Both cod fry and saithe fry swim around the artificial reefs covered with kelp.
Photo: Norwegian Institute of Marine Research.
In northern Norway, more than 80% of the original kelp forests have disappeared in the last 50 years, being replaced by sea urchins as a consequence of overfishing of their natural predators and climate change. With several projects underway to help recover and restore them, the one led by the Norwegian Institute of Marine Research has been the latest to offer good news, achieving results in record time.
Although the results have only just been released, the experiment began a year ago, when, during the fall of 2024 and winter of 2025, marine researchers placed artificial reefs in the Melkøysundet strait, off the town of Hammerfest in Finnmark county, northern Norway.
As in much of Norway's northern coast, the kelp forest in this area had also been grazed down after decades of sea urchins devouring all the sprouts, with almost no new kelp managing to grow before being eaten.
The good news came when, upon re-inspecting the artificial reefs in May 2025, approximately four months after the last structures were set, they were completely covered with kelp.
"They were covered in lush kelp just four months after we placed the last artificial reefs," said marine researcher Hans Kristian Strand. "This is record time," he emphasized.
The reefs installed in Melkøysundet are approximately 20 meters deep and extend between 10 and 15 meters upward in the water column, combining technology with natural regeneration capacity.
The project is a collaboration between the Norwegian Institute of Marine Research, the municipality of Hammerfest, Equinor, an industrial partner responsible for regulating traffic in Melkøysundet, a restricted access area, the technology company GSG AS, which designed and manufactured the artificial reefs, and Polaralge AS, which supplied the kelp plants, which were grown in a laboratory.
It should also be noted that, as the Norwegian Institute of Marine Research points out, kelp forests are extremely valuable as nurseries and shelters for rich marine life, as oxygen producers, and as carbon stores.
As Hans Kristian Strand pointed out, species that we also harvest – such as coastal cod, saithe, and wolffish – all benefit greatly from the kelp forest during their life cycles, and that has been another piece of good news regarding the experiment.
"Kelp grew densely on all the deployed reefs, and we saw both cod fry and saithe fry in large numbers around the structures," explained the marine researcher.
Thus, the Norwegian Institute of Marine Research said that they will closely monitor its evolution over time to see if the reefs can function as biological "hotspots" for both kelp and fish.
This is what the artificial reefs look like. Here are two TareRev units in the foreground, and an outline of interconnected units in the background.
Illustration: Reibo AS / Norwegian Institute of Marine Research.
Although there were already previous projects underway, such as Urchinomics, a pioneering restorative aquaculture venture that transforms ecologically destructive sea urchins into premium seafood, in 2024, the Norwegian Parliament requested a plan on how to restore Norway's kelp forests along the coast.
Since then, more options have been added to the attempt to solve the problem. For example, in the north, one of these options has been to use burned lime to eliminate the sea urchins that devour the forest. Another has been to release predatory fish, such as wolffish, which feed on sea urchins.
Other methods focus on strengthening the kelp forest, for example, by transplanting kelp or spreading "kelp gravel" to give the forest a head start in its growth. One such company is SeaForester, the marine restoration venture that announced last week that it has raised USD 1.9 million to accelerate its global expansion in order to scale ocean reforestation.
Precisely that, scaling up the results now achieved, would be the next step in the Norwegian Institute of Marine Research's project after demonstrating that kelp forests can be established quickly even in areas with an abundance of sea urchins, without the need to remove them beforehand.
"We have shown that it is possible to create a fully developed kelp forest in just four months, if the reefs are deployed at the right time. This could become a new tool for restoring our fjords," Strand concluded.
