“This has been a very interesting and slightly unusual delivery for us,” says Normex CEO Stig Johansen (left), seen here with sales manager Michael Vadseth at the crab hotel in Kløfta just outside Oslo’s Gardermoen airport.
Complete RAS plant for Live Seafood Centre
Live red king crabs caught in northern Norway’s icy coastal waters represent an exclusive delicacy world-wide. Before seafood lovers get to taste them, however, they make a stop-over in the “crab hotel” at Kløfta just outside Oslo’s Gardermoen airport.
Each stage in this journey is carefully monitored to ensure that the crabs arrive in virtually the same condition as when they were taken from the Arctic waters along the Finnmark coast in the far north.
The centre’s crab hotel is halfway through its first operating year, with a complete recirculation aquaculture system (RAS) and water-treatment facility from Norway’s Normex. From left: Michael Vadseth and Stig Johansen, both Normex, and Rune Bergly at the Live Seafood Centre.
Restitution in seawater
Once checked into the “hotel”, the crabs enjoy restitution from the rigours of their voyage in big seawater tanks with a controlled temperature. These carefully mimic their natural habitat to ensure they remain alive and fresh until reaching customers around the world.
As orders are received from gourmet restaurants in New York, Dubai or Hong Kong, or from seafood markets in Vietnam or Japan, it does not take employees at the Live Seafood Centre long to pack the crabs carefully in specially made polystyrene boxes for air freighting.
An unusual delivery
The centre’s crab hotel is halfway through its first operating year, with a complete recirculation aquaculture system (RAS) and water-treatment facility from Norway’s Normex.
“This has been a very interesting and slightly unusual delivery for us,” says Normex CEO Stig Johansen. “We normally supply water-treatment systems, but here we tied together the whole RAS package with help from sub-contractors. Methodology and components are familiar, but delivering to a crab hotel was a new one for us.”
Put into operation just before the start of 2023, the plant comprises a drum filter, level tanks, cooling system, biofilter, a Razone water treatment system and associated piping and control systems.
Other varieties
“Red king crabs (Paralithodes camtschaticus) are undoubtedly where the volume lies, but our facility can accept and handle other varieties of crabs and crustaceans,” says Rune Bergly at the Live Seafood Centre.
Its most important customer is Cape Fish at Honningsvåg, Norway’s northernmost incorporated town. Live red king crabs account for almost half of this company’s annual turnover.
“Cape Fish is a big and important client, but we also offer our services to other players who need intermediate storage of live crustaceans before they’re flown abroad,” explains Bergly. “As part of the ‘hotel’ service, we pack and prepare crabs for air-freighting to buyers worldwide.”
He has worked with handling and intermediate storage of king crabs and other live crustaceans for more than eight years, and was involved in developing the new Kløfta plant from the start.
Good water quality and the right water temperature are crucial for the king crabs to thrive. “Water for a crab is like air to people,” Rune Bergly (left) points out. Michael Vadseth is on the right.
10-20 tonnes a week
“The crabs usually arrive here by air,” says Bergly. “They might then be dry and limp, but revive once they get in the water here. During loading and unloading, we check each crab individually. A typical weight is about three kilograms, but many can be a good deal heavier.”
He and his colleagues have just finished packing and dispatching an air-freight consignment, so only one of the 24 tanks is filled with about 150 kilograms of crab. At peak, a tank can hold 500-600 kilograms.
“Since this is our first operating year, we’ve only just started determining our total capacity,” he reports. “We can hold 10 tonnes of live crab at a time in any event, but I imagine we can handle 10-20 tonnes per week depending on the rotation – perhaps even more.”
The Live Seafood Centre’s 24 tanks can, at peak, hold 500-600 kilograms of crab. Its 150 000 litres of seawater divided between 24 tanks is continuously recirculated and cleaned.
Like air to people
Good water quality and the right water temperature are crucial for the king crabs to thrive. They then retain their vitality, freshness and taste on the journey from catch to consumer.
“Water for a crab is like air to people,” Bergly points out. “Keeping it good and clean means everything for their well-being and freshness.”
Since the crabs are not fed during their stay at the centre, most of the waste in the water comes from their faeces. Cleaning is ensured with both mechanical and biological filtration.
“The water must be treated to ensure that the faeces aren’t converted into toxic substances in the water,” says Bergly. “It’s also important that the water flows and circulates swiftly enough.
“And the water temperature must remain correct. King crabs like it cold. It’s 4°C at the moment, nut we can reduce it to 2°C if desirable.”
In addition to recirculation and cleaning, the plant embraces a cooling unit to reduce the seawater temperature.
Michael Vadseth inspects the cooling system which cools the seawater in the facility.
Full seawater recycling
The seawater was originally pumped up from deep in the Oslo Fjord at a Norwegian Institute for Water Research (Niva) station and delivered by road to the Kløfta tanks. Apart from replenishment for spillage and evaporation, all this water is recycled.
Outlining how 150 000 litres of seawater divided between 24 tanks is continuously recirculated and cleaned, Johansen explains that it is first passed through a drum filter to remove particles.
“It then continues to biological filtration, where toxic chemicals from crab faeces are converted or extracted. The final stage before return to the tanks is our Razone system.”
This adds oxygen and ozone, so that particles of protein and muck in the water flocculate and float up to form a layer of sludge in a flotation tank. This sludge is skimmed from the top and led to a tank, while the clean water returns to the plant with all particles extracted.
“It’s been fun to handle the whole RAS delivery, even though our core business is water treatment and cleaning,” says Johansen. “The spring of 2023 has been devoted to trying out and making fine adjustments to the plant, which now appears to be working really well.”
Live red king crabs represent an exclusive delicacy worldwide. Before seafood lovers get to taste them, however, they make a stop-over in the crab hotel. From left: Michael Vadseth and Stig Johansen, both Normex, and Rune Bergly at the Live Seafood Centre.