When deep diving seals help us to observe rapidly changing of polar oceans
At the European User Conference on Argos Wildlife (EUCAW), Christophe Guinet’s presentation will focus on how polar seals are used to collect in-situ measurements of temperature, salinity, fluorescence and light along their paths during their dives and which complement and extend to deep depth satellite surface observations. Information on sea states, direction and wind strength are also sampled. Simultaneously, biological data on nekton and prey density are also collected using a combination of methods such as assessing prey catch attempts from acceleration and passive acoustic measurements, measuring bioluminescence distribution and active echo-sounding.
Assessing the entire southern ecosystem
By combining these data we aim at assessing study how oceanographic conditions influence the vertical and horizontal distribution of biological fields on a fine spatial scale. Today, southern seals represent a major component of the Southern Ocean observing system and help us to evaluate how quickly that system is changing. Within that observatory system, relying on animal samplers, real time transmission via the Argos System of in-board processed data is the main challenge to be achieved. This requires the development of fast processing, low energy consumption algorithm to process the data on small size and energy constrained satellite tags. These developments are crucial for us to be able to investigate the foraging ecology and the environmental conditions for species we are unable to recapture (such as seals) in a rapidly changing, Arctic marine environment.
Dr Christophe Guinet – A stroke of luck
January 2015, Kerguelen Islands. Two female elephant seals that we had equipped with Argos tags and behavior trackers (including an acoustic recorder) three months before had just returned to land. Hoping to get their tags back, we left by foot early in the morning. First stroke of luck: The weather was nice. After walking for four hours, we arrived at our destination along with nearly 1,000 elephant seals. Despite our efforts, we were unable to find the female we were looking for in the crowd.
Disappointed, we decide to look for the second female. Luckily, we had a reliable position (3), so we were very hopeful as we set off on the 15 kilometer hike to reach her location. Once we arrived in her general vicinity, we zigzagged back and forth to find her, without any luck. Disappointed again, we gave up for the day. But early in the morning, a radio message came in from our base. The female we had looked for without success yesterday had moved inland, and crossed a lake. She was only 4 kilometers away! We left full of hope, and after an hours’ walk, we found her. We managed to collect the Argos beacon and the acoustic marker in her back.
Three’s the charm… Then something on the ground attracted our attention. It was another Argos tag: one that was lost by a male elephant seal when he moulted three years before. As the tag had stopped transmitting before the seal returned to land, our chances of finding it were close to zero. But what a stroke of luck, three years later, the precious data recorded on the tag was still intact! “
350: tags deployed on elephant seals in the Kerguelen since 2003
1996: first studies with Argos satellite tags on Amsterdam Fur seals
22: number of years Christophe Guinet has used Argos
16: number of months of the longest Argos track (a young hooded seal) tagged of the coast of Newfoundland (Terre Neuve) in collaboration with Garry Stensson and other fisheries partners from Océan Canada