# Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to Southwest Fisheries Science Center Fisheries Research > Briefs, arguments, decisions, and more. URL: https://www.frixlaw.com/law-library/documents/fr%3A2020-17848 ## Record - **Collection:** Federal Register - **Document type:** Proposed Rule - **Published:** August 28, 2020 - **Citation:** 85 FR 53606 ## Text DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration 50 CFR Part 219 [Docket No. 200810-0212] RIN 0648-BJ71 Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to Southwest Fisheries Science Center Fisheries Research AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Proposed rule; request for comments. SUMMARY: NMFS's Office of Protected Resources (OPR) has received a request from NMFS's Southwest Fisheries Science Center (SWFSC) for authorization to take marine mammals incidental to fisheries research conducted in multiple specified geographical regions, over the course of five years from the date of issuance. As required by the Marine Mammal Protection Act (MMPA), NMFS is proposing regulations to govern that take, and requests comments on the proposed regulations. NMFS will consider public comments prior to making any final decision on the issuance of the requested MMPA authorization and agency responses will be summarized in the final notice of our decision. DATES: Comments and information must be received no later than September 28, 2020. ADDRESSES: You may submit comments on this document, identified by NOAA-NMFS-2020-0111, by the following method: • Electronic submission: Submit all public comments via the Federal e-Rulemaking Portal. Go to www.regulations.gov/#!docketDetail;D=NOAA-NMFS-2020-0111, click the “Comment Now!” icon, complete the required fields, and enter or attach your comments. Instructions: Comments sent by any other method, to any other address or individual, or received after the end of the comment period, may not be considered by NMFS. All comments received are a part of the public record and will generally be posted for public viewing on www.regulations.gov without change. All personal identifying information ( e.g., name, address), confidential business information, or otherwise sensitive information submitted voluntarily by the sender will be publicly accessible. NMFS will accept anonymous comments (enter “N/A” in the required fields if you wish to remain anonymous). FOR FURTHER INFORMATION CONTACT: Ben Laws, Office of Protected Resources, NMFS, (301) 427-8401. SUPPLEMENTARY INFORMATION: Availability A copy of SWFSC's application and any supporting documents, as well as a list of the references cited in this document, may be obtained online at: www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities. In case of problems accessing these documents, please call the contact listed above (see FOR FURTHER INFORMATION CONTACT ). Purpose and Need for Regulatory Action This proposed rule would establish a framework under the authority of the MMPA (16 U.S.C. 1361 et seq. ) to allow for the authorization of take of marine mammals incidental to the SWFSC's fisheries research activities in the California Current Ecosystem and the Antarctic Marine Living Resources Ecosystem research areas. We received an application from the SWFSC requesting five-year regulations and authorization to take multiple species of marine mammals. Take would occur by Level B harassment incidental to the use of active acoustic devices, as well as by visual disturbance of pinnipeds in the Antarctic, and by Level A harassment, serious injury, or mortality incidental to the use of fisheries research gear. Please see “Background” below for definitions of harassment. Legal Authority for the Proposed Action Section 101(a)(5)(A) of the MMPA (16 U.S.C. 1371(a)(5)(A)) directs the Secretary of Commerce to allow, upon request, the incidental, but not intentional taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region for up to five years if, after notice and public comment, the agency makes certain findings and issues regulations that set forth permissible methods of taking pursuant to that activity and other means of effecting the “least practicable adverse impact” on the affected species or stocks and their habitat (see the discussion below in the “Proposed Mitigation” section), as well as monitoring and reporting requirements. Section 101(a)(5)(A) of the MMPA and the implementing regulations at 50 CFR part 216, subpart I provide the legal basis for issuing this proposed rule containing five-year regulations, and for any subsequent LOAs. As directed by this legal authority, this proposed rule contains mitigation, monitoring, and reporting requirements. Summary of Major Provisions Within the Proposed Rule Following is a summary of the major provisions of this proposed rule regarding SWFSC fisheries research activities. These measures include: • Required monitoring of the sampling areas to detect the presence of marine mammals before deployment of certain research gear. • Required implementation of the mitigation strategy known as the “move-on rule mitigation protocol” which incorporates best professional judgment, when necessary during certain research fishing operations. Background The MMPA prohibits the “take” of marine mammals, with certain exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq. ) direct the Secretary of Commerce (as delegated to NMFS) to allow, upon request, the incidental, but not intentional, taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if certain findings are made and either regulations are issued or, if the taking is limited to harassment, a notice of a proposed incidental take authorization may be provided to the public for review. Authorization for incidental takings shall be granted if NMFS finds that the taking will have a negligible impact on the species or stock(s) and will not have an unmitigable adverse impact on the availability of the species or stock(s) for taking for subsistence uses (where relevant). Further, NMFS must prescribe the permissible methods of taking and other “means of effecting the least practicable adverse impact” on the affected species or stocks and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of the species or stocks for taking for certain subsistence uses (referred to in shorthand as “mitigation”); and requirements pertaining to the mitigation, monitoring and reporting of the takings are set forth. The definitions of all applicable MMPA statutory terms cited above are included in the relevant sections below. National Environmental Policy Act To comply with the National Environmental Policy Act of 1969 (NEPA; 42 U.S.C. 4321 et seq. ) and NOAA Administrative Order (NAO) 216-6A, NMFS must evaluate our proposed action ( i.e., the promulgation of regulations and subsequent issuance of incidental take authorization) and alternatives with respect to potential impacts on the human environment. In 2015, NMFS prepared a Programmatic Environmental Assessment (PEA; Programmatic Environmental Assessment for Fisheries Research Conducted and Funded by the Southwest Fisheries Science Center ) to consider the direct, indirect and cumulative effects to the human environment resulting from SWFSC's activities as well as the NMFS Office of Protected Resources (OPR) issuance of the regulations and subsequent incidental take authorization. NMFS made the PEA available to the public for review and comment, in relation specifically to its suitability for assessment of the impacts of our action under the MMPA. OPR signed a Finding of No Significant Impact (FONSI) related to our action under the MMPA on August 31, 2015. The PEA and the 2015 FONSI are available online at: www.fisheries.noaa.gov/action/incidental-take-authorization-noaa-fisheries-swfsc-fisheries-and-ecosystem-research. On May 11, 2020, NMFS announced the availability of a “ Draft Supplemental Programmatic Environmental Assessment (SPEA) for Fisheries Research Conducted and Funded by the Southwest Fisheries Science Center” for review and comment (85 FR 27719). The purpose of the Draft SPEA is to evaluate potential direct, indirect, and cumulative effects of unforeseen changes in research that were not analyzed in the 2015 PEA, or new research activities along the U.S. West Coast, throughout the Eastern Tropical Pacific Ocean, and in the Scotia Sea area off Antarctica. Where necessary, updates to certain information on species, stock status or other components of the affected environment that may result in different conclusions from the 2015 PEA are presented in this analysis. Information in the PEA, SPEA, SWFSC's application, and this notice collectively provide the environmental information related to proposed issuance of these regulations and subsequent incidental take authorization for public review and comment. We will review all comments submitted in response to this notice prior to concluding our NEPA process or making a final decision on the request for incidental take authorization. Summary of Request On April 30, 2020, we received an adequate and complete request from SWFSC for authorization to take marine mammals incidental to fisheries research activities. On May 8, 2020 (85 FR 27388), we published a notice of receipt of SWFSC's application in the Federal Register , requesting comments and information related to the SWFSC request for thirty days. We did not receive any comments in response. These regulations would be the second consecutive five-year incidental take regulations issued in response to a petition from SWFSC. The initial regulations were finalized in 2015 and remain effective through October 30, 2020 (80 FR 58982; September 30, 2015). Three Letters of Authorization (LOA) were issued to SWFSC pursuant to the regulations, related to SWFSC research survey activities in the California Current Ecosystem (CCE), the Eastern Tropical Pacific (ETP), and the Antarctic Marine Living Resources Ecosystem (AMLR). Information related to this rulemaking and required reporting submitted by SWFSC according to the terms of the LOAs may be found online at: www.fisheries.noaa.gov/action/incidental-take-authorization-noaa-fisheries-swfsc-fisheries-and-ecosystem-research. SWFSC adhered to all mitigation, monitoring, and reporting requirements and did not exceed authorized numbers of take. SWFSC proposes to continue conducting fisheries research using pelagic trawl gear used at various levels in the water column, pelagic longlines with multiple hooks, purse seine gear, and other gear. If a marine mammal interacts with gear deployed by SWFSC, the outcome could potentially be Level A harassment, serious injury ( i.e., any injury that will likely result in mortality), or mortality. However, there is not sufficient information upon which to base a prediction of what the outcome may be for any particular interaction. Therefore, SWFSC has pooled the estimated number of incidents of take resulting from gear interactions, and we have assessed the potential impacts accordingly. SWFSC also uses various active acoustic devices in the conduct of fisheries research, and use of these devices has the potential to result in Level B harassment of marine mammals. Level B harassment of pinnipeds hauled out on ice may also occur, in the Antarctic only, as a result of visual disturbance from vessels conducting SWFSC research. The proposed regulations would be valid for five years from the date of issuance. The SWFSC conducts fisheries research surveys in the CCE, ETP, and the AMLR. However, SWFSC does not plan to conduct research over the five-year period in the ETP. Therefore, these proposed regulations address only the CCE and AMLR. In the CCE, SWFSC requests authorization to take individuals of 24 stocks by Level A harassment, serious injury, or mortality (hereafter referred to as M/SI) and of 38 stocks by Level B harassment. In the AMLR, SWFSC requests authorization to take individuals of fifteen species by Level B harassment. No takes by M/SI are anticipated in the AMLR. Description of the Specified Activity Overview The SWFSC collects a wide array of information necessary to evaluate the status of exploited fishery resources and the marine environment. SWFSC scientists conduct fishery-independent research onboard NOAA-owned and operated vessels or on chartered vessels. Some surveys may be conducted onboard commercial fishing vessels or by cooperating scientists on non-NOAA vessels, but the SWFSC designs and executes the studies and funds vessel time. The SWFSC proposes to administer and conduct approximately 18 survey programs over the five-year period, within two separate research areas. Please see Table 1-2 in SWFSC's application for details relating to the planned survey programs. The gear types used fall into several categories: Towed nets fished at various levels in the water column, longline and other hook and line gear, purse seine nets, and other gear. Only use of trawl nets, hook and line gear, and purse seine nets are likely to result in interaction with marine mammals. Many of these surveys also use active acoustic devices. The Federal government has a responsibility to conserve and protect living marine resources in U.S. waters and has also entered into a number of international agreements and treaties related to the management of living marine resources in international waters outside the United States. NOAA has the primary responsibility for managing marine finfish and shellfish species and their habitats, with that responsibility delegated within NOAA to NMFS. In order to direct and coordinate the collection of scientific information needed to make informed fishery management decisions, Congress created six regional fisheries science centers, each a distinct organizational entity and the scientific focal point within NMFS for region-based Federal fisheries-related research. This research is aimed at monitoring fish stock recruitment, abundance, survival and biological rates, geographic distribution of species and stocks, ecosystem process changes, and marine ecological research. The SWFSC is the research arm of NMFS in the southwest region of the United States. The SWFSC conducts research and provides scientific advice to manage fisheries and conserve protected species in the geographic research areas listed above and provides scientific information to support the Pacific Fishery Management Council and numerous other domestic and international fisheries management organizations. Dates and Duration The specified activity may occur at any time during the five-year period of validity of the proposed regulations. Dates and duration of individual surveys are inherently uncertain, based on congressional funding levels for the SWFSC, weather conditions, or ship contingencies. In