    [From the U.S. Government Printing Office, www.gpo.gov]

    NOAA Technical Memorandum
    NOS MEMD 7

    PINNIPED ASSESSMENT IN POINT REYES,
    CALIFORNIA, 1983 TO 1984

    Sarah G. Allen

    Point Reyes Bird Observatory
    4990 Shoreline Highway
    Stinson Beach, CA 94970

    Washington, D.C.
    August 1987

    UNITED STATEIS        Natii cuN1i an*        National Ocean Service
    DEPARTMENT OF COMMERCE  Ainespheic Admainisttat                  *
                                                                 4*EN Q

                                    NOAA TECHNICAL MEMORANDA

                                      National Ocean Service Series

                             Marine and Estuarine Management Division

          The National Ocean Service, through its Office of Ocean and Coastal Resource Management, conducts
    natural resource management related research in its National Marine Sanctuaries and National Estuarine Reserve
    Research System to provide data and information for natural resource managers and researchers. The National
    Ocean Service also conducts research on and monitoring of site-specific marine and estuarine resources to
    assess the impacts of human activities in its Sanctuaries and Research Reserves and provides the leadership
    and expertise at the Federal level required to identify compatible and potentially conflicting multiple uses of
    marine and estuarine resources while enhancing resource management decisionmaking policies.

          The NOAA Technical Memoranda NOS MEMD subseries facilitates rapid distribution of material that may
    be preliminary in nature and may be published in other referreed joumals at a later date.

    MEMD 1  M.M. Littler, D.S. Littler and B.E. Lapointe. 1986. Baseline Studies of Herbivory and Eutrophication
              on Dominant Reef Communities of Looe Key National Marine Sanctuary.

    MEMD 2   M.M. Groom and N. Stone, Eds. 1987. Current Research Topics in the Marine Environment.

    MEMD 3   C.E. Birkeland, R.H. Randall, R.C. Wass, B. Smith and S. Wilkens. 1987.  Biological Resource
              Assessment of the Fagatele Bay National Marine Sanctuary

    MEMD 4   H. Huber. 1987. Reproduction in Northern Sea Lions on Southeast Farallon Island, 1973-1985.

    MEMD 5   J.A. Bohnsack, D.E. Harper, D.B. McClellan, D.L. Sutherland, and M.W. White. 1987.  Resource
              Survey of Fishes within Looe Key National Marine Sanctuary.

    MEMD 6  S.G.  Allen,  D.G.  Ainley,  L. Fancher,  and D.  Shuford. 1987. Movement  Patterns  of  Harbor
              Seals (Phoca vitulina) from the Drakes Estero Population, Califomia, 1985-86.

    MEMO 7  S.G. Allen. 1987. Pinniped Assessment in Point Reyes, California, 1983 to 1984.

    National Marine Sanctuary Program
    Marine and Estuarine Management Division
    Office of Ocean and Coastal Resource Management
    National Ocean Service
    National Oceanic and Atmospheric Administration
    U.S. Department of Commerce

    NOTICE

    This report has been approved by the National Ocean Service of the National Oceanic and
    Atmospheric Administration (NOAA) and approved for publication. Such approval does not
    signify that the contents of this report necessarily represent the official position of NOAA or
    of the Government of the United States, nor does mention of trade names or commercial
    products constitute endorsement or recommendation for their use.

                               REPORT TO
         NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
                    U.S. DEPARTMENT OF COMMERCE

            NOAA TECHNICAL MEMORANDA SERIES NOS/MEMD

             Pinniped Assessment in Point Reyes, Califronia, 1983 to 1984

                               Sarah G. Allen

                                August 1987

    U.S. DEPARTMENT OF COMMERCE
    NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
    NATIONAL OCEAN SERVICE
    'OFFICE OF OCEAN AND COASTAL RESOURCE MANAGEMENT
    MARINE AND ESTUARINE MANAGEMENT DIVISION
    WASHINGTON, D.C.

                               REPORT TO
    NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
                  U.S. DEPARTMENT OF COMMERCE

       NOAA TECHNICAL MEMORANDA SERIES NOS/MEMD

        Pinniped Assessment in Point Reyes, California, 1983 to 1984

                               Sarah G. Allen

       Point Reyes Bird Observatory, 4990 Shoreline Highway, Stinson
                              Beach, CA 94970

                 This work is the result of research sponsored by the U.S.
                Department of Commerce, National Oceanic and Atmospheric
                Administration, National Ocean Service, Office of Ocean and
           Coastal Resource Management, Marine and Estuarine Management Division
                 Under Interagency Agreement Number NA-81-AA-H-CZ151

                                                                       2

                             ABSTRACT

    We surveyed three species of pinnipeds (harbor seals,

    California sea lions, and northern sea lions) for a

    second year in Point Reyes, California, from March 1983

    through February 1984. Information gathered for both

    years (1982-83, 1983-84) are compared. Harbor seals,

    though present year round, were most abundant during the

    breeding season; the maximum count for the season was

    2449 including 527 pups. The majority of breeding seals

    migrated to coastal locations rather than estuarine ones.

    At Double Point the breeding population has expanded

    three-fold since 1976; the annual rate of growth, though,

    has not been constant. During the non-breeding season,

    population numbers have remained stable. Sea lions also

    were seasonally abundant in Point Reyes. northern sea

    lion numbers peaked during the breeding season;

    California sea lion numbers peaked during the southern

    spring migration and the northern fall migration when

    traveling to and from breeding grounds, and peaked again

    in December during the herring run in Tomales Bay. A

    significantly larger number of California sea lions,

    composed of mostly immatures, was present in 1983-84 than

    in 1982-83. The optimum time to census sea lions in

    Point Reyes was between 1100 and 1600 hr when low tides

    occurred mid day.

                                                                                                                                                                  3

                                                                  TABLE OF CONTENTS

                                                                                                                                                     Page

           I List of Tables........................                                                                                                 4

        II List of Figures........................                                                                                                 5

      III  Part A.  Harbor Seals - Sarah G. Allen

                     Introduction.                                                                                                                    .......................6

                     Study Area and Methods.                                                                                                          ..................7

                     Results .                                                                                                                      ..........................12

                     Discussion.                                                                                                                    ........................21

                     Summary.                                                                                                                       ..........................25

        IV  Part B.  Sea Lions - Harriet R. Huber

                     Introduction.                                                                                                                  .......................26

                    Methods.                                                                                                                        ..........................27

                     Results.                                                                                                                       ..........................29

                     Discussion.                                                                                                                    ........................33

                     Summary.                                                                                                                       ..........................37

          V Acknowledgements.                                                                                                                       ......................38

        VI Literature Cited.                                                                                                                        ......................39

      VII Tables .............................43

    VIII Figures.                                                                                                                                   ...........................62

        IX Appendix.                                                                                                                               ..........................71

                                                                              4

                                  LIST OF TABLES

     Table 1.  Harbor seal counts for all sites in the Point Reyes region for
               1983-84.

