SCANS-IV survey : European scientists track cetaceans from the sky

A campaign to examine the abundance and distribution of cetaceans in European Atlantic waters has been underway since 27 June and is scheduled to run until the end of August, with results potentially influencing European decision-making.

SCANS-IV (Small Cetaceans in European Atlantic waters and the North Sea) is the fourth mission of the kind since its launch in 1994 and involves the monitoring of whales, dolphins and other porpoises by a team trained at the Pelagis Observatory, a support and research unit (UAR 3462) of La Rochelle University and the French National Centre for Scientific Research (CNRS).

At the beginning of July, off the Bay of Biscay, the French SCANS-IV aerial survey team seemed pleased.

“It is confirmed that the slope off Brittany is ‘the place to be’: fin whales, pilot whales, Risso’s dolphin and many common dolphins and striped dolphins have been observed, as well as the first sperm whale of the mission.”

Throughout the project, teams will take turns flying over the Atlantic Ocean, from the North Sea to Gibraltar, to take a census of European cetaceans.

“There is a great diversity of cetaceans in the Bay of Biscay. And there is generally a lack of knowledge of most species,” Matthieu Authier, a research engineer at the Pelagis Observatory, told EURACTIV.

Eight aircraft mobilised simultaneously

Given the size of the area to be surveyed, eight aircraft are deployed to fly over the waters simultaneously, at the same height (180 meters) and speed (180 km/h). They follow well-defined routes for several hours to cover the maritime area in a representative manner.

Inside the aircraft, two people scan the waters through the porthole, and the third one takes notes.

In addition to the identification and visual counting, scientists use a digital system on board, STORMM (Airborne optical remote sensing system to assist the detection and mapping of marine megafauna), which takes high-definition pictures to identify certain species that are similar to each other or to estimate the size of the groups.

Grey dots: Transects already surveyed

Colour: Areas to be surveyed by the different European teams.

Blue whale

As for the encounters, the survey teams were not disappointed. Besides the classical meetings — striped dolphin, common dolphin, Risso’s dolphin — pilot whales, fin whales and Cuvier’s beaked whales were also seen.

The highlight of the mission was the encounter on Saturday, 23 July, with a blue whale in the middle of the Bay of Biscay, about 300 km off the Vendee coast. A “rare and remarkable” encounter, according to the team, as these species are very mobile and dispersed. Scientists estimate that there are approximately 3,000 blue whales in the Northeast Atlantic.

The protocol also includes collecting data on other marine fauna such as birds, turtles, sharks and sharks, as well as human activities such as waste and maritime activity.

European measures

All data will be processed and analysed, and results will be compared with those of previous surveys to understand the distribution and the repartition of the species.

“Between the first and second mission, we noticed a movement of porpoises in the North Sea, a phenomenon that was confirmed in 2016. This could be explained by the movement of preys, but also by human activities, as the North Sea is highly anthropised,” Authier explained.

On the contrary, common bottlenose dolphin populations are increasing in the Bay of Biscay. According to the research engineer, other species’ populations seem relatively stable, even if more data is needed to determine the long-term dynamics.

This survey should be carried out every six years to comply with assessments Member States are required to do under the Marine Strategy Framework Directive (MSFD). Depending on the results, the European Union may take concrete measures to improve the situation of certain cetaceans in European waters.

This SCANS survey is also an example of coordination between European states to implement a joint cetacean monitoring program. It is financed by eight countries bordering the Atlantic: Sweden, Denmark, Germany, the Netherlands, the United Kingdom, Spain, Portugal and France.

Over the next 15 days, the aircraft will fly mainly over the North Sea, the southern areas having almost all been covered. The results will be published at the end of 2023.

[Edited by Alice Taylor]

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