Standardized Methods Developed for Passive Acoustic Surveys of Cetaceans

In November 2012, Erin Oleson and Yvonne Barkley of the PIFSC Cetacean Research Program participated in a 10-day workshop at the NOAA Fisheries Southwest Fisheries Science Center (SWFSC) in La Jolla, CA, to develop standardized methods for passive acoustic data collection. The workshop focused on producing standard equipment for use by each of the 6 NOAA Fisheries Science Centers. Two passive acoustic arrays were built at the workshop for each Center. The equipment will be deployed from NOAA research ships to collect data on line-transect surveys designed to assess the abundance of cetacean species throughout each ocean region under NOAA stewardship.

Development of standard methods and equipment for data collection using passive acoustic arrays will improve the assessment and 
               monitoring of cetacean populations across all ocean regions under NOAA stewardship.
Development of standard methods and equipment for data collection using passive acoustic arrays will improve the assessment and monitoring of cetacean populations across all ocean regions under NOAA stewardship.

During the surveys, scientists detect and locate cetaceans using towed acoustic arrays and visual observations. Acoustic data enable biologists to estimate the number of animals in the survey area and identify the species present. Technology has advanced over the years to improve methods for acoustics data collection and increase the quality and quantity of data.

A new modular design, enabled by underwater connectors, allows each component of the acoustic array system to be easily detached so that parts are interchangeable between all Science Centers. The equipment includes two different oil-filled hydrophone arrays. The 'end array' is consistent with the standard design that has been used during line-transect cetacean surveys by the SWFSC and PIFSC for the past several years. This hydrophone array allows scientists to collect acoustic data using a broad range of frequencies and thus collect data on all species of odontocete cetaceans and employ consistent protocols across all surveys.