ESA Section 7 Consultation Tools for Marine Mammals on the West Coast

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 (National Research Council). 2005. Marine Mammal Populations and Ocean Noise: Determining When Noise Causes Biologically Significant Effects. Washington DC, The National Academies Press.
• NRC (National Research Council). 2016. Approaches to Understanding the Cumulative Effects of Stressors on Marine Mammals. Washington, D.C.: National Academies Press.
• Richardson et al. 1995 Marine mammals and noise. San Diego: Academic Press.
• Southall et al. 2019. Marine Mammal Noise Exposure Criteria: Updated Scientific Recommendations for Residual Hearing Effects. Aquatic Mammals 45: 125-232.
• Southall et al. 2021. Marine mammal noise exposure criteria: Assessing the severity of marine mammal behavioral responses to human noise. Aquatic Mammals 47:421-464.
• 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 2024. The Technical Guidance is a document that compiles, interprets, and synthesizes scientific literature to produce recommended acoustic thresholds to assess how anthropogenic, or human-caused, sound affects the hearing of all marine mammals under NOAA Fisheries jurisdiction. The recommended acoustic thresholds represent the received noise levels at which individual marine mammals are predicted to experience onset of temporary threshold shift (TTS) and auditory injury (AUD INJ).

Acoustic thresholds refer to the levels of sound that, if exceeded, will likely result in temporary or permanent changes in marine mammal hearing sensitivity, or damage to the inner ear. 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.

Technical Guidance

^*Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for calculating AUD INJ or TTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level criteria associated with impulsive sounds, the PK SPL criteria are recommended for consideration for non-impulsive sources.

NOAA Fisheries has also established recommended acoustic thresholds for the onset of behavioral disturbance in marine mammals. Behavioral disturbance can result in adverse impacts such as increased energy expenditure, avoidance of the action area, and disruptions in important biological functions like feeding, resting, and nursing.

¹NOAA. 2005. Endangered Fish and Wildlife; Notice of Intent to Prepare an Environmental Impact Statement. Federal Register 70: 1871-1875.

²Southall et al. 2007 Marine mammal noise exposure criteria: Initial scientific recommendations. Aquatic Mammals 33(4): 411-521.

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 behavioral disturbance 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 NOAA Office of Protected Resources has developed the Multi-Species Pile Driving Calculator as a tool for assessing the potential effects to ESA-listed species exposed to elevated levels of underwater sound produced during pile driving activities.

Evaluating Potential Occurrence of Marine Mammals

NOAA Fisheries provides the guidance below to assess the potential for listed ESA marine mammal occurrence 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 marine mammals and turtles listed under the Endangered Species Act occur more often in the coastal waters of Washington, Oregon, and California 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 biological report for coastal critical habitat reviews recent information on distribution and habitat use of Southern Residents.

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 predominantly 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. For inquiries regarding the Orca Master data set please contact The Whale Museum at hotline@whalemuseum.org.

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.

NOAA Fisheries has developed a GIS visualization of the The Whale Museum Orca Master sightings data set, called the Southern Resident Killer Whale (SRKW) Sightings Dashboard. It reports the number of days Southern Resident killer whales were sighted in Puget Sound waters per quadrant. Number of sightings are reported per month dating back to 1999. The SRKW Sightings Dashboard is a resource for individuals and organizations to determine appropriate marine mammal protections for SRKWs when constructing projects throughout the Puget Sound. Specifically, in conjunction with the known action area of a project, it can help determine whether a marine mammal monitoring plan (MMMP) is needed that includes orcas. The National Marine Fisheries Service uses this tool to determine necessary MMMPs for Endangered Species Act consultations.

Larger scale species density data for other ESA-listed and non-listed marine mammals are available as part of NOAA’s Ocean Noise Strategy CetMap project. Different types of density data may be available for different species and at different months of the year. Another resource is the Biologically Important Areas (BIAs) dataset. BIAs represent areas and times in which cetacean (whales, dolphins, and porpoises) are known to concentrate for activities related to reproduction, feeding, and migration, as well as the known ranges of small and resident populations. BIAs can be used to better understand and predict how individual marine mammals are likely to respond to or be impacted by disturbances, and where populations may be more susceptible to certain types of impacts. BIAs may be used like any other scientific information to support analyses and decisions, as appropriate, for the purposes of environmental planning, compliance, and protection. BIAs are compilations of the best available science and have no inherent or direct regulatory power. The BIAs for the U.S. West Coast are currently being updated and new information may be available soon from Ocean Noise Strategy.

Conservation Measures

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.