As the result of a cooperation between Stora Enso and the company Carelian Caviar, about 100 000 sturgeons are swimming in basins on the Varkaus mill premises.
Varkaus is the home to a Stora Enso board mill, production of wooden elements (LVL) and significant wood supply activities. The fish farm uses excess heat from the mill to heat the water for the indoor fish farm pools. The farm additionally gets its electricity from the mill and uses the mill water treatment plant.
“For us it is a perfect match. We have had a very good cooperation since we started ten years ago. We complement each other well,” says Pekka Hannelin, Production Manager at Carelian Caviar.
Like the mill, the fish farm needs access to clean water which is taken via the same pipeline as the mill from the river passing through Varkaus. “We use much less water than a traditional fish farm. We have 19 tanks of 240 cubic metres each. 100 litres of water per tank is circulated every second – 1% is fresh water and the rest is cleaned and recirculated,” Pekka explains.
The roe is harvested when the sturgeons are between five and nine years old, when the fish weighs between 5 and 15 kg. The main product is the caviar, but the meat is also sold as food. About four tonnes of caviar is produced annually and mostly exported.