Rare event was the cause of fish death
As a follow-up to messages and web meetings about the incident, we have made this note that summarizes the incident, the basis for our assessments and answers a few questions that came up at the web meeting 6. August 2021.
On 18. July 2021, a rare incident occurred at Statt Torsk's facility on Stokkeneset with the result that 48,000 fish died - Studies and results show no signs of disease in the fish.
The test results state that the cause of the incident was not a disease or of a biological nature. With almost 100% certainty, we can now determine that one or more large animals, most likely whales, have entered the facility.
Our analysis is based on how the fish died, that 2 out of 3 pens were affected, as well as samples and measurements. When the test results, as expected, gave no indication of the cause of mortality, we were back to the possibility that something had frightened the fish to ascend without having time to adjust the swim bladder. There is no other plausible explanation to what happened.
What happened on Sunday 18 July?
At 03.00, crew returned to Stokkeneset from work at a neighboring facility and everything was normal in all 3 pens in operation at the facility.
The incident was discovered on Sunday morning at 08.00, when the next crew came to work. They understood that something sudden had happened, that had a dramatic outcome for many of the fish in two out of 3 pens.
There were 3 pens in operation at the facility, with a total of about 200,000 fish, evenly distributed per cage. Since there were so few fish in the facility, the result of this incident with a mortality of 48,000 fish, was as significant as 24%.
Cod thrives and eats best in water with a temperature around 7-13 °C. Depending on the water temperature, the cod find the level where they thrive best. The fish were in the period before the incident at a depth of 12-18 meters.
The sight that met the crew when they arrived was a crowd of fish floating on their backs. Cod has a closed swim bladder, and large and sudden pressure reductions will cause the swim bladder to expand at the expense of other organs in the abdominal cavity. All fish examined had very large swim bladders.
Our assessment and what is the basis for our assessment?
Based on this observation the company suspected from day one that it was an unusual and special event that had occurred. If it had been a disease that caused the incident, development would have occurred gradually over time, not suddenly. In the same way, the consequences of an algae bloom would have given mortality first in neighboring localities, a "drop" in the oxygen would have been measured, and test results would have shown indications of this. Algae and oxygen would also have affected all 3 pens equally, only two were affected. Other possible answers were not likely and were dropped. Without test results we could not go out with more than we did 19. July.
Investigations have shown that there were no holes in the nets. There were also no marks on the outside of the nets that indicated that something had tried to get in. There was no trace of known types of predators.
The test results confirmed that there was no disease or other biological cause to the mortality. This means that there is no other explanation than that the fish were frightened upwards in the water layers without having time to adjust the swim bladder accordingly (de-compression).
It could be a coincidence, a few days later a dead whale of 5.5 meters drifted ashore at Ervik (on the outer side of Stad. Weighing only approx. 1 ton, it had an empty stomach, and with major damage to the body. That type of whale (Sowerby’s whale, ref NRK) has not been seen in Norway for more than 60 years.
Will this have consequences for cod farming?
COO, Statt Torsk AS, Leif Ronny Rætta: “No, with great certainty we can say that it will not. We believe that what happened on Stokkeneset is caused by a large animal that has come under the pens and scared the fish. This type of incident with such consequences is very rare. According to the information we have, a similar, but not comparable incident was reported in 2008. I see no reason to change our plans due to this incident. I do not think there are many such incidents, such would have been known through so many fish farming facilities that are in operation.And, we can say with certainty that such an incident has nothing to do with cod in particular, it is random if it happens, regardless of type of fish in the pens."
Is the consequence of such an incident worse for cod than for salmon?
Synnøve Åhjem, Fish Health Manager, Statt Torsk AS: “There are many large differences between cod and salmon, where the swim bladder is one of these. Cod regulates the amount of gas in the swim bladder by means of a gas gland and its own reabsorption areas; With a rapid reduction in pressure (e.g that the fish is suddenly pulled up from the depths), the swim bladder will expand at the expense of other organs in the abdominal cavity, and the bladder may rupture.If the same situation had happened at a salmon-facility, with fish of similar good health and size as our cod, the salmon would probably have been able to adapt better to the same pressure difference and given a lower sudden mortality. Since large salmon often have one or more diseases, the more realistic comparison in this case, is that such a strain is likely to result in a similar mortality.However, the incident is considered rare, as there is minimal information about similar situations.”
Will the incident have financial or financial consequences for the company?
The company's CFO Bjug Borgund does not consider the incident to have consequences that will affect the company's plans or significantly change the planned financing of future growth: "The market is familiar with the company's plans and financing, and this incident does not affect these plans. The company has so far delivered what the market has envisioned, which still can be expected from Statt Torsk in the future. There is no reason to change plans or adjust goals at this time."