Small Takes of Marine Mammals Incidental to Specified Activities; Seismic Retrofit of the Richmond-San Rafael Bridge, San Francisco Bay, CA

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[I.D. 080897A]

Small Takes of Marine Mammals Incidental to Specified Activities;

Seismic Retrofit of the Richmond-San Rafael Bridge, San Francisco Bay,

CA

AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and

Atmospheric Administration (NOAA), Commerce.

ACTION: Notice of receipt of application and proposed authorization for

a small take exemption; request for comments.

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SUMMARY: NMFS has received a request from the California Department of

Transportation (CALTRANS) for an authorization to take small numbers of

Pacific harbor seals and possibly California sea lions by harassment

incidental to seismic retrofit construction of the Richmond-San Rafael

Bridge, San Francisco Bay, CA (the Bridge). Under the Marine Mammal

Protection Act (MMPA), NMFS is requesting comments on its proposal to

authorize CALTRANS to incidentally take, by harassment, small numbers

of marine mammals in the above mentioned area for a 1-year period

beginning in December 1997.

DATES: Comments and information must be received no later than October

3, 1997.

ADDRESSES: Comments on the application should be addressed to Michael

Payne, Chief, Marine Mammal Division, Office of Protected Resources,

NMFS, 1315 East-West Highway, Silver Spring, MD 20910-3225. A copy of

the application, a draft Environmental Assessment (EA) and a list of

references cited in this document may be obtained by writing to this

address or by telephoning one of the contacts listed below.

FOR FURTHER INFORMATION CONTACT: Kenneth R. Hollingshead, Office of

Protected Resources, NMFS, (301) 713-2055, or Irma Lagomarsino,

Southwest Regional Office, NMFS, (310) 980-4016.

SUPPLEMENTARY INFORMATION:

Background

Section 101(a)(5) (A) and (D) of the MMPA (16 U.S.C. 1361 et seq.)

directs the Secretary of Commerce to allow, upon request, the

incidental, but not intentional, taking 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

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are made and either regulations are issued or, if the taking is limited

to harassment, notice of a proposed authorization is provided to the

public for review.

Permission may 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, and the permissible methods of taking

and requirements pertaining to the 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.''

New section 101(a)(5)(D) of the Marine Mammal Protection Act

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. The MMPA now defines harassment as:

* * * any act of pursuit, torment, or annoyance which (a) has

the potential to injure a marine mammal or marine mammal stock in

the wild; or (b) 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.

New subsection 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 small numbers of marine mammals. Within 45 days of the

close of the comment period, NMFS must either issue or deny issuance of

the authorization.

Summary of Request

On July 7, 1997, NMFS received an application from CALTRANS,

requesting an authorization for the possible harassment of small

numbers of Pacific harbor seals (Phoca vitulina) and possibly some

California sea lions (Zalophus californianus) incidental to seismic

retrofit construction of the Bridge.

The Bridge will be seismically retrofitted to withstand a future

severe earthquake. Construction is scheduled to begin in December 1997,

and extend through December 2001. A detailed description of the work

planned is contained in CALTRANS (1996).1

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\1\ California Department of Transportation. 1996. Final Natural

Environmental Study/Biological Assessment for the Richmond-San

Rafael Bridge Seismic Retrofit Project. CALTRANS District 4.

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Among other things, seismic retrofit work will include: Excavation

around pier bases, hydro-jet cleaning, installation of steel casings

around the piers with a crane, installation of micro-piles and

installation of precast concrete jackets. Foundation construction will

require approximately 2 months per pier, with construction occurring on

more than one pier at a time. In addition to pier retrofit,

superstructure construction and tower retrofit work will also be

carried out. The construction duration for the seismic retrofit of

foundation and towers on Piers 52 through 57 will be approximately 7 to

8 months. Because of work restrictions and mitigation measures, the

seismic retrofit construction in this area will be completed within one

or two seasons.

As the seismic retrofit construction between Piers 52 and 57 may

potentially result in disturbance of pinnipeds at Castro Rocks, an MMPA

authorization is warranted.