    Table 2.  The average number of harbor seals hauled out by season in
               1983-84.

     Table 3.  Maximum number of harbor seal pups counted in the Point Reyes
               region in 1982 and 1983.

     Table 4.  The hourly presence of harbor seals at primary locations in the
               Point Reyes area in June 1983.

     Table 5.  Freeman-Tukey deviates for the deviation of the observed from the
               expected for a log-linear model of independence of year, seal
               location, and seal reproductive status.

     Table 6.  The average monthly number of harbor seals hauled out at Double
               Point for each age class.

    Table 7.  The average percentage of sex and age classes of harbor seals at
               Double Point during the breeding season, 1984.

    Tabli 8.  The yearly population growth rate at Double Point during the
               breeding season from 1976 to 1984.

     Table 9.  The daily variability in the number of seals hauled out at Double
               Point and Bolinas Lagoon during the breeding season, the molt, and
               the end of molt.

    Table 10.  Summary of pupping success of known female harbor seals at Double
               Point.

    Table 11.  Maximum counts of California sea lions at Point Reyes Headlands
               1983-84.

    Table 12.  Maximum counts of California sea lions at Bodega Head, 1983-84.

    Table 13.  Maximum counts of northern sea lions at Point Reyes Headlands
               1983-84.

    Table 14.  Hourly counts of California sea lions at Point Reyes Headlands,
               1982-84.

    Table 15.  Hourly counts of northern sea lions at Point Reyes Headlands,
               1982-84.

                                                                             5

                                 LIST OF FIGURES

    Figure 1. Major pinniped haul-out locations in Point Reyes, California.

    Figure 2.  Maximum number of harbor seals by month in Point Reyes, 1983-84

    Figure 3.  Monthly mean number of harbor seals, 1982-84, at Tomales Bay.

    Figure 4.  Monthly mean number of harbor seals, 1982-84, at Tomales Point.

    Figure 5.  Monthly mean number of harbor seals, 1982-84, at Point Reyes
               Headland.

    Figure 6.  Monthly mean number of harbor seals, 1982-84, at Drakes Estero.

    Figure 7.  Monthly mean number of harbor seals, 1982-84, at Duxbury Reef.

    Figure 8.  Monthly mean number of harbor seals, 1982-84, at Bolinas Lagoon.

    Figure 9.  Monthly mean number of harbor seals, 1982-84, at Double Point.

    Figure 10. Monthly mean number of California sea lions at Point Reyes
                Headlands, 1982-84.

    Figure 11. Monthly mean number of California sea lions at the Farallones,
                1972-1984.

    Figure 12. Monthly mean number of California sea lions at Bodega Rock,
                1982-1984.

    Figure 13. Monthly mean number of northern sea lions at the Farallones,
                1972-1984.

    Figure 14.  Monthly mean number of northern sea lions at Point Reyes,
                1982-1984.

                                                                              6

                               PART A. HARBOR SEALS

                                  Sarah G. Allen

                                   INTRODUCTION

        Throughout historical times, harbor seals, Phoca vitulina, have

    resided at Point Reyes, California. Scammon (1874) was the first to record

    their presence (1850's), but only in recent years have researchers

    attempted to document the seasonal abundance of this species in the

    California coastal zone (Carlisle and Alpin 1966 and 1971, Dohl et al.

    1982, Frey and Alpin 1970, Hanan 1985, Mate 1977, and Miller 1983). The

    results of these surveys, however, are insufficient for designing a

    reliable management plan for harbor seals specific to the Point Reyes area.

    With the more generalized state-wide emphasis of present information, we

    lack insight into the peculiarities of this local population. In addition,

    little information has been available on the reproductive rates of harbor

    seals in the region. Incidental information on pinnipeds in Point Reyes

    has been noted by Chan (1979) in reports on Areas of Special Biological

    Significance (ASBS) and by Allen et al. (1985).

        Our two-year survey, 1982-1984 was designed to provide comprehensive

    information on abundance and seasonal use patterns of harbor seals in the

    coastal zone of the Point Reyes area. In the first survey year, we refined

    our census techniques by evaluating the tidal and diurnal differences in

    seal haul-out behavior as well as identifying haul-out sites and the

                                                                             7

    significance of each. Data from the second survey year validated findings

    on seasonal and spatial trends. We include in this report analyses of data

    collected since 1976 at Double Point, the largest breeding site in the

    region.

                              STUDY AREA AND METHODS

    Study Area

        The coastal zone of the Point Reyes/Farallon Islands National Marine

    Sanctuary extends from Bodega Bay (380 30'N) south to Bolinas Bay (370

    30'N) (Figure 1). Included are embayments such as Tomales Bay, Drakes

    Estero, and Bolinas Lagoon. The Point Reyes National Seashore (PRNS), the

    Golden Gate National Recreation Area (GGNRA), and the Marin County

    Department of Parks and Recreation share boundaries with the Sanctuary over

    segments of this coastline. In addition to the protection afforded by Park

    and Sanctuary status, Bird Rock, Point Reyes Headland, and Double Point

    were designated as Areas of Special Biological Significance (ASBS) by the

    California Department of Fish and Game (CDFG) and the State Water Resources

    Control Board.

        Much of this coastline remained largely undeveloped even before

    inclusion into PRNS and GGNRA during the 1960's and 1970's. An

    agricultural character and the inaccessibility of much of the area afforded

    protection from human disruption. Consequently, use of habitat by seals

    has probably has not changed significantly over the past few decades.

        The topographical diversity of this coastal zone contributed to the

    broad range of substrates in seal habitat, including tidal mud flats,

    offshore tidal ledges, and sandy beaches. Coastal locations included

    Tomales Point, Point Reyes Headland, Double Point, and Duxbury Reef;

    estuarine locations included Tomales Bay, Drakes Estero, and Bolinas Lagoon

    (Figure 1).

