Skip to Content


Takes of Marine Mammals Incidental to Specified Activities; Navy Training Conducted at the Silver Strand Training Complex, San Diego Bay

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

Start Preamble


National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce.


Notice of issuance of an incidental harassment authorization.


In accordance with provisions of the Marine Mammal Protection Act (MMPA) as amended, notification is hereby given that an Incidental Harassment Authorization (IHA) has been issued to the U.S. Navy (Navy) to take marine mammals, by harassment, incidental to conducting training exercises at the Silver Strand Training Complex (SSTC) in the vicinity of San Diego Bay, California.


This authorization is effective from July 18, 2013, until July 17, 2014.


A copy of the application, IHA, and/or a list of references used in this document may be obtained by visiting the internet at:​pr/​permits/​incidental.htm. Documents cited in this notice may also be viewed, by appointment, during regular business hours, at the Office of Protected Resources, National Marine Fisheries Start Printed Page 40437Service, 1315 East-West Highway, Silver Spring, MD 20910-3225.

Start Further Info


Michelle Magliocca, Office of Protected Resources, NMFS, (301) 427-8401.

End Further Info End Preamble Start Supplemental Information



Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.) direct the Secretary of Commerce (Secretary) 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) if certain findings are made and regulations are issued or, if the taking is limited to harassment, notice of a proposed authorization is 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), will not have an unmitigable adverse impact on the availability of the species or stock(s) for subsistence uses (where relevant), and if the permissible methods of taking and requirements pertaining to the mitigation, monitoring and reporting of such taking are set forth. NMFS has defined “negligible impact” in 50 CFR 216.103 as: “. . . an impact resulting from the specified activity that cannot be reasonably expected to, and is not reasonably likely to, adversely affect the species or stock through effects on annual rates of recruitment or survival.” The National Defense Authorization Act of 2004 (NDAA) (Pub. L. 108-136) removed the “small numbers” and “specified geographical region” limitations and amended the definition of “harassment” as it applies to a “military readiness activity” to read as follows (Section 3(18)(B) of the MMPA): (i) Any act that injures or has the significant potential to injure a marine mammal or marine mammal stock in the wild [Level A Harassment]; or (ii) 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 [Level B Harassment].

Section 101(a)(5)(D) of the MMPA established an expedited process by which citizens of the United States can apply for an authorization to incidentally take small numbers of marine mammals by harassment. Section 101(a)(5)(D) establishes a 45-day time limit for NMFS review of an application followed by a 30-day public notice and comment period on any proposed authorizations for the incidental harassment of marine mammals. Within 45 days of the close of the comment period, NMFS must either issue or deny the authorization.

Summary of Request

NMFS received an application on December 19, 2012, from the Navy for the taking, by harassment, of marine mammals incidental to conducting training exercises at the Navy's Silver Strand Training Complex (SSTC) in the vicinity of San Diego Bay, California. On April 24, 2013, NMFS published a Federal Register notice (78 FR 24161) requesting comments from the public concerning the Navy's proposed training activities and NMFS' proposed authorization.

Description of the Specific Activity

The Navy has conducted a review of its continuing and proposed training conducted at the SSTC to determine whether there is a potential for harassment of marine mammals. Underwater detonation training and pile driving, as summarized below (and detailed in the proposed IHA Federal Register notice), may result in the incidental take of marine mammals from elevated levels of sound. Other training events conducted at the SSTC, which are not expected to rise to the level of harassment, are described in the SSTC Final Environmental Impact Statement (​pr/​permits/​incidental.htm#applications).

Underwater Detonations

Underwater detonations are conducted by Explosive Ordnance Disposal (EOD) units, Naval Special Warfare (NSW) units, MH-60S Mine Countermeasure helicopter squadrons, and Mobile Diving and Salvage units at the SSTC. The training provides Navy personnel with hands-on experience with the design, deployment, and detonation of underwater clearance devices of the general type and size that they are required to understand and utilize in combat. EOD units conduct most of the underwater detonation training at the SSTC as part of their training in the detection, avoidance, and neutralization of mines. Tables 1-3 and 2-1 in the Navy's LOA application describe in detail the types of underwater detonation training events conducted at the SSTC. Below is a basic description of some underwater detonation procedures that typically apply to underwater training events at the SSTC, with the exception of the Unmanned Underwater Vehicle Neutralization and Airborne Mine Neutralization System.