Description of Habitat and Marine Mammals Affected by the Activity

A description of the San Francisco Bay ecosystem and its associated

marine mammals can be found in the CALTRANS application (CALTRANS 1997)

and CALTRANS (1996).

Castro Rocks are a small chain of rocky islands located next to the

Bridge and approximately 1,500 ft (460 m) north of the Chevron Long

Wharf. They extend in a south-westerly direction for approximately 800

ft (240 m) from Pier 55. The rocks start at about 55 ft (17 m) from

Pier 55 and end at approximately 250 ft (76 m) from Pier 53. The chain

of rocks is exposed during low tides and inundated during high tide.

Marine Mammals

General information on harbor seals and other marine mammal species

found in Central California waters can be found in Barlow et al.

(1995). The marine mammals likely to be found in the Bridge area are

limited to the California sea lion and harbor seal.

The California sea lion primarily uses the Central San Francisco

Bay area to feed. California sea lions are periodically observed at

Castro Rocks. No pupping or regular haulouts occur in the project area.

The harbor seal is the only marine mammal species found in the

Bridge area in significant numbers and, therefore, is described in

detail below.

Harbor Seals

The California stock of the Pacific harbor seal had an estimated

population size in 1994 of 34,554 (Barlow et al. 1995). Harbor seal

counts have continued to increase by 4.1 percent annually from 1983 and

1994, except during El Nino events of 1983 and 1995 (Barlow et al.

1995). During the same period however, harbor seal numbers within San

Francisco Bay remained stable; their 1994 estimated number being

approximately 350 (CALTRANS 1997).

The harbor seal is a non-migratory pinniped found in estuaries and

marine embayments and typically rests ashore (hauls out) on tidal-

inundated habitats such as mudflats, marshes, and near-shore rocky

outcroppings (Kopec and Harvey 1995; Zeiner et al. 1990). Haul-out

locations are used as resting sites and are important to the health of

harbor seals. Harbor seals feed opportunistically in shallow water on a

variety of fish, crustaceans, and a few cephalopods (Zeiner et al.

1990). Harbor seals often use isolated, undisturbed, sites for pupping

and molting. The numbers of harbor seals on haul-out sites fluctuates

throughout the year, but peaks generally occur during pupping and

molting at some sites, such as Castro Rocks. Typically, in San

Francisco Bay, pupping occurs from March to May, and molting occurs in

June (Kopec and Harvey 1995). Females usually give birth on land, often

at low tide, and the newborn pups are able to swim immediately after

birth (Zeiner et al. 1990).

In the San Francisco Bay area, harbor seals are known to haul out

at the Corte Madera ecological reserve in Marin County; at Castro Rocks

on the southeast end of the Richmond-San Rafael Bridge in the North

Bay; at Yerba Buena Island in Central San Francisco Bay; at several

locations along the western shoreline of the Dumbarton Bridge, on the

east side of the Bay (Newark and Mowry Soughs); and at the adjacent

coastal areas (such as Point Reyes, Bolinas Lagoon, and Pillar Point

(Kopec and Harvey 1995). In addition, several smaller or abandoned

haul-out sites occur in San Francisco Bay (Kopec and Harvey 1995).

The numbers of harbor seals at Castro Rocks varies year-round. The

most current independent surveys of harbor seals at Castro Rocks were

conducted from 1989 to 1992 by Kopec and Harvey (1995). Mean yearly

numbers of adults per count ranged from 76 to 113 during the pupping

season, and ranged from 48 to 67 during the non-pupping seasons.

[[Page 46482]]

Maximum numbers of harbor seal pups were between 13 and 26 for that

four-year period (Kopec and Harvey 1995). During biological surveys at

the Richmond-San Rafael Bridge, CALTRANS personnel counted 101 harbor

seals on June 16, 1994, all seals were adults. On June 25, 1996, census

data was again collected identifying 86 adults and 6 pups.

Harbor seals do not haul out at Castro Rocks at the highest tides.

Harbor seals first come ashore when tide levels drop below 3 ft (1 m)

on the eastern half of the easternmost island, closest to Pier 55. As

the tide drops further, seals haul out on every island in the chain.

