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Technical Summary

NSL GM-20-01

Study Title Nearshore Sound Propagation of and Species Response to Active-Source 

Seismic Surveys

Report Title Nearshore sound propagation of and species response to active-source seismic 

surveys

Report Number(s) (OCS 

Study) 2024-056

Completion Date of Report July 2024

Number of Pages 31

Award Number(s) BOEM Interagency Agreement Number M21PG0008 

National Science Foundation Award Number 2118594

Sponsoring OCS Region or 

Office Gulf of Mexico

Applicable Planning Area(s) Pacific and National

Fiscal Year(s) of Study 

Funding FY 2021 – FY 2023 

Costs by Fiscal Year FY 2021: $211,773; FY2022: $33,391; FY2023: $4,641

Cumulative Project Cost $249,805

Project Manager(s) Sarah K. Henkel

Affiliation of Project 

Manager(s)

Department of Integrative Biology, Hatfield Marine Science Center, Oregon 

State University

Address of Project 

Manager(s) 2030 SE Marine Science Dr., Newport, OR 97365

Principal Investigator(s) Sarah K Henkel, Scott A Heppell, Grace Chang, Taylor K Chapple

Keywords fisheries, noise, acoustic, rockfish, crabs, seismic, tagging

ABSTRACT: An National Science Foundation (NSF)-sponsored geophysical survey to collect data along 

the Cascadia Subduction Zone was conducted using an array of 36 airguns as an energy source. We 

deployed an integrated vector sensor array (NoiseSpotterTM) to measure both the pressure and the particle 

motion components of the acoustic disturbance from the seismic survey. We assessed the behavioral 

responses of rockfishes (Sebastes spp.), lingcod, and Dungeness crab to these seismic pulses using 

acoustic telemetry, tracking 2-D movements and acceleration. Both rockfish species had higher 

accelerations on the first day of the survey pass with potential habituation on subsequent days. Black 

rockfish exhibited clustering around the reef during the survey period, while there was no detectable 

change in China rockfish space use. 

BACKGROUND: An NSF-sponsored airgun survey presented an opportunity to conduct investigations on 

the potential responses of cold-temperate marine fish and invertebrate species to seismic airgun array use. 
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Monitoring and mitigation measures have been developed for protected species; however, marine 

mammals, birds, and turtles are not the only organisms that could be affected. Further, most studies in 

open oceans and shallow-water environments and regulatory guidelines to assess the effects of sound on 

aquatic life largely describe hearing thresholds in terms of sound pressure, and investigations of potential 

impacts of sound on fishes and invertebrates have often overlooked the sensitivity of these animals to the 

accompanying particle motion, rather than just the pressure pulse itself. 

OBJECTIVES: The objectives were to simultaneously measure the particle motion and pressure components 

of the seismic survey activity and measure the behavioral responses of rockfishes, Dungeness crab, and 

longnose skate to the altered soundscape using acoustic telemetry.

METHODS: An array of 38 Vemco VR2W acoustic receivers (InnovaSea Systems, Nova Scotia) with 

overlapping coverage across the Redfish Rocks Marine Reserve (RRMR) study site enabled triangulation 

of acoustically tagged animal positions. Fifteen animals of each species were tagged with V13A tags 

(with the addition of pressure sensors for the black rockfish). The vector sensor array, NoiseSpotterTM, 

was deployed in approximately 36 m deep water using sensors mounted 35 cm, 50 cm, and 75 cm above 

the seabed. Sensors are separated by 1 m in the horizontal. Particle motion measurements are comprised 

of three-dimensional particle velocity vectors (u, v, w), measured in a sensor reference frame. The sensor 

at 50 cm contained an integrated inertial motion unit (IMU), whose measurements were used to translate 

the particle velocity vectors into a true earth-referenced frame. The acoustic vector sensor array was 

deployed within the RRMR amongst the Vemco receivers used to track the fish. Thus, the NoiseSpotterTM 

was receiving the same sound levels as the tagged fish. The NoiseSpotterTM was first deployed on May 

18, 2021, and finally recovered on July 21, 2021. Two equipment turnarounds occurred within this

deployment period June 7–8 and June 28–30, 2021. 

RESULTS: A long-term spectral average of the acoustic pressure shows periods of elevated acoustic energy 

between 0 and 500 Hz associated with the seismic surveys. The contribution of seismic airgun pulses to 

the particle velocity soundscape is discerned in statistics of the frequency spectra (x-component of 

particle velocity) for each of the deployment periods. We were able to detect seismic airgun pulses from 

the R/V Marcus G. Langseth during the seismic surveys that exceeded 160 dB re 1 μPa (pressure) or 95 

dB re 1 nm/s (particle velocity). The mean, maximum, and 99-percentile curves show an elevation in 

particle velocity levels due to the presence of seismic airgun pulses during these periods. In contrast, the 

remaining percentile curves (minimum, 1%, 10%, 50%, and 90%) show the highest levels during the 

postsurvey period, likely due to sustained higher wind speeds during this period. 

