Earth Observatory Blog
A Day in the Life of a Marine Mammal Observer
For cetaceans, sound is of utmost importance. Male humpback whales, for instance, sing to attract females and breed. They also use sound to compete with other males in their pack. Some dolphins depend on sound to locate their prey, coordinate a hunt, and even socialise.
During Mirage II, sound also plays a vital role. The air-guns towed behind R/V Marion Dufresne produce acoustic waves that allow scientists to detect different layers of the ocean’s subfloor. While it is not entirely understood how this noise impacts cetaceans, no one wants to take a chance.
Every day, it is the job of three resident Marine Mammal Observers (MMO) to ensure that there are no species of concern within a five-hundred-metre perimeter of the vessel. If they do spot a marine mammal, they immediately cancel the air-gun operations until the animal is far outside the danger zone.
Fortunately, the ship is sailing in the middle of the ocean, where the flat, deep seafloor means it is unlikely to encounter marine life. Even so, MMOs play an important role in helping the research team keep their impact to a minimum.
Today we follow Erwan Guillon through a typical day as an MMO on board Marion Dufresne.
08:00 MMOs Rebecca Jewel and Jeremie Habasque are just finishing the early portion of the shift. At 8am Erwan (centre) arrives at the Bridge and is briefed by his colleagues.
The tools most indispensable for Marine Mammal Observer are a cap for sun-protection, polarised eye-glasses, a walkie-talkie to keep in touch with the crew, binoculars, a Marine Mammal Guide to help identify species, a computer to keep records, and loads of coffee.
08:12 Every 12 minutes an alarm goes off on the Bridge. The Officer on watch must turn it off in order to prove that he is still alive. If the alarm went on for a few minutes, a concerned crew-member would come and check on the Officer.
The team has not spotted anything for days, only a couple of birds. While birds are not mammals, the MMOs also keep a record of bird-sightings and trash floating in the ocean.
When Mirage II was still close to the coast, the MMOs spotted several dolphins and whales, and even a bait-ball being attacked by seabirds and sharks. At that point, however, Marion Dufresne was in transit, so the air-guns were not being deployed and the marine mammals were put in danger.
10:00 The weather seems to be turning. If the conditions do not improve, Erwan worries that he might need to call to stop the observations. He must keep a vigilant eye, for he knows that, in bad weather, his eyes can begin confusing whitecaps with sea-life.
10:30 The wind begins picking up, disturbing the ocean’s surface and making it increasingly difficult to make accurate observations of marine mammal signals, such as blows or fins.
11:00 When the clouds do clear, the ocean shines and glitters, blinding the eyes of the MMOs. Today is turning out to be complicated in terms of weather.
11:30 The MMOs meet to assess the situation. Their observations are called off until the weather improves. For the time being, one person will continue monitoring the weather conditions and will report to the rest of the team.
14:00 The experts take advantage of the available time to input their records into their log, and work on their report.
16:30 The weather marginally improves, so Erwan and his team get back on deck and resume their work.
17:00 Every now and then, the weather offers a spectacle.
19:00 Soon the sun sets, and it is time for dinner! Today has not been the most eventful day, but years of experience have taught Erwan that it is all part of the job. He spends a lot of time in silence by himself, simply looking at the ocean, not even listening to music. He understands that patience is key.
21:00 After dinner, the MMO’s have a bit of time to relax before they sleep. Tomorrow everything will start all over again.
Follow the progress of MIRAGE II between 25th September and 20th October 2017 on the EOS blog, and spread the word using #MIRAGEcruise.