RELEVANT U.S. LEGISLATION
In the United States, there are many statutes and regulations that are important to the well-being of marine mammals and their habitats. This appendix highlights three primary statutes that provide the general legal framework for addressing impacts to marine mammals. They are the National Environmental Policy Act (NEPA), the Endangered Species Act (ESA), and the Marine Mammal Protection Act (MMPA). The way, and extent to which, these statutes address cumulative impacts or effects varies. In addition, this appendix identifies and briefly discusses four other federal statutes that require or authorize spatial planning and conservation and management measures important to marine mammals and the protection of their habitats. These are the Ports and Waterways Safety Act, the National Marine Sanctuaries Act, the Outer Continental Shelf Lands Act, and the Magnuson-Stevens Fishery Conservation and Management Act. International laws are also discussed briefly. This appendix is not intended to be a comprehensive discussion of all laws and regulations that impact marine mammals, but rather to provide further policy context for the consideration that agencies must give to cumulative impacts of stressors and other noise on marine mammals.
National Environmental Policy Act (NEPA)
Congress enacted NEPA in December 1969, and President Nixon then signed the statute into law on January 1, 1970.1 The stated purpose of NEPA was “[t]o declare a national policy which will encourage productive and enjoyable harmony between man and his environment; to promote efforts which will prevent or eliminate damage to the environment and biosphere and stimulate the health and welfare of man; to enrich the understanding of the ecological systems and natural resources important to the Nation; and to establish a Council on Environmental Quality.”2 “NEPA itself does not mandate particular results” in order to accomplish these ends.3 Rather, NEPA imposes only procedural requirements on federal agencies with a particular focus on requiring agencies to undertake analyses of the environmental impact of their proposals and actions.4 The Council on Environmental Quality (CEQ) was established in the Executive Office of the President and is the primary agency responsible for ensuring that other federal agencies meet the requirements set forth by NEPA. The CEQ regulations promulgated under this act require consideration of cumulative impacts5 and define cumulative impact as noted above.6
At the heart of NEPA is a requirement that federal agencies “include in every recommendation or report on proposals for legislation and other major Federal actions significantly affecting the quality of the human environment, a detailed statement by the responsible official on—(i) the environmental impact of the proposed action, (ii) any adverse environmental effects which cannot be avoided should the proposal be implemented, (iii) alternatives to the proposed action, (iv) the relationship between local short-term uses of man’s environment and the maintenance and enhancement of long-term productivity, and (v) any irreversible and irretrievable commitments of resources which would be involved
1 (Pub. L. 91-190, 42 U.S.C. 4321-4347, January 1, 1970, as amended by Pub. L. 94-52, July 3, 1975, Pub. L. 94-83, August 9, 1975, and Pub. L. 97-258, § 4(b), Sept. 13, 1982).
2 42 U.S.C. § 4321.
3Robertson v. Methow Valley Citizens Council, 490 U.S. 332, 350, 109 S.Ct. 1835, 104 L.Ed.2d 351 (1989).
4 See id., at 349-350, 109 S.Ct. 1835.
5 40 C.F.R. § 1508.25.
6 40 C.F.R. § 1508.7.
