The boundary between kelp forest and urchin barren in Båtsfjorden, filmed with an underwater drone

Method

We remove the sea urchins – and give the forest a second chance.

Kelp forests can come back once the grazing pressure from sea urchins is lifted. We do it with local people, local knowledge and documented methods.

The problem

Where sea urchins graze, the forest turns to desert.

Large areas along the northern coast have gone from living kelp forest to urchin barren. Once there are enough sea urchins, they graze the kelp away and keep the seabed bare – year after year.

That means less shelter and food for fish and other species, a poorer state of nature in the fjord and less CO₂ uptake. Around 5,000 km² of the Norwegian coast is urchin barren, most of it in Northern Norway.

Kelp on the left, bare rock densely covered with sea urchins on the right
Where forest meets barren. Båtsfjorden, 31 March 2025 (ROV, 1.7 m depth).

How we work

Four steps – from map to new forest.

  1. Map

    Underwater drones (ROV), cameras and fieldwork show where the urchins are densest and where the gains are greatest.

  2. Remove

    Sea urchins are removed in defined areas using traps and underwater drones. Local fishers can take part in the work.

  3. Measure

    We measure before and after: how much kelp comes back, and how fast.

  4. Document and share

    Costs, methods and results are documented and shared with people in Båtsfjord and across Norway.

Traps and ROV

An effective, proven method.

The traps are set and hauled with ordinary fishing boats. The underwater drone is used both to map the seabed and to collect sea urchins where traps cannot reach.

The work brings activity to the harbour: boats, people and knowledge from the fjord – and the urchins can become a raw material instead of waste.

Sea urchin trap on the seabed with urchins inside
Sea urchin trap on the seabed in Båtsfjord.

Next

See where we start.

The pilot project in Båtsfjorden and Syltefjorden is where we put the method to work first.

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