Warm mountain water for sustainable fish farming

Warm mountain water for sustainable fish farming

Tropenhaus Frutigen, a tropical house in the alps, as pioneer of land-based aquaculture

by Heini Hofmann

Sturgeon breeding and caviar production in the Alps – a delusional idea? Considered volatile, perhaps; but looking closely, the opposite: pioneering renewable surplus energy combined with sustainable wild stocks of gentler fish farming.

Once, in Frutigen, in the middle of the Kander Valley connecting the Bernese Oberland with the Valais, slates and matches were produced. They were used at many regulars’ tables for playing Jass. Today, the first alpine tropical house stands here producing sturgeon meat, caviar and tropical fruits – including a gastronomical company and adventure area, a globally unique combination of an alpine environment, aquaculture and tropical ambience.
It seems eccentric, but not quite, since tropical climate once also ruled in Frutigen country, as evidenced by fossilised ferns found during the construction of the Lötschberg Tunnel. They lived nearly 300 million years ago and thus are of the same age as the ancestors of today’s sturgeons.

Ingenious vision of a practitioner

But why by all means a tropical house at the foot of the Bernese Alps? Because of a natural phenomenon. From the snowy peaks of the Doldenhorn massif, high above the railway base tunnel through the Lötschberg, rain and melt waters pass through the limestone into the deep, thereby heated by the rock pressure. With a temperature of approximately 18 degrees it escapes again in Frutigen on the north side of the tunnel, with about 70 litres per second.
If one were to dispose of this hot water directly into the Kander, it would lead to a threat to native fish stocks. Therefore, a useful idea was in demand. It is no coincidence that it came from engineer Peter Hufschmied, a Petri Heil follower connected to the region. It was amazingly simple, make use of the excess heat for the cultivation of heat-loving fish and plants. Thus, the idea of Tropenhaus Frutigen was born.
This was a kill of two birds with one stone. On the one hand, a costly energy-intensive cooling of the tunnel water was obsolete and on the other, a meaningful and sustainable use of energy was ensured. In other words, no office desk concept, but the implementation of ​​a visionary practitioner’s idea. After 18 months of construction and an investment of around 30 million Swiss francs, the opening took place in 2009.

Technically supported aquaculture

Not all by now enacted landbased fish farms had a good start. Therefore, right from the outset the secure path was chosen for the aquaculture in Frutigen. This means the cooperation with specialised institutions. The venture started in 2002 with a feasibility study and only in 2005 the first sturgeon arrived at the pilot plant.
In collaboration with the Centre for Fish and Wild Animal Medicine of the Veterinary Medicine Faculty at the University of Berne, the housing conditions were optimised. Minimally burdensome methods for sexing and testing of caviar maturity were developed. Anyway, adequate housing has first priority, and the use of antibiotics is taboo.
Today, Tropenhaus Frutigen is considered a pioneer for land-based aquaculture with a circulation system for breeding of freshwater fish. The Frutigen sturgeons are considered valuable edible fish and caviar suppliers. They grow 80 to 140 centimetres long and reach a weight of approximately 30 kilogrammes. They are light to dark brown on back and flanks and the belly is yellowish white.

Oona – the caviar of the Bernese Alps

Meanwhile, a good 80,000 sturgeons populate the fish tanks in Frutigen. The annual harvest amounts to approximately 6 tons of delicate, boneless filets and approximately one ton of caviar. Processing and finishing such as the smoking of meat or hand-selectioning the caviar pearls according to colour and size take place in an in-house factory.
The luxury sturgeon of Frutigen has cult status. It is obtained from the eggs of females and guaranteed to be genuine. (Latest investigations by the Leibniz Institute for Wildlife Research show that wild roe from Romania and Bulgaria was adulterated or counterfeited to a significant percentage.) The Alpine caviar with its nutty creamy flavour is lightly salted in the traditional way (maximum of 3.5 percent) and free of preservatives. It is produced in four selections, limité, jeune, traditionnel and millésime (the latter pasteurised).
Its brand name is Oona, a word derived from the Celtic (once, the Kander Valley was inhabited by Celtcs) and stands for the unique, the exceptional. Even its packaging is exclusive. It consists of a handcrafted ice cube made from clear glass manufactured in Hergiswil featuring the purity of the product. Last but not least, even the leathery sturgeon skin is made into accessories.