    Data Collection

       We counted seals twice each month at all locations from March 1983

    through February 1984. Censuses occurred simultaneously in the afternoon

    during low to medium-low tides except on a few occasions when weather

    conditions hindered human access to remote sites. Days when low to

    medium-low tides occurred mid-day to early afternoon were chosen to

    maximize counts (Ainley et al. 1977, Allen et al. 1985, Fancher 1979,

    Stewart 1984). In addition, an all day census at primary locations was

    conducted in June when seal numbers reach their annual maxima in the area

    (Allen and ]Iuber 1983, Miller 1983). This all-day census was undertaken to

    confirm that there were no diurnal and tidal differences in haul out

    patterns between locations and to provide a maximum estimate of seals in

    the Point Reyes region.

        Whenever possible we classified seals in three categories based on size

    and color: adults, subadults, and pups. Seals in the eastern Pacific are

    purported to reach sexual maturity between three and six years of age (Bigg

    1969). At locations other than Double Point, Drakes Estero, Point Reyes

    Headland, and Tomales Point, distance from observer and the oblique angle

                                                                                        9

              of view made it difficult to distinguish subadults. Pups were easily

              identified at all locations during the breeding season because of their

              bright coloration and diminutive size.

                  We counted seals on four to five consecutive days at Double Point

              during the breeding season (March through June) and molting period (June

              through August) in 1983 and 1984 in order to determine daily variability in

              the haul out pattern.

              Data Analysis

                  For analysis of seasonal trends, we divided the year into three

              seasons: breeding (March through June), summer (July through October), and

              winter (November through February). We examined seasonal means for the

              region and for each site and used a t-test to compare the average abundance

              for spring, summer and winter of 1982 with that of 1983. Age class

              representation for subadults and pups was expressed as a percentage of the

              total herd. Maximum counts of pups for the region were based on

              simultaneous censuses in the event that females with pups might travel

              between locations. To test whether the seasonal haul-out pattern was

              different at coastal compared to estuarine locations during breeding and

              non-breeding seasons (summer and winter seasons combined) in 1982 and 1983,

              we made two 2 x 2 contingency tables. We used a log-linear model to

              analyze the tables and then we used Freeman-Tukey deviates to see which

    *         ~~~cells did not fit the model (Fienberg 1981).

                  Examination of trends in abundance at Double Point included data

              collected by Allen (unpublished data) from January 1976 to June 1984.

                                                                            10

    During that period seals were censused on 325 days with over 625 hours of

    observation. Seasonal coverage was similar for all years except 1979 and

    1980. Most censuses were confined to the hours 0700-1630 because the

    remoteness of the area required three hours of hiking, round trip. We

    estimated the increase in the number of seals at Double Point from 1976 to

    1984 by dividing the seasonal mean of 1984 by that of 1976. The change in

    abundance for each year was determined from the formula         =Nt+

                                                                   N
                                                                     t
    where N is the mean population size and t is the year (Caughley 1977).

        We examined the representation of sex and age classes at Double Point

    in spring 1984 to identify more accurately which animals accounted for this

    annual peak. The period was divided into early (March to mid-April),

    middle (mid-April to mid-May), and late (mid-Hay Lo June). Seals were

    categorized as male, female, female with pup, subadult, and pup. We then

    calculated the percent representation of each category by dividing the

    number identified for each category by the total number of animals

    classified. Since male and female adult seals are almost identical in

    size, we were not able to sex all adult animals and did not attempt to sex

    subadults.

        The daily variability in the number of seals hauled out at Double Point

    during the breeding season was compared with that of the molt period (late

    June through July) and the end of molt (August) using the coefficient of
                   SD
    variation CV   -      (Snedecor and Cochran 1967).  Only counts from

    1200-1400 hr and from 1-3 hr .fter low tide were used in the analysis. For

    comparison, we calculated an analogous CV from data gathered at Bolinas

    Lagoon by Allen (unpubi. data).

       We were able to identify a number of individual females at Double Point

    by scars and unusual spot patterns. For eight years we noted the

    recurrence of many of these animals during successive breeding seasons

    (Allen, unpubl. data). To verify ifhe accuracy of our ability to identify

    individuals, we compared the presence of known females during consecutive

    three-day periods during the 1977, 1983 and 1984 breeding seasons,

    excluding days when excessive disturbance occurred. We calculated the

    probability of sighting, P, by the formula:

               N
          P=  Iand 3

                1-3

    where N    I     n  is the number of females seen only on days one and three,

    and N1-       is the number seen on all three days.  The average for all

    three-day periods was used as the probability of sighting (P). Our

    estimated average probability of sighting was 0.9 (n = 3, range 0.8-1.0).

    The sample size of known individuals was small (7, 5, 6), but these animals

    were easily distinguished within a herd composed of 400-700 animals. Since

    our probability of sighting was within an acceptable range, we felt

    confident in calculating the pupping frequency of known females and the

    probability of pupping.

        The pupping frequency (pf) of females was figured from the conditional

    probabilities for successive samples of females in three-year sets using

    the formula:

                                                                             12

                No. of same females in denominator seen w/pup in yr i + 1
           pf =

                            Noo of females seen in yri

    Known individual adult females identified from 1977 to 1979 represented set

    I and from 1982 to 1984 represented set 2. We eliminated from our

    tabilations two groups of known females: 1) females not seen all three

    years (Siniff et al. 1977); and 2) those that did not have pups in year 1

    -Cse they may not have been sexually mature then.  We included these two

    groups of females, however, when presenting a summary of pupping success.

    The probability of pupping (X) was estimated from a binomial pupping model

    (Siniff et al. 1977) with the equation Xp = _ --i ,where P.  is years with
                                                n
    pup for female   divided by total years female   was present, and n = the
                  i
    number of known females. Only known females present in three successive

    years were included in the model. If a female was determined to be

    pregnant by the size and shape of her abdomen, but was not seen attending a

    pup later, she was included in the sample as having pupped.

                                      RESULTS

                         Seasonal and Spatial Use Patterns

    Regional

        Harbor seals were present year round at all locations censused within

    the Point Reyes area in 1983 and, as determined in the 1982 survey, the

    numbers fluctuated seasonally with more seals hauled out in spring (x =

    1653 ,, SE = 121.0, n = 9) and summer (  = 1270.1, SE = 210.6, n = 8) than

    in winter (X = 1089.1, SE = 70l1, n = 8)(Table 2).  Seasonal means in 1982

    versus those in 1983 were not significantly different (spring: t = 1.225, p

    > 0.1; summer: t = .3318, p > 0.1ol; winter: t = .7421, 0.2 > p > 0.1). The

                                                                              13

    highest counts for the region in 1983 occurred in May (2449) and July (2323)

    (Figure 2). Tomales Point, Drakes Estero, and Double Point were the areas

    of highest seal concentration contributing most to the total number of pups

    (Tables 1 and 3). Pups were first identified at haul-out sites in late

    March, and their numbers peaked during the first week of May for both years

    with 566 in 1982 and 527 in 1983. Pups represented 24% of the total count

    (2339) in 1982 and 22% (2449) in 1983 (Table 3). The mean percentage

    representation of subadult seals at Tomales Point, Point Reyes Headland,

    Drakes Estero, and Double Point was much the same for all seasons in 1983

    (spring:  =   18.0, SD = 7.0, n   8; summer:  x = 17.4, SD = 3.0, n = 8;

    winter:  x = 15.0, SD = 4.4, n = 9).  As was observed in the 1982 survey,

    subadult representation declined in May 1983 (x = 8.5%) (173/1820, 79/1101).