in the proposed action should it be implemented.”7 CEQ regulations clarify that “major Federal actions” may include “projects and programs entirely or partially financed, assisted, conducted, regulated, or approved by Federal agencies; new or revised agency rules, regulations, plans, policies, or procedures; and legislative proposals.” Significance, according to the regulations, is determined based on the context and intensity of the action, and the regulations require the agency to consider “[w]hether the action is related to other actions with individually insignificant but cumulatively significant impacts.”8 “Significance exists if it is reasonable to anticipate a cumulatively significant impact on the environment. Significance cannot be voided by terming an action temporary or by breaking it down into small component parts.”9
The detailed statement called for in 42 U.S.C. § 4332(2) (C) is termed an Environmental Impact Statement (EIS). The CEQ regulations allow an agency to prepare a more limited document, an Environmental Assessment (EA), if the agency’s proposed action neither is categorically excluded from the requirement to produce an EIS nor would clearly require the production of an EIS.10 The EA is to be a “concise public document” that “[b]riefly provide[s] sufficient evidence and analysis for determining whether to prepare an [EIS].”11 If, pursuant to the EA, an agency determines that an EIS is not required under applicable CEQ regulations, it must issue a “finding of no significant impact,” which briefly presents the reasons why the proposed agency action will not have a significant impact on the human environment.12 EISs and EAs developed in accordance with NEPA and the corresponding CEQ regulations are required to consider direct, indirect, and cumulative impacts.13 It is worth noting that, according to CEQ regulations, NEPA does not require an EA or EIS for those actions that are categorically excluded, meaning that the responsible agency has determined that the action falls within a category of actions that do “not individually or cumulatively have a significant effect on the quality of the environment.”14
Courts have further considered how well federal agencies implement NEPA and how cumulative impacts should be addressed in environmental documents developed in accordance with NEPA. The Supreme Court has stated that, in light of agencies’ broad discretion, the role of the courts with regard to NEPA is to ensure that the agencies take a “hard look” at the environmental consequences of their proposed major actions and alternatives.15 Multiple circuit courts have weighed in on what constitutes a “hard look.”16
The Ninth Circuit has held that the analysis of cumulative impacts must “be more than perfunctory; it must provide a useful analysis of the cumulative impacts of past, present and future projects.”17 Courts have also signaled that the analysis must involve more than “generalized, conclusory assertions from agency experts.”18 Instead, the Ninth Circuit requires that agencies provide supporting data in a manner that can be understood by members of the public.19
Litigants have also used the NEPA “hard look” mandate to clarify federal agencies’ legal duties to consider the habitat impacts of federally licensed extractive activities. For example, in American Oceans Campaign v. Daley, 183 F. Supp.2d 1 (D.D.C. 2000) the court found that the environmental assessments for current fishery management plans lacked sufficient analysis of alternative habitat protection measures. Similar rulings have resulted from NEPA litigation over oil and gas development on the continental shelf or the construction of oil and liquefied natural gas terminals. In this litigation, courts may be asked whether the federal agency had a responsibility to find or fund additional research on reasonably foreseeable environmental impacts of its preferred alternative. Courts often find that the duty depends on severity of the potential impacts or the ready availability of simulation studies or models.20 When scientific experts express conflicting views regarding the scope and significance of potential impacts, the courts have interpreted NEPA as affording the agency with discretion to rely on the reasonable opinions of its own qualified experts.21
Access to courts for judicial opinions such as these is most available for species listed as either endangered or threatened because the ESA has a citizen suit provision. For non-ESA-protected species, agency decisions based on insufficient or conflicting scientific evidence may be challenged as a violation of the Administrative Procedures Act.
7 42 U.S.C. § 4332(2)(C).
8 40 C.F.R. § 1508.27.
9 40 C.F.R. § 1508.27(b)(7).
10 40 C.F.R. §§ 1501.4(a)-(b).
11 40 C.F.R. § 1508.9(a).
12 40 C.F.R. §§ 1501.4(e), 1508.13.
13 “Effects” and “impacts” are considered synonymous according to the CEQ regulations.
14 40 C.F.R. § 1508.4.
15Kleppe, Secretary of the Interior, et al. v. Sierra Club et al. citing NRDC v. Morton.
16Britt v. U.S. Army Corps of Eng’rs, 769 F.2d 84, 90 (2d Cir. 1985); Northwest Indian Cemetery Protective Ass’n v. Peterson, 764 F.2d 581, 588 (9th Cir. 1985), rev’d on other grounds, 485 U.S. 439 (1988); Maryland Wildlife Fed’n v. Dole, 747 F.2d 229 (4th Cir. 1984) (reasonable alternatives must be considered but not every alternative conceivable to the mind of man).
17Oregon Natural Resources Council Fund v. Brong citing Klamath-Siskiyou Wildlands Center v. BLM (2004) citing Ocean Advocates 361 F.3d 1108 (2003) quoting Kern, 284 F.3d at 1075 (quoting Muckleshoot Indian Tribe v. United States Forest Serv., 177 F.3d 800, 810 (9th Cir. 1999) for the “useful analysis…”).
18Or. Natural Res. Council Fund v. Goodman, 505 F.3d 884, 893 (9th Cir. 2007).
19Or. Natural Res. Council Fund v. Goodman, 505 F.3d 884, 893 (9th Cir. 2007).
20Roosevelt Campobello International Park Comm’n v. US EPA, 684 F.2d 1041 (1st Cir. 1982).
