Contact

  • Academic
    jackbark@stanford.edu
    University - Student Department: Department of Oceans Position: Graduate

All Publications

  • Sprint-like cardiac dynamics support repeated acrobatic lunges in foraging rorqual whales. Proceedings of the National Academy of Sciences of the United States of America Blawas, A. M., Fahlbusch, J., Barkowski, J., Cade, D. E., Calambokidis, J., Friedlaender, A. S., Southall, B., Ponganis, P. J., Goldbogen, J. A. 2026; 123 (31): e2613082123

    Abstract

    The dive response decreases heart rate, regulates blood flow distribution, conserves oxygen, and extends dive duration. In diving animals, dive heart rate can be modulated to meet increased demands of exercise during foraging. However, lunge-feeding rorquals represent an extreme example of exercise under breath-hold conditions: Though most of their dive time is spent gliding and filtering, lunges require high-power, acrobatic sprints to engulf massive volumes of prey-laden water. Our biologging data show that heart rate repeatedly increases with lunging but only gradually declines during filtering, dissimilar from the heart rate-activity coupling observed in other divers. We suggest that the unique nature of rorqual exercise likely requires glycolytic metabolic substrates, rather than aerobic substrates, during short, powerful lunges. During slow filtering, high heart rates may help partially renew these energy sources via oxygen-dependent pathways. By temporarily buffering oxygen demand from supply, the flexible dive response appears to optimize oxygen use in lunging rorquals and support aerobically "cheap" foraging. The data also show that dive cycle heart rate scope increases with rorqual size. We propose that cardiovascular plasticity during high and low power phases of foraging dives underpins rorquals' ability to achieve high foraging efficiencies and combine explosive predation with grazing-like efficiency in a single lineage.

    View details for DOI 10.1073/pnas.2613082123

    View details for PubMedID 42507932

  • Audible changes in marine trophic ecology: Baleen whale song tracks foraging conditions in the eastern North Pacific. PloS one Ryan, J. P., Oestreich, W. K., Benoit-Bird, K. J., Waluk, C. M., Rueda, C. A., Cline, D. E., Zhang, Y., Cheeseman, T., Calambokidis, J., Fahlbusch, J. A., Barkowski, J., Fleming, A. H., Turner Tomaszewicz, C. N., Santora, J. A., Margolina, T., Joseph, J. E., Friedlaender, A. S., Goldbogen, J. A. 2025; 20 (2): e0318624

    Abstract

    Among tremendous biodiversity within the California Current Ecosystem (CCE) are gigantic mysticetes (baleen whales) that produce structured sequences of sound described as song. From six years of passive acoustic monitoring within the central CCE we measured seasonal and interannual variations in the occurrence of blue (Balaenoptera musculus), fin (Balaenoptera physalus), and humpback (Megaptera novaeangliae) whale song. Song detection during 11 months of the year defines its prevalence in this foraging habitat and its potential use in behavioral ecology research. Large interannual changes in song occurrence within and between species motivates examination of causality. Humpback whales uniquely exhibited continuous interannual increases, rising from 34% to 76% of days over six years, and we examine multiple hypotheses to explain this exceptional trend. Potential influences of physical factors on detectability - including masking and acoustic propagation - were not supported by analysis of wind data or modeling of acoustic transmission loss. Potential influences of changes in local population abundance, site fidelity, or migration timing were supported for two of the interannual increases in song detection, based on extensive local photo ID data (17,356 IDs of 2,407 individuals). Potential influences of changes in foraging ecology and efficiency were supported across all years by analyses of the abundance and composition of forage species. Following detrimental food web impacts of a major marine heatwave that peaked during the first year of the study, foraging conditions consistently improved for humpback whales in the context of their exceptional prey-switching capacity. Stable isotope data from humpback and blue whale biopsy samples are consistent with observed interannual variations in the regional abundance and composition of forage species. This study thus indicates that major interannual changes in detection of baleen whale song may reflect underlying variations in forage species availability driven by energetic variations in ecosystem state.

    View details for DOI 10.1371/journal.pone.0318624

    View details for PubMedID 40009591

    View details for PubMedCentralID PMC11864538

  • Advancing the Interpretation of Shallow Water Marine Soundscapes FRONTIERS IN MARINE SCIENCE McKenna, M. F., Baumann-Pickering, S., Kok, A. C. M., Oestreich, W. K., Adams, J. D., Barkowski, J., Fristrup, K. M., Goldbogen, J. A., Joseph, J., Kim, E. B., Kugler, A., Lammers, M. O., Margolina, T., Reeves, L., Rowell, T. J., Stanley, J. A., Stimpert, A. K., Zang, E. J., Southall, B. L., Wall, C. C., Van Parijs, S., Hatch, L. T. 2021; 08

    View details for DOI 10.3389/fmars.2021.719258

    View details for Web of Science ID 000708461900001