addition, cooperative research is designed to provide flexibility on a yearly basis in order to address issues as they arise. Some cooperative research projects last multiple years or may continue with modifications. Other projects only last one year and are not continued. Most cooperative research projects go through an annual competitive selection process to determine which projects should be funded based on proposals developed by many independent researchers and fishing industry participants. SWFSC survey activity does occur during most months of the year; however, trawl surveys typically occur during May through June and September and longline surveys are typically completed during June-July and September. Specified Geographical Region The SWFSC plans to conduct research within two research areas considered to be distinct specified geographical regions: the CCE and AMLR. No research activity is planned within the ETP over the next five years. Please see Figures 1-1, 2-1, and 2-2 in the SWFSC application for maps of the research areas. We note here that, while the specified geographical regions within which the SWFSC operates may extend outside of the U.S. Exclusive Economic Zone (EEZ), the MMPA's authority does not extend into foreign territorial waters. Detailed descriptions of the SWFSC's research areas were provided in our notice of proposed rulemaking for SWFSC's previous incidental take regulations (80 FR 8166; February 13, 2015). Those descriptions remain accurate and sufficient, and we refer the reader to that notice rather than reprinting the information here. Detailed Description of Activities The Federal government has a trust responsibility to protect living marine resources in waters of the United States. These waters extend to 200 nm from the shoreline and include the EEZ. The U.S. government has also entered into a number of international agreements and treaties related to the management of living marine resources in international waters outside of the EEZ ( i.e., the high seas). To carry out its responsibilities over U.S. and international waters, Congress has enacted several statutes authorizing certain Federal agencies to administer programs to manage and protect living marine resources. Among these Federal agencies, NOAA has the primary responsibility for protecting marine finfish and shellfish species and their habitats. Within NOAA, NMFS has been delegated primary responsibility for the science-based management, conservation, and protection of living marine resources under statutes including the MSA, MMPA, Endangered Species Act (ESA), and the Antarctic Marine Living Resources Convention Act. Within NMFS, six regional fisheries science centers direct and coordinate the collection of scientific information needed to inform fisheries management decisions. Each science center is a distinct entity and is the scientific focal point for a particular region. SWFSC conducts research and provides scientific advice to manage fisheries and conserve protected species along the U.S. West Coast, throughout the eastern tropical Pacific Ocean, and in the Southern Ocean off Antarctica. SWFSC provides scientific information to support the Pacific Fishery Management Council and other domestic and international fisheries management organizations. The SWFSC collects a wide array of information necessary to evaluate the status of exploited fishery resources and the marine environment. SWFSC scientists conduct fishery-independent research onboard NOAA-owned and operated vessels or on chartered vessels, and some SWFSC-funded research may be conducted by cooperative scientists. The SWFSC proposes to administer and conduct approximately 18 survey programs over the five-year period. The gear types used fall into several categories: Towed nets fished at various levels in the water column, longline and other hook and line gear, purse seine nets, and other gear. Only use of trawl nets, hook and line gear, and purse seine nets are likely to result in interaction with marine mammals. Many of these surveys also use active acoustic devices. These surveys may be conducted aboard NOAA-operated research vessels (R/V), aboard vessels owned and operated by cooperating agencies and institutions, or aboard charter vessels. In the following discussion, we summarily describe various gear types used by SWFSC, with reference to specific fisheries and ecosystem research activities conducted by the SWFSC. This is not an exhaustive list of gear and/or devices that may be utilized by SWFSC but is representative of gear categories and is complete with regard to all gears with potential for interaction with marine mammals. Additionally, relevant active acoustic devices, which are commonly used in SWFSC survey activities, are described separately in a subsequent section. Please see Appendix B of SWFSC's application for further description, pictures, and diagrams of research gear and vessels. Full details regarding planned research activities are provided in Tables 1-2 and 1-3 of SWFSC's application, with specific gear used in association with each research project and full detail regarding gear characteristics and usage provided. Full detail is not repeated here. Trawl nets —A trawl is a funnel-shaped net towed behind a boat to capture fish. The codend (or bag) is the fine-meshed portion of the net most distant from the towing vessel where fish and other organisms larger than the mesh size are retained. In contrast to commercial fishery operations, which generally use larger mesh to capture marketable fish, research trawls often use smaller mesh to enable estimates of the size and age distributions of fish in a particular area. The body of a trawl net is generally constructed of relatively coarse mesh that functions to gather schooling fish so that they can be collected in the codend. The opening of the net, called the mouth, is extended horizontally by large panels of wide mesh called wings. The mouth of the net is held open by hydrodynamic force exerted on the trawl doors attached to the wings of the net. As the net is towed through the water, the force of the water spreads the trawl doors horizontally apart. The top of a net is called the headrope, and the bottom is called the footrope. The trawl net is usually deployed over the stern of the vessel and attached with two cables (or warps) to winches on the deck of the vessel. The cables are played out until the net reaches the fishing depth. Trawl vessels typically travel at speeds of 2-5 kn while towing the net for time periods up to several hours. The duration of the tow depends on the purpose of the trawl, the catch rate, and the target species. At the end of the tow the net is retrieved and the contents of the codend are emptied onto the deck. For research purposes, the speed and duration of the tow and the characteristics of the net are typically standardized to allow meaningful comparisons of data collected at different times and locations. Active acoustic devices (described later) incorporated into the research vessel and the trawl gear monitor the position and status of the net, speed of the tow, and other variables important to the research design. Most SWFSC research trawling activities utilize pelagic (or midwater) trawls, which are designed to operate at various depths within the water column but not to contact the seafloor. Midwater and surface trawls are used in the juvenile rockfish, juvenile salmon and sardine surveys at fixed stations from southern California to Washington annually from April-July and in August-September. The tows are conducted near the surface down to approximately 15-30 m deep, mainly at night using a charter vessel or a NOAA vessel. These nets are also used in juvenile salmon surveys between southern California and Oregon during daytime trawls that last approximately 45 minutes at the target depth. Compared to the Nordic 264 trawl, takes of marine mammals by Modified-Cobb trawl have been historically small. While the Nordic 264 rope trawl is intended to fish at the surface, the Cobb trawl is typically fishing at 30 m headrope depth, thus it is rarely at the surface aside from the deployment and retrieval stages. Fishing at depth, at slower speeds, and for shorter duration, along with having a smaller opening and mesh size, mitigate marine mammal takes by the modified Cobb. Table 6-3 of the SWFSC application summarizes the number of trawls, fishing depth and average tow time for modified Cobb and Nordic 264 trawl gear over the period 2015-2018. The table shows that while Nordic 264 gear is used more frequently, the total number of trawls using this gear has been reduced while the use of modified Cobb gear has remained at generally the same level. Please see Section 1 and Appendix B of SWFSC's application for additional detail. Longline —Longline vessels fish with baited hooks attached to a mainline (or groundline). The length of the longline and the number of hooks depend on the species targeted, the size of the vessel, and the purpose of the fishing activity. Hooks are attached to the mainline by another thinner line called a gangion. The length of the gangion and the distance between gangions depends on the purpose of the fishing activity. Depending on the fishery, longline gear can be deployed on the seafloor (bottom longline), in which case weights are attached to the mainline, or near the surface of the water (pelagic longline), in which case buoys are attached to the mainline to provide flotation and keep the baited hooks suspended in the water. Radar reflectors, radio transmitters, and light sources are often used to help fishers determine the location of the longline gear prior to retrieval. A commercial longline can be miles long and have thousands of hooks attached, although longlines used for research surveys are often shorter. The pelagic longline gear used for SWFSC research surveys typically use 200-400 hooks attached to a steel or monofilament mainline from 2-12 miles long (3-19 km). There are no internationally-recognized standard measurements for hook size, and a given size may be inconsistent between manufacturers. Larger hooks, as are used in longlining, are referenced by increasing whole numbers followed by a slash and a zero as size increases ( e.g., 1/0 up to 20/0). The numbers represent relative sizes, normally associated with the gap (the distance from the point tip to the shank). Bottom longlines used for commercial fishing can be up to several miles long, but those used for SWFSC research use shorter lines with approximately 75 hooks per line. SWFSC sablefish and rockfish life history surveys using bottom longline gear are extremely small scale with a low level of effort (approximately 200 hooks per month). The time period between deployment and retrieval of the longline gear is the soak time. Soak time is an important parameter for calculating fishing effort. For commercial fisheries the goal is to optimize the soak time in order to maximize catch of the target species while minimizing the bycatch rate and minimizing damage to target species that may result from predation by sharks or other predators. SWFSC also uses deep-set buoy gear. Deep-set buoy gear is a particular type of pelagic longline that includes a buoy flotation system ( i.e., a strike-indicator float/flag, a large, non-compressible buoy and a float affixed with a radar reflector). A set of gear consists of 500-lb (227-kg) test mainline monofilament rigged with a 1-2 kg drop sinker to orient the mainline and terminal fishing gear vertically in the water column. Other pelagic longline gear typically uses a long monofilament mainline suspended horizontally near the surface of the water. However, deep-set buoy gear uses a vertically-oriented mainline with two monofilament gangions that branch from the mainline at a target depth below the thermocline (250-400 m for SWFSC). SWFSC also uses hook-and-line, i.e., rod-and-reel, for some survey efforts. Highly migratory species surveys are conducted June-July from a NOAA vessel or a charter vessel. Table 6-5 of SWFSC's application summarizes hook and line survey efforts over the period 2015-2017; hook and line surveys were not conducted in 2018. Thresher shark surveys are not planned for the 2020-2025 survey period. Please see Section 1 and Appendix B of SWFSC's application for additional detail. Seine nets —Seine nets typically hang vertically in the water with the bottom edge held down by weights and the top edge buoyed by floats. Commercial fishers use purse seines to capture schooling pelagic species by encircling the fish and then using a line at the bottom that enables the net to be closed like a purse. Commercial purse seines vary in size according to vessel, mesh size, and target species. The SWFSC proposes to conduct purse seine surveys in nearshore areas. Seining will be based on SWFSC and Washington Department of Fish and Wildlife protocols to allow dip-netting of fish from the seine for sample processing onboard. As an example, a seine net 230 fathoms in length, 2800 meshes deep, with a mesh size of 11/16 may be used for this research. Transects may occur from the northernmost sampling location to the vicinity of Eureka, California in the nearshore area approximately 5 nmi apart, alternating direction (east-west and vice versa) for 3-7 transects each day, ideally coincident with NOAA trawl surveys further offshore, for about 100 total transects. SWFSC may set an average of 3 times/day for 60 minutes for approximately 60 sets total. To conduct day-night comparative surveys, SWFSC may set approximately 4/day in a 24-hour period (each for 60 minutes) over about 5 days ( i.e., minimum of 2 sets each during daytime and nighttime for a total of 20 sets). Please see Section 1 and Appendix B of SWFSC's application for additional detail. Other nets —SWFSC surveys utilize various small, fine-mesh, towed nets designed to sample small fish and pelagic invertebrates. These nets can be broadly categorized as small trawls (which are separated from large trawl nets due to small trawls' discountable potential for interaction with marine mammals) and plankton nets. Please see Section 1 and Appendix B of SWFSC's application for additional detail. 1. The Tucker trawl is a medium-sized single-warp net used to study pelagic fish and zooplankton. The Tucker trawl consists of a series of nets that can be opened and closed sequentially via stepping motor without retrieving the net from the fishing depth. It is designed for deep oblique tows where up to three replicate nets can be sequentially operated by a double release mechanism and is typically equipped with a full suite of instruments, including inside and outside flow meters; conductivity, temperature, and depth profilers (CTD); and pitch sensor. 