21NRDC v. Evans, 232 F.Supp.2d 1003 (N.D. Cal. 2002).
Under this law, courts will defer to agencies’ expert judgments in interpreting and applying key statutory terms and standards, such as “harassment” or “unmitigable adverse impact.” Judicial review is deferential to agency expertise but will entail an examination of information that was presented to the agency prior to its decision. Under this deferential standard of review, the agency’s decision will be upheld unless the record shows the agency considered factors, including political pressures, other than those which Congress directed it to consider.22
Endangered Species Act (ESA)
The Endangered Species Act (ESA) was passed by the U.S. Congress and signed into law in 1973.23 The ESA calls for the listing and protection of endangered and threatened species, and the designation of critical habitat for endangered species. According to the ESA, an endangered species is a species that “is in danger of extinction throughout all or a significant portion of its range.”24 The ESA defines threatened species as those species that are “likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.”25
The U.S. Fish and Wildlife Service (FWS) is the lead agency for implementing the ESA for most species. However, most threatened or endangered anadromous fish and marine species are managed by the National Marine Fisheries Service (NMFS) with the exception of walrus, polar bear, sea otters, and sirenians, which are managed by FWS under both the ESA and the MMPA. For listing of shared species, for example, sea turtles, or for policies applicable to all species, the two agencies often issue joint listings or joint guidance, for example, on designation of critical habitat or on inter-agency consultation.
The ESA protects endangered species from both private and public actions. Section 9 of the ESA states that no one, public or private, may “take” any endangered species.26 The ESA broadly defines “take” to mean “harass, harm, pursue, hunt, shoot, wound, kill, trap, capture or collect.”27 Section 7 of the ESA also directs federal agencies to carry out programs for the conservation of threatened and endangered species. It further requires federal agencies to ensure that their actions (i.e., all actions authorized, funded, or carried out by the agency) are not likely to jeopardize the existence of a listed species or adversely modify the critical habitat of a listed species. As part of these assurances, Section 7 also requires agencies to consult with FWS or NMFS (Steiger, 1994) regarding any activities that may affect listed species.28 “Procedurally, before initiating any action in an area that contains threatened or endangered species, federal agencies must consult with the FWS (for land based species and selected marine mammals) or NMFS (for all other marine species) to determine the likely effects of any proposed action on species and their critical habitat.”29
Although the text of the ESA does not directly address cumulative impacts or effects, the implementing agencies (FWS and NMFS) and the courts have interpreted Section 7 as to require consideration of cumulative effects during the consultation process. The regulations promulgated under the ESA define “cumulative effects” as “those effects of future State or private activities, not involving Federal activities, that are reasonably certain to occur within the action area of the Federal action subject to consultation.”30 Guidance produced by the FWS and NMFS regarding Section 7 consultations specifically states that this more narrow definition should not be conflated with the broader definition of “cumulative impacts” used in NEPA and pertains only to ESA Section 7 analyses.31 The Ninth Circuit in Conservation Congress v. USFS has reiterated this point also.
After listing, two other processes under Section 4 of the ESA are important. These are the requirement to prepare and update recovery plans for listed species and the obligation to designate critical habitat. The latter requirement is central to ensuring that under Section 7 federal agencies do not take or approve actions that adversely modify critical habitat or its key components. Failure to do so can be a basis for litigation, which may result in an injunction until further analysis is done. Recent developments suggest the critical habitat provisions are increasingly important in protecting the marine acoustic environment and in incorporating the latest scientific findings and impact assessment methods. In 2015, NMFS made a legal determination that newly available scientific information warranted proceeding with a petition to revise the critical habitat designation for the Southern Resident killer whale (Orcinus orca) Distinct Population Segment. The revision would expand the designation to include essential foraging and wintering areas along the
22Earth Island Institute v. Hogarth, 494 F.3d 757 (9th Cir. 2007).
23 This law repealed the earlier legislation aimed at protecting “selected species” and habitats, including the Endangered Species Preservation Act of 1966 and the Endangered Species Conservation Act of 1969. The ESA has since been amended in 1978, 1979, and 1982.
24 16 U.S.C. § 1532 (6).
25 16 U.S.C. § 1532 (20).
26 16 U.S.C. § 1538 (a)(1).
27 16 U.S.C. § 1532 (19).
