[Top] [All Lists]

Report: Future Directions for Acoustic Marine Mammal Surveys

Subject: Report: Future Directions for Acoustic Marine Mammal Surveys
From: Dave Mellinger <>
Date: Tue, 27 May 2003 15:24:45 -0700
marine mammal surveys.  The workshop report is now available; 
 an executive summary is below.  An on-line copy of the report 
 may be found at 
 If this link is split across two lines, you will need to paste it
 together to make it work.
 If you would like a printed copy of the report, please let me 
 Dave Mellinger
 Future Directions for Acoustic Marine Mammal Surveys:
 Stock Assessment and Habitat Use
 Report of a workshop held Nov. 21-23, 2002,
 Southwest Fisheries Science Center, NOAA Fisheries, San Diego, CA.
 Executive Summary
 Current uses of acoustics:
 Acoustic survey methods are now used primarily to augment visual
 sighting methods. During line-transect surveys, acoustic observers who
 monitor towed hydrophone arrays routinely detect more groups of
 animals than visual observers. In some cases, acoustic detections are
 being used to make more accurate estimates of marine mammal
 populations than would be possible with visual methods
 alone. Autonomous recorders are cost effective for use in regions that
 are difficult or expensive to reach, such as Antarctica, the Indian
 Ocean, and areas far offshore in the Atlantic and Pacific Oceans, and
 they are effective for seasonal coverage when visual surveys are not
 feasible. They may also be useful to survey areas infrequently
 occupied by marine mammals, where routine visual surveys would have a
 very high cost per sighting.
 Future uses of acoustics:
 Acoustics holds eventual promise of gathering information about marine
 mammals at very low cost. Research is needed in several areas to
 realize this possibility. Discussion at the workshop centered on these
 broad categories:
     1. Population structure. If acoustic differences between
     populations of marine mammals are tied to genetic differences,
     then acoustics would offer a relatively fast and inexpensive
     method to assess population structure. The foremost research need
     is to determine the relationship between the population structures
     as indicated by acoustics and by genetics.
     2. Abundance and density. Acoustic observation can complement
     visual observation to provide more accurate estimates of marine
     mammal populations. This has been done for some populations, as
     for example the Bering-Beaufort-Chukchi Sea stock of bowhead
     whales and the eastern Pacific stock of sperm whales, but it could
     be done more widely. For effective acoustic censuses, calibration
     methods must be determined by joint visual-acoustic studies;
     determining such factors offers the promise of low-cost surveys
     for many species of marine mammals using acoustic
     methods. Research is also needed in acoustic species
     identification, particularly for smaller odontocetes.
     3. Impacts of noise. Responses of marine mammal to natural noise
     have not been well studied. Natural noise can include sounds of
     other marine mammals, especially conspecifics, as well as physical
     noise sources such as from geological sound sources and
     wind. Responses of marine mammals to anthropogenic noise was seen
     as a topic well covered by other work; discussion here was limited
     to the contribution that passive acoustics can make. Assisting in
     the constructing of an "ocean noise map" was strongly supported,
     as was better public communication of information on ocean noise
     4. Relative density, seasonal distribution, and trends. For
     determining relative density or abundance, and trends in
     abundance, many of the same calibration factors are needed as for
     determining absolute abundance. But in the absence of those
     calibration factors, acoustic methods can offer estimates of
     minimum population size, and can be used to track large-scale
     movement patterns.
 Workshop discussion culminated in a list of recommendations for management,
 research, and field operations.

<Prev in Thread] Current Thread [Next in Thread>
  • Report: Future Directions for Acoustic Marine Mammal Surveys, Dave Mellinger <=

The University of NSW School of Computer and Engineering takes no responsibility for the contents of this archive. It is purely a compilation of material sent by many people to the Bioacoustics-L mailing list. It has not been checked for accuracy nor its content verified in any way. If you wish to get material removed from the archive or have other queries about the archive e-mail Andrew Taylor at this address: andrewt@cse.unsw.EDU.AU