2. The Multiple Opening/Closing Net and Environmental Sensing System (MOCNESS) uses a stepping motor to sequentially control the opening and closing of the net. The MOCNESS uses underwater and shipboard electronics to control the device. The electronics system continuously monitors the functioning of the nets, frame angle, horizontal velocity, vertical velocity, volume filtered, and selected environmental parameters, such as salinity and temperature. The MOCNESS is used for specialized zooplankton surveys. 3. The Isaacs-Kidd midwater trawl (IKMT) is used to collect deepwater biological specimens larger than those taken by standard plankton nets. The mouth of the net is approximately 1.5 x 1.8 m, and is attached to a wide, V-shaped, rigid diving vane that keeps the mouth of the net open and maintains the net at depth for extended periods. The IKMT is a long, round net approximately 6.5 m long, with a series of hoops decreasing in size from the mouth of the net to the codend, which maintain the shape of the net during towing. While most trawls must be towed at speeds of 1-2 kn because of the high level of drag exerted by the net in the water, an IKMT can be towed at speeds as high as 5 kn. 4. SWFSC also uses various neuston nets, which are frame trawls towed horizontally at the top of the water column in order to capture neuston ( i.e., organisms that inhabit the water's surface), and plankton nets, which usually consist of fine mesh attached to a weighted frame which spreads the mouth of the net to cover a known surface area in order to sample plankton and fish eggs from various parts of the water column. Examples include manta nets, which are towed horizontally at the surface of the water; bongo nets, which are towed through the water at an oblique angle to sample plankton over a range of depths; and the Oozeki net, which is a frame trawl used for quantitative sampling of larval and juvenile pelagic fishes. Conductivity, temperature, and depth profilers —A CTD profiler is the primary research tool for determining chemical and physical properties of seawater. A shipboard CTD is made up of a set of small probes attached to a large (1-2 m diameter) metal rosette wheel. The rosette is lowered through the water column on a cable, and CTD data are observed in real time via a conducting cable connecting the CTD to a computer on the ship. The rosette also holds a series of sampling bottles that can be triggered to close at different depths in order to collect a suite of water samples that can be used to determine additional properties of the water over the depth of the CTD cast. A standard CTD cast, depending on water depth, requires two to five hours to complete. The data from a suite of samples collected at different depths are often called a depth profile. Depth profiles for different variables can be compared in order to glean information about physical, chemical, and biological processes occurring in the water column. Salinity, temperature, and depth data measured by the CTD instrument are essential for characterization of seawater properties. Tables 1-2 and 1-3 of the SWFSC's application provide detailed information of all surveys planned by SWFSC; full detail is not repeated here. Many of these surveys also use small trawls, plankton nets, and/or other gear; however, only gear with likely potential for marine mammal interaction is described. Here we provide a summary of projected annual survey effort for those gears that we believe present the potential for marine mammal interaction (Table 1). This summary is intended only to provide a sense of the level of effort, and actual level of effort may vary from year to year. Gear specifications vary; please see Table 1-2 and Appendix B of SWFSC's application. Please note that no trawl surveys are planned within AMLR over the next five years. Take of marine mammals incidental to SWFSC research is expected to occur in the form of Level B harassment only as a result of the use of active acoustic systems or due to visual disturbance of hauled-out pinnipeds. Table 1—Projected Annual SWFSC Survey Effort by Gear Type Survey type Gear type Tows/sets Duration per tow/set CCE Midwater trawl NETS Nordic 264 (380 m 2 mouth area) 50 30 min. Midwater trawl Modified Cobb (80 m 2 mouth area) 150 15 min. Purse seine Varies 10-25 Varies. Pelagic longline 200-400 hooks Varies 2-4 hr (up to 4-6 hr for certain target species). Pelagic longline 75 hooks Varies 2-4 hr. Hook and line/handline Various 100-500 casts/cruise 3 hr. Hook and line Micro-troll 50 2 hr. Description of Active Acoustic Sound Sources —This section contains a brief technical background on sound, the characteristics of certain sound types, and on metrics used in this proposal inasmuch as the information is relevant to SWFSC's specified activity and to an understanding of the potential effects of the specified activity on marine mammals. We also describe the active acoustic devices used by SWFSC. For general information on sound and its interaction with the marine environment, please see, e.g., Au and Hastings (2008); Richardson et al. (1995); Urick (1983). Sound travels in waves, the basic components of which are frequency, wavelength, velocity, and amplitude. Frequency is the number of pressure waves that pass by a reference point per unit of time and is measured in Hz or cycles per second. Wavelength is the distance between two peaks or corresponding points of a sound wave (length of one cycle). Higher frequency sounds have shorter wavelengths than lower frequency sounds, and typically attenuate (decrease) more rapidly, except in certain cases in shallower water. Amplitude is the height of the sound pressure wave or the “loudness” of a sound and is typically described using the relative unit of the dB. A sound pressure level (SPL) in dB is described as the ratio between a measured pressure and a reference pressure (for underwater sound, this is 1 microPascal (μPa)) and is a logarithmic unit that accounts for large variations in amplitude; therefore, a relatively small change in dB corresponds to large changes in sound pressure. The source level (SL) represents the SPL referenced at a distance of 1 m from the source (referenced to 1 μPa), while the received level is the SPL at the listener's position (referenced to 1 μPa). Root mean square (rms) is the quadratic mean sound pressure over the duration of an impulse. Root mean square is calculated by squaring all of the sound amplitudes, averaging the squares, and then taking the square root of the average. Root mean square accounts for both positive and negative values; squaring the pressures makes all values positive so that they may be accounted for in the summation of pressure levels. This measurement is often used in the context of discussing behavioral effects, in part because behavioral effects, which often result from auditory cues, may be better expressed through averaged units than by peak pressures. Peak sound pressure (also referred to as zero-to-peak sound pressure or 0-pk) is the maximum instantaneous sound pressure measurable in the water at a specified distance from the source and is represented in the same units as the rms sound pressure. Sound exposure level (SEL; represented as dB re 1 μPa 2 -s) represents the total energy in a stated frequency band over a stated time interval or event, and considers both intensity and duration of exposure. The per-pulse SEL is calculated over the time window containing the entire pulse ( i.e., 100 percent of the acoustic energy). SEL is a cumulative metric; it can be accumulated over a single pulse, or calculated over periods containing multiple pulses. Cumulative SEL represents the total energy accumulated by a receiver over a defined time window or during an event. When underwater objects vibrate or activity occurs, sound-pressure waves are created. These waves alternately compress and decompress the water as the sound wave travels. Underwater sound waves radiate in a manner similar to ripples on the surface of a pond and may be either directed in a beam or beams (as for the sources considered here) or may radiate in all directions (omnidirectional sources). The compressions and decompressions associated with sound waves are detected as changes in pressure by aquatic life and man-made sound receptors such as hydrophones. Sounds are often considered to fall into one of two general types: pulsed and non-pulsed (defined in the following). The distinction between these two sound types is important because they have differing potential to cause physical effects, particularly with regard to hearing ( e.g., Ward, 1997 in Southall et al., 2007). Please see Southall et al. (2007) for an in-depth discussion of these concepts. The distinction between these two sound types is not always obvious, as certain signals share properties of both pulsed and non-pulsed sounds. A signal near a source could be categorized as a pulse; but, due to propagation effects as it moves farther from the source, the signal duration becomes longer ( e.g., Greene and Richardson, 1988). Pulsed sound sources ( e.g., airguns, explosions, gunshots, sonic booms, impact pile driving) produce signals that are brief (typically considered to be less than one second), broadband, atonal transients (ANSI, 1986, 2005; Harris, 1998; NIOSH, 1998; ISO, 2003) and occur either as isolated events or repeated in some succession. Pulsed sounds are all characterized by a relatively rapid rise from ambient pressure to a maximal pressure value followed by a rapid decay period that may include a period of diminishing, oscillating maximal and minimal pressures, and generally have an increased capacity to induce physical injury as compared with sounds that lack these features. Non-pulsed sounds can be tonal, narrowband, or broadband, brief or prolonged, and may be either continuous or intermittent (ANSI, 1995; NIOSH, 1998). Some of these non-pulsed sounds can be transient signals of short duration but without the essential properties of pulses ( e.g., rapid rise time). Examples of non-pulsed sounds include those produced by vessels, aircraft, machinery operations such as drilling or dredging, vibratory pile driving, and active sonar systems. The duration of such sounds, as received at a distance, can be greatly extended in a highly reverberant environment. All active acoustic systems used by SWFSC produce non-pulsed intermittent sound. A wide range of active acoustic devices are used in SWFSC fisheries surveys for remotely sensing bathymetric, oceanographic, and biological features of the environment. Most of these sources involve relatively high frequency, directional, and brief repeated signals tuned to provide sufficient focus and resolution on specific objects. SWFSC also uses passive listening sensors ( i.e., remotely and passively detecting sound rather than producing it), which do not have the potential to impact marine mammals. SWFSC active acoustic sources include various echosounders ( e.g., multibeam systems), scientific sonar systems, positional sonars ( e.g., net sounders for determining trawl position), and environmental sensors ( e.g., current profilers). Mid- and high-frequency underwater acoustic sources typically used for scientific purposes operate by creating an oscillatory overpressure through rapid vibration of a surface, using either electromagnetic forces or the piezoelectric effect of some materials. A vibratory source based on the piezoelectric effect is commonly referred to as a transducer. Transducers are usually designed to excite an acoustic wave of a specific frequency, often in a highly directive beam, with the directional capability increasing with operating frequency. The main parameter characterizing directivity is the beam width, defined as the angle subtended by diametrically opposite “half power” (-3 dB) points of the main lobe. For different transducers at a single operating frequency the beam width can vary from 180° (almost omnidirectional) to only a few degrees. Transducers are usually produced with either circular or rectangular active surfaces. For circular transducers, the beam width in the horizontal plane (assuming a downward pointing main beam) is equal in all directions, whereas rectangular transducers produce more complex beam patterns with variable beam width in the horizontal plane. The types of active sources employed in fisheries acoustic research and monitoring, based largely on their relatively high operating frequencies and other output characteristics ( e.g., signal duration, directivity), should be considered to have very low potential to cause effects to marine mammals that would rise to the level of a “take,” as defined by the MMPA. Acoustic sources operating at high output frequencies (>180 kHz) that are outside the known functional hearing capability of any marine mammal are unlikely to be detected by marine mammals. Although it is possible that these systems may produce subharmonics at lower frequencies, this component of acoustic output would also be at significantly lower SPLs. While the production of subharmonics can occur during actual operations, the phenomenon may be the result of issues with the system or its installation on a vessel rather than an issue that is inherent to the output of the system. Many of these sources also generally have short duration signals and highly directional beam patterns, meaning that any individual marine mammal would be unlikely to even receive a signal that would likely be inaudible. Acoustic sources present on most SWFSC fishery research vessels include a variety of single, dual, and multi-beam echosounders (many with a variety of modes), sources used to determine the orientation of trawl nets, and several current profilers with lower output frequencies that certain marine mammals may detect ( e.g., 10-180 kHz). However, while likely potentially audible to certain species, these sources also have generally short ping durations and are typically focused (highly directional) to serve their intended purpose of mapping specific objects, depths, or environmental features. These characteristics reduce the likelihood of an animal receiving or perceiving the signal. A number of these sources, particularly those with relatively lower output frequencies coupled with higher output levels can be operated in different output modes ( e.g., energy can be distributed among multiple output beams) that may lessen the likelihood of perception by and potential impact on marine mammals. We now describe specific acoustic sources used by SWFSC. The acoustic system used during a particular survey is optimized for surveying under specific environmental conditions ( e.g., depth and bottom type). Lower frequencies