        The all day census conducted in June 1983 confirmed that more seals were

    present at all haul-out sites mid-day, a couple of hours after low tide,

    with only Tomales Bay being exceptional, but did not provide a maximum

    estimate for the seal population in the Point Reyes region (Table 4). More

    seals were counted in Tomales Bay early in the morning, but the numbers were

    only slightly lower mid-day. Though mid-day yielded maximum numbers, many

    seals remained at haul-out sites into mid-afternoon, despite rising tides.

    Duxbury Reef could accomodate large numbers of seals until about four hours

    after low tide when it was awash. Seals that hauled out on offshore rocks

    at Bird Rock and Double Point shifted to higher ground as the tide rose and

    consequently, even at five hours after low tide, many seals were hauled out.

    At estuarine locations haul-out space was reduced slightly beginning a

    couple of hours prior to high tide, and so a substantial number of seals

                                                                              14

    remained until late afternoon.

        Coastal areas accomodated a large influx of seals during the breeding

    season (x = 992.7, SE = 75.8, n = 9) in comparison to estuarine sites

    (R-= 660.8, SE = 59.0, n = 9). During the non-breeding season the coastal

    populations declined substantially (x = 618.3, SE = 83.1, n = 15), whereas

    estuarine ones declined only slightly (x = 595.9, SE = 37.6, n = 15). The

    log-linear model comparing coastal and estuarine locations during breeding

    and non-breeding seasons for 1982 and 1983 revealed that none of the
                            2
    variables were equal (X = 26.45, p < 0.001). The variable which least fit

    the model was the figure for estuarine locations during the breeding season

    in 1983 (Table 5). The estuarine pattern changed significantly in 1983 with

    fewer seals recorded during the breeding season and more during the

    non-breeding season compared to that of 1982. Thus, the coastal pattern was

    similar though not identical for both years. These findings suggested that

    more seals were migrating to coastal areas than to estuaries during the

    breeding season.

        The seasonal pattern for each haul-out site reflected this difference

    between coastal and estuarine groups, and when examining each we can

    identify where the deviation from the 1982 estuarine pattern took place.

    Bodega Rock

        Seals were seen hauled out on tidal reefs of this offshore sea stack.

    We counted a maximim of 54 seals in February 1984.  Pups were not seen in

    1.983 (Table 1).

                                                                             15

    Tomales Bay

        Seals hauled out predominantly on tidal sand bars extending from Toms

    Point to Sand Point in 1983. They were seen infrequently at Hog Island.

    Seasonal means revealed that numbers remained relatively stable throughout

    the spring and summer months and were slightly higher in winter (Table 2).

    The winter peak in 1983 was in contrast to a distinct decline in numbers in

    the winter of 1982. Here is where the main divergence from the estuarine

    model occurred. In 1983 both spring and summer numbers were markedly lower

    than those in 1982 (Appendix I), possibly because of disturbance. Though

    the frequency of disturbance was similar in 1982 and 1983 (1982: 16 of 26

    censuses; 1983: 16 of 28 censuses), the level of human activity was much

    greater in 1983 (Allen and Huber 1984).  A maximum of 45 pups was counted in

    May which is slightly lower than the figure in 1982 (58) and represents 16%

    (45/275) of the population in Tomales Bay and 10% (45/527) of all pups

    censused in the Point Reyes area. A graph of the average number of seals by

    month, combining data for 1982 and 1983, displays the apparent decline in

    attendance in early winter and again in June and July when visitor use in

    the area is high (Figure 3). Seal numbers in January through March were

    higher than for most other months. Herring, Clupea pallasii, spawn in

    Tomales Bay at this time [a known prey item of seals in the area (Miller

    1983)], and may be related to increased seal abundance.

    Tomales Point

        The largest concentrations of seals in the vicinity of Tomales Point

    hauled out on Bird Rock, north tidal rocks and Driftwood Beach. The

                                                                              16

    seasonal haul-out patterns were nearly identical in 1982 and 1983 with most

    seals recorded during the breeding season (Table 2). A graph of the average

    number of seals present by month, combining data for 1982 and 1983

    illustrates the rapid increase that occurs there in May, June and July, and

    the equally rapid decline from August through February (Figure 4). Tomales

    Point is one of the three most important breeding areas in the Point Reyes

    region with pups representing 24% (122/514) of total seals censused at the

    Point and 23% (120/527) of all pups censused in 1983.

    Point Reyes Headland

        Point Reyes Headland is a minor coastal haul-out area where seals were

    scattered along offshore rocks and in pocket beaches around Split Rock and

    Sea Lion Coves. Counts were highest during the breeding season (Table 2);

    one pup was seen in June. In contrast to 1982, the mean count during winter

    1983 was slightly larger than that of the summer. The combined data of 1982

    and 1983 reveal an irregular pattern: small numbers of seals were present

    during April and May, the peak of breeding, and again in winter, but were

    most abundant just prior to and just after the breeding season (Figure 5).

    Geographically, this point bisects the distance between two major coastal

    haul-out sites, and may be frequented by animals moving to or from breeding

    grounds. We often observed harbor seals sharing pocket beaches here with

    northern elephant seals, Mirounga angustirostrus, and occasionally observed

    them displaced by these larger seals.

                                                                              17

    Drakes Estero

        Drakes Estero is one of the three largest breeding areas in the Point

    Reyes area. Seals hauled out on virtually every sand bar far up into the

    estero during the breeding season, and Limantour Spit was used primarily

    then. The 1983 pattern resembled closely that of 1982 with high counts

    during spring and summer and lower counts during winter (Table 2). A

    maximum of 122 pups was counted in May 1983, accounting for 19% (122/656) of

    the total breeding population there. Twenty-three percent (122/527) of all

    pups in the Point Reyes area occurred at Drakes Estero in 1983. A graph of

    the combined data from 1982 and 1983 reveals that seals were present in

    large numbers year round in contrast to the two other most important

    breeding areas, Tomales Point and Double Point (Figure 6).

