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Major mortality incident at flagship salmon RAS

The Fish Site
by The Fish Site
24 March 2021, at 10:42am

Atlantic Sapphire has reported another significant mortality incident this week at its Miami recirculation aquaculture system (RAS) facility.

Around 500,000 salmon, averaging 1kg each, have been lost - the equivalent of around 5 percent of their planned phase one annual harvest volume (10,000 tonnes a year).

The company notes that the incident follows temporary challenges due to maturation and contractor workmanship, but will not affect the continuity of supply to customers.

“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. This resulted in elevated turbidity and possibly gasses; and caused abnormal fish behavior. Fish gathered at the bottom of the tanks, disrupting the flow of new water, causing increasing mortality,” Atlantic Sapphire said in a statement.

The company – which is the first large-scale land-based salmon producer in the world – added that it was in the process of rectifying a technical hitch in its system, which could have prevented the incident had it been carried out in time.

“The company has, from a previous incident, identified an opportunity to ensure undisrupted water flow by modifying the center drain design in all of its grow out tanks. This work had already started prior to this incident. The center drain in the affected system had not yet been modified. Keeping an undisrupted water flow is critical to the operation of a RAS system,” the statement continued.

Issues in Atlantic Sapphire’s Miami site are contained, to a certain degree, by the division of the facility into a number of separate systems, and the company notes that the fish in the other systems were unaffected. However, they now plan to subdivide the facility further.

“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,” they explained.