Black rockfish had more incidences of higher acceleration in the survey periods with detected airgun 

pulse noise as compared to before with potential habituation of behavior over the three passes of the 

seismic survey vessel as the coefficient of the increase in acceleration values decreased each of the days 

with detected airgun pulse noise. Black rockfish were detected across a larger area of the study before the 

arrival of the seismic survey and appear to cluster closer to the reef in the middle of the study area in the 

“during” period. Similarly, China rockfish acceleration values were higher in the first day of seismic 

survey noise as compared to before, but were not different on subsequent days. No detectable change in 

area use was discerned for China rockfish. Most of the tagged lingcod and Dungeness crab in this study 

were undetected within the acoustic array during the days of the seismic survey noise presence. The few 

observed lingcod accelerated less on the days of the seismic survey noise, with both mean and maximum 

values lower than those observed in the before periods. For the Dungeness crab that were detected on the 

day of the first pass, the range of values in instantaneous acceleration contracted, but the mean 

acceleration value increased as compared to values in the before period while both the range and mean 

were lower on the subsequent pass.
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CONCLUSIONS: Our results show that there is some effect of seismic survey noise on black and China 

rockfish but no detectable lasting changes on their movement behavior in response to seismic survey 

airgun discharge. One of the most striking effects seemed to be a contraction of black rockfish space use, 

but it was around the high-quality rocky reef habitat, with a return to the observed “typical” use a few 

days after the seismic survey disturbance. Of note, the seismic survey was approximately 20 km away 

from the study area at its closest, so the attenuation of response may have been due to the distance of the 

disturbance. While the results of this study suggest that rockfish and lingcod movement behavior are only 

slightly affected by seismic survey noise and only for a short period of time, further investigations into 

physiological responses should be conducted.

STUDY PRODUCT(S): 

1. Henkel SK, Borland LK, Chang G, Chapple TK, Heal K, Heppell SA, Raghukumar K, Rasmuson L. 

2023. Nearshore sound propagation of and species response to active-source seismic surveys. New 

Orleans (LA): US Department of the Interior, Bureau of Ocean Energy Management. 31 p. Obligation 

No.: M21PG0008. Report No.: OCS Study BOEM 2024-056. 

2. Borland LK. 2023. Seismic survey vessel noise pollution in nearshore Southern Oregon: spatial and 

temporal analysis of demersal fish movements [thesis]. Corvallis (OR): Oregon State University.

3. Borland LK, Heppell SA, Chapple TK, Raghukumar K, Henkel SK. 2023. Responses of Oregon 

demersal species to seismic survey noise: evaluating behavior and movement. In: Popper AN, 

Hawkins AD, editors. The effects of noise on aquatic life III. New York (NY): Springer Science and 

Business Media. 6 p. 

4. Raghukumar K, Heal K, Spada F, Chang G, Chapple TK, Heppell SA, Henkel SK. 2023. Acoustic 

measurements during a seismic airgun survey of the Cascadia Subduction Zone. In: Popper AN, 

Hawkins AD, editors. The effects of noise on aquatic life III. New York (NY): Springer Science and 

Business Media. 8 p. 

5. Borland LK, Heppell SA, Chapple TK, Raghukumar K, Henkel SK. 2022. Understanding modified 

behavior and movement of Oregon species in response to seismic survey noise. Presented at: Western 

Society of Naturalists 103rd Annual Meeting. November 10–13, 2022. Oxnard, CA. 

6. Borland LK, Heppell SA, Chapple TK, Raghukumar K, Henkel SK. 2022. Understanding modified 

behavior and movement of Oregon species in response to seismic survey noise. [poster] Sixth 

International Conference on the Effects of Noise on Aquatic Life. July 10–15, 2022. Berlin, Germany.

7. Raghukumar K, Heal K, Spada F, Chang G, Chapple TK, Heppell SA, Henkel SK. 2022. Acoustic 

measurements during a seismic airgun survey of the Cascadia Subduction Zone. Presented at: Sixth 

International Conference on the Effects of Noise on Aquatic Life. July 10–15, 2022. Berlin, Germany.

MAP OF STUDY AREA: Figure 2 of report OCS Study BOEM 2023-xxx
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Figure 1. Locations of the 38 hydrophones deployed and recovered for the study within the 

Redfish Rocks Marine Reserve off southern Oregon, USA. White polygons in the midst of the 

array are emergent rocks.