    Duxbury Reef

        The majority of seals hauled out on an intertidal reef extending from

    Bolinas Headland; we identified a secondary haul-out site in 1983 which was

    another reef 1/2 mi further north at Bolinas Point. Duxbury Reef was the

    only coastal site in 1983 where the seasonal mean number of seals was higher

    in summer than in spring; the average in winter was similar to that in

    spring (Table 2). The monthly pattern exhibited in Figure 7 displayed a

    peak in September and October and a decline in July; numbers varied greatly,

    however, within July. Few pups (<5) were observed in 1982 and 1983.

    Bolinas Lagoon

        Bolinas Lagoon is an estuarine habitat where seals haul out on tidal mud

                                                                             18

    flats bordering two islands, Kent and Pickleweed. In a previous study, Kent

    Island was the preferred site for all seasons (Allen et al. 1985). In 1982

    and 1983, however, Pickleweed Island was the preferred location. The

    seasonal pattern in 1983 was nearly identical to that of 1982 with a summer

    annual peak, rather than one in spring, and a much reduced number in winter

    (Table 2). Bolinas Lagoon was not an important pupping ground; only 17 pups

    were counted in May both of 1982 and 1983. Bolinas Lagoon, like Drakes

    Estero, did not display the monthly extremes in seal numbers characteristic

    of coastal colonies (Figure 8).

    Double Point

        The seasonal variation in the average number of seals at Double Point in

    1983 followed the pattern recorded since 1976 with a large influx of animals

    occuring in spring and then dispersing rapidly in summer and winter (Table 2).

    Maximum numbers in 1982 and 1983 occurred during the months from April

    through July; we observed fewer seals from September through January (Figure

    9). The months August/September and February/March were transition periods

    when numbers declined or increased, respectively. Counts during November

    reached the annual low. Pups accounted for 32% (262/832) of all seals

    censused at Double Point in May 1983 and 50% (262/527) of all pups censused

    in the Point Reyes area (Table 3).

        Since 1976, pups have been initially sighted each year in late March or

    early April; the maximum pup count has occurred consistently during the

    first two weeks of May. The May peak for all years coincided with the

    annual peak for all age classes combined, but surprisingly more adult seals

    hauled out in June (74%) and July (80%) than in May (59%). The peaks

    coincided with the mating period and the onset of molt, respectively (Figure

    9, Table 6). Females come into estrus after pups are weaned, and mating

    apparently extends into August (Bigg 1969). We observed mating on four

    occasions in late May and early June 1983 (Allen 1985). Seals at Double

    Point molted from early June to early August.

        The mean number of subadult seals was largest during the months flanking

    the breeding season, February and March and June and July (Figure 9, Table

    6). During May, the number of subadults declined only slightly, but their

    proportion to all seals counted then was much lower than in other months.

    The percent representation of subadults was highest in September, October,

    and December (Table 6).

        A closer examination of sex and age classes of the main herd at Double

    Point during the breeding season in 1984 revealed distinct trends in the

    representation of each category (Table 7). Early in the season females

    (33%), males (30%), and subadults (27%) were equally abundant. At the height

    of the season, though, the herd consisted primarily of females (38%),

    particularly females with pups (33%), and pups (39%). Late in the season,

    the herd also consisted mostly of females (38%) and pups (33%), but fewer

    females were with pups and the percentage of subadults began to increase.

    The representation of males remained low from April 17 through May 31.

        A comparison of the mean number of seals counted during the 1976

    breeding season (iR  195.2, SE = 17.6, n = 14, range = 112-320) with that of

    1984 (R = 578.3, SE = 41.5, n = 22, range = 101-897) showed a three-fold

    increase. The change in abundance for each year, however, was not linear

                                                                             20

    over this nine-year period (Table 8). For most years there was no change,

    but in 1977 and 1982 seal numbers rose. The summer and winter seasonal means

    for 1976 (summer: i = 165.7, SE = 35.7, n = 13; winter: _ = 123.8, SE =

    34.0, n = 9) and 1977 (summer: x = 222.6, SE = 35.9, n = 21; winter: x =

    106.8, SE = 22.1, n = 10) were not substantially different from those of

    1983 (summer:  R = 174.3, SE = 53.7, n = 14; winter:  x = 215.8, SE = 32.2,

    n = 15).

                                 Daily Variability

        The variability in the number of seals hauled out at Double Point over

    successive days was greater during the breeding season than during the molt

    (Table 9). The same was true for the herd in Bolinas Lagoon. At the end of

    the molting period (August), the daily variability increased substantially

    at Double Point, but in Dolinas Lagoon it remained the same. Disturbance

    and inclement weather at Double Point are partially responsible for the

    increased variation during the breeding season. Because of these

    uncontrolled factors influencing the daily variability, we are not

    completely confident with the results of these analyses.

                                 Reproductive Rates

        A summary of pupping success of known individual females is presented in

    Table 10. The proportion of known females observed in a given year that had

    pups was similar for all years. A small proportion of females were not

    seen in successive years with the exception of 1984. A larger proportion of

    females also did not bear pups in 1984. A total of 13 females (present all

                                                                             21

    three years) were observed with pups in 1977. Eleven of the females were

    resighted with pups in the second year, yielding a pupping rate of 0.85

    (11/13). The proportion of known females that pupped all three years for

    this set was 0.77 (10/13). In the second set, a total of 11 females

    (present all three years) were seen with pups and all of these were

    resighted with pups in 1983. This yielded a pupping rate of 1.0 (11/11);

    the proportion of females that pupped all three years was 9/11 for a rate of

    0.82. Both three-year sets yielded a high probability that females with

    pups in year 1 would have a pup in successive years. The probability of

    pupping was 0.89 for set 1 and 0.92 for set 2.

                                    DISCUSSION

       The results of the 1982 survey in combination with those of 1983 provide

    a much clearer understanding of harbor seal aggregations in Point Reyes. We

    have identified when and where seals are seasonally abundant and when is the

    optimum time to census. In 1982 we determined that diurnal and tidal

    effects on seal haul-out behavior vary within an optimum range from mid-day

    to late afternoon at low to medium tides depending upon the physical

    attributes of each location. This was verified in the all day simultaneous

    census in June, 1983. The diurnal pattern was similar to that of other

    locations in California: Mowry Slough in San Francisco Bay (Fancher 1979),

    Southeast Farallon Island (Ainley et al. 1977), Bolinas Lagoon (Allen et al.