of sound travel further in the water ( i.e., good range) but provide lower resolution ( i.e., are less precise). Pulse width and power may also be adjusted in the field to accommodate a variety of environmental conditions. Signals with a relatively long pulse width travel further and are received more clearly by the transducer ( i.e., good signal-to-noise ratio) but have a lower range resolution. Shorter pulses provide higher range resolution and can detect smaller and more closely spaced objects in the water. Similarly, higher power settings may decrease the utility of collected data. Power level is also adjusted according to bottom type, as some bottom types have a stronger return and require less power to produce data of sufficient quality. Power is typically set to the lowest level possible in order to receive a clear return with the best data. Survey vessels may be equipped with multiple acoustic systems; each system has different advantages that may be utilized depending on the specific survey area or purpose. In addition, many systems may be operated at one of two frequencies or at a range of frequencies. Primary source categories are described below, and characteristics of representative predominant sources are summarized in Table 2. Predominant sources are those that, when operated, would be louder than and/or have a larger acoustic footprint than other concurrently operated sources, at relevant frequencies. (1) Multi-Frequency Narrow Beam Scientific Echosounders —Echosounders and sonars work by transmitting acoustic pulses into the water that travel through the water column, reflect off the seafloor, and return to the receiver. Water depth is measured by multiplying the time elapsed by the speed of sound in water (assuming accurate sound speed measurement for the entire signal path), while the returning signal itself carries information allowing “visualization” of the seafloor. Multi-frequency split-beam sensors are deployed from SWFSC survey vessels to acoustically map the distributions and estimate the abundances and biomasses of many types of fish; characterize their biotic and abiotic environments; investigate ecological linkages; and gather information about their schooling behavior, migration patterns, and avoidance reactions to the survey vessel. The use of multiple frequencies allows coverage of a broad range of marine acoustic survey activity, ranging from studies of small plankton to large fish schools in a variety of environments from shallow coastal waters to deep ocean basins. Simultaneous use of several discrete echosounder frequencies facilitates accurate estimates of the size of individual fish, and can also be used for species identification based on differences in frequency-dependent acoustic backscattering between species. (2) Multibeam Echosounder and Sonar —Multibeam echosounders and sonars operate similarly to the devices described above. However, the use of multiple acoustic “beams” allows coverage of a greater area compared to single beam sonar. The sensor arrays for multibeam echosounders and sonars are usually mounted on the keel of the vessel and have the ability to look horizontally in the water column as well as straight down. Multibeam echosounders and sonars are used for mapping seafloor bathymetry, estimating fish biomass, characterizing fish schools, and studying fish behavior. (3) Single-Frequency Omnidirectional Sonar —These sources provide omnidirectional imaging around the source with different vertical beamwidths available, which results in differential transmitting beam patterns. The cylindrical multi-element transducer allows the omnidirectional sonar beam to be electronically tilted down to -90°, allowing automatic tracking of schools of fish within the entire water volume around the vessel. (4) Acoustic Doppler Current Profiler (ADCP) —An ADCP is a type of sonar used for measuring water current velocities simultaneously at a range of depths. Whereas current depth profile measurements in the past required the use of long strings of current meters, the ADCP enables measurements of current velocities across an entire water column. The ADCP measures water currents with sound, using the Doppler effect. A sound wave has a higher frequency when it moves towards the sensor (blue shift) than when it moves away (red shift). The ADCP works by transmitting “pings” of sound at a constant frequency into the water. As the sound waves travel, they ricochet off particles suspended in the moving water, and reflect back to the instrument. Due to the Doppler effect, sound waves bounced back from a particle moving away from the profiler have a slightly lowered frequency when they return. Particles moving toward the instrument send back higher frequency waves. The difference in frequency between the waves the profiler sends out and the waves it receives is called the Doppler shift. The instrument uses this shift to calculate how fast the particle and the water around it are moving. Sound waves that hit particles far from the profiler take longer to come back than waves that strike close by. By measuring the time it takes for the waves to return to the sensor, and the Doppler shift, the profiler can measure current speed at many different depths with each series of pings. An ADCP anchored to the seafloor can measure current speed not just at the bottom, but at equal intervals to the surface. An ADCP instrument may be anchored to the seafloor or can be mounted to a mooring or to the bottom of a boat. ADCPs that are moored need an anchor to keep them on the bottom, batteries, and a data logger. Vessel-mounted instruments need a vessel with power, a shipboard computer to receive the data, and a GPS navigation system so the ship's movements can be subtracted from the current velocity data. ADCPs operate at frequencies between 75 and 300 kHz. (5) Net Monitoring Systems —During trawling operations, a range of sensors may be used to assist with controlling and monitoring gear. Net sounders give information about the concentration of fish around the opening to the trawl, as well as the clearances around the opening and the bottom of the trawl; catch sensors give information about the rate at which the codend is filling; symmetry sensors give information about the optimal geometry of the trawls; and tension sensors give information about how much tension is in the warps and sweeps. Table 2—Operating Characteristics of Representative SWFSC Active Acoustic Sources Active acoustic system Operating frequencies Maximum source level Single ping duration (ms) and repetition rate (Hz) Orientation/directionality Nominal beamwidth Simrad EK60/EK80 narrow beam echosounders 18, 38, 70, 120, 200, 333 kHz (Primary frequencies are 38, 70, 120, 200 kHz) 226 dB Variable, commonly 1 ms at 0.5 Hz Downward looking 7° Simrad ME70 multibeam echosounder 70-120 kHz 205 dB 0.06-5 ms at 1-4 Hz Primarily downward looking 130° Simrad MS70 multibeam sonar 75-112 kHz 206 dB 2-10 ms at 1-2 Hz Primarily side looking 60° Simrad SX90 narrow beam sonar 20-30 kHz 219 dB Variable Omnidirectional 4-5° Teledyne ADCP, Ocean Surveyor 75 kHz 224 dB 0.2 Hz Downward looking 30° Simrad ITI catch monitoring system 27-33 kHz 214 dB 0.05-0.5 Hz Downward looking 40° Description of Marine Mammals in the Area of the Specified Activity We have reviewed SWFSC's species descriptions—which summarize available information regarding status and trends, distribution and habitat preferences, behavior and life history, and auditory capabilities of the potentially affected species—for accuracy and completeness and refer the reader to Sections 3 and 4 of SWFSC's application, instead of reprinting the information here. Additional information regarding population trends and threats may be found in NMFS's Stock Assessment Reports (SAR; www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments ) and more general information about these species ( e.g., physical and behavioral descriptions) may be found on NMFS's website ( www.fisheries.noaa.gov/find-species ). Table 3 lists all species with expected potential for occurrence in the specified geographical regions where SWFSC proposes to continue the specified activities and summarizes information related to the population or stock, including regulatory status under the MMPA and ESA and potential biological removal (PBR), where known. For taxonomy, we follow Committee on Taxonomy (2020). PBR, defined by the MMPA as the maximum number of animals, not including natural mortalities, that may be removed from a marine mammal stock while allowing that stock to reach or maintain its optimum sustainable population, is discussed in greater detail later in this document (see “Negligible Impact Analysis”). Marine mammal abundance estimates presented in this document represent the total number of individuals that make up a given stock or the total number estimated within a particular study or survey area. NMFS's stock abundance estimates for most species represent the total estimate of individuals within the geographic area, if known, that comprises that stock. For some species, this geographic area may extend beyond U.S. waters. Survey abundance (as compared to stock or species abundance) is the total number of individuals estimated within the survey area, which may or may not align completely with a stock's geographic range as defined in the SARs. These surveys may also extend beyond U.S. waters. All stocks occurring in the CCE are assessed in either NMFS's U.S. Alaska SARs or U.S. Pacific SARs. All values presented in Table 3 are the most recent available at the time of writing and are available in the 2018 SARs (Carretta et al., 2019; Muto et al., 2019) or draft 2019 SARs (available online at: www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports ). Antarctic stocks are not generally defined by NMFS, and information relating to species occurring in the AMLR is lacking relative to those occurring in the CCE. For species occurring in AMLR, we provide International Union for the Conservation of Nature (IUCN) status. The IUCN systematically assesses the relative risk of extinction for terrestrial and aquatic plant and animal species via a classification scheme using five designations, including three threatened categories (Critically Endangered, Endangered, and Vulnerable) and two non-threatened categories (Near Threatened and Least Concern) ( www.iucnredlist.org/; accessed June 22, 2020). These assessments are generally made relative to the species' global status, and therefore may have limited applicability when marine mammal stocks are defined because we analyze the potential population-level effects of the specified activity to the relevant stock. However, where stocks are not defined, IUCN status can provide a useful reference. California Current In the CCE, 33 species (with 40 managed stocks) are considered to have the potential to co-occur with SWFSC activities. Species that could potentially occur in the research area but are not expected to have the potential for interaction with SWFSC research gear or that are not likely to be harassed by SWFSC's use of active acoustic devices are described briefly but omitted from further analysis. These include extralimital species, which are species that do not normally occur in a given area but for which there are one or more occurrence records that are considered beyond the normal range of the species. Species considered to be extralimital here include the North Pacific right whale ( Eubalaena japonica ) and the Bryde's whale ( Balaenoptera edeni brydei ). In addition, the sea otter is found in coastal waters, with the southern sea otter ( Enhydra lutris nereis ) found in California and the northern (or eastern) sea otter ( E. l. kenyoni; Washington stock only) found in Washington. However, sea otters are managed by the U.S. Fish and Wildlife Service and are not considered further in this document. Most survey activity occurs offshore and is therefore less likely to interact with coastal species such as harbor porpoise, the coastal stock of bottlenose dolphin, or gray whales (during the northbound migration), although these species are considered further in this document. SWFSC does not conduct research activities in the inland waters of Washington. Therefore, stocks occurring solely in those waters ( i.e., harbor porpoise and harbor seal) are not addressed herein. Two populations of gray whales are recognized, eastern and western North Pacific (ENP and WNP). WNP whales are known to feed in the Okhotsk Sea and off Kamchatka before migrating south to poorly known wintering grounds, possibly in the South China Sea. The two populations have historically been considered geographically isolated from each other; however, data from satellite-tracked whales indicate that there is some overlap between the stocks. Two WNP whales were tracked from Russian foraging areas along the Pacific rim to Baja California (Mate et al., 2011), and, in one case where the satellite tag remained attached to the whale for a longer period, a WNP whale was tracked from Russia to Mexico and back again (IWC, 2012). Between 22-24 WNP whales are known to have occurred in the eastern Pacific through comparisons of ENP and WNP photo-identification catalogs (IWC, 2012; Weller et al., 2011; Burdin et al., 2011). Urban et al. (2013) compared catalogs of photo-identified individuals from Mexico with photographs of whales off Russia and reported a total of 21 matches. Therefore, a portion of the WNP population is assumed to migrate, at least in some years, to the eastern Pacific during the winter breeding season. However, the SWFSC does not believe that any gray whale (WNP or ENP) would be likely to interact with its research gear, as it is extremely unlikely that a gray whale in close proximity to SWFSC research activity would be one of the few WNP whales that have been documented in the eastern Pacific. The likelihood that a WNP whale would interact with SWFSC research gear or be exposed to elevated levels of sound due to the use of active acoustic sources is insignificant and discountable, and WNP gray whales are omitted from further analysis. Table 3—Marine Mammals Potentially Present in the Vicinity of SWFSC Research Activities in the CCE Common name Scientific name Stock ESA/MMPA status; Strategic (Y/N) 1 Stock abundance (CV, N min , most recent abundance survey) 2 PBR Annual M/SI 3 Order Cetartiodactyla—Cetacea—Superfamily Mysticeti (baleen whales) Family Eschrichtiidae: Gray whale Eschrichtius robustus Eastern North Pacific (ENP) -; N 26,960 (0.05; 25,849; 2016) 801 139 Family Balaenopteridae (rorquals): Humpback whale Megaptera novaeangliae kuzira California/Oregon/Washington (CA/OR/WA) E/D; Y 2,900 (0.03; 2,784; 2014) 9 16.7 ≥42.1 Minke whale Balaenoptera acutorostrata scammoni CA/OR/WA -; N 636 (0.72; 369; 2014) 3.5 ≥1.3 Sei whale B. borealis borealis ENP E/D; Y 519 (0.4; 374; 2014) 0.75 ≥0.2 Fin whale B. physalus physalus CA/OR/WA E/D; Y 9,029 (0.12; 8,127; 2014) 81 ≥43.5 Blue whale B. musculus musculus ENP E/D; Y 1,496 (0.44; 1,050; 2014) 9 1.2 ≥19.4 Superfamily Odontoceti (toothed whales, dolphins, and porpoises) Family Physeteridae: Sperm whale Physeter macrocephalus CA/OR/WA E/D; Y 1,997 (0.57; 1,270; 2014) 2.5 0.4 Family Kogiidae: Pygmy sperm whale Kogia breviceps CA/OR/WA -; N 4,111 (1.12; 1,924; 2014) 19.2 0 Dwarf sperm whale K. sima CA/OR/WA 5 -; N Unknown n/a 0 Family Ziphiidae (beaked whales): Cuvier's beaked whale Ziphius cavirostris CA/OR/WA -; N 3,274 (0.67; 2,059; 2014) 21 <0.1 Baird's beaked whale Berardius bairdii CA/OR/WA -; N 2,697 (0.6; 1,633; 2014) 16 0 Hubbs' beaked whale Mesoplodon carlhubbsi CA/OR/WA 6 -; N 3,044 (0.54; 1,967; 2014) 20 0.1 Blainville's beaked whale M. densirostris Ginkgo-toothed beaked whale M. ginkgodens Perrin's beaked whale M. perrini Lesser (pygmy) beaked whale M. peruvianus Stejneger's beaked whale M. stejnegeri Family Delphinidae: Common bottlenose dolphin Tursiops truncatus truncatus CA/OR/WA Offshore -; N 1,924 (0.54; 1,255; 2014) 11 ≥1.6 California Coastal -; N 453 (0.06; 346; 2011) 2.7 ≥2.0 Striped dolphin Stenella coeruleoalba CA/OR/WA -; N 29,211 (0.2; 24,782; 2014) 238 ≥0.8 ENP long-beaked common dolphin Delphinus delphis bairdii California -; N 101,305 (0.49; 68,432; 2014) 657 ≥35.4 Common dolphin D. d. delphis CA/OR/WA -; N 969,861 (0.17; 839,325; 2014) 8,393 ≥40 Pacific white-sided dolphin Lagenorhynchus obliquidens CA/OR/WA -; N 26,814 (0.28; 21,195; 2014) 191 7.5 Northern right whale dolphin Lissodelphis borealis CA/OR/WA -; N 26,556 (0.44; 18,608; 2014) 179 3.8 Risso's dolphin Grampus griseus CA/OR/WA -; N 6,336 (0.32; 4,817; 2014) 46 ≥3.7 Killer whale Orcinus orca 4 West Coast Transient 7 -; N 243 (n/a; 2009) 2.4 0 ENP Offshore -; N 300 (0.1; 276; 2012) 2.8 0 ENP Southern Resident E/D; Y 75 (n/a; 2018) 0.13 0 Short-finned pilot whale Globicephala macrorhynchus CA/OR/WA -; N 836 (0.79; 466; 2014) 4.5 1.2 Family Phocoenidae (porpoises): Harbor porpoise Phocoena phocoena vomerina Morro Bay -; N 2,917 (0.41; 2,102; 2012) 21 ≥0.6 Monterey Bay -; N 3,715 (0.51; 2,480; 2011) 25 0 San Francisco-Russian River -; N 9,886 (0.51; 6,625; 2011) 66 0 Northern CA/Southern OR -; N 35,769 (0.52; 23,749; 2011) 475 ≥0.6 Northern OR/WA Coast -; N 21,487 (0.44; 15,123; 2011) 151 ≥3 Dall's porpoise Phocoenoides dalli dalli CA/OR/WA -; N 25,750 (0.45; 17,954; 2014) 172 0.3 Order Carnivora—Superfamily Pinnipedia Family Otariidae (eared seals and sea lions): Guadalupe fur seal Arctocephalus philippii townsendi Mexico to California T/D; Y 34,187 (n/a; 31,019; 2013) 1,062 10 ≥3.8 Northern fur seal Callorhinus ursinus Pribilof Islands/Eastern Pacific D; Y 620,660 (0.2; 525,333; 2016) 11,295 399 California -; N 14,050 (n/a; 7,524; 2013) 451 1.8 California sea lion Zalophus californianus United States -; N 257,606 (n/a; 233,515; 2014) 14,011 ≥321 Steller sea lion Eumetopias jubatus monteriensis Eastern U.S. -; N 43,201 (n/a; 2017) 2,592 113 Family Phocidae (earless seals): Harbor seal Phoca vitulina richardii California -; N 30,968 (n/a; 27,348; 2012) 1,641 43 OR/WA Coast 8 -; N 24,732 (0.12; 22,380; 1999) n/a 10.6 Northern elephant seal Mirounga angustirostris California Breeding -; N 179,000 (n/a; 81,368; 2010) 4,882 8.8 1 Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed under the ESA is automatically designated under the MMPA as depleted and as a strategic stock. 2 NMFS marine mammal stock assessment reports at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments. CV is coefficient of variation; N min is the minimum estimate of stock abundance. In some cases, CV is not applicable. For most stocks of killer whales, the abundance values represent direct counts of individually identifiable animals; therefore there is only a single abundance estimate with no associated CV. For certain stocks of pinnipeds, abundance estimates are based upon observations of animals (often pups) ashore multiplied by some correction factor derived from knowledge of the species' (or similar species') life history to arrive at a best abundance estimate; therefore, there is no associated CV. In these cases, the minimum abundance may represent actual counts of all animals ashore. 3 These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined ( e.g., commercial fisheries, subsistence hunting, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value. All M/SI values are as presented in the draft 2019 SARs. 4 Transient and resident killer whales are considered unnamed subspecies (Committee on Taxonomy, 2020). 5 No information is available to estimate the population size of dwarf sperm whales off the U.S. West Coast, as no sightings of this species have been documented despite numerous vessel surveys of this region (Carretta et al., 2017). Dwarf and pygmy sperm whales are difficult to differentiate at sea but, based on previous sighting surveys and historical stranding data, it is thought that recent ship survey sightings were of pygmy sperm whales. 6 The six species of Mesoplodont beaked whales occurring in the CA/OR/WA region are managed as a single stock due to the rarity of records and the difficulty in distinguishing these animals to species in the field. Based on bycatch and stranding records, it appears that M. carlhubbsi is the most commonly encountered of these species (Carretta et al., 2008; Moore and Barlow, 2013). 7 The abundance estimate for this stock includes only animals from the “inner coast” population occurring in inside waters of southeastern Alaska, British Columbia, and Washington—excluding animals from the “outer coast” subpopulation, including animals from California—and therefore should be considered a minimum count. For comparison, the previous abundance estimate for this stock, including counts of animals from California that are now considered outdated, was 354. 8 Abundance estimate for this stock is not considered current. PBR is therefore considered undetermined, as there is no current minimum abundance estimate for use in calculation. We nevertheless present the most recent abundance estimates, as it represents the best available information for use in this document. 9 These stocks are known to spend a portion of their time outside the U.S. EEZ. Therefore, the PBR presented here is the allocation for U.S. waters only and is a portion of the total. The total PBR for blue whales is 2.1 (7/12 allocation for U.S. waters), and the total for CA/OR/WA humpback whales is 33.4 (one half allocation for U.S. waters). Annual M/SI presented for these species is for U.S. waters only. 10 This represents annual M/SI in U.S. waters. However, the vast majority of M/SI for this stock—the level of which is unknown—would likely occur in Mexican waters. There is insufficient information to determine whether mortality in Mexico exceeds the PBR for this stock, but given the observed growth of the population over time, this is unlikely (Carretta et al., 2019). Prior to 2016, humpback whales were listed under the ESA as an endangered species worldwide. Following a 2015 global status review (Bettridge et al., 2015), NMFS established 14 distinct population segments (DPS) with different listing statuses (81 FR 62259; September 8, 2016) pursuant to the ESA. The DPSs that occur in U.S. waters do not necessarily equate to the existing stocks designated under the MMPA and shown in Table 3. Because MMPA stocks cannot be portioned, i.e., parts managed as ESA-listed while other parts managed as not ESA-listed, until such time as the MMPA stock delineations are reviewed in light of the DPS designations, NMFS considers the existing humpback whale stocks under the MMPA to be endangered and depleted for MMPA management purposes ( e.g., selection of a recovery factor, stock status). Within U.S. West Coast waters, three current DPSs may occur: The Hawaii DPS (not listed), Mexico DPS (threatened), and Central America DPS (endangered). According to Wade et al. (2016), whales off of Washington are most likely to be from the Hawaii DPS (52.9 percent), but are almost equally likely to be from the Mexico DPS (41.9 percent), and could also be from the Central America DPS (14.7 percent). Off of Oregon and California, whales are most likely to be from the Mexico DPS (89.6 percent), with a 19.7 percent probability of an encountered whale being from the Central America DPS. Note that these probabilities reflect the upper limit of the 95 percent confidence interval of the probability of occurrence; therefore, numbers may not sum to 100 percent for a given area. Take Reduction Planning —Take reduction plans are designed to help recover and prevent the depletion of strategic marine mammal stocks that interact with certain U.S. commercial fisheries, as required by Section 118 of the MMPA. The immediate goal of a take reduction plan is to reduce, within six months of its implementation, the M/SI of marine mammals incidental to commercial fishing to less than the PBR level. The long-term goal is to reduce, within five years of its implementation, the M/SI of marine mammals incidental to commercial fishing to insignificant levels, approaching a zero serious injury and mortality rate, taking into account the economics of the fishery, the availability of existing technology, and existing state or regional fishery management plans. Take reduction teams are convened to develop these plans. For marine mammals in the CCE, there is currently one take reduction plan in effect (Pacific Offshore Cetacean Take Reduction Plan). The goal of this plan is to reduce M/SI of several marine mammal stocks incidental to the California thresher shark/swordfish drift gillnet fishery (CA DGN). A team was convened in 1996 and a final plan produced in 1997 (62 FR 51805; October 3, 1997). Marine mammal stocks of concern initially included the California, Oregon, and Washington stocks for all CCE beaked whales, short-finned pilot whales, pygmy sperm whales, sperm whales, and humpback whales. The most recent five-year averages of M/SI for all stocks except the humpback whale are below PBR. For humpback whales, the majority of total annual M/SI is attributed to other fisheries—notably pot/trap fisheries—and ship strikes, with no observed M/SI in the DGN fishery from 2013-2017, and estimated mean annual M/SI in the fishery at <0.1 (CV = 1.9) over the same period. The most recent observed take of a sperm whale in the DGN fishery was in 2010, though the mean annual estimated M/SI attributed to the fishery over the period from 2008-2017 is 0.56 (CV = 0.78). Two short-finned pilot whales were observed taken in the DGN fishery in 2014, leading to a mean annual M/SI estimate of 1.2 (CV = 0.39) for the fishery. None of the other species were observed taken in the fishery in the most recent five-year period for which data are available, though some have estimated mean annual M/SI values for the fishery that are > 0. More information is available online at: www.fisheries.noaa.gov/national/marine-mammal-protection/pacific-offshore-cetacean-take-reduction-plan. Of the stocks of concern, the SWFSC has requested the authorization of incidental M/SI for the short-finned pilot whale only (see “Estimated Take by Incidental Harassment” later in this document). The SWFSC does not use drift gillnets in its fisheries research program; therefore, take reduction measures applicable to the CA DGN fisheries are not relevant to the SWFSC. Unusual Mortality Events (UME) —A UME is defined under the MMPA as a stranding that is unexpected; involves a significant die-off of any marine mammal population; and demands immediate response. From 1991 to the present, there have been 16 formally recognized UMEs on the U.S. West Coast involving species under NMFS' jurisdiction. The only currently ongoing investigations involve Guadalupe fur seals and gray whales along the west coast. Increased strandings of Guadalupe fur seals (up to eight times the historical average) have occurred along the entire coast of California and extending into Oregon and Washington. Increased strandings in California were reported beginning in January 2015 and peaked from April through June 2015, but have remained well above average. Strandings in Oregon and Washington became elevated starting in 2019 and are five times higher than the historical average. Findings from the majority of stranded animals include malnutrition with secondary bacterial and parasitic infections, and the UME has been attributed to ecological factors. For more information, please visit: www.fisheries.noaa.gov/national/marine-life-distress/2015-2020-guadalupe-fur-seal-unusual-mortality-event-california. Since January 1, 2019, elevated gray whale strandings have occurred along the west coast of North America from Mexico through Alaska. As of June 5, 2020, there have been a total of 340 whales reported in the event, with approximately 168 dead whales in Mexico, 159 whales in the United States (53 in California; 9 in Oregon; 42 in Washington, 55 in Alaska), and 13 whales in British Columbia, Canada. For the United States, the historical 18-year 5-month average (Jan-May) is 14.8 whales for the four states for this same time-period. Several dead whales have been emaciated with moderate to heavy whale lice (cyamid) loads. Necropsies have been conducted on a subset of whales with additional findings of vessel strike in three whales and entanglement in one whale. In Mexico, 50-55 percent of the free-ranging whales observed in the lagoons in winter have been reported as “skinny” compared to the annual average of 10-12 percent “skinny” whales normally seen. The cause of the UME is as yet undetermined. For more information, please visit: www.fisheries.noaa.gov/national/marine-life-distress/2019-2020-gray-whale-unusual-mortality-event-along-west-coast-and. Additional UMEs in the past ten years include those involving California sea lions (2013-2016; ecological factors) and large whales in Alaska and British Columbia (2015-2016; undetermined cause with secondary ecological factors). For more information on UMEs, please visit: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-unusual-mortality-events. Antarctic The SWFSC's Antarctic Research Area (ARA) comprises a portion of the AMLR ecosystem. In the ARA, seventeen species are considered to have the potential to co-occur with SWFSC activities. Marine mammals in the AMLR do not constitute stocks under U.S. jurisdiction; therefore, the stocks are not managed by NMFS, there are no SARs, and substantially less information is available for these species in relation