An exotic all round adventure

With its almost 80 employees, Tropenhaus Frutigen houses besides the sturgeon walk-in aquaculture and interactive exhibitions on renewable energy and sustainable food an exotic park with plants, vegetables and orchids in large greenhouses. Embedded within is the theme gastronomy with two restaurants, a bar, lounge, summer terrace and event zone. For the youngest there is a separate mini lounge.
In the tropical plantations one encounters all those exotic fruits known to us from the shopping shelves. Here they flourish and ripen in all its glory and bouquet, from bananas, dwarf bananas and papayas via carambolas, guavas, physalis, lychees and durian to mangosteen, avocados, pineapples and kumquats. Each year it reveals a production of approximately 2.5 tons, which is offered in the in-house restaurants and in the Tropenhaus shop, along with the sturgeon and caviar products. The latter of which can also be ordered.
In short, this tropical oasis in the Bernese Oberland is the result of a pioneering combination of the use of renewable energy and sustainable food production. Apart from the warm tunnel water solar energy and biomass are used as well. Even a water turbine produces power from excess drinking water. Such sophisticated combination of nature and technology made the Tropenhaus Frutigen an attraction for families, events and seminaries, known beyond the country’s borders.     •

Little science of sturgeons

H.H. They are one of the largest-growing type of freshwater fish in the world. They have a distinctive appearance: a spindle-shaped, elongated body, a snout with a long appendix, a toothless, epigynous mouth and four big barbels as well as fleshy lips, that can be rolled to the front like a trunk, five longitudinal rows of bone plates within the skin along the torso and one asymmetric tail fin.
Among sturgeons, there are the subspecies “Hausen” and “true” sturgeons, the first one with two different types (beluga and kaluga), the latter one with seventeen types located throughout Europe, Asia and North America. Of those seventeen types, five well-known sturgeon suppliers are from the Black, Asov and the Caspian Sea (common sturgeon, sterlet, starry sturgeon, waxdick and fringe barbel sturgeon), two more are from further east (Siberian and Amur sturgeon), five are from the Asian Pacific coast, four from Northern America and one from the Adriatic Sea.
The sturgeon has almost entirely vanished from European waterways (the sterlet used to have his home in Southern Germany) due to pollution, illegal fishing and river barrages. The streams of Elbe (Germany), Gironde (France), Guadalquivir (Spain) and the lower course of the Danube river (Austria) are the last refuges where they can still be observed on their upstream migration to the spawning sites during spring.
Tropenhaus Frutigen decided to acquire Siberian sturgeon (Acipenser baeri). That subspecies established a population that no longer migrates to the sea, for example at Lake Baikal.

Two sister institutions

H.H. A tropical House cannot only be found in Bernese Oberland (since 2009), but also within the Lucerne area, between Napf and Pilatus (since 2010). In Frutigen, warm water from Lötschberg base tunnel primarily is being used to cultivate an aquaculture for sturgeon and caviar production, as well as tropical fruits.
In contrast, Wolhusen’s machinery is being heated by industrial waste heat from a nearby gas compression station for the natural gas pipeline from the North Sea to Italy. Production is specialised on tropical fruits, vegetables and spices, while also integrating a food fish breeding facility (tilapia).

Tropenhaus Frutigen BE:  www.tropenhaus-frutigen.ch /www.oona-caviar.ch/ 0041 33 672 11 44.
Tropenhaus Wolhusen LU: www.tropenhaus-wolhusen.ch/0041 41 925 77 99.

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