  • Prior to getting underway, all EOD and NSW personnel conduct a detailed safety and procedure briefing to familiarize everyone with the goals, objectives, and safety requirements (including mitigation zones) applicable to the particular training event.
  • For safety reasons, and in accordance with Navy directives, given the training nature of many of these events, underwater detonations only occur during daylight and are only conducted in sea-states of up to Beaufort 3 (presence of large wavelets, crests beginning to break, presence of glassy foam, and/or perhaps scattered whitecaps).
  • EOD or NSW personnel can be transported to the planned detonation site via small boat or helicopter depending on the training event. Small boats can include 7-m Rigid Hull Inflatable Boats (RHIB), zodiacs, or other similar craft as available to the particular unit.
  • Once on site, the applicable mitigation zone is established and visual survey commences for 30 minutes. Divers enter the water to conduct the training objective which could include searching for a training object such as a simulated mine or mine-like shape.
  • For the detonation part of the training, the explosive charge and associate charge initiating device are taken to the detonation point. The explosives used are military forms of C-4. In order to detonate C-4, a fusing and initiating device is required.
  • Following a particular underwater detonation, additional personnel in the support boats (or helicopter) keep watch within the mitigation zone for 30 minutes.
  • Concurrent with the post-detonation survey, divers return to the detonation site to confirm the explosives detonated correctly and retrieve any residual material (pieces of wire, tape, large fragments, etc.).

The Navy uses both time-delay and positive control to initiate underwater detonations, depending on the training event and objectives. The time-delay method uses a Time-delay Firing Device (TDFD) and the positive control method most commonly uses a Remote Firing Device (RFD). TDFDs are the simplest, safest, least expensive, most operationally acceptable method of initiating an underwater detonation. TDFDs are preferred due to their light weight, low magnetic signature (in cases of mines sensitive to magnetic fields), and reduced risk of accidental Start Printed Page 40438detonation from nearby radios or other electronics. The Navy considers it critical that EOD and NSW platoons qualify annually with necessary time-delay certification, maintain proficiency, and train to face real-world scenarios that require use of TDFDs.

Pile Driving

Installation and removal of Elevated Causeway System (ELCAS) support piles may also result in the harassment of marine mammals. The ELCAS is a modular pre-fabricated causeway pier that links offshore amphibious supply ships with associated lighterage (i.e., small cargo boats and barges). Offloaded vehicles and supplies can be driven on the causeway to and from shore.

During ELCAS training events, 24-inch wide hollow steel piles would be driven into the sand in the surf zone with an impact hammer. About 101 piles would be driven into the beach and surf zone with a diesel impact hammer over the course of about 10 days, 24-hours per day (i.e., day and night). Each pile takes an average of 10 minutes to install, with around 250 to 300 impacts per pile. Pile driving includes a semi-soft start as part of the normal operating procedure based on the design of the drive equipment. The pile driver increases impact strength as resistance goes up. At first, the pile driver piston drops a few inches. As resistance goes up, the pile driver piston drops from a higher distance, providing more impact due to gravity. The pile driver can take 5 to 7 minutes to reach full impact strength. As chapters of piles are installed, causeway platforms are then hoisted and secured onto the piles with hydraulic jacks and cranes. At the end of training, the ELCAS piles would be removed with a vibratory extractor. Removal takes about 15 minutes per pile over a period of around 3 days. ELCAS training may occur along both the ocean side (SSTC-North boat and beach lanes) and with the designated training lane within Bravo beach on the bayside of SSTC. Up to four ELCAS training/installation events may occur during the year.