    1985), and San Miguel Island (Stewart 1984).

        It is apparent that the Point Reyes area accomodates a large

    harbor seal breeding population. Peak figures tabulated in May (2449) and

                                                                             22

    July (2323) 1983 and in May (2339) and June (2502) 1982 are comparable.

    Population estimates by the California Department of Fish and Game (CDFG)

    based on aerial surveys in April and June, 1982 and 1983 (Miller 1983; D.

    Hanan 1985), are similar to our censuses for those months. The Point Reyes

    harbor seal population during the breeding season represented 19% of the

    total estimated California population, excluding the Channel Islands, in

    1982 considered to be the largest concentration in the state (Miller 1983).

    Preliminary analysis of the CDFG survey in 1983 confirms this estimate with

    a state-wide figure of 9,010 animals in April and 10,763 in June, including

    an estimated 1852 and 1985 seals, respectively, in Point Reyes (D. Hanan,

    pers. comm.). Miller calculated an estimate of 1309 pups in California,

    excluding the Channel Islands, in April 1982. The April 1983 pup count for

    the state was 642 (D. Hanan pers. comm.). The respective pup estimates

    calculated by CDFG for Point Reyes were 217 (10% of the total state pup

    estimate) in 1982 and 157 (25% of the total pup estimate) in 1983. Nearly

    three-quarters of pups censused by CDFG in Point Reyes in 1983 were at

    Double Point. The representation of pups at Point Reyes to the state-wide

    estimate is likely even greater because most pups are born in May rather

    than April. Consequently, Point Reyes is perhaps even more important as a

    breeding ground for harbor seals.

         Coastal areas accomodated the major portion of migratory animals again

    in 1983.  There was no evidence that estuarine animals shifted to coastal

    areas to breed. However, a subadult, male seal, rescued from Tomales Bay on

    4 March 1984 by the California Marine Mammal Center and released the

    following day at Point Reyes Headland with a rear flipper tag was identified

                                                                             23

    by us at Double Point on April 11 and 12, 1984 (L. Amaya, California Marine

    Mammal Center, Fort Cronkhite, CA., pers. comm.).   That the animal arrived

    at a major coastal haul-out site rather than returning to an estuarine one

    indicates that the animal was probably familiar with the area. Although

    seals radio-tagged by Brown and Mate (1983) traveled locally between a

    coastal haul-out site and estuarine ones, the majority of migrants in the

    Point Reyes area likely travel from outlying areas. A comparison of aerial

    surveys conducted by Dohl (1982) in May and January suggested a northward

    movement of seals from this region to Sonoma and Mendocino Counties in

    winter. Slater and Markowitz (1983) believed that adult seals dispersed

    from San Mateo County haul-out sites during the breeding season.

        The large influx of animals to coastal areas in Point Reyes during the

    breeding season is composed primarily of adult seals. The absence of

    subadult seals during the breeding season also has been documented in other

    harbor seal populations (Naito and Konno 1979, Slater and Markowitz 1983).

    Based on our analysis of herd composition at Double Point, adult females may

    be the primary migrants to the region in April and May. "Nursery" herds in

    harbor seals have been remarked upon by others (Brown and Mate 1983,

    Knudtson 1975, Naito and Konno 1979, Slater and Markowitz 1983). In

    addition, we have documented seasonal breeding site fidelity in females at

    Double Point where several known females were resighted over successive

    years. We did not gather information on the sex composition of the herd in

    June at Double Point; we would expect, though, that males would represent an

    increasingly larger proportion then because June is the mating season and

    the onset of molt. The larger number of adult animals at Double Point in

                                                                              24

    June and July rather than MCay corroborates this. Thus there may actually be

    two distinct waves of migrants to rookeries in coastal areas, the first one

    consisting of mostly pregnant, adult females, and the second one mostly of

    adult males.

        There is little information available for determining whether seal

    abundance has been increasing in the Point Reyes region. Earlier surveys

    (Carlisle and Alpin 1966 and 1971, Mate 1977, Risebrough et al. 1978) and

    data collected at Double Point indicates an increase during the breeding

    season, but there is no indication that the resident population has changed

    because summer and winter averages at Double Point have been about the same

    since 1976. Nevertheless, the rate of expansion in seal numbers at Double

    Point has not been constant. Instead, 1977 and 1982 are remarkable as years

    when seal numbers rose substantially and then leveled out during the

    intervening years. Why these increases occurred is not known.

                                                                              25

                                      SUMMARY

    1. The optimum time during a day to census seals in Point Reyes is from

    mid-day to late afternoon at low to medium tides depending upon the physical

    attributes of each location.

    2. Day to day variability in the number of seals at haul-out sites appears

    to be less during the molt than during the breeding season. We feel a

    minimum of three successive-day censuses are required for more reliable

    estimates during the breeding season because of the unpredictable influences

    of other factors such as human disturbance and extreme weather conditions.

    3. Seals should be censused in the first two weeks of May, when pup

    representation is highest in order to determine an index on the health of

    the breeding population. A second census in late June or early July, when

    more adult seals are present at haul-out sites to molt, would provide more

    reliable estimates for the total population.

    4. Annual censuses would provide data for determining trends in abundance.

    Data at Double Point indicate that the growth rate is not constant.

    5. Information on summer and winter movements of breeding animals would be

    invaluable for any long-term management programs since the breeding

    population in Point Reyes represents a sizeable proportion of the state

    population and since these animals migrate from unknown areas. Radio-tagging

    is the most reliable method for tracking-seal movements.

                                                                             26

                                PART B. SEA LIONS

                                 Harriet R. Huber

                                   INTRODUCTION

       A two-year survey of the California (Zalophus californianus) and

    northern (Steller) sea lion (Eumetopias jubatus) populations in the Point

    Reyes/Farallon Islands National Marine Sanctuary was initiated in March

    1982. This survey was designed to determine the size of the Point Reyes

    sea lion population, its breeding status, seasonal and diurnal fluctuations

    in haul-out patterns, and how the Pacific herring (Clupea pallasi) run in

    Tomales Bay affects sea lion numbers along the coast.

