Pseudochattonella bloom raises risk for farmed fish in southern production areas.
Bloom concentrations of the harmful alga Pseudochattonella have been detected in several Norwegian aquaculture production areas, with the highest risk currently assessed in production area 1 (PO1), according to the latest weekly status report from Havforskningsinstituttet (HI).
Monitoring data show increasing concentrations of the algae in the central and southern parts of PO1. Authorities warn that the bloom could lead to behavioural changes and increased mortality in farmed fish.
In production areas 2 and 3, bloom concentrations of Pseudochattonella have also been registered, with the risk level for week 13 assessed as moderate. In PO2, monitoring currently indicates a relatively low immediate risk, but a potential spread of the bloom from PO1 could increase the threat in the coming days.
In PO3, the risk is also considered moderate, particularly in the southern and outer parts of the production area, where algae densities vary between monitoring stations.
In production areas 4, 5, 6, 7 and 8, only low densities of potentially harmful algae were detected during week 13. HI said these concentrations are not expected to cause negative consequences for farmed fish.
Fish farmers in PO1 and PO2 have been advised to monitor fish behaviour closely and report any signs of abnormal behaviour or increased mortality to Havforskningsinstituttet.