to the stocks or populations and their occurrence in the ARA than is available for CCE stocks ( e.g., PBR is not calculated for AMLR stocks, and strategic designations are not made). Extralimital species in the ARA include the pygmy right whale ( Caperea marginata ), sei whale, Cuvier's beaked whale, Shepherd's beaked whale ( Tasmacetus shepherdi ), Gray's beaked whale ( Mesoplodon grayi ), and strap-toothed beaked whale ( M. layardii ), which have distributions that only border the northernmost edge of the ARA. The Ross seal ( Ommatophoca rossii ) is also considered extralimital to the ARA due to its preference for dense pack ice, which is not typically present in the ARA. Table 5—Marine Mammals Potentially Present in the Vicinity of SWFSC Research Activities in the AMLR Common name Scientific name Stock 2 ESA/MMPA/IUCN status 3 Abundance (CV) 4 Order Cetartiodactyla—Cetacea—Superfamily Mysticeti (baleen whales) Family Balaenidae (right whales): Southern right whale Eubalaena australis E/D/LC 1,755 (0.62) 5 Family Balaenopteridae (rorquals): Humpback whale Megaptera novaeangliae australis E/D/LC 9,484 (0.28) 5 Antarctic minke whale Balaenoptera bonaerensis -/NT 18,125 (0.28) 5 Fin whale B. physalus quoyi E/D/VU 4,672 (0.42) 5 Blue whale B. musculus intermedia E/D/EN 1,700 (95% CI 860-2,900) 6 Superfamily Odontoceti (toothed whales, dolphins, and porpoises) Family Physeteridae: Sperm whale Physeter macrocephalus E/D/VU 12,069 (0.17) 7 Family Ziphiidae (beaked whales): Arnoux' beaked whale Berardius arnuxii -/DD Unknown Southern bottlenose whale Hyperoodon planifrons -/LC 53,743 (0.12) 8 Family Delphinidae: Hourglass dolphin Lagenorhynchus cruciger -/LC 144,300 (0.17) 9 Killer whale Orcinus orca 1 -/DD 24,790 (0.23) 8 Long-finned pilot whale Globicephala melas edwardii -/LC 200,000 (0.35) 9 Family Phocoenidae (porpoises): Spectacled porpoise Phocoena dioptrica -/LC Unknown Order Carnivora—Superfamily Pinnipedia Family Otariidae (eared seals and sea lions): Antarctic fur seal Arctocephalus gazella South Georgia -/LC 2,700,000 10 Family Phocidae (earless seals): Southern elephant seal Mirounga leonina South Georgia -/LC 401,572 11 Weddell seal Leptonychotes weddellii -/LC 500,000-1,000,000 12 Crabeater seal Lobodon carcinophaga -/LC 5,000,000-10,000,000 12 Leopard seal Hydrurga leptonyx -/LC 222,000-440,000 12 1 Three distinct forms of killer whale have been described from Antarctic waters; referred to as types A, B, and C, they are purported prey specialists on Antarctic minke whales, seals, and fish, respectively (Pitman and Ensor, 2003; Pitman et al., 2010). 2 For most species in the AMLR, stocks are not delineated and entries refer generally to individuals of the species occurring in the research area. 3 Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed under the ESA or designated as depleted under the MMPA. Any species listed under the ESA is automatically designated under the MMPA as depleted. IUCN status: Endangered (EN), Vulnerable (VU), Near Threatened (NT), Least Concern (LC), Data Deficient (DD). 4 CV is coefficient of variation. All abundance estimates, except for those from Reilly et al. (2004) (right, humpback, minke, and fin whales), are for entire Southern Ocean ( i.e., waters south of 60°S) and not the smaller area comprising the SWFSC research area. 5 Abundance estimates reported in Reilly et al. (2004) for the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) survey area from 2000. Surveys include Antarctic Peninsula (473,300 km 2 ) and Scotia Sea (1,109,800 km 2 ) strata, which correspond roughly to ARA, as reported by Hewitt et al. (2004). 6 Southern Ocean abundance estimate (Branch et al., 2007). CI is confidence interval. 7 Southern Ocean abundance estimate (IWC, 2001 in Whitehead, 2002). 8 Southern Ocean abundance estimate from circumpolar surveys covering 68 percent of waters south of 60°S from 1991-98 (Branch and Butterworth, 2001). 9 Southern Ocean abundance estimate derived from surveys conducted from 1976-88 (Kasamatsu and Joyce, 1995). 10 South Georgia abundance estimate; likely >95 percent of range-wide abundance (Forcada and Staniland, 2009). Genetic evidence shows two distinct population regions, likely descended from surviving post-sealing populations at South Georgia, Bouvetøya, and Kerguelen Islands (Wynen et al., 2000; Forcada and Staniland, 2009). Individuals from the South Georgia population (including breeding populations at the South Orkney and South Shetland Islands, which are within the ARA) are likely to occur in the ARA. 11 Four genetically distinct populations are recognized: The Peninsula Valdés population in Argentina, the South Georgia population in the South Atlantic Ocean, the Kerguelen population in the South Indian Ocean and the Macquarie population in the South Pacific Ocean (Slade et al., 1998; Hoelzel et al., 2001). Animals occurring in ARA are likely to belong to South Georgia population, which includes subpopulations at South Georgia Island (>99% of population) and at the South Orkney and South Shetland Islands; South Georgia population abundance estimate from 2001 (McMahon et al., 2005). 12 Range-wide abundance estimates (Thomas and Terhune, 2009; Bengtson, 2009; Rogers, 2009). Marine Mammal Hearing Hearing is the most important sensory modality for marine mammals underwater, and exposure to anthropogenic sound can have deleterious effects. To appropriately assess the potential effects of exposure to sound, it is necessary to understand the frequency ranges marine mammals are able to hear. Current data indicate that not all marine mammal species have equal hearing capabilities ( e.g., Richardson et al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al. (2007) recommended that marine mammals be divided into functional hearing groups based on directly measured or estimated hearing ranges on the basis of available behavioral response data, audiograms derived using auditory evoked potential techniques, anatomical modeling, and other data. Note that no direct measurements of hearing ability have been successfully completed for mysticetes ( i.e., low-frequency cetaceans). Subsequently, NMFS (2018) described generalized hearing ranges for these marine mammal hearing groups. Generalized hearing ranges were chosen based on the approximately 65 dB threshold from the normalized composite audiograms, with an exception for lower limits for low-frequency cetaceans where the result was deemed to be biologically implausible and the lower bound from Southall et al. (2007) retained. Marine mammal hearing groups and their associated hearing ranges are provided in Table 5. Table 5—Marine Mammal Hearing Groups (NMFS, 2018) Hearing group Generalized hearing range * Low-frequency (LF) cetaceans (baleen whales) 7 Hz to 35 kHz. Mid-frequency (MF) cetaceans (dolphins, toothed whales, beaked whales, bottlenose whales) 150 Hz to 160 kHz. High-frequency (HF) cetaceans (true porpoises, Kogia, river dolphins, cephalorhynchid, Lagenorhynchus cruciger & L. australis ) 275 Hz to 160 kHz. Phocid pinnipeds (PW) (underwater) (true seals) 50 Hz to 86 kHz. Otariid pinnipeds (OW) (underwater) (sea lions and fur seals) 60 Hz to 39 kHz. * Represents the generalized hearing range for the entire group as a composite ( i.e., all species within the group), where individual species' hearing ranges are typically not as broad. Generalized hearing range chosen based on ~65 dB threshold from normalized composite audiogram, with the exception for lower limits for LF cetaceans (Southall et al., 2007) and PW pinniped (approximation). For more detail concerning these groups and associated frequency ranges, please see NMFS (2018) for a review of available information. Within the CCE, 33 marine mammal species (27 cetacean and six pinniped [four otariid and two phocid] species) have the potential to co-occur with SWFSC research activities. Please refer to Table 3. Of the 27 cetacean species that may be present, six are classified as low-frequency cetaceans ( i.e., all mysticete species), seventeen are classified as mid-frequency cetaceans ( i.e., all delphinid and ziphiid species and the sperm whale), and four are classified as high-frequency cetaceans ( i.e., porpoises and Kogia spp.). Within the AMLR, seventeen marine mammal species (twelve cetacean and five pinniped [one otariid and four phocid] species) have the potential to co-occur with SWFSC research activities. Please refer to Table 4. Of the twelve cetacean species that may be present, five are classified as low-frequency cetaceans ( i.e., all mysticete species), five are classified as mid-frequency cetaceans ( i.e., all delphinid and ziphiid species [excluding the hourglass dolphin] and the sperm whale), and two are classified as high-frequency cetaceans ( i.e., the hourglass dolphin and spectacled porpoise). Potential Effects of the Specified Activity on Marine Mammals and Their Habitat Detailed descriptions of the potential effects of the various elements of the SWFSC's specified activity on marine mammals and their habitat were provided in association with the 2015 SWFSC rulemaking (80 FR 8166; February 15, 2015). Additionally, detailed descriptions of the potential effects of similar specified activities have also been provided in other Federal Register notices ( e.g., 81 FR 38516; 83 FR 37638; 84 FR 6576), and section 7 of SWFSC's application provides a discussion of the potential effects of their specified activity, which we have reviewed for accuracy and completeness. No significant new information is available, and these discussions provide the necessary adequate and relevant information regarding the potential effects of SWFSC's specified activity on marine mammals and their habitat. Therefore, we refer the reader to these documents rather than repeating the information here. The referenced information includes a summary and discussion of the ways that components of the specified activity ( e.g., gear deployment, use of active acoustic sources, visual disturbance) may impact marine mammals and their habitat. As stated previously, the use of certain research gears, including trawl nets, hook and line gear, and purse seine nets, has the potential to result in interaction with marine mammals. In the event of a marine mammal interaction with research gear, injury, serious injury, or mortality may result from entanglement or hooking. Exposure to sound through the use of active acoustic systems for research purposes may result in Level B harassment. However, as detailed in the previously referenced discussions, Level A harassment in the form of permanent threshold shift (PTS) is extremely unlikely to occur, and we consider such effects discountable. Finally, in the Antarctic only, it is expected that hauled pinnipeds may be disturbed by approaching researchers such that Level B harassment could occur. Ship strike is not a reasonably anticipated outcome of SWFSC research activities, given the small amount of distance covered by research vessels and their relatively slow speed in comparison to commercial shipping traffic ( i.e., the primary cause of marine mammal vessel strikes). With specific reference to Level B harassment that may occur as a result of acoustic exposure, we note that the analytical methods from the original 2015 analysis are retained here. However, the state of science with regard to our understanding of the likely potential effects of the use of systems like those used by SWFSC has advanced in the preceding five years, as have readily available approaches to estimating the acoustic footprints of such sources, with the result that we view this analysis as highly conservative. Although more recent literature provides documentation of marine mammal responses to the use of these and similar acoustic systems ( e.g., Cholewiak et al., 2017; Quick et al., 2017; Varghese et al., 2020), the described responses do not generally comport with the degree of severity that should be associated with Level B harassment, as defined by the MMPA. We retain the 2015 analytical approach for consistency with existing analyses and for purposes of efficiency here, and consider this acceptable because the approach provides a conservative estimate of potential incidents of Level B harassment. In summary, while we propose to authorize the amount of take by Level B harassment indicated in the “Estimated Take” section, and consider these potential takings at face value in our negligible impact analysis, it is uncertain whether use of these acoustic systems are likely to cause take at all, much less at the estimated levels. The “Estimated Take” section later in this document includes a quantitative analysis of the number of individuals that are expected to be taken by this activity. The “Negligible Impact Analysis and Determination” section considers the potential effects of the specified activity, the “Estimated Take” section, and the “Proposed Mitigation” section, to draw conclusions regarding the likely impacts of these activities on the reproductive success or survivorship of individuals and how those impacts on individuals are likely to impact marine mammal species or stocks. Estimated Take This section provides an estimate of the number of incidental takes proposed for authorization, which will inform both NMFS's consideration of whether the number of takes is “small” and the negligible impact determination. Except with respect to certain activities not pertinent here, section 3(18) of the MMPA defines “harassment” as: Any act of pursuit, torment, or annoyance which (i) has the potential to injure a marine mammal or marine mammal stock in the wild (Level A harassment); or (ii) has the potential to disturb a marine mammal or marine mammal stock in the wild by causing disruption of behavioral patterns, including, but not limited to, migration, breathing, nursing, breeding, feeding, or sheltering (Level B harassment). Take of marine mammals incidental to SWFSC research activities could occur as a result of (1) injury or mortality due to gear interaction in the CCE (Level A harassment, serious injury, or mortality); (2) behavioral disturbance resulting from the use of active acoustic sources (Level B harassment only); or (3) behavioral disturbance of pinnipeds resulting from incidental approach of researchers in the Antarctic (Level B harassment only). Below we describe how the potential take is estimated. Estimated Take Due to Gear Interaction In order to determine the number of incidental takes requested for authorization, SWFSC retained the approach to estimating their requested take numbers that was developed in support of the 2015 rule. That approach was based on historical incidents of gear interaction and on an assessment of which species of marine mammal that have not historically