Tom Bech Letessier takes on the story of the remarkably good quality deep (and shallow) stereo film being taken of the reef and pelagic fish:

We are now reaching the end of our expedition, and from a BRUVing perspective, it has been a resounding success. We have conducted over 200 camera deployments, giving unprecedented insights into Chagossian reefs and fish ecology. Our collection amounts to over 500 hours of film, which will be used for species identification, estimates of the relative numbers of fish, and size measurement, important variables in ecology.

The support we have received from the master, officers, and crew of the Marlin in conducting our activities has been extraordinary. Long hours, heavy seas, equipment failures, demanding scientists: nothing has affected the good mood or the daily running of the ship. Today for example, the chief engineer Les and his team spend the better part of the morning AND the evening fixing the engine of the ships Fast Rescue Crafts, enabling us to get 16 camera drops in during the afternoon.

On a daily basis, my personal work at the Centre for Marine Future in the University of Western Australia aims to understand the influence of underwater features such as seamounts and canyon heads on the distribution of megafauna. Globally, these features are especially productive for pelagic fish, through mechanisms still poorly understood, and are intensively targeted by fishing fleets. During our expedition in Chagos, we have been dropping cameras on coral mounts and drop-offs, in the hope that the pristine ecological systems can yield valuable insights and improve understanding elsewhere.

Tomorrow will be our final day at sea, and will perhaps be our greatest challenge yet! We hope to deploy BRUVs on shallow seamounts situated on our last leg to Diego Garcia. The prospect of sampling at 100 m depth is exciting, but will provide some interesting challenges, similar to landing an aircraft in a Swiss airport. These mounts are very easy to miss, and are apparently needle sized! Wish us luck!

Previously in this series:

Conserving Chagos: Science Expedition to World’s Largest “Ocean Park”

Conserving Chagos: Starting Out

Conserving Chagos: Manta Rays

Conserving Chagos: Last Day around Diego Garcia

Conserving Chagos: Salomons Atoll

Conserving Chagos: Stormy weather

Conserving Chagos: Nelsons Island

Conserving Chagos: Peros Banhos atoll

Conserving Chagos: Thoughts from the Diving Officer

Conserving Chagos: Last Day at Peros Banhos atoll

Conserving Chagos: On our way to Three Brothers

Conserving Chagos: More on the Three Brothers

Conserving Chagos: More rough seas and Crowns of Thorns

Conserving Chagos: Pascaline

About the Author: Dr. Tom Letessier, Scientist

Tom is a Research Assistant Professor at the Centre for Marine Futures at the University of Western Australia. His main expertise is in the meso- and basin-scale processes at the low-end of pelagic ecosystems. His PhD research focused mainly on the ecology of the model zooplankton order Euphausiacea. He has participated in several research cruises in the Atlantic and Indian Ocean and previously conducted SCUBA-based research on coral reefs on fish and coral taxonomy in the tropical Atlantic and Pacific Oceans.