Dates and Duration of Activities

The Navy's activities will occur between July 2013 and July 2014. Most underwater detonation training events include one or two detonations. Table 2-1 in the Navy's LOA application shows the 19 different types and number of training events per year in the SSTC. Pile installation and removal would occur over an approximate 13-day period, up to four times per year. NMFS has issued a 1-year IHA that may be superseded if we issue a Letter of Authorization under regulations for the Navy's Hawaii-Southern California Training and Testing (HSTT) (which would include the SSTC) prior to expiration of the IHA.

Location of Activities

The SSTC (Figure 1-1 of the Navy's IHA application) is located in and adjacent to San Diego Bay, south of Coronado, California and north of Imperial Beach, California. The complex is composed of ocean and bay training lanes, adjacent beach training areas, ocean anchorages, and inland training areas. To facilitate range management and scheduling, the SSTC is divided into numerous training sub-areas. A more detailed description of the area can be found in the proposed IHA Federal Register notice (78 FR 24161, April 24, 2013).

Comments and Responses

A notice of proposed authorization and request for public comment was published on April 24, 2013 (78 FR 24161). During the 30-day public comment period, we received comments from the Marine Mammal Commission (Commission), the Bureau of Ocean Energy Management (BOEM), and two private citizens. BOEM's comments related to typos in the proposed IHA notice and recommended clarifications. One of the private citizens was generally opposed to naval activities, while the other commended the Navy for minimizing threats to marine mammals. NMFS' responses to specific comments on the proposed mitigation and monitoring measures are provided below.

Comment 1: The Commission recommends that the Navy ensure protection of marine mammals in the areas where detonations will occur by (1) conducting in-situ sound measurements of underwater detonations and (2) using that information to establish appropriately sized mitigation and buffer zones.

Response: The Navy conducted empirical field measurements of underwater detonations at San Clemente Island and the SSTC in 2002. During these tests, 2-pound and 15-pound net explosive weight charges were placed at 6 and 15 feet of water and peak pressures and energies were measured for both bottom placed detonations and detonations off the bottom. The Navy found that, in general, single-charge underwater detonations, empirically measured, were similar to or less than propagation model predictions. Results from these tests were used to determine ZOIs and mitigation zones for Very Shallow Water (VSW) underwater detonations.

The Navy plans to conduct a new set of empirical underwater detonation propagation measurements at SSTC in the summer/fall of 2013 and winter of 2014. Data from that study will be incorporated into the Navy's model for future actions.

As described in the proposed IHA notice (78 FR 24161, April 24, 2013), the Navy will conduct an underwater acoustic propagation monitoring project during the first available ELCAS deployment at the SSTC. The acoustic monitoring will provide empirical field data on actual ELCAS pile driving and removal underwater source levels, and propagation specific to ELCAS training at the SSTC. These results will be used to either confirm or refine the Navy's exposure predictions and expand the mitigation zones if necessary.

Comment 2: The Commission recommends that the Navy adjust the size of the mitigation zones (and subsequent monitoring) using the average swim speed of the fastest swimming marine mammal occurring in the area during the use of TDFDs.

Response: NMFS disagrees that the size of the mitigation zones needs to be adjusted.

The Navy already accounts for swim speeds above 3 knots by including at least an additional 200 yards when practicable. NMFS believes that there is a very low likelihood of an animal entering the buffer zone during the brief amount of time that exposure may occur without being detected. Even in the absence of mitigation, the Navy's modeling suggests that zero animals are likely to randomly enter the safety radius in the small amount of times that the detonations actually occur and no take by Level A harassment or mortality was requested or authorized. It is unlikely that an animal will swim into the zone during the brief amount of time that it might be exposed to a detonation without being detected by the multiple boats encircling the detonation area and observing the mitigation zone.

Additionally, given the Navy's available resources, and considering the small size of boats typically used for monitoring, the required mitigation zones are the maximum distances that can be effectively monitored. Due to the type of training required during the use of TDFDs, the Navy has limited survey vessels and manpower available for monitoring. Scheduling additional vessels and crews would degrade the overall training readiness of the other unit(s) involved. If the Navy adopted a more precautionary swim speed and implemented larger mitigation zones, Start Printed Page 40439surveillance resources could not be increased and the same number of boats would be spread out over a larger area, diluting the Navy's ability to effectively monitor the mitigation zone.

