A large number of salmon have died after being bathed in warm water to combat lice. ‘Marine Harvest’ lost nearly 100,000 salmon in one plant in Scotland.
The method involved the fish being bathed for a short period in water at a temperature of over 30 degrees celsius. Several plants in Norway have reported ‘increased mortality’ after treatment, reported newspaper Bergens Tidende.
Since sea-lice have become resistant to chemical delousing agents, several new methods have been tried out to tackle the problem.
One of these methods is to bathe fish in warm water for about half a minute. The salmon are subjected to rough treatment when they are sucked up and pumped into the temperate, freshwater bath. The Norwegian Food Safety Authority (Mattilsynet) believes that it is during the actual handling that fish die off.
‘We are concerned about repeated mechanical treatments, because these treatments increase stress’, said senior advisor, Inger Fyllingen.
There is also uncertainty about whether the rapid temperature change creates problems, and the agency has asked the Institute of Marine Research (IMR or Havforskningsinstituttet) to investigate this.
In one case in Scotland, the company, Marine Harvest, lost 95,400 salmon, which caused financial losses of several million.
‘The welfare of the fish is our highest priority, but we are not going to hide the fact that some plants have experienced high mortality during treatment’, said communications director, Ola Helge Hjetland.
Source: NTB scanpix / Norway Today