In 2012 a seismic survey campaign involving four vessels was conducted in Baffin Bay, West Greenland. Long-distance (150 km) pre-survey acoustic modeling was performed in accordance with regulatory requirements. Four acoustic recorders, three with hydrophones at 100, 200, and 400 m depths, measured ambient and anthropogenic sound during the survey. Additional recordings without the surveys were made from September 2013 to September 2014. The results show that (1) the soundscape of Baffin Bay is typical for open ocean environments and Melville Bay's soundscape is dominated by glacial ice noise; (2) there are distinct multipath arrivals of seismic pulses 40 km from the array; (3) seismic sound levels vary little as a function of depth; (4) high fidelity pre-survey acoustic propagation modeling produced reliable results; (5) the daily SEL did not exceed regulatory thresholds and were different using Southall, Bowles, Ellison, Finneran, Gentry, Greene, Kastak, Ketten, Miller, Nachtigall, Richardson, Thomas, and Tyack [(2007) Aquat. Mamm. 33, 411–521] or NOAA weightings [National Marine Fisheries Service (2016). NOAA Technical Memorandum NMFS-OPR-55, p. 178]; (6) fluctuations of SPL with range were better described by additive models than linear regression; and (7) the survey increased the 1-min SPL by 28 dB, with most of the energy below 100 Hz; energy in the 16 000 Hz octave band was 20 dB above the ambient background 6 km from the source.

Concerns about the potential environmental impacts of geophysical surveys using air gun sources, coupled with advances in geophysical surveying technology and data processing, are driving research and development of commercially viable alternative technologies such as marine vibroseis (MV). MV systems produce controllable acoustic signals through volume displacement of water using a vibrating plate or shell. MV sources generally produce lower acoustic pressure and reduced bandwidth (spectral content) compared to air gun sources, but to be effective sources for geophysical surveys they typically produce longer duration signals with short inter-signal periods. Few studies have evaluated the potential effects of MV system use on marine fauna. In this desktop study, potential acoustic exposure of marine mammals was estimated for MV and air gun arrays by modeling the source signal, sound propagation, and animal movement in representative survey scenarios. In the scenarios, few marine mammals could be expected to be exposed to potentially injurious sound levels for either source type, but fewer were predicted for MV arrays than air gun arrays. The estimated number of marine mammals exposed to sound levels associated with behavioral disturbance depended on the selection of evaluation criteria. More behavioral disturbance was predicted for MV arrays compared to air gun arrays using a single threshold sound pressure level (SPL), while the opposite result was found when using frequency-weighted sound fields and a multiple-step, probabilistic, threshold function.

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.

To support Canada's efforts in addressing underwater radiated noise (URN), a novel ship noise rating system was developed using the distribution of Radiated Noise Levels (RNL) measurements from over 49,000 transits of 5947 different ships. The system sets category-specific URN targets for nine ship categories and allows for URN evaluations using semi-controlled measurements made during routine ship operations. The approach extends the framework recommended by the national Underwater Vessel Noise Reduction Targets (UVNRT) Working Group, by using scaled RNL measurements to account for operating condition differences during measurements, and vessel dimensional differences within the same ship category. Ships are rated according to their URN quartile, allowing for future refinements as vessel RNL distributions evolve. Integration into automated monitoring tools, including the Boundary Pass Underwater Listening Station, facilitates cost-effective ratings of large numbers of ships and allows for data-driven refinements. The rating system contributes to Canada's development of ship URN management methods and target setting approaches and provides information to support the country's continued engagement at the International Maritime Organization (IMO) as international policy frameworks evolve.