Atlantic Sapphire blames RAS ‘design weakness’ for US fish die-off
On-land salmon farmer Atlantic Sapphire has revealed a mass mortality of fish due to a filter malfunction at its recirculating aquaculture system (RAS) facility in Miami.
In an ambiguous stock market announcement, the company said: “500 tons (head on gutted) of fish is expected to be lost, equivalent of around 5% of annualised phase 1 harvest volumes, with an average weight of approximately 1kg.”
The statement can be interpreted to mean that the unspecified number of 1kg fish lost would have amounted to 500 tonnes at harvest weight, or that the company has lost 500 tonnes of 1kg fish, which would be half a million salmon. Atlantic Sapphire refused to elaborate when contacted.
The incident occurred in one of the six grow-out systems at the Miami “Bluehouse” facility. The other systems were unaffected.
Drum filter
Atlantic Sapphire has been making improvements to its grow-out systems but the system where the mortality occurred has not yet been altered.
“The Company’s preliminary analysis, which remains subject to change, indicates that an identified design weakness from its RAS supplier caused significant amounts of particles to flow from the drum filters (particle filtration systems) into the biofilters and trickling filters,” stated Atlantic Sapphire.
“This resulted in elevated turbidity and possibly gases; and caused abnormal fish behaviour. Fish gathered at the bottom of the tanks, disrupting the flow of new water, causing increasing mortality.
Centre drain
“The Company has, from a previous incident, identified an opportunity to ensure undisrupted water flow by modifying the centre drain design in all of its grow-out tanks. This work had already started prior to this incident. The centre drain in the affected system had not yet been modified. Keeping an undisrupted water flow is critical to the operation of a RAS system.
“As earlier communicated, the Company is in the process of splitting its US phase 1 grow out systems in half in order to reduce the impact of a potential incident. Currently, four out of six systems have been split. The splitting of the affected system has not yet been completed.”
The company added that the incident comes in addition to temporary challenges due to maturation and contractor workmanship but will not affect the continuity of supply to customers.