been taken might have similar risk of interaction to those species that have been taken. In particular, records from the year 2008—which remains the year with the highest number of gear interaction incidents—were used as the basis for generating a precautionary, worst-case assessment of potential takes. Reporting from 2015-19 under the current regulations demonstrates that this approach was indeed a precautionary one, as annual numbers of takes have remained well below those recorded in 2008, and only one additional species that had not historically been taken in SWFSC research gear in 2015 has subsequently been taken (common dolphin; see Table 6). SWFSC has elected to carry forward this precautionary approach to their take authorization request in support of this rulemaking, and we incorporate it into our proposed rulemaking, as described in further detail below. The approach to estimating the number of potential incidents of take that could occur through gear interaction first requires consideration of SWFSC's record of past such incidents. We then consider in addition other species that may have similar vulnerabilities to SWFSC trawl and longline gear as those species for which we have historical interaction records. Historical interactions with research gear are described in Tables 6 and 7, and we anticipate that all species that interacted with SWFSC fisheries research gear historically could potentially be taken in the future. Available records are for the years 2006 through present. All historical SWFSC interactions have taken place in the CCE. The locations of incidental take events from 2015-2019 are shown in Figure 6-1 of SWFSC's application. Table 6—Historical Interactions With Trawl Gear Gear 1 Survey Date Species Number killed Number released alive Total Midwater trawl Coastal Pelagic Species (CPS) 4/24/2006 Northern fur seal (CA stock) 1 1 Midwater trawl CPS 4/29/2007 Northern fur seal (CA stock) 1 1 Midwater trawl 2 Juvenile Rockfish 5/30/2007 Northern fur seal (eastern Pacific stock) 1 1 Midwater trawl CPS 4/18/2008 California sea lion 1 1 Midwater trawl CPS 4/21/2008 Pacific white-sided dolphin 1 1 Midwater trawl CPS 4/26/2008 Pacific white-sided dolphin 2 2 Midwater trawl CPS 4/27/2008 California sea lion 1 1 Midwater trawl CPS 4/27/2008 Northern fur seal (eastern Pacific stock) 1 1 Midwater trawl 2 Juvenile Rockfish 6/15/2008 California sea lion 1 2 3 Midwater trawl CPS 7/19/2008 Pacific white-sided dolphin 1 1 Midwater trawl CPS 7/28/2008 California sea lion 1 1 Midwater trawl CPS 7/31/2008 Northern fur seal (CA stock) 1 1 Midwater trawl CPS 8/3/2008 Northern fur seal (CA stock) 1 1 Midwater trawl CPS 8/9/2008 Pacific white-sided dolphin 11 11 Midwater trawl CPS 8/9/2008 Northern right whale dolphin 6 6 Midwater trawl CPS 8/14/2008 California sea lion 9 9 Midwater trawl CPS 5/1/2009 Pacific white-sided dolphin 3 3 Midwater trawl 2 Juvenile Rockfish 5/25/2009 California sea lion 1 1 Midwater trawl CPS 4/18/2010 Pacific white-sided dolphin 1 1 Midwater trawl CPS 4/25/2010 Pacific white-sided dolphin 1 1 Midwater trawl 2 Juvenile Rockfish 9/10/2010 Pacific white-sided dolphin 1 1 Midwater trawl CPS 4/3/2011 Pacific white-sided dolphin 1 1 Midwater trawl Juvenile Salmon 9/9/2011 California sea lion 1 1 Midwater trawl Juvenile Salmon 9/10/2011 Pacific white-sided dolphin 6 6 Midwater trawl CPS 6/29/2012 Pacific white-sided dolphin 1 1 Midwater trawl CPS 8/18/2012 Pacific white-sided dolphin 1 1 Midwater trawl CPS 8/24/2012 Pacific white-sided dolphin 2 2 Midwater trawl CPS 8/1/2013 Pacific white-sided dolphin 1 2 3 Midwater trawl Juvenile Salmon 9/14/2013 Pacific white-sided dolphin 3 3 Midwater trawl 2 Juvenile Rockfish 6/1/2014 Pacific white-sided dolphin 1 1 Surface trawl Sardine-Hake Acoustic Trawl 8/26/2015 Pacific white-sided dolphin 1 1 Surface trawl Juvenile Salmon 9/14/2015 California sea lion 1 1 Midwater trawl 2 Juvenile Rockfish 5/15/2016 Pacific white-sided dolphin 1 1 Surface trawl CPS 7/17/2016 Pacific white-sided dolphin 7 1 8 Midwater trawl 2 Juvenile Rockfish 6/14/2018 Pacific white-sided dolphin 1 1 Midwater trawl 2 Juvenile Rockfish 6/21/2018 California sea lion 1 1 Midwater trawl CPS 7/24/2018 Pacific white-sided dolphin 1 1 Midwater trawl CPS 8/27/2018 Pacific white-sided dolphin 1 1 Surface trawl CCE Survey (CCES) 6/22/2019 Pacific white-sided dolphin 2 2 Midwater trawl CCES 8/8/2019 Pacific white-sided dolphin 2 2 Midwater trawl CCES 8/8/2019 Pacific white-sided dolphin 1 1 Midwater trawl CCES 8/26/2019 Common dolphin (long-beaked) 1 1 Total individuals captured (total number of interactions given in parentheses) Northern fur seal (6) California sea lion (9) 6 15 4 6 19 Pacific white-sided dolphin (25) 49 8 57 Northern right whale dolphin (1) 6 6 Common dolphin (1) 1 1 1 All incidents involved use of the NETS Nordic 264 midwater trawl, except as noted below. 2 These incidents involved use of the modified-Cobb midwater trawl. Table 7—Historical Interactions With Longline Gear Gear Survey Date Species Number killed Number released alive Total Pelagic longline Highly Migratory Species (HMS) 9/6/2008 California sea lion 1 1 Pelagic longline HMS 9/15/2008 California sea lion 1 1 Pelagic longline Thresher Shark 9/18/2009 California sea lion 1 1 Pelagic longline HMS 7/27/2010 California sea lion 1 1 Pelagic longline HMS 6/23/2012 California sea lion 1 1 Pelagic longline HMS 7/10/2013 California sea lion 1 1 Pelagic longline HMS 7/2/2014 California sea lion 1 1 Pelagic longline HMS 7/8/2015 California sea lion 1 1 Pelagic longline Thresher Shark 9/20/2015 California sea lion 1 1 Total 1 8 9 In order to use these historical interaction records as the basis for the take estimation process, and because we have no specific information to indicate whether any given future interaction might result in M/SI versus Level A harassment, we conservatively assume that all interactions equate to mortality for these fishing gear interactions. The SWFSC has no recorded interactions with any gear other than midwater trawl and pelagic longline gear, and we do not anticipate any future interactions in any other gears historically used by SWFSC, including the bottom trawl gear periodically employed by the SWFSC in the AMLR. However, SWFSC has not historically used purse seine gear, and we do anticipate that the planned future use of purse seine gear in the CCE could present some risk of marine mammal interaction. During trawl surveys, SWFSC has recorded interactions with northern fur seals (California and eastern Pacific stocks); California sea lions; Pacific white-sided dolphins; northern right whale dolphins; and common dolphins (long-beaked stock). No northern fur seal has been captured since 2008, and northern right whale dolphins have been involved in only one incident, also in 2008. Common dolphins have been involved in only one incident. Therefore, California sea lions and Pacific white-sided dolphins are the species most likely to interact with SWFSC trawl gear. For longline gear, only California sea lions have been captured. Take records from 2008 were used as the basis for estimation of potential incidental take in support of the 2015 rule, as this year was the worst on record and therefore was assumed to provide a worst-case basis for predicting potential future take. Take interactions from 2008 remain the historical maximum. Therefore, as noted above, the 2015 analysis is retained here as a potential worst-case scenario for marine mammal take in SWFSC gear over the five years considered in this proposed rulemaking. In the 2015 analysis, the annual average over the most recent five-year period that included 2008 (rounded up to the next whole number) was used to estimate the potential annual take level over the next five years. A five-year time frame provides enough data to adequately capture year-to-year variation in take levels, reflecting environmental conditions that may change over time. In order to incorporate records from the year 2008, we retain 2008-12 as the five-year period over which we consider interaction records. Those annual averages are 7 Pacific white-sided dolphins, 4 California sea lions, 2 northern right whale dolphins, and 1 northern fur seal, and the prior assumption was that this number could be taken in each of the five years ( i.e., 35 Pacific white-sided dolphins, 20 California sea lions, 10 northern right whale dolphins, 5 northern fur seals). These take numbers are retained, with the exception of the Pacific white-sided dolphin. Historically, the CPS survey has only surveyed in water depths >50 m and consequently does not sample the nearshore area, potentially under-sampling any nearshore CPS aggregations. The aim of planned collaborative research over the next five years is to quantify this potential sampling bias by using an industry fishing vessel to extend the sampling closer to shore. In order to account for the potential for increased interactions with Pacific white-sided dolphins in nearshore waters, SWFSC added 1 additional take per year. For the species most commonly taken, the maximum number of individuals taken through any one interaction was 11 Pacific white-sided dolphins and 9 California sea lions. Similarly, the annual average of California sea lions taken in longline gear from 2008-12 was 1. Therefore, the assumption is that 5 California sea lions may be taken in hook and line gear over the next five-year period. In order to evaluate the potential vulnerability of additional species to midwater trawl and pelagic longline gear as part of the take estimation process for the 2015 rule, we consulted NMFS' List of Fisheries (LOF), which classifies U.S. commercial fisheries into one of three categories according to the level of incidental marine mammal M/SI that is known to occur on an annual basis over the most recent five-year period (generally) for which data has been analyzed: Category I, frequent incidental M/SI; Category II, occasional incidental M/SI; and Category III, remote likelihood of or no known incidental M/SI. Information related to incidental M/SI in relevant commercial fisheries is not, however, the sole determinant of whether it may be appropriate to authorize take incidental to SWFSC survey operations. A number of factors ( e.g., species-specific knowledge regarding animal behavior, overall abundance in the geographic region, density relative to SWFSC survey effort, feeding ecology, propensity to travel in groups commonly associated with other species historically taken) were taken into account by the SWFSC to determine whether a species may have a similar vulnerability to certain types of gear as historically taken species. In some cases, we have determined that species without documented M/SI may nevertheless be vulnerable to capture in SWFSC research gear. Similarly, we have determined that some species groups with documented M/SI are not likely to be vulnerable to capture in SWFSC gear. This review led to our inference that common dolphin, Risso's dolphin, Dall's porpoise, Steller sea lion, harbor seal, and northern elephant seal could have risk of capture in midwater trawl gear given the demonstrated risk of capture in commercial fishing gear that is similar to the gear used by SWFSC. In addition, as a result of presumed similarities to Pacific white-sided dolphin or California sea lion or to other species for which there are recorded interactions in similar commercial fishing gear, SWFSC determined that there was risk of capture for striped dolphin, bottlenose dolphin, and harbor porpoise despite a lack of relevant LOF records. The LOF review similarly led to our inference that Kogia spp., bottlenose dolphin, common dolphin, striped dolphin, Risso's dolphin, and short-finned pilot whale could have risk of capture in pelagic longline gear given the demonstrated risk of capture in commercial fishing gear that is similar to the gear used by SWFSC. We note that, due to the expected distribution of longline sampling effort in offshore waters, no take of coastal bottlenose dolphins in longline gear is expected. In addition, as a result of presumed similarities to California sea lion or to other species for which there are recorded interactions in similar commercial fishing gear, SWFSC determined that there was risk of capture for Steller sea lion despite a lack of relevant LOF records. As noted above, the worst-case single interactions with trawl gear for the two most commonly taken species (Pacific white-sided dolphin and California sea lion) involved 11 and 9 individuals, respectively. For species deemed by SWFSC to have a similar risk profile as these two species, these numbers were taken to represent the potential total take over the five-year period. Use of these numbers is sufficient to appropriately analyze either of two scenarios: (1) More frequent interactions with a lesser number of individuals; or (2) a single, worst-case interaction. For trawl gear, species deemed to have a similar risk profile as the Pacific white-sided dolphin include the Risso's dolphin, bottlenose dolphin, striped dolphin, and common dolphins. (Note that the 11 takes proposed for authorization for bottlenose dolphin in trawl gear are split across stocks based on the spatial distribution of SWFSC trawl survey effort; 8 takes are proposed for the offshore stock and 3 takes for the coastal stock.) Species deemed to have a similar risk profile as the California sea lion include the Steller sea lion and harbor seal. The remainder of species determined to be at risk of potential interaction with trawl gear are expected to have a relatively lower risk profile and, therefore, the expected potential take is one per year, or five over the five-year period. Note that a common dolphin has subsequently been captured in SWFSC trawl gear. However, we retain the original approach, which yields a five-year take estimate of 11 animals, versus the approach for historically captured species, which would produce a rounded annual average of 1 and, therefore, a five-year estimate of 5. For hook and line gear, no species is expected to have a similar risk profile as the California sea lion and, therefore, the expected potential take for all other cetacean species is two over the five-year period, with the exception of bottlenose dolphin, for which only one take over five years is requested. Although take due to use of deep-set buoy gear is generally considered unlikely, SWFSC increased their take request for most cetacean species over the 2015 request (from 1 to 2 over five years) due to the potential that their use of this gear in cetacean habitat could lead to an increased risk of interaction compared with only their use of typical pelagic longline gear. Regarding potential interactions with purse seine