        Historical information on the Point Reyes sea lion population is

    sketchy, because identification of the two species was frequently confused

    during the 1800's. However, both species were present at the Farallones and

    at Seal Rock in San Francisco, and so presumably they were present at the

    Point Reyes Headlands as well. During the 1800's northern sea lions

    apparently bred on the Farallones and California sea lions hauled out

    in large numbers during the non-breeding season (Allen 1870, Scammon 1874,

    Allen 1880). In the early twentieth century, mostly northern sea lions

    occupied what is now Marine Sanctuary waters and only northern sea lions

    bred there (Everman 1921, Starks 1921, Rowley 1929).   California

    Department of Fish and Game censuses of breeding sea lions along the

    California coast between 1930 and 1970 (Bonnot 1937, Bonnot et al. 1938,

    Bureau of Marine Fisheries 1947, Bonnot and Ripley 1948, Carlisle and Alpin

                                                                              27

    1966, 1971, Frey and Alpin 1970, Ripley et al. 1962) and other censuses

    (Chan 1979, Dohl 1982, Mate 1977, BLM 1981) are summarized in Allen and

    Huber 1983, as are the results of the first year of this study (March 1982

    to February 1983). These articles describe fluctuations in numbers on the

    mainland in recent years.

                                      METHODS

        We censused California and northern sea lions at the Point Reyes

    Headlands (Figure 1) twice a month for the first year (March 1982-February

    1983) and weekly during the second year (March 1983-February 1984). During

    both breeding seasons we censused once a week, checking for evidence of

    births. One census each month lasted from 0700 h to 1800 h to assess sea

    lion haul-out patterns, to discover when maximum numbers haul out and to

    determine how seasonal, diurnal and tidal changes affect each species.

    Some censuses were incomplete because weather (fog, rain, high winds or

    heat waves) impeded the count.   We censused California sea lions  at

    Bodega Rock once a month during the first year and twice a month during the

    second year. During the herring run in Tomales Bay (December to March)

    we conducted censuses by boat of California sea lions in the water; nine

    occurred during the first year and five during in the second year.

        All counts of the Point Reyes Headlands were made from Sea Lion

    Overlook with a 25X spotting scope. In August 1982, a hidden cove

    containing up to 100 animals was found south of the main haul-out site; from

    then on we censused regularly from the antenna emplacement north of Sea

                                                                              28

    Lion Overlook. Descriptions of animals with distinctive scars or marks

    were recorded whenever seen. Weather and tidal conditions were also noted.

        Whenever possible, we separated both sea lion species into five age and

    sex classes: adult male, subadult male, female-size, immature, and pup.

    Adult males were defined as full-grown males with completely developed

    igital crests, sub-adult males were animals with the beginnings of a

    . ,iti] crest, female-size were large immature animals of either sex

    -i. nrtt evidence of sagital crest (this size also included adult females),

    immratures were small animals of either sex (yearlings and 2 year olds) and

    pup-. Tere pups of the year (May through December). These categories were

    fairly e.asy to distinguish among northern sea lions and all animals of this

    spcedi, described as female were indeed females. With California sea lions

    almost all female-size animals were, in fact, immature males. If we assume

    that sex ratios of animals hauled out at Point Reyes are similar to animals

    hauled out at the Farallones, then the number of females changed from

    virtually no females in the years prior to 1983 to a proportion of one

    female to every three males in 1983-84 in the female-size and smaller

    category. We compared mainland censuses with weekly sea lion censuses from

    the Farallones during the same time period.  Because of the difficulty in

    separating age classes when counting thousands of animals, California sea

    ioas on the Farallones were divided into only four age classes: male,

    female-size, immature, and pup. Males were defined as any animal with a

    .agital crest.

                                                                              29

                                      RESULTS

    California sea lions

       Major differences in the number of California sea lions present and the

    seasonal variation in age/sex classes occurred in all three areas during

    the second year of censusing (March 1983 to February 1984).

        The peak number of animals was 763 on 5 August 1983 at the Point Reyes

    Headlands (Table 11), 1530 on 31 October at Bodega Head (Table 12), and

    5570 on 28 July at the Farallones. These counts are all two to three times

    greater than peak numbers counted in the first year of the study. Up to

    116 Zalophus (95% of them immatures) were counted at Double Point between

    May and August 1983, another indication of increased numbers at Point

    Reyes. N'o California sea lions had been seen at Double Point during

    theprevious seven years (Allen, unpubl. data).

       At Bodega Rock the two years were similar with peaks during the spring

    and fall migration. Numbers during the second year, however, exhibited a

    third peak coincident with the Tomales Bay herring run (Figure 10). At the

    other two sites there was less similarity between years. The monthly mean

    number of California sea lions was significantly larger during the second

    year from May to August at Point Reyes (Mann-Whitney U-test p<0.05) and from

    July to September at the Farallones (Mann-Whitney U-test p<0.025).

       At Point Reyes and the Farallones, not only did the number of animals

    change between the two years but so did the yearly pattern. In the first

    year there were three peaks at Point Reyes: in March at the beginning of

                                                                             30

    the southward migration to the breeding rookeries, in early September

    during the northward migration, and in late December during the herring run

    in Tomales Bay (Figure 11). In 1983-84, there was one large peak from May

    to August which began during the southward migration and lasted through the

    period of the northward migration. This was followed by a much smaller peak

    coinciding with the herring run in late December (Figure 11). At the

    Farallones during 1982-83, there were two peaks, which corresponded to the

    spring and fall migrations (Figure 12). In 1983-84, a peak persisted through

    the breeding season when there is normally a decline in numbers (Figure

    12), similar to the situation at Point Reyes Headlands.

       In looking at the proportion of different age classes in the Point Reyes

    Zalophus population during 1982-83, we found adult males present in large

    numbers from Iarch through the first week of June, when numbers dropped

    dramatically. Numbers remained low during the summer breeding season

    except for a short peak in August. These peaks in the number of adult males

    coincided with migration to and from southern rookeries and is the same

    pattern we have found on the Farallones from 1972 to 1982. The pattern for

    adult males in 1983-84 was quite different. The southward migration peak

    began earlier (in March) and was essentially completed by mid-May. During

    the summer of 1983 the actual number of adult male California sea lions was

    three times larger than in 1982 but the proportion of adult males in the

    population dropped significantly from about 20% in 1982 to 10% in 1983

    (t-test, p<O.05)> This indicates that the increase in total numbers was

    due to a tremendous influx of immature animals rather than an equal

    increase in all age classes.

                                                                              31

        At the Farallones, where census results for adult and subadult males

    were combined into a single category, the changes are not quite as clear.

    The Farallon situation appears to be similar, however, for during the first

    year the highest monthly mean number of males and the highest proportion of

    males (over a third of the population) occurred during the same months, May

    and October. This indicates that peak numbers were the result of males stopping

    briefly at the Farallones during migration. In 1983-84, the highest

    monthly means were in June, July, and August, when adult males comprised

    only 12 to 14% of the population, again indicating that peak numbers in

    the summer of 1983 were due to higher numbers of immature animals.

