bird surveys have ever been done, the expedition also provides an opportunity to document seabird diversity.
Stepping back on to the Marlin also feels a bit like coming home. At nearly 58 m, the Marlin is a fantastic research platform. Without the support of Captain Neil Sandes, who appears able to turn the Marlin on a penny, Chief Engineer Les Swart who can manufacture anything from nothing, and the able crew , we would not be setting out to sea so quickly.Our outreach coordinator, Rudy Pothin - ably assisted by the scientists - will be providing regular updates on our research activities over the next three weeks.
Jessica Meeuwig, Expedition Leader.