ESA Section 7 Consultation Tools for Marine Mammals on the West Coast
Section 7 of the Endangered Species Act (ESA) requires interagency consultation on activities that may affect any listed species. NOAA Fisheries conducts Section 7 consultations for ESA-listed species, including marine mammals that occur in Washington, Oregon, and California
NOAA Fisheries provides information and resources for the topics below to guide you in developing biological assessments for actions that may affect marine mammals.
Intersection of Marine Mammal Protection Act and Endangered Species Act
The Marine Mammal Protection Act (MMPA) prohibits the taking (harassment, injury, killing) of marine mammals unless exempted or specifically permitted or authorized as described in Section 101(a) (5) (A) and (D). NOAA Fisheries' Office of Protected Resources in Silver Spring, MD, issues incidental take authorizations.
The connection with the Endangered Species Act (ESA) Section 7: NOAA Fisheries' issuance of incidental take authorizations under the MMPA is a federal action that requires ESA Section 7 consultation. Generally, NOAA Fisheries cannot issue an incidental take statement for marine mammals under the ESA until an MMPA incidental take authorization has been issued.
Effects of Sound on Marine Mammals
Sound can affect marine mammals in a broad range of ways. Sound can cause physical injury and effects on hearing, communication masking, stress response, and behavioral effects that can range in severity from no observable response to panic and stranding. There are many factors that affect this broad response range. For example, a marine mammal’s frequency range of hearing compared to a sound source, as well as the intensity and energy from the source that is received by the animal, affect the potential for sound to cause physical injury. Behavioral responses are hard to predict, but the received level of sound intensity contributes to such responses.
Recommended Literature Reviews for More Detailed Information:
- Clark et al. 2009. Acoustic masking in marine ecosystems: intuitions, analysis, and implications. Marine Ecology Progress Series 395: 201-222.
- NRC. 2005. Marine Mammal Populations and Ocean Noise: Determining When Noise Causes Biologically Significant Effects. Washington DC, The National Academies Press.
- Richardson et al. 1995 Marine mammals and noise. San Diego: Academic Press.
- Southall et al. 2007 Marine mammal noise exposure criteria: Initial scientific recommendations. Aquatic Mammals 33(4): 411-521.
- Wartzok et al. 2003. Factors Affecting the Responses of Marine Mammals to Acoustic Disturbance. Marine Technology Society Journal 37(4):6-15.
Marine Mammal Acoustic Thresholds
NOAA Fisheries finalized its Technical Guidance for Assessing the Effects of Anthropogenic Noise on Marine Mammal Hearing in July of 2016. The Technical Guidance is a document that compiles, interprets, and synthesizes scientific literature to produce updated acoustic thresholds to assess how anthropogenic, or human-caused, sound affects the hearing of all marine mammals under NOAA Fisheries jurisdiction. The updated acoustic thresholds cover the onset of both temporary (TTS) and permanent hearing threshold shifts (PTS) for Level A, though not yet for level B.
Acoustic thresholds refer to the levels of sound that, if exceeded, will likely result in temporary or permanent changes in marine mammal hearing sensitivity. Notably, the Technical Guidance's updated acoustic thresholds do not represent an entire impact assessment. Instead, they serve as one tool to help evaluate the effects of a proposed action on marine mammals and make findings required by various statutes.
|NOAA Fisheries In-water Acoustic Thresholds|
PK: 219 dB
|SELcum: 199 dB|
PK: 230 dB
|SELcum: 198 dB|
PK: 202 dB
|Phocid Pinnipeds (PW)||
PK: 218 dB
|Otariid Pinnipeds (OW)||
PK: 232 dB
Behavioral disruption for impulsive noise
(e.g., impact pile driving)
Behavioral disruption for continuous noise
(e.g., vibratory pile driving, drilling)
|NOAA Fisheries Current In-air Acoustic Thresholds|
|Level A||PTS (injury) conservatively based on TTS||None established|
|Level B||Behavioral disruption for harbor seals||90 dBrms|
|Level B||Behavioral disruption for non-harbor seal pinnipeds||100 dBrms|
|All decibels referenced to 20 micro Pascals (re: 20uPa). Note: all thresholds are based off root mean square (rms) levels.|
Defining Areas of Potential Sound Effects
For activities that produce sound above these acoustic thresholds, it will be necessary to evaluate sound propagation from the source and estimate the area(s) within which sound levels are above the acoustic threshold(s). Propagation of sound in the sea is a complex science.
