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  • Report of the Joint Marine Mammal Commission – National Marine Fisheries Service Passive Acoustic Surveying Workshop Dennis Heinemann Jason Gedamke Erin Oleson Jay Barlow Jessica Crance Marla Holt Melissa Soldevilla Sofie Van Parijs

    U.S. Department of Commerce National Oceanic and Atmospheric Administration (NOAA) National Marine Fisheries Service (NMFS) NOAA Technical Memorandum NMFS-F/SPO-164 July 2016

  • Report of the Joint Marine Mammal Commission – National Marine Fisheries Service Passive Acoustic Surveying Workshop

    Dennis Heinemann, Marine Mammal Commission Jason Gedamke, Office of Science & Technology, NMFS Erin Oleson, Pacific Islands Fisheries Science Center, NMFS Jay Barlow, Southwest Fisheries Science Center, NMFS Jessica Crance, Alaska Fisheries Science Center, NMFS Marla Holt, Northwest Fisheries Science Center, NMFS Melissa Soldevilla, Southeast Fisheries Science Center, NMFS Sofie Van Parijs, Northeast Fisheries Science Center, NMFS

    NOAA Technical Memorandum NMFS-F/SPO-164 July 2016

    U.S. Department of Commerce Penny S. Pritzker, Secretary National Oceanic and Atmospheric Administration Kathryn D. Sullivan, Administrator National Marine Fisheries Service Eileen Sobeck, Assistant Administrator for Fisheries

    Marine Mammal Commission Rebecca J. Lent, Executive Director

  • Recommended citation:

    Heinemann, D., J. Gedamke, E. Oleson, J. Barlow, J. Crance, M. Holt, M. Soldevilla, and S. Van Parijs. 2016. Report of the Joint Marine Mammal Commission-National Marine Fisheries Service Passive Acoustic Surveying Workshop, 16–17 April, 2015, La Jolla, CA. Marine Mammal Commission, Bethesda, MD, and National Marine Fisheries Service, Silver Spring, MD., U.S. Dept. Commerce. NOAA Tech. Memo. NMFS-F/SPO-164, 107 p.

    Copies of this report may be obtained from:

    NOAA Fisheries Office of Science and Technology National Oceanic and Atmospheric Administration 1315 East-West Highway, SSMC 3-Room 12538 Silver Spring, MD 20910 or Marine Mammal Commission 4340 East-West Highway, Rm 700 Bethesda, MD 20814

    Or online at:

    Disclaimer The workshop Steering Committee prepared this report for the National Marine Fisheries Service. Any mention of, or reference to, trade names or commercial products does not constitute endorsement by the Marine Mammal Commission or the National Marine Fisheries Service.


  • Passive Acoustic Surveying Workshop, La Jolla, CA, April 2015


    Executive Summary

    The National Marine Fisheries Service (NMFS) is responsible for gathering the information needed to support its stock assessments of marine mammals. The distribution and abundance of each stock is the core of those assessments. Data to support stock assessments are traditionally gathered by conducting visual observations during shipboard and/or aerial surveys. Increasingly, however, the agency is having difficulty provide abundance estimates and other data needed for marine mammal stock assessments. These challenges have spurred NMFS to increase its investment in alternative monitoring methods that may fill some critical data gaps more effectively and efficiently than large-scale ship and aerial surveys alone.

    For the last several years, research teams across NMFS have been investigating the use of advanced survey techniques to fill the stock assessment data gap or to supplement traditional survey data. Passive acoustic monitoring (PAM) is a promising approach that can be pursued within the context of existing ship-based survey efforts or as part of an autonomous monitoring system. Research teams around the world are developing new vehicles, recorders, software and analytical techniques to study marine mammals. However, it is clear that one approach will not adequately address all NMFS science goals and research requirements for stock assessments. Technological, scientific and funding constraints are hindering the full and efficient use of passive acoustics by NMFS to inform its marine mammal stock assessments.

