A trait-based framework to identify North Sea fauna vulnerable to underwater noise

In the absence of an internationally coordinated management strategy, continued exploitation of the North Sea is expected to exacerbate underwater radiated noise (URN), heightening risks of adverse impacts on marine life. Identifying indicator species and their habitats is a fundamental step in the EU framework for setting a scientifically grounded underwater noise limit value (UNLV). While past research has primarily emphasized marine mammals, there is an increasing effort to highlight that the impacts of URN extend to fishes and invertebrates. To support indicator species selection in the North Sea for URN risk assessment, a trait-based vulnerability scoring system for marine mammals, fishes and invertebrates was developed. Each scoring system evaluates multiple attributes related to a species' capacity to detect and produce sound, as well as the documented impacts from both impulsive and continuous anthropogenic noise, and highlights species of particular concern and socio-ecological significance. Five potential indicator species were identified from each of the three taxonomic groups (marine mammals, fishes and invertebrates) for URN risk assessment. The proposed vulnerability scoring system serves as an adaptive framework, open to iterative refinement as bioacoustics knowledge advances. Although data gaps persist, the establishment of regional UNLV to safeguard vulnerable species should not be delayed. By linking URN exposure with key habitats of identified indicator species, this approach facilitates an ecosystem-based management of URN in the North Sea and provides a transferable framework for other regions.