Harbor Seal Behavior Under Shipping Noise: A Coupled Soundscape and Agent-Based Modeling Approach

Schaffeld, T., N. Maurer, A.S. Frankel, M.-N.R. Matthews, F. Campo, F. Pace, R. Racca, D.A. Nachtsheim, J.G. Schnitzler, U. Siebert, A. Gilles

The Effects of Noise on Aquatic Life IV. Springer Nature Switzerland, Cham. pp. 1–14.

DOI: 10.1007/978-3-031-94229-7_125-1

The harbor seal (Phoca vitulina) is a sentinel top predator in the North Sea, inhabiting regions with high shipping activity. The rapid expansion of offshore wind farms (OWFs) is expected to further increase vessel traffic and underwater noise levels. The population-relevant behavioral consequences for harbor seals remain difficult to infer from tagging or visual surveys alone due to limited sample sizes, uneven coverage, and strong interindividual variability. This chapter presents a methodological framework that couples a large-scale, time-varying vessel noise soundscape with a telemetry-informed agent-based model (ABM) to explore potential future scenarios and mitigation efforts. Behavioral parameters were derived from 13 seals equipped with sound and movement sensing biologgers (DTAGs). Simulated animals were programmed with empirically derived parameters within four defined behavioral states, while the behavioral response functions are integrated as state-probability modifiers. Four scenarios are defined: a 2018 baseline, OWF-2030 and OWF-2050 traffic projections, and a speed-reduction policy within marine protected areas. The chapter provides a reproducible blueprint for constructing, parameterizing, and coupling soundscape and ABM components, enabling transparent what-if analyses beyond the reach of observational studies.