Comment 3: The Commission recommends that the Navy monitor the extent of the Level B harassment zones using additional shore- or vessel-based observers to (1) determine the numbers of marine mammals taken during pile driving and removal activities and (2) characterize the effects on them.

Response: Consistent with previous authorizations for activities at SSTC, the Navy proposed to monitor a 50-yard radius during ELCAS pile driving and removal events. This mitigation zone is based on the predicted range to Level A harassment (180 dB) for cetaceans, and is applied conservatively to both cetaceans and pinnipeds. The Navy proposed to monitor for the presence of marine mammals beginning 30 minutes before any ELCAS pile driving or removal event, continuing during pile driving and removal, and ending 30 minutes after completion of any pile driving or removal event. At least one observer would monitor the mitigation zone from shore. If a marine mammal is seen within the 50-yard radius, pile driving and removal events would be shutdown or delayed until the animal has voluntarily left the mitigation zone.

The 50-yard mitigation zone for ELCAS mitigation is practical for the Navy and NMFS believes that this distance will prevent Level A harassment and reduce the potential for Level B harassment. Monitoring of the Level B harassment zone is impractical for the Navy given the size of the zone (>1,000 yards) and limited number of resources (e.g., small boats and personnel). NMFS believes that the 50-yard mitigation zone will prevent Level A harassment and reduce the potential for Level B harassment, especially considering the limited duration of the activity (about 3 days of pile driving and 10 days of pile removal) and the close proximity to shore (1,000 yards).

Potential Effects on Marine Mammals

The Potential Effects on Marine Mammals section of the proposed IHA included a qualitative discussion of the different ways that underwater detonation events and pile driving and removal activities would impact marine mammals without consideration of mitigation and monitoring measures (78 FR 24161, April 24, 2013; pages 24167-24172). Marine mammals may experience direct physiological effects (e.g., threshold shift and non-acoustic injury), acoustic masking, impaired communication, and behavioral disturbance. The information contained in this section of the proposed IHA has not changed.

Mitigation Measures

In order to issue an incidental take authorization under section 101(a)(5)(D) of the MMPA, NMFS must set forth the permissible methods of taking pursuant to such activity, and other means of effecting the least practicable adverse impact on such species or stock and its habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of such species or stock for taking for certain subsistence uses. The NDAA of 2004 amended the MMPA as it relates to military-readiness activities and the authorization process such that “least practicable adverse impact” shall include consideration of personnel safety, practicality of implementation, and impact on the effectiveness of the military readiness activity. The activities described in the Navy's LOA application and summarized earlier in this document are considered military readiness activities.

NMFS reviewed the proposed activities and the proposed mitigation measures as described in the Navy's LOA application to determine if they would result in the least practicable adverse effect on marine mammals, which includes a careful balancing of the likely benefit of any particular measure to the marine mammals with the likely effect of that measure on personnel safety, practicality of implementation, and impact on the effectiveness of the military readiness activity. NMFS described the Navy's proposed mitigation measures in detail in the proposed IHA (78 FR 24161, April 24, 2013; pages 24172-24175). These required mitigation measures, summarized below, have not changed.

Mitigation zones for all underwater detonation events and pile driving and removal activities;

Underwater detonations will only occur during daylight hours;

Anchored floats will be used to mark the outer limits of the mitigation zone (vsw, pos);

A safety observer will ensure the detonation site is clear before an underwater detonation event;

Boat-based and shore-based observers will monitor for marine mammals before, during, and after underwater detonation events, depending on the type of activity;

Any observed injured or stressed marine mammal will be reported to the Navy and NMFS;

Time-delays longer than 10 minutes will not be used;

If a marine mammals is sighted within a mitigation zone, underwater detonation events and ELCAS training will be delayed or stopped until the animal voluntarily leaves or the zone is clear from sightings for 30 minutes, depending on the type of activity; and

The Navy will implement a soft start for all ELCAS pile driving.

