Acoustic ecology of marine mammals in the era of blue economy: Navigating development and ocean noise challenges

Industrialisation and ocean economy development have led to a steady increase in underwater noise across the world’s oceans. Concerns about marine noise, research on the effects of noise on ocean ecosystems, engineering solutions to minimise noise and mitigate effects, and policies to manage noise have been developed as corollaries. Given how well sound travels under water, compared to other cues, such as light and chemicals, we assume most animals in the ocean have evolved to rely on sound to support key life functions, including environmental sensing and communication. However, the actual information we have on marine fauna hearing, sound usage, and noise impacts is limited to perhaps a hundred species, with marine mammals being amongst the best studied. Bioacoustic research outputs do not seem to be able to keep up with the pace of offshore development (e.g., subsea mining, subsea processing)—leaving us in a situation where we must manage underwater noise in a great absence of data. Let us review what we do know, what we do not know, and what we need to know. Is the Blue Economy as “green” as we want it to be?