It doesn’t look like the stealthy science-fiction drones of Hollywood as it bobs along the surface (it glides smoothly on a calm day), but this bright yellow surfboard packs major scientific punch… for low-cost and low-risk.
Canada’s first and only Wave Glider completed its mission to remotely offload fish-migration data from 184 fixed, underwater tracking units, called receivers. The receivers are part of a 205-kilometre-long (127 mile) tracking-array used by Canadian scientists to track the movements of sharks, seals, tuna, salmon, eels, and other fishes and marine mammals carrying acoustic tags.
Receivers detect and store individual animal tag-ID-signals as well as dates and times of detections. This information gives researchers a look into the animals’ behaviour and survival over time; however, technicians must manually retrieve receivers from the ocean floor to access the tracking data for researchers to analyze. That is, until now.
Duncan Bates is the Ocean Tracking Network’s lead technician. He takes most of December off to go lobster fishing and spend with his family. His vacation started early when news that the Wave Glider completed its mission meant he didn’t have to go to sea in November.
“It can be a bit rough this time of year—we wait for a good weather window to open up then we go and do the offload until either it’s completed or we run into bad seas. Sometimes we’ve had to go out on two or three separate trips to get all the data,” says Bates.
The glider, built by the U.S. company Liquid Robotics, uses wave-motion to flip “wings” down then forward on its underwater component. The differential wave-movement thrusts the glider along a preprogrammed path in the ocean—no fuel needed. It’s equipped with a solar panel to power the weather and communications stations as well as the science-bay, which records data for oceanographers. The only battery on board is used to power communications when the solar panels can’t collect enough energy during prolonged overcast weather.
The real advantage comes from the hydrophone mounted on the subunit, which uploads data from the underwater receivers to the glider’s science-bay without the need to bring the receivers to the surface.
“It acts just like an underwater telephone—it calls the receivers and says, ‘hey, tell me about the fish you saw’,” says Richard Davis, head of the glider group for OTN. “We’ve modified this thing to do our work for us with amazing results.”
Bates and his team spend up to a week at sea hauling receivers off the ocean floor, pulling them on board, downloading the tracking data and putting them back. Ship-time needed to maintain such receiver array runs almost $10,000 a trip; however, piloting the Wave Glider costs $150 per day, and though the glider took somewhat longer to offload the array, that’s nearly a third of the cost to collect data.
The Wave Glider is also equipped with a modified receiver, developed in collaboration with local acoustic telemetry manufacturer, VEMCO. The Wave Glider and two more gliders in OTN’s fleet are capable of picking up detections of tagged animals along their trajectories in the open ocean. So far, the gliders, dubbed “roboprobes,” have logged tagged blue sharks, grey seals, lobster, and Atlantic salmon providing important contributions to studies on residency and seasonal migrations of these species.
“The capacity this thing has to revolutionize the way we’re doing research in Canada and around the world is phenomenal. Canadians can continue to be world-leaders in science and technology as long as we keep pushing the envelope like this,” says Sara Iverson, Scientific Director of OTN.
The ability to remotely offload tracking equipment is a major proof-of-concept for the ocean-science community and frees up research budgets to purchase more tags, hire specialized staff and expand operations to critical or unexplored areas. Most importantly, it markedly reduces the safety-risk to personnel who are on the front lines of research being conducted at sea, particularly in the Arctic, in the northwest Atlantic, and other areas with extreme conditions and unpredictable weather.
“It’s a lot of work to keep up with equipment prep, knowing that we have to go at any time, as soon as the weather’s good,” says Bates. “It’s hard on my kids to be away so often, but maybe that’ll change.”