August 22, 2024

More than 400,000 fry culled at Salmar's Tjuin, Norway hatchery

SalMar had to cull more than 400,000 fry at its hatchery in Tjuin, Norway, as a closed valve meant that a sensor system couldn't do its job.

This led to the fish being exposed to a pH level that was far too high for nearly eight hours, leading to SalMar's decision to cull the fry for welfare reasons.

In a notification of non-conformity to the Norwegian Food Safety Authority, SalMar wrote that on August 7, 418,000 fish were sorted into department 'Fry 2' at Tjuin. There were previously no fish in the department.

Following the end of sorting for the day, an on-duty operations manager noticed that the fish were displaying very unusual behaviour two hours later, SalMar said.

It was quickly discovered that sensors that track the acid-alkaline (pH) balance of the water were not receiving new water for analysis due to a closed valve. The liming system, which rebalances the pH if water becomes too acidic, had run for eight hours without receiving feedback on the correct pH in the operating water. The pH was then read and showed 10.9; pH should be neutral at around 6.2-6.8.

The liming system was stopped immediately, and a number of measures were taken to replace the water in the entire system.

"Based on literature from our subject expertise and observation of the fish in department 'Fry 2', we decided to cull all 418,000 fish on Thursday, 8 August," SalMar said. "This was for welfare reasons, as the extent of damage from both short-term and long-term exposure to such a high pH is irreversible."

- Fish Farming Expert