Underwater robots tracking right whales and their prey

Knowing where North Atlantic right whales will roam in search of the tiny organisms they eat to survive could be key to saving the endangered species, says one of the scientists leading a research project at Dalhousie University. 

For years, the endangered whales fed on a type of zooplankton known as copepods in the Bay of Fundy and Gulf of Maine and on the Scotian Shelf.

The amazing thing about right whales is that they're so large, and yet they feed on some of the smallest organisms in the ocean.- Hansen Johnson, whale researcher

But last year, when 12 whales were found dead on the East Coast of Canada, it was clear their feeding grounds had shifted north to New Brunswick and the Gulf of St. Lawrence.

Hansen Johnson, a PhD student in the oceanography department at Dalhousie University, said it's crucial to the whales' survival to track where their food, the plankton, is going. Then scientists and governments will know where to expect the mammals and can take steps to protect them.

Copepods, each less than a millimetre long, float in patches of billions, and the right whales can consume millions of the little crustaceans in a mouthful.

"The amazing thing about right whales is that they're so large, and yet they feed on some of the smallest organisms in the ocean," said Johnson, a co-leader of the Dalhousie research underway this summer in the gulf.

"And because they rely on such small things, they need to find these plankton in really, really dense patches.''

In 2017, the increased number of deaths — six whales also died off the U.S. coast — coincided with unexpectedly high numbers of North Atlantic right whales in the Gulf of St. Lawrence.

Ship strikes and entanglement in fishing gear were blamed in most cases, but the Dalhousie project suggests the changing availability of food could be a contributing factor.

The Department of Fisheries and Oceans ordered ships to reduce speeds and the fishing industry was subject to closures in some areas where right whales were spotted. 

"Everyone in the community understands the urgency of the situation," Johnson said. " I mean with 18 whales dying last year and no calves, we are in a position where — you know I'm a PhD student. I may not be able to have a career studying right whales."

Seeking answers

This summer, research scientists are deploying underwater devices called hydrophones in the Gulf of St. Lawrence, where they've found a lot of plankton. 

Jude Van Der Meer,  a technician at Dalhousie University, said the robot both floats and sinks, depending on what researchers want it to do — go up or go down.

The machine looks like a tiny plane and uses its wings to move up and down in the water as it scours the ocean and sends data back to researchers in Halifax. 

Johnson said the researchers want to find out why this is a feeding habitat, and why it has emerged as a more important feeding habitat than places the right whales have gone in the past. 

"That's an open question for us right now." 

Why do the whales move?

Johnson said the project has two of the robots that swim up and down in the water for weeks and months at a time, listening for whales using underwater microphones.

"Basically, it picks up the pitch track of different whales, and based on the shape of the track, it can identify what kind of whale it is," Van Der Meer said. 

The robots use their sensor to measure the ocean for different things, including the patches of zooplankton that attract right whales.

"There's actually two goals with those gliders," Van Der Meer said. "The first is to report when we hear a right whale so that effective mitigation measures can happen.

"And the second thing we do with that information is we compare the acoustic detections with the ocean's information that we record from the gliders and try to understand what about the ocean is causing whales to go to a particular place at a particular time."

If the researchers can learn why the food is where it is, then more effective steps to reduce the risk to the animals can be developed.  

"It's important for us to figure out where these patches are showing up because that is what will drive right whales to a particular place at a particular time."  

With the research project in its third year, Johnson is hopeful the data can be used to come up with some explanations for the patterns the scientists have been seeing. 

Sensitive to change

Johnson said the right whales are very sensitive to changes in the ocean environment, and scientists want to find out why. 

Estimates of the number of North Atlantic right whales ranged from about 400 to 450. Their plight has become a global issue, with many people watching to see what will be done to save the species. 

Nick Hawkins, a photojournalist with the Smithsonian Magazine in Washington, is working on a photo essay about the right whale, a story he said has captivated people around the world. 

While the magazine's essay will focus on the science and the measures being taken to prevent ship strikes and entanglements in fishing gear, Hawkins said the story is about more than that. 

''This is a global issue, entanglements and ship strikes," Hawkins said. "It's not just the right whale. And the story's bigger than just the whale itself. 

"The oceans are getting busier and busier, and if we want to have these whales around and other marine life we're going to have to figure out new ways to prevent problems in the interests of these animals coming into conflict of their own."