28 16 U.S.C. § 1536 (a). The agency first determines whether their proposed action “may affect” a listed species or its habitat. If the agency determines it may, then formal consultation with either FWS or NOAA Fisheries is automatically required. If the agency determines that the action is not likely to affect a listed species or its habitat and the consulting agency agrees with this assessment, then further formal consultation is not necessary. If, however, the consulting agency does not agree with the assessment, then a formal consultation is required. Conservation Congress v. USFS, 720 F.3d 1048 (9th Cir. 2013).
29Conservation Congress v. USFS, 720 F.3d 1048 (9th Cir. 2013) citing Natural Res. Defense Council v. Houston, 146 F.3d 1118, 1125 (9th Cir. 1998) and Forest Guardians v. Johanns, 450 F.3d 455, 457 n.1.
30 50 C.F.R. § 1508.7.
West Coast and adopt as a “primary constituent element” of that habitat protective underwater noise levels.32 In the 2008 recovery plan for the Southern Resident killer whale, the National Oceanic and Atmospheric Administration (NOAA) did not include sound levels as a primary constituent element (PCE),33 likely because of limitations of available information (Williams et al., 2014).
Marine Mammal Protection Act (MMPA)
The MMPA was passed and signed into law in 1972 at a time when environmental issues resonated particularly strongly with the public. By 1971, 42 marine mammal protection and conservation bills had been filed in Congress (Ray and Potter, 2011). The death of hundreds of thousands of pelagic dolphins annually in the tuna fishing industry, where purse seine nets were set on dolphin schools that were associated with tuna below; the apparent impotence of the International Whaling Commission to prevent the continued decline of great whale stocks; and the harvesting of pup and juvenile harp and northern fur seals by clubbing were primary drivers of the public demand for congressional action. The MMPA charted new territory in environmental legislation by focusing on the ecosystem and requiring that marine mammals be maintained at the optimal sustainable population at which they are significant functioning elements of their ecosystem. With few exceptions, the MMPA prohibited the taking or importing any marine mammal or marine mammal product34 where a “take” was defined as “harass, hunt, capture, or kill, or attempt to harass, hunt, capture, or kill.35 The rights of Alaskan Natives to take marine mammals for subsistence purposes, however, were preserved under the MMPA.36
The Act is enforced in the 200-mile Exclusive Economic Zone of the United States, and any person, vessel, or other conveyance subject to the jurisdiction of the United States is also prohibited from taking any marine mammal on the high seas.37 Exemptions to these prohibitions may be made in specific cases in which the Secretary of the Interior or Commerce (depending on whether the species in question falls under FWS or NMFS jurisdiction) authorizes a permit for such activity. Permits may be acquired for scientific research; enhancing the survival or aiding in the recovery of a marine mammal stock or species; commercial and educational photography; first-time import for public display; capture of wild animal for public display; and incidental, i.e., nondirected, take.38 An incidental take permit may be issued provided that the taking would (1) be of small numbers, (2) have no more than a “negligible impact” on those marine mammal species or stocks, and (3) not have an “unmitigable adverse impact” on the availability of the species or stock for subsistence uses.39 Fisheries are allowed incidental take outside the normal permit process subject to take reduction plans that seek to reduce mortality and serious injury rates to a rate approaching zero.
Takes by harassment account for almost all takes for which permits are issued. The MMPA has defined two levels of harassment with a somewhat different definition when the harassment is caused by a “military readiness activity” or “a scientific research activity conducted by or on behalf of the Federal Government.” Level A harassment occurs when the action “has the potential to injure a marine mammal or marine mammal stock in the wild”40 or for military readiness “any act that injures or has the significant potential to injure a marine mammal or marine mammal stock in the wild.”41 Level B harassment occurs when the action “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.”42 Or for military readiness “any act that disturbs or is likely to disturb a marine mammal or marine mammal stock in the wild by causing disruption of natural behavioral patterns, including, but not limited to, migration, surfacing, nursing, breeding, feeding, or sheltering, to a point where such behavioral patterns are abandoned or significantly altered.”43
In developing regulations to implement the MMPA in so far as acoustic harassment is concerned, NMFS has determined that injury equates to a permanent threshold shift (PTS), which is a loss of hearing within a particular frequency range that is not reversible. A temporary threshold shift (TTS) is one in which hearing sensitivity within a particular frequency range is reduced for a period of minutes to hours but recovers to its prior level of sensitivity. NMFS recently published acoustic thresholds for the onset of TTS and PTS (NMFS, 2016a) based on the best current available science. These guidelines have separate PTS thresholds for impulsive and nonimpulsive sounds for five categories of marine mammals: low-, mid-, and high-frequency cetaceans, phocids, and otariids.44 For each marine mammal category
32 NOAA, 80 Fed. Reg. 9682-87 (Feb. 24, 2015).
34 16 U.S.C. § 1372.