Monitoring and Reporting

In order to issue an ITA for an activity, section 101(a)(5)(D) of the MMPA states that NMFS must set forth, where applicable, “requirements pertaining to the monitoring and reporting of such taking.” The MMPA implementing regulations at 50 CFR 216.104(a)(13) indicate that requests for ITAs must include the suggested means of accomplishing the necessary monitoring and reporting that will result in increased knowledge of the species and of the level of taking or impacts on populations of marine mammals that are expected to be present in the proposed action area.

This section of the proposed IHA included a detailed description of the Navy's proposed monitoring measures (78 FR 24161, April 24, 2013; pages 24175-24176). These required monitoring measures, summarized below, have not changed. In addition to the mitigation monitoring described above, the Navy will monitor a subset of SSTC underwater detonation events to validate the Navy's pre- and post-event mitigation effectiveness, and observe marine mammal reaction, or lack of reaction to SSTC training events. The Navy will also conduct an acoustic monitoring project during the first field deployment of the ELCAS.


In order to issue an ITA for an activity, section 101(a)(5)(A) of the MMPA states that NMFS must set forth “requirements pertaining to the monitoring and reporting of such taking.” Effective reporting is critical both to compliance as well as ensuring that the most value is obtained from the required monitoring. This section of the proposed IHA included a detailed description of the Navy's proposed reporting measures. These required reporting measures, summarized below, have not changed.

General notification of injured or dead marine mammals; and

Monitoring/exercise report due 90 days after the expiration of the IHA.

Past Monitoring and Reporting

The Navy has complied with monitoring and reporting requirements under their previous IHAs for the SSTC. Start Printed Page 40440To date, two underwater demolition training events have been observed by protected species observers between July 2012 and November 2012. Broad scale Navy-funded monitoring in support of the Navy's Southern California (SOCAL) Range Complex Letter of Authorization has typically focused on the offshore waters north and west of the SSTC. The Navy obtained special flight permission to survey the vicinity of the SSTC during part of three aerial surveys under the SOCAL monitoring plan in 2011-2012. As anticipated, marine mammal sightings were limited and included several California sea lions and a few unidentified dolphins, although the dolphin sightings were several miles offshore from the normal SSTC training area.

Estimated Take by Incidental Harassment

In the Estimated Take by Incidental Harassment section of the proposed IHA, NMFS provided a detailed description of the potential effects to marine mammals from underwater detonations and ELCAS pile driving and removal under the MMPA's definitions of Level A and Level B harassment and attempted to quantify the effects that might occur from the specified activities (78 FR 24161, April 24, 2013; pages 24176-24178). The proposed IHA also included a description of the Navy's quantitative exposure modeling methodology. That information has not changed; however, there was an error in the column headlines of Table 6, which were corrected and are provided below. In summary, for all underwater detonations and ELCAS pile driving activities, the Navy's impact model predicts that no mortality and/or Level A harassment (injury) will occur to marine mammal species and stocks within the action area (Tables 5 and 6).

Table 5—The Navy's Modeled Estimates of Species Exposed to Underwater Detonations Without Implementation of Mitigation Measures

SpeciesAnnual marine mammal exposure (all sources)
Level B behavior (multiple successive explosive events only)Level B TTSLevel AMortality
177 dB re 1 μPa182 dB re 1 μPa2−s/23 psi205 dB re 1 μPa2−s/13.0 psi-ms30.5 psi-ms
Gray Whale:
Bottlenose Dolphin:
California Sea Lion:
Harbor Seal:
Long-beaked common dolphin:
Pacific white-sided dolphin:
Risso's dolphin:
Short-beaked common dolphin:
Total Annual Exposures33947300

Table 6—Exposure Estimates From ELCAS Pile Driving and Removal Prior to Implementation of Mitigation

