Everyone knows that Atlantic salmon spawn in freshwater and make their way to the sea as adults. In fact, however, there are small communities of landlocked salmon that never make it to salt water.
Now, a Norwegian company is looking to farm one type of freshwater Salmo salar. Success would represent an amazing turnaround for a fish that, half a century ago, was teetering on the brink of extinction.
The bleke (also spelled “bleka”, from the Norwegian word for “pale”) is a dwarf salmon that spends its adult life in the Otra river system and the Byglandsfjord, a freshwater lake in southern Norway.
When ocean levels rose after the last ice age, Atlantic salmon entered the lake, but as the climate changed the Byglandsfjord became cut off from the sea. Now the adult bleke live in the lake, which at 33km2 and a depth of 167m is a sizeable body of water.
The bleke formed a regular part of the diet for locals until two environmental threats nearly wiped the whole population out. First, a hydroelectric dam built in 1905 made many of the spawning grounds inaccessible; then, from the 1950s onwards, acid rain from the industries of northern Europe wreaked further havoc. By the early 1970s it was estimated that there were only around 200 breeding adults left.
Bjørn Barlaup, research director at independent research institute NORCE, says: “A local rescue operation was launched with assistance from the environmental authorities to obtain a brood stock for the local fishery at Bygland. After numerous failed attempts to save the population, the bleke looked doomed.”
In the end only eight females and eight males provided the basis for hatchery operations. This brought the bleke back from the brink of extinction.
Barlaup says: “In the five decades that followed, the bleke has benefited from a coordinated action plan based on management decisions including cultivation efforts with stocking of fry and eggs, and multiple habitat restoration efforts focusing on spawning habitats and water quality.
“Today, 50 years after the population collapse, the continuous and ongoing rescue efforts have taken us a long way towards the goal to restore a self-reproducing and harvestable bleke population. If this goal is achieved, the bleke may regain its previous position as an important part of local culture, with positive implications for recreation, tourism and business development.”
Otteraaens Brugseierforening (OB), which represents hydroelectric businesses in the Otra river system, has a duty to release 100,000 juvenile bleke each year. OB owns the hatchery Syrtveit Fiskeanlegg, where the bleke are produced, working in collaboration with the University of Bergen.
Each year, approximately 100,000 bleke eggs are placed at potential spawning grounds in Byglandsfjorden. In addition, spawning gravel has been laid down at appropriate locations, and OB has introduced minimum flow rules for the period when the eggs are in the gravel.
Bleke are now caught again (and eaten) by locals – and now Fyri, an aquaculture venture, aims to raise bleke for the restaurant trade.
Bleke are small – typically coming in at 30cm in length and weighing just 200 grams – so unlike seagoing salmon they are usually served as a portion fish.
Fyri partner Atle Kristoffersen says: “My dream and target are that restaurants worldwide will know about this unique fish and that customers shall seek out restaurants to enjoy this great product.
“I also picture enthusiastic chefs telling the unique story of the bleke while the guests can have a look at the fantastic, healthy fish and dream back to the very long journey it has been on since the ice age.”
He explains: “The ambition is to produce the bleke and make it available so the rest of the world can taste this fantastic fish that holds a unique old history. Since the fish has a limited growth in the wild, we plan to produce it up to a portion size. We plan to produce the fish in a top, modern RAS [recirculating aquaculture systems] facility in a sustainable way where we reuse the same crystal-clear water that the fish normally lives in.
“In my opinion, bleke taste very different and unique compared with all other fish. I would say the taste reminds me more of white fish than red fish, even though the bleke is a red fish.”
Fyri is an independent company, jointly owned on a 70/30 basis by FishCo Holding and Oslo-based biotech company Tempogene, respectively. FishCo also owns Baring Farsund, which is developing a RAS salmon farm in Farsund, southern Norway.
If Fyri gets the necessary approvals in place, the aim is to produce the bleke in a land-based RAS facility.
Kristoffersen explains: “Today we have access to Syrtveit Fish farm, a flow-through plant that has cultivated the bleke for over 30 years. The employees at the facility have important experience that we want to bring further with us into the project. In addition to this, it already has a great infrastructure with water supply/water intake, drainage and building stocks that can be reused.”
He is confident that bleke will be a suitable fish for RAS production: “There are several advantages to using freshwater in RAS production and we do believe there is an advantage of not producing the fish larger than a portion size.
“New and unknown challenges related to the commercial production of the bleke may appear, but we are prepared for these potential challenges and see it as a benefit that we can take advantage of, and use the tools that are already in place and have been developed through traditional salmon farms since the bleke is also a salmon fish.
“Throughout the latest 30 years of production of the bleke at the facility in Setesdalen, a high level of experience and competence of hatching and feeding of the fish has been built, resulting in a very high survival rate of the fish during this phase.”
He is also confident that this unique variety of Atlantic salmon will appeal to restaurateurs looking for something new.
Local celebrity chef and blogger Margit Dale agrees. She says: “The bleke salmon is a unique fish. It was originally a seagoing salmon that was trapped in the Byglandsfjord after the last ice age. During thousands of years, it has evolved for a life in freshwater. The water in the Byglandsfjord is the purest drinking water, a good base for a great taste.
“The taste of the bleke salmon is not ‘muddy’ like the brown trout. I think it has something to do with the fact that the bleke eats plankton in free water and does not go to the bottom to hunt for food like the trout.”
She adds that bleke would represent a different dining experience: “The bleke salmon differs from the seagoing salmon in many ways. It is smaller in size, finer in texture and it tastes a bit milder.
“Traditionally the bleke was served as a portion fish either fried, cooked or smoked. But it has many areas of use. It is delicious served raw as a ceviche or sashimi, grilled, in soups or even in salads.”
Kristoffersen says, however, that the aim is about more than providing a new option for restaurant menus: “Not only will the bleke be produced as a food fish in a modern and sustainable way, but we will also take on important sustainable responsibility, ensuring that the bleke as a wild fish will have a safe future in case it should be threatened with extinction.”