Harbor seals haul out onto dry land for various biological reasons,

including sleep (Krieber and Barrette 1984), predator avoidance and

thermoregulation (Barnett 1992). As harbor seals spend most of the

evening and nighttime hours in the ocean (Bowles and Stewart 1980),

hauled-out seals spend much of their daytime hours in apparent sleep

(Krieber and Barrette 1984, Terhune 1985). In addition to sleep, seals

need to leave the ocean to avoid aquatic predators and excessive heat

loss to the sea water (Barnett 1992).

However, the advantages of hauling out are counterbalanced by

dangers of the terrestrial environment including predators. In general,

because of these opposing biological forces, haulout groups are

temporary, unstable aggregations (Sullivan 1982). The size of the

haulout group is thought to be an anti-predator strategy (da Silva and

Terhune 1988). By increasing their numbers at a haulout site, harbor

seals optimize the opportunities for sleep by minimizing the

requirement for individual vigilance against predators (Krieber and

Barrette 1984). This relationship between seals and their predators is

thought to have represented a strong selection pressure for startle

behavior patterns (da Silva and Terhune 1988). As a result, harbor

seals, which have been subjected to extensive predation or hunting,

rush into the water at the slightest alarm.

Startle response in harbor seals can vary from a temporary state of

agitation by a few individuals to the complete abandonment of the beach

area by the entire colony. Normally, when harbor seals are frightened

by noise, or the approach of a boat, plane, human, or other potential

predator, they will move rapidly to the relative safety of the water.

Depending upon the severity of the disturbance, seals may return to the

original haul out site immediately, stay in the water for some length

of time before hauling out, or haulout in a different area. When

disturbances occur late in the day, harbor seals may not haul out again

until the next day.

Disturbances have the potential to cause a more serious effect when

herds are pupping or nursing, when aggregations are dense, and during

the molting season. However, evidence to date has not indicated that

anthropogenic disturbances have resulted in increased mortality to

harbor seals. Bowles and Stewart (1980) for example, found that harbor

seals tendency to flee, and the length of time before returning to the

beach, decreased during the pupping season. They also found that

maternal-pup separations in crowded colonies are considered frequent,

natural occurrences that can result from several causes, including

normal female-female or male-female interactions. Both factors

apparently giving some protection to young seals from the startle

response of the herd.

Potential Effects on Marine Mammals

The impact to the harbor seals and California sea lions would be

disturbance by the presence of workers, construction noise, and

construction vessel traffic. Disturbance from these activities is

expected to have a short-term negligible impact to a small number of

harbor seals and sea lions. These disturbances will be reduced by

implementation of the proposed work restrictions and mitigation

measures (see below).

During the work period, harbor seal and on rare occasions,

California sea lion incidental harassment is expected to occur on a

daily basis upon initiation of the retrofit work. When harbor seals no

longer perceive construction noise and activity as being threatening,

they are likely to resume their regular hauling out behavior. The

number of seals disturbed will vary daily depending upon tidal

elevations. It is expected that disturbance to harbor seals during peak

periods of abundance will not occur since construction activities will

not take place within the restricted work area during the peak period

(see Mitigation below).

It is not known whether California sea lions will react to

construction noise and move away from the rocks during construction

activities. Sea lions are generally thought to be more tolerant of

human activities than harbor seals and are likely therefore to be less

impacted.

Potential Effect on Habitat

Short-term impacts of the activities are expected to result in a

temporary reduction in utilization of the Castro Rocks haul out site

while work is in progress or until seals acclimate to the disturbance.

This will not likely result in any permanent reduction in the number of

seals at Castro Rocks. The abandonment of Castro Rocks as a harbor seal

haul out and rookery is not anticipated since existing traffic noise

from the Bridge, commercial activities at the Chevron Long Wharf used

for off-loading crude oil, and considerable recreational boating and

commercial shipping currently occur within the area. In addition,

mitigation measures and proposed work restrictions are designed to

preclude abandonment.

Therefore, as described in detail in CALTRANS (1996), other than

the potential short-term abandonment by harbor seals, of part or all of

Castro Rocks during retrofit construction, no impact on the habitat or

food sources of marine mammals are likely from this construction

project.

