Excerpt of the report summary
Mortality is a crude, but measurable, indicator of fish health and fish welfare. 60.3 million Norwegian farmed salmon were lost from production between sea-transfer and harvest, of which 52.1 million were categorised as mortality-related, not far short of the record number registered in 2019 (53.2 million). The high figure in 2019 could be partly explained by losses associated with algal blooms in Nordland and Troms, which alone killed approximately 8 million fish. We have not identified any particular event which could be linked to the high mortality registered in 2020. We see that the increase in mechanical delousing continued again between 2019 and 2020. There are no indications of decreasing prevalence of infectious diseases. on the contrary, an increase is indicated where comparable statistics are available.
Reliable statistics related to mortalities experienced during the juvenile stages of salmon production are lacking, as are mortality rates in cleaner-fish species at work in salmon cages. They way in which these mortalities are registered make analyses of changes over time and identification of the causes challenging.
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