Activity trackers for aquatic life: What researchers plan to learn by tagging marine giants with Fitbit‑like devices

- July 13, 2023

A bowhead whale and her calf. (NOAA photo)
A bowhead whale and her calf. (NOAA photo)

They are small — about the size of a baseball — but can capture a trove of vital data on the sounds, movements and location of one of the world's largest, most elusive and threatened creatures.
They are suction-cup tags used by researchers trying to answer some of the enduring questions when it comes to a variety of whale species.
In effect, they are the Fitbits of the animal world.
The challenge, however, is in getting the devices on mammals that can weigh up to 30 tonnes, stay under water for prolonged periods of time and dart off once they are found, which itself is no easy feat.
That is not stopping a handful of researchers at Dalhousie University, who are fanning out this summer in a rare mission to affix the tags to four different species of whales in a bid to learn more about them so they can better protect them against their greatest threats. They are collaborating with colleagues from several other institutes, including St. Andrews University, the University of New Brunswick, the University of Windsor and the University of Wisconsin, as well as the Department of Fisheries and Oceans.
"These tags will capture sound, video and three-dimensional movement of the whale, and there is a temperature sensor and GPS," says marine biologist Sarah Fortune, an associate professor in Dalhousie's Department of Oceanography who is leading the missions that started this month and extend until late September.
"It's going to be tricky getting the tags on! But the data we're collecting is designed to help fill in some of the gaps in knowledge needed to help with conservation, and conservation is the underlying theme for everything."

From Baffin Island to the Gulf of St. Lawrence

Dr. Fortune’s lab and collaborators will set off on three trips to study several whale species: bowhead whales off Baffin Island, North Atlantic right whales in the Gulf of St. Lawrence, and sperm and northern bottlenose whales in Baffin Bay. She and her team are asking slightly different questions for each species around environmental variability and human-made stressors but are using the same or similar tools.

About half of the work is tagging-based and the rest is oceanographic sampling near whales using zooplankton nets, underwater vision profilers and multi-frequency echosounders.
For bowheads, the researchers have modified the tags to attach to the whales' rough skin since conventional tags may not adhere as well. Once a whale is spotted, a team member will stand on the bow of the vessel and use an eight-metre carbon fibre pole to stick the tag onto the animal. A drone will give them an aerial view of the whale's movements and help the team co-ordinate the attachment, while also collecting video data on whale behaviour and images that can help assess body condition.
"We're hoping for a 24-hour deployment and then we retrieve the tag, which is by far the most stressful part of the process. You don't want to lose it," says Dr. Fortune. "We use receivers that pick up signals, but if it's rainy or foggy it's difficult to spot. Sometimes you have to jump off the boat with little notice -- it's surprising what you will do to get a tag back!"
They are also working with Dartmouth Ocean Technologies to test out a new environmental DNA sampler.

Nutritional insights

The team also wants to see if the species are getting adequate nutrition and what their food requirements are. Members will do that by sampling prey fields and building fine resolution energetics models that predict the food requirements of individuals of different ages, sexes and reproductive statuses. For example, they will determine how much a pregnant female needs versus a juvenile male.
The tags will also have cameras which will provide a unique perspective on how the whales feed and what they are doing when they eat.
For Dr. Fortune, the technology may also provide insight into the nutritional status of endangered North Atlantic right whales, which have shifted their habitat from the Bay of Fundy and into the Gulf of St. Lawrence in recent years.
"We want to get a sense of how they're doing in this newer habitat and in the context of shifting environmental conditions," says Dr. Fortune, who is also the Canadian Wildlife Federation Chair in Large Whale Conservation.
A key part of the right whale research is trying to determine where they might be in relation to their greatest risks -- ship strikes and entanglements in fishing gear. There are only roughly 350 of the slow-moving giants left and fewer than 80 reproductive females, a grim statistic for an animal that has been on the brink of extinction for decades.
"We'll record the underwater movement of whales while simultaneously mapping the prey field. Hopefully what we'll find is the depths where the whales are spending the most time is the depth where maximum zooplankton abundance occurs," says Dr. Fortune.
"Then we can compare that depth with bottom-set fishing gear and see whether the depth of whale foraging is where that gear is. Alternatively, if the whales are feeding at the surface at night, you could have increased risk of vessel strikes."

Support for species

The results of their research will be invaluable to agencies trying to protect the whales, other researchers who study them, fisheries and industry groups that encounter them, and governments responsible for managing activities that intersect with whales.
Sean Brillant, an adjunct professor in Dal's Department of Oceanography and a conservation biologist with the Canadian Wildlife Federation, specializes in right whale research and ways to mitigate the harmful interactions between humans and the cetaceans. For him, this work could measure fine-scale movements and provide data critical to understanding how the whales are doing, where they are and how they behave.
"Whales are at the surface for only about 20 per cent of the time and then we don't know what they do. This is an opportunity to get fine-scale movement of the whales, like where do they go under the water, how close to the bottom are they and how deep do they go," he says.
"So, this fine-scale data on the invisible life of whales is really, really valuable to the work I do in particular when it comes to how often these whales encounter ships and fishing line."
Researchers estimate that the work could yield 12 papers on bowhead and right whales, while the sperm and bottlenose projects could produce at least four.
"The fact that we've got this team going out and doing some oceanographic measurements and seeing if they can attach some instruments to whales is really quite astounding and not something that is done lightly and not something that is done often, so it's really exciting."


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