Shark likely to blame for taking chomp out of DFO ocean glider off N.S. coast
DFO researchers say one of their ocean gliders likely had a run-in with a shark after it was recovered severely damaged over the weekend nearly 300 kilometres off the coast of Halifax.
The rocket-shaped device had been deployed for about two weeks when researchers at Fisheries and Oceans Canada received a distress alarm because the glider could no longer be navigated along its route.
It wasn’t until Saturday when a research ship was able to recover it that DFO could assess the damage.
“Whatever hit it, whatever caused it to start [navigating] very poorly happened about 300 metres below the surface,” said Clark Richards, a research scientist with DFO.
“There wasn’t a boat, it was certainly an animal of some kind. And the bite marks also are a pretty good clue that it wasn’t just a whale or something playing with a toy that it found.”
One of my <a href=”https://twitter.com/FishOceansCAN?ref_src=twsrc%5Etfw”>@FishOceansCAN</a> <a href=”https://twitter.com/alseamar?ref_src=twsrc%5Etfw”>@alseamar</a> <a href=”https://twitter.com/SeaExplorerUUV?ref_src=twsrc%5Etfw”>@SeaExplorerUUV</a> ocean gliders had some kind of malfunction a couple of weeks ago, ~150nm offshore of NS. We managed to recovery it today (from the RRS Discovery!), and discovered that the “malfunction” was a shark attack! It took two wings off! <a href=”https://t.co/982ZF7W46S”>pic.twitter.com/982ZF7W46S</a>
—@ClarkGRichards
Richards said the glider was on a mission along what researchers call the Halifax route gathering data on seawater properties like temperature, salinity and the amount of small particles in the ocean. This particular model cost about $250,000 when it was purchased eight years ago, he said.
The gliders don’t have a propulsion system so they move through the water by changing their buoyancy. With the help of small wings on the gliders’ bodies, researchers are able to slowly navigate the devices through the water.
The Halifax route takes the gliders out around 300 kilometres from the shore, so it was nearly at the farthest point in its journey when it sent out the alarm signal.
Strong enough to bend aluminum frame
Along with taking off a couple of the plastic wings on the glider, whatever attacked it also bit into the equipment’s body.
“The glider weighs about 60 kilograms [and] whatever grabbed on to that glider had enough strength that it bent that aluminum frame,” he said.
He added that, thankfully, the glider is salvageable. Once it’s off the research ship, it will be sent back to the manufacturer for repairs and back out into the ocean for more data collection.
This isn’t the first time in recent years a glider has lost a fight against a shark. In 2021, a glider listening for tagged halibut was disabled by a shark attack near Sable Island.
That led to an emergency 76-hour effort to retrieve the equipment.
Despite that, shark-proofing the gliders is not on the table.
“[The gliders] are not much bigger than a large seal would be,” Richards said. “We colour them yellow, so they certainly look different, but there isn’t anything I know of that would actively discourage an interaction.”
The gliders actually receive pings from tagged animals, like seals and fish, which is why Richards said researchers don’t necessarily want to scare marine life away from their equipment.
“We always know if you put something in the ocean, there’s a risk, for all kinds of reasons, that you might not get it back,” Richards said.
