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Words
Donna Black

Photography
Valeport, Mike Fedak and Christophe Guinet

Sea mammal tags- improving understanding of our oceans, climate change and sea mammal behaviour

Seals, whales and turtles wearing specially designed tags are gathering vital data on sea mammal behaviour and information about our oceans, which is crucial to our understanding of climate change.

Valeport has worked with the Sea Mammal Research Unit (SMRU) at the University of St Andrews to provide sensors for the tags for the last 16 years.

Learning more about sea mammal behaviour

SMRU began placing tags on seals in the 1990s. The starting point for the project was a desire to find out more about the marine mammals themselves. “Initially the tags helped us to learn about seal behaviour, allowing us to see where the tagged animals travelled to find food,” explains SMRU’s Professor Mike Fedak.

The majority of tags are placed on seals. They are not invasive and are placed on seals when they are on land during the breeding season. The tags send data to scientists regularly via satellite and then fall off when the seals moult, between 9 months and a year later.

“We have monitored the tagged animals carefully to ensure that they are not adversely affected. We know that they continue to breed and thrive and that the tags do not damage them. One of the biggest advantages of this approach is that the tagged animals travel to remote and inaccessible places, giving us access to data we never had before,” says Mike Fedak.

Since the project began many species have been tagged, including narwhal, beluga whales, salmon shark, southern elephant seals, crabeater seals, Australian sea lions and loggerhead turtles.

Learning more about the oceans

Mike Fedak says: “The data we receive about the behaviour of sea mammals is still crucial. But we realised that the tags could do even more. They had the potential to give oceanographers information about the state of the world’s oceans. That is when we approached Valeport.”

“The team at Valeport were immediately open to the idea of working with us. They had been developing their own conductivity, temperature and depth instruments and were happy to see how they could be incorporated into our tags,” adds Mike Fedak.

Jay Nicholson, Valeport’s Head of Research and Development was at that initial meeting with Mike Fedak and his SMRU colleagues. “Jay is intellectually curious. He loves to get his teeth into a problem,” says Mike Fedak. “That meeting was the start of a great partnership between SMRU and Valeport that has lasted a long time.”

“The conductivity, temperature and depth (CTD) instrument for the sea mammal tag needed to be small, light and low power,” says Jay. “We worked hard to develop it and improve its accuracy over several years. It has been a real team effort. Around half of our R&D team at Valeport have worked on the sea mammal tags; from mechanical design to optics, electronics and calibration.”

The first tags incorporating Valeport’s CTD sensors were produced in 2004. The measurement of temperature and salinity allow scientists to understand ocean currents, changes in the mixed layer depth and estimate if the ocean is warming up and how quickly.

Valeport then worked with SMRU to introduce a fluorometer into the tags. These tags have been available since 2017. Fluorescence measurements allow scientists to estimate the variation in phytoplankton. As phytoplankton are at the bottom of the food chain, their abundance affects all marine life. This data is also important as it gives an indication of the amount of excess CO2 produced by human activity, which can be fixed in the ocean.

Tagged seals are also providing data on sea temperatures for use in weather forecasting.

Sharing the data

Since the first marine mammal tags incorporating Valeport technology were first deployed in 2004 over half a million profiles of ocean temperature and salinity have been collected. The data is freely available on the Marine Mammals Exploring the Oceans Pole to Pole (MEOP) portal.

“The data collected by our sea mammal tags is a vital resource to help scientists understand the changes in the polar oceans, as this can have global ramifications, with a significant influence on weather and climate. Over one hundred scientific papers have been published using data from the sea mammal tags,” says Mike Fedak.

The data from sea mammal tags adds to the knowledge obtained through other research, including scientific research vessels.

“It costs a great deal to take a vessel to the polar regions,” says Mike Fedak. “A six-week deployment may enable scientists to gather 120 profiles. Compare that to tagging 14 elephant seals. The seals would gather 12,000 profiles in a few months, ranging widely over remote and often inaccessible areas. The sea mammal tags radically increase the reach of data available to scientists.”

“This programme was made possible by the CTD and fluorescence sensors developed by Valeport. We are extremely pleased by the quality of the fluorescence measurements and the measurements we are obtaining are very consistent between tags.” - Christophe Guinet

Sea mammal tags in action

“When I first started studying seals in the 70s, as soon as they slid into the water we were in the dark,” says Mike Fedak. “Now I can sit at my desk in St Andrews and look at what tagged seals in the polar seas are doing, almost in real time.”

“The sea mammal tags have helped us learn so much. In just one example we used tags to learn more about elephant seals that had been spotted on the Pine Island Glacier in Antarctica. This was a very unusual place for them to be. We collected data from tagged seals for a season to see where they were going and our findings greatly enhanced our understanding of why they were there,” adds Mike Fedak.

Christophe Guinet, currently Directeur de Recherche at the Centre d’Etude Biologique de Chizé-CNRS, France has been undertaking research in the field of marine biology for over 30 years, specialising in the behavioural and foraging ecology of marine mammals. He played a key role, with an engineer from SMRU, in developing the latest generation of seal oceanographic tags incorporating Valeport’s fluorometer sensors.

He explains how he is using the SMRU tags in his research: “By placing SMRU tags, equipped with CTD-fluorescence sensors developed by Valeport, on southern elephant seals, we are measuring oceanographic temperature, salinity and fluorescence profiles during the ascent phase of the seal dive. Currently elephant seals provide more than 80% of the CTD-Fluorescence profiles available south of 60°S and 98% of the profiles available within the Antarctic sea-ice zone.”

Christophe Guinet added: “This programme was made possible by the CTD and fluorescence sensors developed by Valeport. We are extremely pleased by the quality of the fluorescence measurements and the measurements we are obtaining are very consistent between tags.”

“When I started out, I couldn’t have imagined what we have achieved and how much we now understand thanks to the sea mammal tags. I was excited when we first started exploring this and I continue to be excited about it,” says Mike Fedak.

The project means just as much to the Valeport team who work on it. “It is enormously satisfying to see how much data scientists have access to thanks to the tags and what it has enabled them to learn,” says Jay Nicholson.