Transmission loss is highly variable in nearshore environments, and hydroacoustic data are needed to accurately estimate spreading and attenuation loss. Spreading loss represents a regular weakening of sound as it spreads from the source, and can be expressed as dB loss per doubling of distance. Spreading loss is a geometric effect that is either spherical or cylindrical. Attenuation loss includes the effects of absorption and scattering, among other effects.
The West Coast Region encourages the collection of acoustic data to inform transmission loss estimates, and review of previous sound propagation studies in the area that may be applicable to the project site. Knowledge of the background sound in the sea is also important to evaluate whether a sound source is audible over the background level. Through consultation with NOAA Fisheries staff, the 120 dB rms threshold may be adjusted if background sound is at or above this level. In the absence of background sound data, in-water acoustic effect thresholds should be used to define areas of potential sound effects. The West Coast Region and Northwest Fisheries Science Center developed the following documents for use in marine mammal ESA consultations and MMPA permit applications.
Guidance to Characterize Pile Driving Source Levels (PDF, 7 pages)
Sound Propagation Modeling (PDF, 6 pages)
Guidance for Collecting Background Sound Data (PDF, 5 pages)
Evaluating Potential Occurrence of Sound
NOAA Fisheries provides the guidance below to assess the potential for listed ESA marine mammal occurrences in project areas. There are 8 marine mammal species on the West Coast of the United States. Southern Resident killer whales occur predictably in Washington and Oregon water, but their range includes California up to Southeast Alaska. Other Endangered Species Act-listed marine mammals and turtles can occur in Washington and Oregon waters but are generally less likely to occur in nearshore areas. More information about these species is available in stock assessment reports and status reviews.
Southern Resident killer whales spend considerable time in the Georgia Basin from late spring to early autumn, with concentrated activity in the inland waters of the state of Washington around the San Juan Islands, and then move south into Puget Sound in early autumn. While these are seasonal patterns, Southern Resident killer whales have the potential to occur throughout their range, from central California north to Southeast Alaska, at any time of the year.
The Whale Museum manages a long-term database of Southern Resident killer whale sightings and geospatial locations in inland waters of Washington State. While these data are predominately opportunistic sightings from a variety of sources (public reports, commercial whale watching, Soundwatch, Lime Kiln State Park land-based observations, and independent research reports), these orcas are highly visible in inland waters, and widely followed by the interested public and research community.
The dataset does not account for the level of observation effort by season or location; however, it is the most comprehensive long-term dataset available to evaluate broad-scale habitat use by Southern Resident killer whales in inland waters. For these reasons, NOAA Fisheries relies on the number of past sightings to assess the likelihood of Southern Resident killer whale presence in a project area when work would occur. The Whale Museum developed a set of maps that reports the number of unique Southern Resident killer whale sighting days (PDF, 1 page) in inland waters per quadrate (PDF, 1 page) and month over a near 20-year timeframe.
You can use conservation measures to avoid exposing marine mammals to sound levels that may cause injury or behavioral disruption. Two primary measures are available to avoid exposure:
Conduct work when Endangered Species Act-listed marine mammals are extremely unlikely to occur. Use the tools provided in the links on this page to evaluate species occurrence and the area of sound effects. Identify months of the year that ESA-listed marine mammals are not likely to occur in the area of sound effects. Conduct work during this time period, or a portion of this time period that coincides with the approved in-water work windows for fish.
Develop a marine-mammal monitoring plan. The basic premise is to observe for marine mammals in the defined area of potential sound effects. Stop or do not start work if a marine mammal is sighted in the monitoring area. Do not start work again until the marine mammal has moved out of the monitoring area. The following section provides guidance for developing a marine mammal monitoring plan. We can provide additional assistance upon request.