    NMFS sponsored a previous workshop on stock assessment using passive acoustics (Mellinger and Barlow, 2003). Since then, however, there has been rapid growth in the hardware and

    software for collecting passive acoustic data and in the analytical approaches for processing these large datasets. In April 2015, the Marine Mammal Commission and NMFS convened a workshop to explore how passive acoustics may now best contribute to the significant challenges in surveying marine mammals and fulfilling stock assessment requirements. The workshop addressed the breadth and depth of passive acoustics development and use across the Science Centers in the context of its broader development and use throughout the marine mammal community. Workshop participants included researchers from all six Science Centers, a representative of NMFS’s Office of Science & Technology (OS&T), a representative of the Marine Mammal Commission, and experts from academic institutions.

    Science Center Resources Information collected from NMFS’s Science Centers before the workshop uncovered a number of important issues. The use of passive acoustics to gather critical data and to augment visual surveys of marine mammals is clearly growing in importance. Passive acoustics are used to augment ship-based, line-transect surveys; to contribute to stock delineation; to assess the occurrence and seasonality of marine mammals; and to estimate the density, abundance, and trends of marine mammals. However, limited resources have caused the Science Centers to rely primarily on outside organizations and researchers for support and expertise. Most NMFS staff members engaged in passive acoustics are temporary employees or students, making it very difficult to build the necessary in-house expertise and institutional knowledge. In addition, the availability of equipment is an issue for several Science Centers: often they do not have the resources to develop,

  • Passive Acoustic Surveying Workshop, La Jolla, CA, April 2015


    purchase or lease the equipment they require. An exception to this limitation is the Southwest Fisheries Science Center (SWFSC), which has led the Science Centers in a concerted effort to standardize the technology and increase the efficiency of NMFS in using and maintaining towed-array systems. Another issue affecting the Science Centers is that they do not have the information technology infrastructure to store and disseminate the vast quantities of digital data associated with passive acoustic studies.

    Using Passive Acoustics in Stock Assessment

    Occurrence and Seasonality

    Deriving a list of species that occur in a management area is one of the most basic components of stock assessment. When it is not feasible to conduct regular surveys to evaluate species’ seasonal occurrence in a region, passive acoustics has contributed significantly to marine mammal stock assessments. When a vocalization from a species is characteristic and well described, its detection in an acoustic recording can document occurrence of that species in a region. In addition, a collection of detections over a longer time series helps to determine whether the species is common or rare and whether it occurs year-round, seasonally or infrequently. There are many examples of PAM providing rich datasets from which species’ occurrence and seasonality have been evaluated. However, there is more to be done in the field, especially as associations with habitat and environmental change become increasingly important aspects of stock assessment.

    The assessment of occurrence and seasonality requires long-term monitoring, and for this, autonomous instruments are ideal. Such instrumentation can be deployed at relatively low

    cost, although the large volume of resulting data may require significant resources for analysis and storage. Increasing capacity in this area will require research in a number of areas, including establishing species/stock specific vocalization1 repertoires; understanding the influence of ecological and social context on vocalization behavior; development of autonomous platforms that can be used over the vast pelagic ocean basins; and the development of much better automatic vocalization detectors and classifiers.

    Stock Delineation

    Distinguishing stocks and defining their boundaries is challenging, often requiring genetic or morphological differences between groups of animals to delineate putative stocks. There has been growing interest in using other lines of evidence for stock delineation, including differences in the characteristics of vocalizations. Geographic mapping of the vocalization characteristics for some baleen whale and delphinid species suggests differences in vocalizations may be a promising avenue of pursuit for identifying putative stocks for further study using other non-acoustic lines of evidence. Several factors can confound the apparent differences in vocalizations among putative stocks. Vocalization differences may reflect habitat, social or seasonal context, necessitating the delineation of differences in vocalizations that hold up over long periods and that encompass the full range of environmental and social contexts.

    1 In this report, the term “vocalization” refers to the

    wide range of sounds