Acoustic Signatures of Shipping, Weather and Marine Life: Comparison of NE Pacific and Arctic Soundscapes

Acoustic signatures of shipping, weather and marine life are relatively well constrained, but there are strong variations with their oceanographic context and human activities. We investigate two contrasted settings, for timescales up to a year and frequencies up to 2 kHz. Arctic data from NOAA Noise Reference Station(NRS) NRS01, 500 m deep in the Arctic Chukchi Sea and away from major shipping areas is compared with measurements from Folger Deep, part of the Ocean Networks Canada network, 95 m deep and close to shipping lanes. PAMGuide is used to quantify broadband Sound Pressure Levels (SPLs), Third-Octave band Levels (TOLs), Power Spectral Densities (PSDs) and percentile contributions. The Acoustic Complexity Index (ACI) is an emerging metric to measure the apparent acoustic biodiversity, and we use its Seewaveimplementation. We compare the third-octave bands centred on 63 Hz and 125 Hz (“shipping” bands of the European Marine Strategy Framework Directive) in each environment and assess their use in the presence of heavy ice and little to no shipping. Metrics designed for open waters are not directly applicable to icyenvironments, or at least not on their own. They must be supplemented with multivariate analyses of context-specific third-octave bands

Arctic Acoustic Environments – Federating observations and analyses with the International Quiet Ocean Experiment

Arctic waters are experiencing rapid changes due to global warming, affecting ecosystems and leading to increasing economic activities. Many of these changes can be measured directly or indirectly with underwater acoustics. The Working Group on the Arctic Acoustic Environment (AAE) of the International Quiet Ocean Experiment (IQOE) aims to stimulate observations of sound (levels and distribution) in the Arctic Ocean and its impacts. We organised a virtual conference in November 2020 to share recent results from the international community and discuss common issues and possible solutions. The COVID-19 pandemic amplified the challenges of Arctic deployments and recoveries, curtailing access to ships at very short notice, but also opening the way for more direct collaboration. The post-COVID task will be to establish more resilient international back-up mechanisms for Arctic operations to support acoustic (and other) observations. The increasing length of the measurements, spanning several decades now, with sampling rates often close to 100,000 samples/second, results in “big data” challenges of storage, sharing, data retrieval and long-term archiving. Discussions also addressed the emerging trends in acoustic propagation models across complex terrains and machine learning (with the need for accessibility and traceability). Finally, the embedding of local and traditional knowledge must be accomplished through dialogue and co-ownership of the science and results

Acoustic interaction of humpback whales and recreational fishing vessels in a temperate fjord - Measurements in Rivers' Inlet, British Columbia

Underwater environments are acoustically complex and highly variable. Natural processes, biological organisms and human activities all emit sound, at various levels and over broad frequency ranges. To facilitate ocean resources management and mitigate impacts of anthropogenic noise, areas where these sources interact in the space, time and frequency domains need to be identified. This paper presents analyses of field measurements taken on the west coast of Canada in August/September 2008, along the temperate fjord of Rivers’ Inlet (British Columbia). Humpback whales (Meganoptera novaeangliae) use this fjord as a feeding ground, sharing it with recreational fishing craft mostly consisting of small boats (20 m or less). Measurements were taken over several days at regularly-spaced locations in deep water from the mouth of the fjord inward, using a broadband (0.1 – 30 kHz effective bandwidth) hydrophone deployed 10 m deep. Analysis focused on the joint use of acoustic bandwidths by humpback whales and recreational fishing vessels. Recorded spectra of humpback whale vocalizations and vessel noise overlapped considerably in the range 0.1 – 1 kHz. At the distances recorded (> 1 km) vessel noise produced a mean increase of 4 dB above background levels in this range. Ambient noise levels are also discussed briefly with reference to previous studies