35 16 U.S.C. § 1362. See also 50 C.F.R. § 216.3.
36 16 U.S.C. § 1371(b).
37 16 U.S.C. § 1372.
38 16 U.S.C. § 1374.
44 Low-frequency cetaceans are all the baleen whales. High-frequency cetaceans are all porpoises, river dolphins, pygmy and dwarf sperm whales, all dolphins in the genus Cephalorhynchus, and two species of Lanenorhynchus, L. australis and L. cruciger. Mid-frequency cetaceans are all the odontocetes not in the high-frequency group.
two thresholds are given for impulsive sounds: one for peak sound pressure level (SPLpk) and one for cumulative sound exposure level (SELcum) accumulated over 24 hours; and one threshold for nonimpulsive sounds: the cumulative sound exposure level (SELcum) accumulated over 24 hours. The SPLpk ranges from 202 dB re 1 μPa for high-frequency cetaceans to 232 dB re 1 μPa for otariid pinnipeds in water. The SEL values for impulsive sounds range from 155 dB re 1 μPa2-s for high-frequency cetaceans to 203 dB re 1 μPa2-s for otariids, and the threshold values for nonimpulsive sounds range from 173 dB re 1 μPa2-s for high-frequency cetaceans to 219 dB re 1 μPa2-s for otariids.
NMFS has not proposed any update to their Level B behavioral harassment criteria. They remain SPLRMS of 160 dB for impulsive sounds and 120 dB for nonpulse sounds.45 Currently NMFS classifies a variety of sonar signals as impulsive for Level B criteria, although the recently released Technical Guidance (NMFS, 2016a) classifies them as nonimpulsive for Level A criteria. The Navy has adopted more conservative criteria for behavioral response thresholds for beaked whales (140 dB re 1 μPa) and for harbor porpoises (120 dB re 1 μPa) exposed to sonar (Finneran and Jenkins, 2012).
Other Important U.S. Laws
The U.S. Coast Guard has responsibility to implement the Ports and Waterways Safety Act as well as to enforce all other marine environmental laws. As the international shipping community continues to address the issue of shipping noise, this law will be the basis for implementing any resulting international standards or regulations for environmentally sensitive “Areas to Be Avoided” aproved by the International Maritime Organization (IMO). The Papahanaumokuakea Marine National Monument in Hawaii is an example of marine mammal habitat subject to such shipping regulations. Standards for ship noise are under consideration by a correspondence working group of the IMO’s Marine Environmental Protection Committee in which both the Coast Guard and NOAA participate. In addition, the Coast Guard conducts ship routing and port access studies under the Ports Act; the law proved to be an important authority in reducing deadly ship strikes of endangered North Atlantic right whales through real-time, whale location reporting and reduced speed limits.
The National Marine Sanctuaries Act can also be used to designate as marine protected areas those marine mammal habitats that are currently quiet, with a minimal amount of anthropogenic noise, preserving this protective status quo as a precautionary measure (Williams et al., 2015) and to offset acoustic degradation that cannot be avoided or mitigated. If a marine sanctuary is established and its management plan identifies the in-water sound levels as sanctuary resources, federal agencies will review proposed federal activities, leases, or licenses for their potential impact on these resources. This process would protect all marine mammals that use the marine sanctuary but would be especially valuable for a species that is neither “depleted” under the MMPA nor listed under the ESA and therefore not protected by the “negligible impact” and “adversely modify” habitat provisions of those laws.
