From simple to sophisticated: characterization of new signals in the expanding vocal repertoire of the East Indian Ocean pygmy blue whale

Jolliffe, C.D., C.R. McPherson, R.D. McCauley, and G. Genty

Frontiers in Marine Science 13: 1821993 (2026)

DOI: 10.3389/fmars.2026.1821993

In an underwater world, acoustic signaling is an important aspect of the social communication of marine mammal species with the complexity of a species’ vocal repertoire often considered to reflect the social complexity of the population. The acoustic behavior of blue whales is relatively well studied, though much of what is known is limited to the characteristically loud, low frequency songs that are believed to be produced as a reproductive display by male animals. Blue whales are known to produce song units outside of stereotypical song sequences, along with short duration down swept signals known as ‘D calls’ leading researchers to believe their acoustic communication, and by proxy their social cognition is relatively less complex when compared to other baleen whales such as humpback and bowhead whales. Drawing from a multidecadal data set of acoustic recorders deployed throughout the migratory range of blue whales, this paper characterizes four previously undescribed signals for the East Indian Ocean pygmy blue whales and presents the first known evidence of a large baleen whale producing these social sounds in stereotyped patterned sequences that bear similarity to song. This indicates a higher level of complexity in the social communication of blue whales than previously understood and provides further support that blue whales have a higher level of social cognition than has been considered previously.

Geographe bay as an opportunistic foraging habitat for baleen whales

Genty, G., C.D. Jolliffe, J.C. Perkins, and C.R. McPherson

Marine Biology 173(6): 91 (2026)

DOI: 10.1007/s00227-026-04830-9

Geographe Bay, located along the southwest coast of Western Australia, is increasingly recognised as a region of ecological significance for migrating baleen whales. This study investigates the bay’s potential role as an opportunistic feeding ground, particularly for species such as pygmy blue whales, which are typically considered krill specialists but may exhibit dietary flexibility under varying prey conditions. Over three years, drone-based observations recorded frequent whale defecation events, with faecal colouration consistently ranging from green to yellow, hues commonly associated with copepod digestion due to their carotenoid content. To examine the underlying prey availability, this study provides the first investigation of applying environmental DNA metabarcoding on plankton tows within bay to assess food availability for baleen whales. A total of 3.2 million quality-filtered reads were assigned to 600 amplicon sequence variants (ASVs), with Arthropoda dominating the assemblage. Notably, the copepod order Calanoida accounted for over 20% of total reads and up to 95% of the relative abundance at individual transects. Key calanoid taxa included Clausocalanus furcatus, Temora turbinata, and Paracalanus indicus, all consistently detected across the transects. The strong dominance of copepods, paired with behavioural evidence and faecal pigmentation, supports the hypothesis that whales may be actively feeding in Geographe Bay. These findings highlight Geographe Bay as not only a sheltered resting habitat, particularly for mother/calf pairs, but also an energetically valuable area that may help buffer whales against variable offshore prey availability.

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.

A ship noise rating system for underwater vessel noise reduction targets

Matthews, M.-N.R., J.N. Dolman, Z. Li, D.E. Hannay, and A. Cosandey-Godin

Marine Pollution Bulletin 228: 119483 (2026)

DOI: 10.1016/j.marpolbul.2026.119483

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.

Collaborating for Conservation: A Summary of Current and Future Directions in Blue Whale Science

Capri D. Joliffe, K. Edyvane, G. Genty, R. D. McCauley, C. McPherson, D. Barlow, B. L. Southall, L. Irvine, T. A. Branch, C. Jenner, M. Jenner, C. Burton, G. Whittome, P. Gill, G. Russell, B. Elsdon, J. Quintas

Aquatic Conservation: Marine and Freshwater Ecosystems (2026)

DOI: 10.1002/aqc.70331

The blue whale has been the focus of considerable research effort worldwide, yet significant gaps remain in the understanding of this species' ecology, behaviour, distribution and resilience to anthropogenic pressures. This review synthesizes insights from an international workshop held during the 25th Biennial Conference on the Biology of Marine Mammals 2024 hosted in Perth, Western Australia, which convened over 40 scientists specializing in blue whale research. The workshop aimed to consolidate the current state of knowledge, identify key research gaps and develop collaborative strategies to advance blue whale science with a focus on the local population of blue whales, the eastern Indian Ocean pygmy blue (EIOPB) whale. With research efforts into the species intensifying in recent years, there exist considerable opportunities for collaboration across research groups to avoid unnecessary duplication of effort and maximize the value of research efforts. Further, filling critical knowledge gaps that limit conservation and effective population management will require holistic studies focused not only on blue whales but on their prey species, krill and the mechanistic links between environmental drivers, krill and blue whales.

Estimating sediment properties using a new source level function for wind-driven underwater sound derived from long-term archival data (PDF)

Martin, S.B. and M. Siderius.

The Journal of the Acoustical Society of America 159(1): 300–314 (2026)

DOI:10.1121/10.0042217

Wind-driven breaking waves generate the background sound throughout the ocean. An accurate source level for wind-driven breaking waves is needed for estimating the ambient sound levels needed for sound exposure modeling, environmental assessments, and assessing the detection performance of sonars. Previous models applied a constant roll-off of sound levels at −16 dB/decade at all wind speeds, and these models' source levels were flat at frequencies below ∼1000 Hz due to a lack of measurements. Here, we analyzed 16 long-term archival datasets with limited anthropogenic sound sources to estimate the wind-driven source level down to 100 Hz. We estimated the site-specific areic propagation loss (APL) using a ray-based model and then added the APL to the median received levels at each wind speed to obtain the source level. An equation for the areic dipole source level is provided that increases as wind speed cubed, like most other air-ocean coupling processes. The model may be used to estimate sediment properties (given a wind speed history and measured sound levels) or to estimate wind speeds (given the sediment type and measured sound levels). It is well suited for estimating ambient sound levels from wind for soundscape modeling. An open-source implementation is available.