gear, we adopt the analysis that was developed in support of a similar incidental take rulemaking requested by NMFS' Northwest Fisheries Science Center (NWFSC) (83 FR 36370; July 27, 2018). Unlike SWFSC, NWFSC has historically used purse seine gear and similarly operates in the CCE. NWFSC has not had any historical interactions with purse seine gear. Therefore, we followed a similar approach as described above, in which the LOF was consulted and assumptions regarding species that may be vulnerable to interactions with the gear developed. Species with presumed risk of interaction with purse seine gear, based on LOF records, include common dolphins, harbor seal, and California sea lion. In addition, despite a lack of relevant LOF records, NWFSC deemed the following species as having risk of potential interaction with purse seine gear: Dall's porpoise, Pacific white-sided dolphin, Risso's dolphin, northern right whale dolphin, Steller sea lion, and harbor porpoise. SWFSC reviewed the assumptions made by NWFSC and has concurred and adopted the same assumptions in support of their requested take authorization. SWFSC additionally reviews records of marine mammal interactions with commercial purse seines in section 6.2.2 of their application. For most species, the risk of interaction is expected to be relatively low and, therefore, SWFSC has requested authorization of one take per potentially affected stock over the five-year period. However, based on the greater number of recorded interactions with purse seine gear for California sea lions and harbor seals, SWFSC has requested 5 takes for each species over the five-year period. We have reviewed subsequent LOFs and determined that there are no new records that would change the assumptions regarding potential vulnerability to gear interaction described above. For a summation of the LOF records discussed above for trawl and longline gear, please see Table 13 (80 FR 8166) and Table 6 (81 FR 38516). The final 2020 LOF was published on April 16, 2020 (85 FR 21079), and more information about the LOF is available online at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-protection-act-list-fisheries. It is also possible that a captured animal may not be able to be identified to species with certainty. Certain pinnipeds and small cetaceans are difficult to differentiate at sea, especially in low-light situations or when a quick release is necessary. For example, a captured delphinid that is struggling in the net may escape or be freed before positive identification is made. Therefore, the SWFSC has requested the authorization of incidental take in trawl gear for one unidentified pinniped and one unidentified small cetacean, and additionally one take of unidentified pinnipeds in both purse seine and longline gear, over the course of the five-year period of proposed authorization. Table 8 summarizes the total proposed M/SI take authorization due to gear interaction in the CCE. Table 8—Total Estimated Take Due to Gear Interaction in the CCE, 2020-25 1 Species Estimated 5-year total, trawl Estimated 5-year total, hook and line Estimated 5-year total, purse seine Total Kogia spp. 2 2 2 Bottlenose dolphin (CA/OR/WA offshore) 3 8 1 9 Bottlenose dolphin (CA coastal) 3 3 3 Striped dolphin 11 2 1 14 Common dolphin (short-beaked) 11 2 1 14 Common dolphin (long-beaked) 11 2 1 14 Pacific white-sided dolphin 40 1 41 Northern right whale dolphin 10 1 11 Risso's dolphin 11 2 1 14 Short-finned pilot whale 2 2 Harbor porpoise 4 5 1 6 Dall's porpoise 5 1 6 Northern fur seal 5 5 5 California sea lion 20 5 5 30 Steller sea lion 9 1 10 Harbor seal 4 9 5 14 Northern elephant seal 5 5 Unidentified pinniped 1 1 1 3 Unidentified cetacean 1 1 1 Please preceding text for derivation of take estimates. 2 We expect that Kogia spp. taken over the five-year timespan could be either a pygmy or dwarf sperm whale. 3 As a species believed to have similar propensity for capture in trawl gear as that demonstrated by the Pacific white-sided dolphin, we assume that eleven bottlenose dolphins could be captured over the five-year timespan. Total potential take of bottlenose dolphins in trawl gear has been apportioned by stock according to typical occurrence of that stock relative to SWFSC survey locations. We assume that the requested take of a bottlenose dolphin in longline gear would be from the offshore stock due to the typical location of SWFSC longline sampling. 4 Incidental take may be of animals from any stock, excluding Washington inland waters stocks. 5 Incidental take may be of animals from either the eastern Pacific or California stocks. Whales —For large whales (baleen whales and sperm whales), beaked whales, and killer whales, observed M/SI is extremely rare for trawl gear and, for most of these species, only slightly more common in longline gear. Although whale species could become captured or entangled in SWFSC gear, the probability of interaction is extremely low considering the lower level of effort relative to that of commercial fisheries. We believe it extremely unlikely that any large whale, beaked whale, or killer whale would be captured or entangled in SWFSC research gear. Estimated Take Due to Acoustic Harassment As described previously, we believe it unlikely that SWFSC use of active acoustic sources is realistically likely to cause Level B harassment of marine mammals. However, per SWFSC request, we conservatively assume that, at worst, Level B harassment may result from exposure to noise from these sources, and we carry forward the analytical approach developed in support of the 2015 rule. At that time, in order to quantify the potential for Level B harassment to occur, NMFS developed an analytical framework considering characteristics of the active acoustic systems, their expected patterns of use, and characteristics of the marine mammal species that may interact with them. The framework incorporated a number of deliberately precautionary, simplifying assumptions, and the resulting exposure estimates, which are presumed here to equate to take by Level B harassment (as defined by the MMPA), may be seen as an overestimate of the potential for such effects to occur as a result of the operation of these systems. Regarding the potential for Level A harassment in the form of permanent threshold shift to occur, the very short duration sounds emitted by these sources reduces the likely level of accumulated energy an animal is exposed to. An individual would have to remain exceptionally close to a sound source for unrealistic lengths of time, suggesting the likelihood of injury occurring is exceedingly small. Potential Level A harassment is therefore not considered further in this analysis. The assessment paradigm for active acoustic sources used in SWFSC fisheries research is relatively straightforward and has a number of key simplifying assumptions. Sound produced by these sources is intermittent and, therefore, evaluated against the 160 dB rms criterion for Level B harassment by behavioral disturbance. Estimating the number of exposures at the specified received level requires several determinations: (1) A detailed characterization of the acoustic characteristics of the effective sound source or sources in operation; (2) The operational areas exposed to levels at or above those associated with Level B harassment when these sources are in operation; (3) A method for quantifying the resulting sound fields around these sources; and (4) An estimate of the average density for marine mammal species in each area of operation. We provide a summary of the analytical approach here, but invite the reader interested in additional detail to review the detailed description provided in support of the 2015 rule (80 FR 8166) as well as the detailed description provided in section 6.4.2 of SWFSC's application. Quantifying the spatial and temporal dimension of the sound exposure footprint (or “swath width”) of the active acoustic devices in operation on moving vessels and their relationship to the average density of marine mammals enables a quantitative estimate of the number of events in which sound levels exceed the relevant threshold. The number of potentially harassing exposures is ultimately estimated as the product of the volume of water ensonified at 160 dB rms or higher (to a maximum depth of 500 m) and the volumetric density of animals determined from simple assumptions about their vertical stratification in the water column. Specifically, reasonable assumptions based on what is known about diving behavior across different marine mammal species were made to segregate those that predominately remain in the upper 200 m of the water column versus those that regularly dive deeper during foraging and transit. Because depths range dramatically along the margin of the continental slope that define the outer edge of the survey areas, but deeper surveyed depths rarely range over 500 m in practice, the depth range for determining volumes was set at 500 m for deep diving species. An initial characterization of the general source parameters for the primary active acoustic sources operated by the SWFSC was conducted, enabling a full assessment of all sound sources used by the SWFSC (see Table 2). This auditing of the active acoustic sources also enabled a determination of the predominant sources that, when operated, would have sound footprints exceeding those from any other simultaneously used sources. These sources were effectively those used directly in acoustic propagation modeling to estimate the zones within which the 160 dB rms received level would occur. Many of these sources can be operated in different modes and with different output parameters. In modeling their potential impact areas, those features among those given previously in Table 2 ( e.g., lowest operating frequency) that would lead to the most precautionary estimate of maximum received level ranges ( i.e., largest ensonified area) were used. The effective beam patterns took into account the normal modes in which these sources are typically operated. While these signals are brief and intermittent, a conservative assumption was taken in ignoring the temporal pattern of transmitted pulses in calculating potential Level B harassment events. Operating characteristics of each of the predominant sound sources were used in the calculation of effective line-kilometers and area of exposure for each source in each survey. Three predominant sources were identified as having the largest potential impact zones during operations, based on their relatively lower output frequency, higher output power, and their operational pattern of use. These sources are the SX90, EK60/EK80, and ME70 (Table 2). Estimated effective cross-sectional areas of exposure were estimated for each of these sources. In determining the effective line-kilometers for each of these predominant sources, the operational patterns of use relative to one another were further applied to determine which source was the predominant one operating at any point in time for each survey. When multiple sound sources are used simultaneously, the one with the largest potential impact zone in each relevant depth strata is considered for use in estimating exposures. The cross-sectional area of water ensonified at or above the 160 dB rms threshold was calculated using a simple model of sound propagation loss, which accounts for the loss of sound energy over increasing range. We used a spherical spreading model (where propagation loss = 20 * log [range]; such that there would be a 6-dB reduction in sound level for each doubling of distance from the source), a reasonable approximation over the relatively short ranges involved. Spherical spreading is a reasonable assumption even in relatively shallow waters since, taking into account the beam angle, the reflected energy from the seafloor will be much weaker than the direct source and the volume influenced by the reflected acoustic energy would be much smaller over the relatively short ranges involved. We also accounted for the frequency-dependent absorption coefficient and beam pattern of these sound sources, which is generally highly directional. The lowest frequency was used for systems that are operated over a range of frequencies. The vertical extent of this area is calculated for two depth strata. These results were applied differentially based on the typical vertical stratification of marine mammals. Following the determination of effective sound exposure area for transmissions considered in two dimensions, the next step was to determine the effective volume of water ensonified at or above 160 dB rms for the entirety of each survey. For each of the three predominant sound sources, the volume of water ensonified is estimated as the athwartship cross-sectional area (in square kilometers) of sound at or above 160 dB rms multiplied by the total distance traveled by the ship. Where different sources operating simultaneously would be predominant in each different depth strata, the resulting cross-sectional area calculated took this into account. Specifically, for shallow-diving species this cross-sectional area was determined for whichever was predominant in the shallow stratum, whereas for deeper-diving species this area was calculated from the combined effects of the predominant source in the shallow stratum and the (sometimes different) source predominating in the deep stratum. This creates an effective total volume characterizing the area ensonified when each predominant source is operated and accounts for the fact that deeper-diving species may encounter a complex sound field in different portions of the water column. The best available information regarding marine mammal occurrence in the CCE was used to develop volumetric density values for use in calculating estimated exposures. This information was determined through review of available information, as indicated through NOAA's CetMap catalogue, available online at: cetsound.noaa.gov/cda-index. More detail, and the density values used, are provided in section 3 and Appendix A of the SWFSC application. For marine mammals occurring in the AMLR, no new information is available, and the density values used in the 2015 rule are carried forward. Estimates of potential incidents of Level B harassment ( i.e., potential exposure to levels of sound at or exceeding the 160 dB rms threshold) are then calculated by using (1) the combined results from output characteristics of each source and identification of the predominant sources in terms of acoustic output; (2) their relati [Text truncated at 120,000 characters. The full text is on the page linked above.] --- Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2020-17848. Public record. Not legal advice.