SpeciesAnnual marine mammal exposure (all sources)
Level B behavior (Non-Impulse)Level B Behavior (Impulse)Level A (Cetacean)Level A (Pinniped)
120 dBrms re 1 μPa160 dBrms re 1 μPa180 dBrms re 1 μPa190 dBrms re 1 μPa
Gray Whale:
Bottlenose Dolphin:
California Sea Lion:
Start Printed Page 40441
Harbor Seal:
Long-beaked common dolphin:
Pacific white-sided dolphin:
Risso's dolphin:
Short-beaked common dolphin:
Total Annual Exposures84614000

Anticipated Effects on Habitat

The Anticipated Effects on Habitat section of the proposed IHA included a detailed discussion of the potential impacts on habitats used by marine mammals (78 FR 24161, April 24, 2013; pages 24178-24179). The information contained in the proposed IHA has not changed. In summary, the specified activities are not expected to result in any permanent impact on marine mammal habitat or food resources.

Subsistence Harvest of Marine Mammals

NMFS has determined that the Navy's training activities at the SSTC will not have an unmitigable adverse impact on the availability of the affected species or stocks for subsistence use since there are no such uses in the specified area.

Negligible Impact Analysis and Determination

Pursuant to NMFS' regulations implementing the MMPA, an applicant is required to estimate the number of animals that will be “taken” by the specified activities (i.e., takes by harassment only, or takes by harassment, injury, and/or death). This estimate informs the analysis that NMFS must perform to determine whether the activity will have a “negligible impact” on the species or stock. Level B (behavioral) harassment occurs at the level of the individual(s) and does not assume any resulting population-level consequences, though there are known avenues through which behavioral disturbance of individuals can result in population-level effects. A negligible impact finding is based on the lack of likely adverse effects on annual rates of recruitment or survival (i.e., population-level effects). An estimate of the number of Level B harassment takes, alone, is not enough information on which to base an impact determination. In addition to considering estimates of the number of marine mammals that might be “taken” through behavioral harassment, NMFS must consider other factors, such as the likely nature of any responses (their intensity, duration, etc.), the context of any responses (critical reproductive time or location, migration, etc.), or any of the other variables mentioned in the first paragraph (if known), as well as the number and nature of estimated Level A takes, the number of estimated mortalities, and effects on habitat.

The proposed IHA included a section that addressed the analysis and negligible impact determination of the Navy's activities on the affected species or stocks (78 FR 24161, April 24, 2013; pages 24179-24180). The information in the proposed IHA has not changed and our determination is summarized here. Taking the discussion in the proposed IHA into account, we have determined that the Navy's underwater detonations and ELCAS pile driving and removal will have a negligible impact on the marine mammal species and stocks present in the SSTC. This determination is based on relatively small zones of influence for the underwater detonations; shallow water areas that will contain the spreading of explosive energy; low marine mammal densities within the action area; NMFS' anticipation that no mortalities or injuries to marine mammals will occur; and the required mitigation and monitoring measures detailed in the IHA.

Endangered Species Act (ESA)

No marine mammal species are listed as endangered or threatened under the ESA with confirmed or possible occurrence in the study area. Therefore, section 7 consultation under the ESA for NMFS's issuance of an MMPA authorization is not warranted.

National Environmental Policy Act (NEPA)

The Navy prepared a Final Environmental Impact Statement (EIS) for the proposed SSTC training activities, which was released in January 2011 and is available at​EIS.aspx/​. NMFS is a cooperating agency (as defined by the Council on Environmental Quality (40 CFR 1501.6)) in the preparation of the EIS. NMFS has subsequently adopted the FEIS for the SSTC training activities.

As a result of these determinations, NMFS has issued an IHA to the Navy to Start Printed Page 40442conduct training activities at the SSTC Study Area, provided the previously mentioned mitigation, monitoring, and reporting requirements are incorporated.

Start Signature

Dated: July 1, 2013.

Helen M. Golde,

Deputy Director, Office of Protected Resources, National Marine Fisheries Service.

End Signature End Supplemental Information

[FR Doc. 2013-16156 Filed 7-3-13; 8:45 am]