Hydrography and oxygen data from Norwegian shelves and coastal regions, 2010-2023

Offshore salmon farms are being planned on the Norwegian Shelf. However, there are concerns of low oxygen levels within sea cages during periods of low water exchange. Hypoxia will compromise fish welfare and production performance, and it is therefore important to characterize oxygen dynamics at new offshore aquaculture sites. Here, we investigated oxygen variability in Norwegian waters by utilizing data from repeated sections and fisheries surveys collected between 2010 and 2023.
Oxygen conditions were investigated using a combination of water samples with titration analysis of oxygen and direct measurement of oxygen with a probe. First, we used data from the Torungen-Hirtshals hydrographic section operated at nominally monthly intervals. Water samples for oxygen analysis were here taken at standard depths [0 5 10 20 30 50 75 100 (125) (150) 200 300 400 500 600] meter but limited to 12 bottles per profile. Each bottle sample was analyzed for oxygen using Winkler titration that are accurate to about 0.1 % (Winkler, 19888; Carpenter, 1965). A Seabird 911 CTD (Conductivity, Temperature, Depth) probe was mounted on the same water sampler rig providing simultaneous temperature, salinity and pressure data. Measurements obtained between 2016 and 2023 from the Torungen-Hirtshals section were included.
To obtain a broader spatial variability representing the entire Norwegian coast and shelf we utilized data sampled during fisheries - and ecosystem surveys as well as from repeated hydrographic sections. The profiles were measured with a Seabird 911 CTD system with an SBE43 oxygen optode. These data contain the period from 2010 and 2023.
For further information and use of the data we refer to Skagseth et al. 2025.