Mitigation

Several mitigation measures to reduce the potential for marine

mammal harassment will be implemented by CALTRANS as part of their

proposed activity. General restrictions include: No piles installed

between 7 p.m. and 7 a.m., imposition of a construction noise limit of

86 dBA at 50 ft (15 m) between 7 p.m. and 7 a.m., and a limitation on

construction noise levels for 24 hrs/day in the vicinity of Castro

Rocks during the pupping/molting restriction period.

Marine mammal mitigation measures include: (1) A February 1 through

June 30 restriction on work in the water south of the Bridge center

line and on piers and pilings from Piers 52 through 57; and (2) no

watercraft will be deployed during the year within the exclusion zone

located between Piers 52 and 57 on the south side of the Bridge, except

for when construction equipment is required for seismic retrofitting of

piers 52 through 57. This exclusion area will be restricted as a

controlled access area on plans and will be marked off with buoys

located 200 ft (60 m) from the rocks.

To further minimize potential harassment, NMFS proposes to require

CALTRANS to the following: (1) Minimize vessel traffic in the exclusion

zone when conducting construction activities between piers 52 and 57;

(2) construction noise levels on the superstructure will be limited to

86 dB re 20 Pa-m for 24 hours/day in the vicinity of Castro

Rocks during the pupping/molting restriction period; and (3) no

retrofit construction work will occur on the towers associated with

piers 52 through 57 between February 1 and June 30.

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Monitoring

During the time that seismic retrofit construction activities occur

on Piers 52 through 57, harbor seal monitoring at Castro Rocks will be

made for an 8-hour period once a week. Sound levels will be recorded on

those days that seals are being monitored. Monitoring will be conducted

by a minimum of one trained biologist approved by NMFS.

Monitoring of harbor seals at Castro Rocks will continue on a

quarterly basis for one year after the retrofit construction is

completed.

Reporting

CALTRANS will provide weekly reports to NMFS and a final report

will be provided within 3 months of completion of construction work on

Piers 52 through 57. These reports will provide dates, time, tidal

height, maximum number of harbor seals ashore, number of adults and

sub-adults, number of females/males, number of redcoats, and any

observed disturbances. A description of retrofit activities at the time

of observation and any sound pressure levels measurements made at the

haulout.

CALTRANS will provide NMFS with a follow-up report on the post-

construction monitoring activities within 18 months of project

completion in order to evaluate whether haul-out patterns are similar

to the pre-retrofit haul-out patterns at Castro Rocks.

National Environmental Policy Act

In conjunction with this notice, NMFS has released a draft EA that

addresses the impacts on the human environment from issuance of the

authorization and the alternatives to the proposed action. A copy of

the draft EA is available upon request (see ADDRESSES).

Conclusions

NMFS has preliminarily determined that the short-term impact of a

seismic retrofit construction of the Bridge will result, at worst, in a

temporary modification in behavior by harbor seals and possibly some

California sea lions. While behavioral modifications, including

temporarily vacating the haul-out, may be made by these species to

avoid the resultant noise, this action is expected to have a negligible

impact on the animals. In addition, no take by injury and/or death is

anticipated and takes will be at the lowest level practicable due to

incorporation of the mitigation measures mentioned above.

Proposed Authorization

NMFS proposes to issue an incidental harassment authorization to

CALTRANS for the possible harassment of small numbers of harbor seals

and California sea lions incidental to seismic retrofit construction of

the Bridge, provided the above mentioned mitigation, monitoring and

reporting requirements are incorporated. NMFS has preliminarily

determined that the proposed activities would result in the harassment

of only small numbers of harbor seals and possibly California sea lions

and will have no more than a negligible impact on these marine mammal

stocks.

Information Solicited

NMFS requests interested persons to submit comments, information,

and suggestions concerning this request (see ADDRESSES).

Dated: August 26, 1997.

Hilda Diaz-Soltero,

Director, Office of Protected Resources, National Marine Fisheries

Service.

[FR Doc. 97-23251 Filed 9-2-97; 8:45 am]

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