All around the world, caviar is seen as both a delicacy and a luxury. Traditionally, true caviar is produced by sturgeon. Overfishing, smuggling, and pollution caused by sewage have considerably reduced the world's sturgeon population. Most of the 26 sturgeon species are threatened with extinction. 

The Tropenhaus Frutigen fish farm in Switzerland is considered a pioneering effort for the sustainable breeding of Siberian sturgeon. It's also the production site of the pure Swiss Alpine caviar made by Oona. Let's take a closer look at how Tropenhaus Frutigen and Oona connect producing sustainable caviar with growing a tropical garden of fruits and spices. 

Warm Water - Great for Tropical Fruit, Bad for Native Swiss Rivers

To understand the connection between fruit and caviar, we must first return to Tropenhaus Frutigen's original produce: tropical fruit. The commercial and worldwide unique project uses geothermal energy from warm water that flows out of the NEAT Lötschberg base tunnel to produce exotic fruit like cocoa, pineapple, and papaya, only picked when fully ripe. 

50 liters of crystal clear water flow from one end of the tunnel to the other every second, exiting it with a temperature of 18 degrees - far warmer than the native surrounding rivers, which would pose a threat to the native fish, like lake trout. Yet cooling the water down would use unnecessary and costly resources. 

So Tropenhaus Frutigen decided to use the already heated water to breed sturgeon in order to produce caviar, sturgeon fillet, as well as sturgeon leather products. 

Sustainable Fish Farming Done Right

Because most of the sturgeon species are on the verge of extinction, wild sturgeon fishing is prohibited almost everywhere worldwide. Fish farming is the only way to not only make sure the sturgeon population isn't decimated further but also to produce the sought-after caviar. 

Of course, fish farming doesn't have the best reputation; inhumane slaughter methods, as well as the addition of medication and hormones to the farmed fish's diets, are some of the bigger issues that come with fish farming. But it can be a sustainable alternative to wild fishing - if done right. 

Together with the Centre for Fish and Wildlife Health at the University of Berne, Tropenhaus Frutigen has optimized fish husbandry conditions and developed animal-friendly methods, such as determining when the caviar has reached optimal maturity. 

Another great success is the recirculation system at Tropenhaus Frutigen. The breeding tanks are arranged so the water continuously circulates. Pumps move the water from the treatment plant to the top tanks, from where it flows down, tank by tank, and back into the plant to be treated. The efficient filtration system is responsible for above-average water quality in the tanks - which, in turn, makes the addition of medication or hormones unnecessary. 

Read more about Tropenhaus Frutigen in our interview with Beate Makowsky

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