The latest Norwegian herring spawning survey recorded one of the lowest stock levels in decades, with the measured biomass down 33% from last year. That follows a 23% drop in the year before. Researchers say such low levels have not been observed since 1994.
Sharp decline confirmed in 2026 survey
The findings come from the annual spawning survey led by the Institute of Marine Research. The survey leader, Erling Kåre Stenevik, said the results are based on observations collected during the February cruise. He stressed that the survey is only one of several data sources used to assess the stock.
Shift in age structure
The stock is now changing. Older fish from the strong 2016 year class are declining. At the same time, the 2021 year class is entering the spawning stock. Five-year-old fish from this group made up 34% of the observed stock.
However, researchers warn that not all of these fish may have been detected. Large year classes often mature later. Some may not have joined the spawning grounds this year.
Lower weight and delayed spawning
The 2021 year class had a lower average weight than five-year-olds did last year. Researchers link this to density-dependent growth, in which more fish compete for the same food.
Only 12% of the herring were fully ready to spawn. This suggests spawning is later than in the previous nine years.
Most of the stock was again located outside Lofoten and Vesterålen, continuing a pattern seen in recent years.