Abstract
The aim of the cruise was to follow up the pre-construction studies in Hywind Tampen in 2022. In march 2023, when this cruise was carried out, seven of the eleven planned turbines were in operation. As in 2022, the experiments were based on a gradient fish capture study using bottom gillnets at pre-determined stations. The catches were sampled and analysed to obtain information about species richness, abundance, maturity stage, sex, condition and diet and how these vary with distance to the windfarm. In addition, acoustic data were collected. The highest number of species and the highest abundances were registrered in the shallow areas furthest away from the windfarm (15 -18 nm). The most common species, that also are of commercial interest, were ling, hake, saithe, cod, pollock, whiting and haddock. Elasmobranch species were mainly caught in the deeper areas closer to the wind farm. The results from this cruise were similar to those in 2022, except for some differences in depth patterns in fish abundances. No fish schools were registered in the acoustic data. However, layers of weak scattering organisms were present in most of the transects. Poor weather conditions resulted in a small sample size for the deep region in this survey. Therefore, the power of the statistical tests for differences with depth or distance is low. This and the 2022 cruise have collected valuable fine resolution biological data about the demersal fish species in the Hywind Tampen area. With continued sampling these experiments can reveal potential effects of the installation of Hywind Tampen wind farm on the marine ecosystems.