The initial offshore leg of the Marine Geophysical Survey by the R/V Marcus G. Langseth taking place in the north Pacific this summer is near completion. Monitors have not seen any killer whales.
The National Oceanic and Atmospheric Administration (NOAA) has issued an incidental harassment authorization for a second portion of this survey off the coast of Oregon. This portion will last two days.
Conditions of the authorization include monitoring and mitigation measures to protect marine mammals in the survey area, including a requirement to shut-down if any killer whales are sighted or detected acoustically at any distance. Consultation under the Endangered Species Act and Marine Mammal Protection Act for one remaining portion of the survey that could overlap with Southern Residents is still underway.
NOAA is coordinating with NOAA Fisheries Headquarters staff members, who are conducting the consultation and issuing permits, along with the action proponents, to evaluate the proposed activities and information on marine species in the region, including Southern Resident killer whales.
NOAA staff members are working closely with the action proponents and have made progress in developing appropriate and necessary monitoring and mitigation measures, including an additional monitoring vessel with observers and incorporating real-time sighting data.
The project team will continue to coordinate with local research groups (i.e., Cascadia and Oregon State University) and sighting networks (i.e., Orca Network and The Whale Museum) to inform this process.
Check NOAA's headquarters web page for more information on the project. Scroll down to see documents posted under “2012 L-DEO Seismic Survey in the Northeast Pacific Ocean.”
Authorization of Marine Seismic Geophysical Survey underway
The first portion of the Marine Geophysical Survey by the R/V Marcus G. Langseth off the coast of Washington and Oregon has been authorized by the National Oceanic Atmospheric Administration.
The project which uses airguns and multi-beam echosounder signals, includes two ridge-to-trench transects, the first complete such transects ever acquired of an oceanic plate.
It is expected that differences in hydration of the down-going plate from Oregon to Washington may play a significant role in the seismic hazard of the Cascadia subduction zone along this heavily populated Pacific northwest margin. The survey is being conducted by the Lamont-Doherty Earth Observatory with funding from the National Science Foundation.
The project involves multiple universities, scientists and graduate students. In addition to the data on the Juan de Fuca plate, the project:
(2) Cascadia Thrust Zone would result in a 3-D image of the seismic velocity structure of the Cascadia thrust zone which would provide information on complex buried structures in this region that appear to affect the frictional behavior of the plate boundary megathrust fault.
A better image of the structure in this region, which coincides with apparent north-south changes in the frequency of occurrence of very large earthquakes and in contemporary patterns of strain accumulation would provide background information for generating improved earthquake hazards analyses and a better understanding of the processes that control megathrust earthquake characteristics.
(3) Cascadia Subduction Margin would use the results of a 2-D seismic survey of the Cascadia subduction margin off Grays Harbor, WA, to address key scientific issues regarding the location, physical state, fluid budget, and associated methane systems of the subducting plate boundary and overlying crust.
This system, which is the target of all three studies, is of great scientific and societal interest, as it is capable of very large (~9 MW) earthquakes, creates volcanic hazards in the Cascades, and hosts periodic episodic tremor and slip episodes.
The application for the survey includes information on the possible effects the project on marine species and proposed mitigation.
Since the two remaining portions of the project could overlap with the three southern resident killer whale pods, NOAA Fisheries Headquarters staff members are still evaluating the proposed activities. The southern resident pods are protected under the Endangered Species Act.
Conditions of the authorization for the first portion include monitoring and mitigation measures to protect marine mammals in the survey area.
The survey involves one source vessel, the R/V Marcus G. Langseth. The Langseth will deploy a 36-airgun array as an energy source. The receiving system will consist of one 8-km long hydrophone streamer and/or ocean bottom seismometers (OBSs).
As the airgun array is towed along the survey lines, the hydrophone streamer will receive the returning acoustic signals and transfer the data to the on-board processing system. The OBSs record the returning acoustic signals internally for later analysis.
This image is on page 8 of the 283 page PDF
- Request by Lamont-Doherty Earth Observatory for an Incidental Harassment Authorization
LINKS
PROJECT:
The Request by Lamont-Doherty Earth Observatory for an Incidental Harassment Authorization to Allow the Incidental Take of Marine Mammals during a Marine Geophysical Survey by the R/V Marcus G. Langseth in the Northeast Pacific Ocean, June–July 2012
NOAA headquarters webpage www.nmfs.noaa.gov/pr/permits/incidental.htm. Scroll down to see documents posted under "2012 L-DEO Seismic Survey in the Northeast Pacific Ocean."
Biological Opinion - issued June 13, 2012 - NOAA's National Marine Fisheries Service Endangered Species Act Section 7 Consultation
SOUND:
What We Learn from the Oceans Using Soundwaves - From Columbia University
Sounds in the Sea - University of Rhode Island
Sound in the Sea: Facts and Myths - University of Rhode Island
FAQs on Marine Sound - University of Rhode Island
ORCAS
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