Other relevant legislation regulating the introduction of pollution stressors into the ocean are the Rivers and Harbors Act (RHA) and Clean Water Act (CWA). The RHA regulates activity affecting navigation in U.S. waters. Section 13 of the RHA, commonly named The Refuse Act, 33 U.S.C. § 407 (1976), prohibits discharge of “any refuse matter of any kind or description” into navigable waters. In a similar vein Section 404 of the CWA regulates the discharge of dredged or fill material resulting from water resource projects, infrastructure development, and mining projects in U.S. waters. Applying for a permit to discharge requires showing that steps have been taken to avoid impacts on aquatic resources.46
Marine resource development laws such as the Outer Continental Shelf Lands Act (OCSLA), as amended, and the Magnuson-Stevens Fishery Conservation and Management Act, as amended, have important environmental planning and permitting processes that are subject to judicial review under the Administrative Procedures Act or NEPA or both. The OCSLA process could be used to identify and exclude from leasing for offshore renewable energy development (e.g., wind farms) those tracts that are acoustically significant marine mammal habitat. In addition, anthropogenic noise can scatter prey and interact with fisheries extractions to reduce the quality of marine mammal habitat, especially in foraging areas near rookeries. NEPA analyses of fishery operations and catch levels provide an opportunity to review these potential impacts. Again, this could prove especially important for marine mammal life stages that are vulnerable to prey disruption but are not yet listed as MMPA-“depleted” or in danger of extinction and do not trigger Section 7 inter-agency consultation.
INTERNATIONAL SOUND REGULATIONS
Several national and international regulatory bodies have adopted regulations or guidelines for the effects of underwater sound on marine life, including marine mammals. These share the same scientific underpinning as U.S. regulations but may emphasize different effects, different taxa, and different spatial and temporal scales.
McCarthy (2007) pointed out that low-frequency sound travels so far in the ocean that some sound sources create noise that must be treated as a transboundary pollutant.
Gillespie (2010) and McCarthy (2007) identify the United Nations Convention on the Law of the Sea (UNCLOS) as the appropriate international body to regulate ocean noise. UNCLOS article 1(4) says “‘pollution of the marine environment’ means the introduction by man, directly or indirectly, of substances or energy into the marine environment, including estuaries, which results or is likely to result in such deleterious effects as harm to living resources and marine life.” This definition includes acoustic energy along with other forms of energy if it harms marine life.
The International Maritime Organization is tasked with regulating pollution by vessels under the International Convention for the Prevention of Pollution by Ships (MARPOL Convention). In 2013, the Marine Environment Protection Committee of the IMO issued voluntary guidelines for the reduction of underwater noise from commercial shipping (MEPC 66/17).
The International Convention on Migratory Species (CMS, also known as the Bonn Convention) was signed by 117 countries (known as Parties to the Convention) under the auspices of the United Nations Environment Programme (UNEP). In 2008 the Parties to the CMS adopted resolution 9.19 on Adverse Anthropogenic Marine/Ocean Noise Impacts on Cetaceans and Other Biota, which urges the Parties to the Convention “to control the impact of emission of man-made noise pollution in habitat of vulnerable species and in areas where marine mammals or other endangered species may be concentrated.” Several regional agreements that operate under the auspices of the Bonn convention of UNEP have also established guidelines on ocean noise for their regions. The ACCOBAMS (Agreement on the Conservation of Cetaceans in the Black Sea Mediterranean Sea and Contiguous Atlantic Area) agreement has passed a resolution on “Guidelines to address the impact of anthropogenic noise on cetaceans in the ACCOBAMS area” and the ASCOBANS (Agreement on the Conservation of Small Cetaceans in the Baltic, North East Atlantic, Irish and North Seas) has issued a report on the assessment of acoustic disturbance (Bräger et al., 2009) and passed resolutions on effects of anthropogenic noise on marine mammals. The Convention for the Protection of the Marine Environment of the North-East Atlantic (the OSPAR Convention) involves the European Union (EU) and 15 European nations in support of conservation of the northeastern Atlantic. In 2009 the OSPAR Commission reviewed the effects of underwater sound on marine life, calling for more research on this problem. There are thus many international agreements, especially within Europe, that have addressed the impacts of anthropogenic noise on marine life, including the cumulative effects of noise plus other stressors, but none of these have established regulations to control these impacts.
