A ban to save a fjord under pressure
The Oslofjord has been under pressure for decades: overfishing, oxygen-poor bottom water, and a lobster and groundfish population that has shrunk year after year. On 1 January 2026, the Norwegian government introduced three large no-take zones: the Indre Oslofjord from Moss to Oslo, and the Færder and Ytre Hvaler national parks. All fishing is banned in these zones, both commercial and recreational. The exceptions are children's crab fishing with a hand line, and a few permits for research and removal of Pacific oysters.
One of the biggest single problems isn't the fishing that's still happening, but the fishing that stopped happening a long time ago. Lost pots, nets, and lines stay on the seabed for years, still catching fish and shellfish with nobody there to retrieve them. This kind of ghost fishing is a quiet, ongoing strain on an ecosystem that's already struggling. The environmental organization OceanFront alone recovered around 10 tonnes of ghost gear from the Indre Oslofjord in a single month in the summer of 2026.
To fund this kind of work, the Norwegian Environment Agency set aside a pool of almost NOK 100 million for nature restoration in the Oslofjord. The applications that came in totaled around NOK 400 million, four times what was available.
From fisherman to fjord guardian: a new job on the same fjord
Today, the same fjord is Karlsen's workplace again, just with a different assignment. After applying for restoration funding and being turned down in the first round, he won his case on appeal in June. The money arrived late, not until August, but it came with a Blueye X3 Ultra and a gripper claw. Since then, he's been out on the fjord almost every day.
"None of this work brings in any income. So you're completely dependent on getting funding to do it year-round: equipment, but also salary and operations." - Arild Karlsen
The funding he has received runs through the end of 2026. After the new year, he'll have to apply again, and he's one of several fishermen waiting to see whether the Norwegian Environment Agency will follow up next year too.
Karlsen also works with Green Bay, which has received funding to map the seabed using AUVs and sonar systems. When Green Bay confirms a find of lost gear, Karlsen takes over the coordinates and dives down with the ROV to recover it.
The choice of ROV supplier was no accident.
"I chose Blueye for a few reasons. One is the AI model. I think that's very forward-looking. Another is the Blueye Cloud system, the logging and reporting. It saves me a lot of work." - Arild Karlsen
He now spends his evenings on something few ROV operators do themselves: building his own training dataset to recognize ghost gear in the Oslofjord. With the Blueye X3 Ultra, operators can upload their own AI models trained to recognize objects automatically and have them flagged directly in the Blueye App during the dive. Ready-made datasets exist, but they were collected elsewhere in the world, under completely different conditions. "The Oslofjord is special. The visibility is poor, and the fouling is a completely different type," he says. Every evening, he feeds the day's finds into a model that trains overnight. The goal is an AI model trained specifically on conditions in the Oslofjord, one he can eventually load into Blueye, and that should, in time, make it possible to detect ghost gear at a longer range than he can see on camera himself.
Karlsen isn't alone in doing this kind of work on the fjord. The volunteer environmental organization Marinreparatørene has been cleaning up the Indre Oslofjord since 2014, and has, with funding from the Norwegian Environment Agency, hired two full-time staff for a similar project further north in the fjord, in partnership with OceanFront.
How it works in practice: from mapping to recovery
A typical workday starts with mapping. Karlsen uses sonar images, described as an "X-ray of the seabed," to look for signs of lost gear, but pots are often overgrown with fouling or hidden between rocks, and are hard to spot even on sonar. When he doesn't have a confirmed point to go on, the method is to find an edge on the bottom and follow it. Most lost gear collects along edges and in rope lines like this over the decades.
The operation requires the boat to hold its position underwater. He also uses the Sailorsmate chart system, which he knows from his fishing career and which is now integrated with Blueye and positioning systems such as USBL. That lets him follow the ROV's exact position and track in real time on the chart display, and take screenshots as documentation for the national parks and the Norwegian Environment Agency.
"Having USBL on the ROV is the single most important thing for understanding where you're operating. Where have I searched, and where haven't I? You can only get that with USBL." - Arild Karlsen
That documentation isn't just useful, it's a requirement. Karlsen is one of around five operators who have been granted a three-year permit to clear ghost gear with an ROV in the Færder and Ytre Hvaler national parks, precisely because the method is gentler on the seabed fauna than traditional grapnel dragging. The national park managers require video and reporting from every dive, even when nothing is found, since a cleared area is also valuable mapping information.
What makes this work possible for people without an ROV background is that none of them had to retrain to use the equipment. For fishermen like Karlsen, who know the fjord from decades on the water, the real expertise is knowing where things collect and what the seabed looks like. The ROV is simply the tool that lets that knowledge be put to a new use.
Blueye operators also use Blueye Cloud to share their findings with the Norwegian Environment Agency. Mapping data and finds from each mission can be uploaded and made available to those managing the restoration work.
What this means going forward for the Oslofjord and its fishermen
In theory, the no-take zones are meant to do two things at once: stop new fishing gear from entering the water, and give the fjord room to recover. Karlsen's story shows a third effect: some of the people hit hardest by the ban are now among those cleaning up after decades of fishing, their own and everyone else's.
Karlsen also believes the road ahead needs careful thought. He supports reusing old fishing gear, but he's concerned that cheap replacement traps could lead to more ghost fishing, not less: a brand new trap can cost NOK 800–900 today, against as little as NOK 250 for a restored, reused one.
"My guess is that some people will end up setting them pretty carelessly." - Arild Karlsen
Everything he brings up himself goes to recycling or destruction, not back onto the market.
The funding Karlsen has received runs through the end of 2026. After that, he'll have to apply again, competing against far more applications than the Norwegian Environment Agency has funds to cover. He isn't alone in this work. The volunteer environmental organization Marinreparatørene, among others, is doing the same kind of cleanup further north in the fjord. But for Karlsen, much of what happens next comes down to whether a fisherman who has rebuilt his entire career gets to keep doing it.
He's far from the only one who has turned the fishing ban into a new job. But Karlsen's story is the story of how someone who knows the seabed better than most is now using that knowledge to clean it up, and to build his own method for finding what other fishermen have lost.
