Expanding Discoveries on Canada’s Deep Seamounts
Post-Cruise Impact – NEPDEP 2025 Seamounts and Mapping
During the September 2025 NEPDEP expedition, the team made several remarkable discoveries that deepen understanding of the Northeast Pacific’s deep-sea ecosystems. Building on years of collaboration between Indigenous Nations, Fisheries and Oceans Canada, and international partners, the mission combined advanced mapping, ROV surveys, and seafloor sampling to reveal new insights into one of the most biodiverse and least explored regions of the Canadian offshore.
At the Tuzo Wilson Seamount Complex, scientists produced a high-resolution map of the seamount, revealing a major expansion of Canada’s only known Precious Coral bed. They also significantly expanded the known extent of the Pacific white skate nursery area and increased estimates of egg density on the seamount. Using multibeam and ROV technologies, the team found signs of hydrothermal activity and even documented a female Pacific white skate in the process of laying an egg – only the second time this behaviour has ever been recorded.
In addition, multibeam mapping near a newly proposed marine protected area within the Haida Gwaii MPA network revealed bubbles rising more than 800 m through the water column. Follow-up dives confirmed a new cold seep habitat, home to chemosynthetic animals, young carbonate concretions, and pockmark-like blow-out craters – with evidence of gas hydrates below.
At the nearby Endeavour Seamount, the team made another landmark finding: a second deep-sea skate nursery ground, showing densities possibly similar to those first found at the Tuzo Wilson Seamount Complex in 2021.
For Julian Smith of Fisheries and Oceans Canada, who has been part of the NEPDEP team since that first discovery, the experience marked another milestone in understanding these unique habitats:
“It has been very exciting to be a part of the team since the first discovery of the nursery ground on NEPDEP 58 back in 2021. These expeditions have been the highlight of my early career as a scientist. It’s amazing to see what a group of people can accomplish through such great teamwork, outreach, collaborations, and hard work. Everyone from ship to shore is so passionate about NEPDEP and exploring the deep to protect its future.”
Julian’s role included collecting oceanographic data, assisting with ROV sample collections, and capturing imagery from the dives – documenting discoveries that help build awareness of the deep sea’s ecological importance.
“The impact NEPDEP and its collaborators – such as the Challenger 150 programme – are creating is critical and ever-growing. This team has made a phenomenal impact in creating awareness about a fascinating, understudied yet exploited environment.”
The continued collaboration between NEPDEP, Fisheries and Oceans Canada, and global partners through Challenger 150 shows how teamwork and shared knowledge are advancing deep-sea science under the UN Ocean Decade.
This story forms part of the Challenger 150 Post-Cruise Impact series, sharing reflections and discoveries from expeditions contributing to the goals of the UN Ocean Decade.