Explicit guidelines or regulations have been developed by international or national authorities for three intense sources of underwater sound: pile driving, seismic survey, and naval sonar. Erbe (2013) describes how some countries may prohibit seismic surveys in habitats and seasons when marine mammals are concentrated. Some countries stipulate that seismic surveys use the minimum practicable power or that construction of foundations of offshore wind turbines use methods other than pile driving in some settings. Where pile driving is used, some countries require the use of mitigation measures such as bubble curtains to reduce the sound that propagates from pile driving. Other mitigation measures required by some nations for pile driving, seismic survey, and naval sonar include visual and/or acoustic monitoring to make sure that protected animals do not enter a shutdown zone, 30 minutes of monitoring before starting transmissions to reduce the risk that animals are in the shutdown zone, and a ramp-up procedure that starts at low acoustic power and slowly increases to the full power over tens of minutes to allow animals to move away from aversive or harmful sound levels. The North Atlantic Treaty Organization (NATO) Undersea Research Centre (NURC; now called the Center for Maritime Research and Exploration) has for 50 years provided technical and scientific guidance to NATO nations on anti-submarine warfare, including the use of naval sonar. Frantzis (1998) documented an atypical mass stranding of beaked whales in the Mediterranean that coincided with a sonar trial by NURC in 1996. This evidence of adverse impact led NURC to conduct research on the effects of sonar on cetaceans and to develop Marine Mammal Risk Mitigation Rules and Procedures (NURC, 2006) for their own sonar trials that include similar mitigation measures to those listed above. However, each nation maintains its own procedures for operating naval sonar, including risk mitigation.
The EU has developed a very different strategy for protecting the marine environment and maintaining Good Environmental Status. In 2008, the EU adopted a Marine Strategy Framework Directive (MSFD) to protect the marine environment across the EU. The goal of the MSFD is to achieve Good Environmental Status (GES) by 2020 (European Union, 2008). The goals of the MSFD were to be incorporated into national legislation by July 15, 2010. Good Environmental Status represents a resilient ecosystem in which biodiversity is preserved and human effects, including pollution and noise, do not exceed that which is compatible with a functioning marine ecosystem. The Directive identifies 11 qualitative descriptors that assist member states in identifying what a GES ecosystem should look like. Qualitative Descriptor 11 deals with energy and noise. Technical Subgroups prepared implementation guidelines in 2010 and 2012. The 2010 guidelines (Tasker et al., 2010) identified three underwater noise indicators:
- The proportion of days within a calendar year, over areas of 15°N × 15°E/W in which anthropogenic sound sources exceed either of two levels, 183 dB re 1μPa2-s (i.e., measured as SEL) or 224 dB re 1μPa peak (i.e., measured as peak sound pressure
level) when extrapolated to 1 meter, measured over the frequency band 10 Hz to 10 kHz.
- The total number of vessels that are equipped with sonar systems generating sonar pulses below 200 kHz should decrease by at least x% per year starting in . (The x% was to be set by Member States.)
- The ambient noise level measured by a statistical representative sets of observation stations in Regional Seas where noise within the 1/3 octave bands 63 and 125 Hz (center frequency) should not exceed the baseline values of year  or 100 dB (re 1 μPa RMS; average noise level in these octave bands over 1 year).
The 2012 guidelines (Van der Graaf et al., 2012) defined an impulsive sound as “a sound for which the effective time duration of individual sound pulses is less than ten seconds and whose repetition time exceeds four times this effective time duration.” However, they abandoned the criteria established in 2010 for impulsive sounds and simply noted that “At the moment it is difficult to provide a more specific description of GES beyond the text of the Directive, due to insufficient knowledge on the cumulative impacts of impulsive sound on the marine environment.” In terms of ambient noise, they concluded “At the moment it is impossible to define those elevations of ambient noise from anthropogenic sources that would cause the marine environment to not be at GES. This is mainly due to a lack of knowledge on the impacts of elevated ambient noise on the marine environment. The TSG cannot therefore advise on a level of ambient noise that could be set as a target for this indicator.”
Many of the national regulations and guidelines to protect marine mammals from the effects of underwater sound emphasize short time scales (tens of minutes) and small spatial scales (hundreds of meters) around intense sound sources. However, the EU MSFD takes a much broader (regional sea) and longer (yearly) view of indicators for cumulative effects of noise to maintain good environmental status. This broader scale may be more appropriate for addressing cumulative effects of noise over time, but this approach is vulnerable to gaps in current scientific ability to predict cumulative effects of different combinations of stressors. There is currently little scientific basis for the indicators of GES for noise, but these kinds of large-scale indicators may prove to be important methods for monitoring stressors in a way that can be linked to effects.
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