De-lousing kills 32,700 fish at Marine Harvest operation

Company says it is 'fine tuning' its operations to avoid future problems.

Marine Harvest recently reported 32,700 fish died during a de-lousing procedure.

The incident occurred when the company carried out a de-lousing of all the cages at one of its farm sites, the company wrote in a report to the Norwegian Food Safety Authority (NFSA).

"Unfortunately we had excessive mortalities with this treatment," Eivind Naevdal-Bolstad, communications director at Marine Harvest, told IntraFish.

"The reason was the fish that were being treated were far weaker than had been anticipated."

Around 19,620 fish died immediately after treatment, but this figure increased to a total of 32,700 fish a week later.

"Even though we attempted to solve this as gently as possible, we figure it was the handling and overcrowding that led to the mortalities," Marine Harvest said in the report.

The fish groups had both a pancreatic disease (PD) diagnosis and circulatory system collapse. Retrieval of the dead fish was executed as quickly as was practicably possible, the company said.

Used Thermolicer

In the report the company also stressed a critical assessment would be made of the problems associated with Thermolicer usage.

The company said it will "fine tune" its best practices with the method.

"It’s only a few months since we started treating with Thermolicer, and we are working continuously to optimize the treatment process to reduce mortalities," the company wrote.

Naevdal-Bolstad said lice figures in the area are fortunately low and under good control.

“From now on we will be working further with preventive measures to reduce the need for treatments, in that all handling of fish carries a level of risk. Therefore we have several initiatives ongoing with cleaner fish, lice skirts, deep-water feeding and lasers,” he said.