IESNS - International Ecosystem Survey in the Nordic Seas This survey aims to monitor the distribution, stock sizes and annual recruitment of pelagic fish stocks in the Norwegian Sea between 62⁰ -74⁰ N, with a particular focus on the target species herring and blue whiting. IESNS takes place once a year in the 2nd quarter of May. During this survey, acoustics are used to derive acoustic indications for the fish stock sizes. In addition, pelagic trawls are used to validate the species composition for the acoustic data and all catches are recorded for species, and additional biological parameters are measured for herring, sprat and mackerel (length, age, sex, sexual maturity). IESNS is internationally coordinated through the ICES working group WGIPS and data is used by the working groups WGIPS and HAWG for assessment and advice.

• Environmental state
• Human activities
• In-situ sampling offshore
• Pressures
• Essential Ocean subvariables (EOV subvariables) & Essential Biodiversity Variables (EBVs)
  • Fish abundance
  • Fish abundance by size/age/stage
• GOOS Essential Ocean Variables (EOVs)
  • Fish abundance and distribution