Artificially Fertilized Atlantic Wolffish Set to Restore Arctic Kelp Forests

Overfishing of of the sea urchin's natural predators has caused urchin populations to explode along the coast of Northern Norway. In the regions of Troms and Finnmark in particular, sea urchins have grazed down the kelp forest, leaving behind barren marine areas.

Kelp forest are among Norway’s most important marine ecosystems. They serve as a safe habitat, spawning ground, and hunting territory for a wide range of fish species. Additionally, they absorb and store carbon, as well as dampen underwater noise in areas with increased maritime traffic.

Last year, the Bellona Environmental Foundation released 20 wolffish into artificially established kelp forests in Melkøysundet in Hammerfest, Northern Norway.

Now, another research team is working toward the same overarching goal: to reverse this negative trend and restore the valuable underwater forests along the Arctic Norwegian coast.

Successful breeding

Through the BlueRewilding project, led by Akvaplan-niva and funded by Restorae and Trefadder / Vår Energi, researchers are developing methods to farm juvenile Atlantic wolffish. The plan is to breed 500 fish ready for release in field trials.

Researchers at Akvaplan-niva’s research station outside Tromsø have used wild-caught broodstock for the effort. In June 2025, 30 Atlantic wolffish were caught. Since the species does not mate naturally in captivity, researchers must use artificial fertilization, known as "strip-spawning".

On December 10 last year, the first female was stripped for eggs, resulting in around 5.000 fertilized eggs.

According to Marianne Frantzen, Departmental Director at Akvaplan-niva, the first fish are already well underway in their development.

"They have hatched, started feeding, and are growing. The first ones hatched at the end of May, and hatching continued through mid-June," Frantzen tells High North News.

Many unanswered questions

Researchers do not yet know how many wolffish are needed to bring the sea urchin population back into balance.

"There are a lot of questions we don't have answers to yet. We don't know how many wolffish we need to release, or how large the population must be to achive balance," says Frantzen.

She emphasizes that 500 fish will not be enough to solve the problem along the entire coast. The release is primarily intended to give researchers more insight into how many fish are required, how often they must be released, and how well they survive in the wild.

Researchers suspect that the overfishing of wolffish and other predators was one of the main causes of the massive sea urchin invasions that began in the 1970s. Because wolffish take a long time to reach sexual maturity, it has been difficult for the population to recover on its own.

While the species is not protected, there is no commercial wolffish fishery in coastal waters. Nevertheless, there is a risk that the wolffish could be caught if the population begins to grow.

"That is why we want to do this in protected areas, or in areas with a statutory or voluntary bans on fishing wolffish. This gives the fish a better chance to establish themselves," she explains.

The road ahead for kelp

The next step in the project is to secure funding and the necessary permits to release the fish. Researchers hope the first releases can take place next summer, though they are also considering 2028.

"We believe the fish will be large enough to avoid being eaten by next summer, but that is something we don't know for certain yet," Frantzen explains.

Among other things, researches will investigate how well the fish survive, where they stay, and to what extent they effectively reduce the sea urchin population.

"We have to start somewhere and take small steps. It is only when we can follow the fish in the field that we will find out how quickly this restoration can proceed," Frantzen concludes.