Searching a changing ocean for a disappearing whale species

Listening beneath the waves

This July, researchers deployed an autonomous underwater vehicle known as a Slocum glider from the research vessel SV Barba. The glider will travel through the Cape Farewell Grounds and Denmark Strait before being recovered off Iceland in late September 2026.

Rather than relying on scientists to see whales from the surface, the glider will listen for them. Equipped with an underwater microphone called a hydrophone, the vehicle continuously monitors the sounds of the ocean and detects the calls of large whales.

Acoustic data will be transmitted via satellite to an acoustician in Canada, who will analyse the recordings and identify the species present. Confirmed detections will then be shared through WhaleMap, allowing researchers to follow findings from the expedition while the glider is still at sea.

The glider is also equipped with sensors that measure ocean conditions, including temperature and depth. By collecting acoustic and environmental data at the same time, researchers can begin to build a clearer picture of which whales are present and the conditions they encounter.

For researchers, the ability to listen continuously across such a large and remote area offers an important opportunity. Ships can only be in one place at a time, and visual surveys depend on weather, daylight, and sea conditions. An autonomous glider can spend months at sea, quietly gathering information from places that would otherwise receive little sustained monitoring.

Following whales through a changing ocean

North Atlantic right whales depend on dense concentrations of tiny organisms called copepods for food. To survive, whales must find areas where billions of these small animals gather. Changes in ocean temperature, currents, and productivity drastically affects food availability.

As the climate changes, the distribution of copepods is changing, too. Over the past 15 years, the changing climate has brought whales into areas where conservation measures were not designed for their presence, creating new challenges for scientists and governments working to protect them.

The Gulf of St Lawrence offers a stark example. As North Atlantic right whales began appearing there in greater numbers, they entered busy fishing grounds and shipping routes, prompting Canada to introduce new measures to reduce the risks of entanglement and vessel strikes. Entanglement in fishing gear and collisions with vessels remain the two leading causes of human-caused mortality for North Atlantic right whales.

As Arctic sea ice declines and shipping routes become more accessible, vessel traffic is expected to increase in parts of the region. Understanding whether North Atlantic right whales are using these waters can help scientists identify emerging risks and inform monitoring and conservation efforts.