        During censuses we noted the presence of up to 22 immature California

    sea lions tagged on the Channel Islands. Ten of these were tagged at San

    Miguel Island and 12 were tagged at San Nicolas Island.

    Northern sea lions

        The difference between 1983-84 and the previous year of study was not

    as distinct with the northern sea lions as with the California sea lions.

    The northern sea lion population is quite small at both Point Reyes and the

    Farallones, and the numbers remained essentially the same for the two

    years. The yearly patterns in both areas were similar: low numbers in

    fall and winter with a peak during the breeding season (Figure 13, Figure

    14). Maximum numbers reached 20 on 8 May at Point Reyes (Table 13) and 141

    on 2 June at the Farallones in 1983-84. When comparing the monthly mean

    numbers we found no significant differences between the two years in either

    area (Mann-Whitney U-test, p>0.05).

                                                                             32

       Patterns in occurrence of the various age and sex classes differed

    between years. At Point Reyes, in 1983 adult males arrived three weeks

    later and remained six weeks longer than in 1982 whereas subadult males

    arrived earlier and stayed into November. This was three months longer than

    in 1982, a "normal" year. Immature animals, seen throughout the

    year in 1982, disappeared in 1983 after the end of August. Adult females

    were present the entire year (Table 13). These changes at Point Reyes

    Headlands reflect similar changes on the Farallones.

       Two adult females, one adult male, and one subadult male northern sea

    lion recognizable by distinctive scars were seen on both Point Reyes and

    the Farallones.-

     All day watches

       Regardless of season, the sea lions exhibited a strong diurnal haul-out

    pattern, with low counts morning and evening and a sustained peak from 1100

    h to 1600 h (Table 14, Table 15). Two other factors affected numbers at

    Point Reyes as well: tidal and weather conditions. Lower numbers occurred

    when the haul-out area was reduced by high tides or large swells, as well

    as on calm hot days when sea lions frequently went into the water.

        No pupping or breeding was observed in either species in 1983-84 at Pt.

    Reyes.

    Tomales Bay

        During the winter herring run we censused California sea lions in

    Tomales Bay five times. A peak number of 37 Zalophus were seen on 20

                                                                              33

    January 1983. Few Zalophus were seen on other censuses. Five percent of

    all animals seen in December 1983 and January 1984 were adult males

    compared to 20% in the previous year.

                                    DISCUSS ION

        It was fortunate that this study took place between 1982-1984, for we

    were able to document some dramatic changes in the sea lion populations

    within the Point Reyes/Farallon Islands National Marine Sanctuary. The

    changes, which we attribute to the effects of warm waters associated with

    El Nino, include a remarkable three-fold increase in the California sea

    lion population and a shift in the haul out pattern of age and sex classes

    in both species.

        The warmer than usual water temperature measured at the Farallones

    (PRBO, unpublished) and throughout the northeast Pacific altered the

    distribution of fish species and reduced numbers and breeding success of

    marine birds and mammals in California (Heath and Francis 1983, DeLong

    pers. comm., Stewart pers. comm., PRBO unpubl.). Both California and

    northern sea lions are at the edge of their breeding ranges in the Point

    Reyes/Farallon Islands National Marine Sanctuary, therefore any unfavorable

    perturbation to food supply such as occurred during El Ni'ino, may have

    significant effect on local populations. California sea lions breed

    primarily south of Point Conception with major rookeries at San Miguel and

    San Nicolas Islands, California, and the islands off Baia California,

    Mexico; major breeding areas of northern sea lions are on the Aleutian and

                                                                              34

    Pribilof Islands in Alaska (Scheffer 1958). Both species have small

    breeding colonies on the Farallon Islands where up to 27 northern and up to

    3 California sea lion pups have been born each year since 1974 (Huber et

    al. 1985). Ten northern sea lion pups and 3 Zalophus pups were born in

    1983 on the Farallones. No cows of either species gave birth on the

    mainland in 1982 or 1983.

    California sea lions

        The population of California sea lions has increased throughout its

    range in the last 50 years; since 1960 the increase has been about 5% each

    year in California (DeMaster et al. 1982). In the past, only adult and

    subadult males migrated north, while adult females and juveniles

    remained near the southern rookeries (Bartholmew 1967)> A change in

    migration pattern was first noted at the Farallones in 1978 when large

    numbers of immature sea lions began to haul out in the fall. By 1981 the

    population at the Farallones had tripled. Ainley et al. (1981) proposed

    that the increase in numbers and in the proportion of immatures at the

    Farallones was due primarily to changes in the availability of Pacific

    whiting (Merluccius productus), a primary prey species, near the islands.

    The availability of whiting to sea lions increased dramatically when the

    foreign whiting fishery, which was competing directly with sea lions, was

    eliminated by the imposition of the 200 mile fishing limit in 1977.

    Unfortunately we do not have comparative censuses for the mainland sea lion

    population to see if similar changes occurred there.

        Changes in the Farallon California sea lion population from 1972 to

                                                                              35

    1984 are summarized in Figure 12. Prior to 1978 there was only one

    peak (in the spring) at the Farallones. Between 1978 and 1981 the number

    of Zalophus on the Farallones grew by 15 to 20% each year, a much higher

    rate than the rest of the state. This growth which was due primarily to

    immature animals created a second peak (in the fall). The remarkable

    increase that occurred during the 1983 breeding season was unprecedented,

    although the numbers for the rest of the 1983 were within normal ranges.

    Most of the summer increase in both areas was due to large numbers of one

    to four year old animals, the number of adult males increased to double the

    number seen the previous year.

        The population at Point Reyes (Figure 11) reflected the same trend that

    we saw on the Farallones 1982-84. During this time, Heath and Francis

    (1983) reported reduced numbers of breeding animals at the Channel

    Islands. Apparently many adult Zalophus remained in central California

    rather than migrating to southern rookeries during the El Nino summer of

    1983. We do not know for certain why so many immature sea lions

    congregated at the Farallones and Point Reyes, but we can speculate that it

    was likely the result of an altered distribution of prey.

        High numbers of California sea lions seen at Bodega Head and Point

    Reyes Headland during the 1983-84 winter were probably attracted to the

    herring spawn in Tomales Bay. That this peak was not recorded at Bodega

    Head in December 1982 (Figure 10) is probably due to the large winter

    swells which reduced available haul-out area during censuses.

                                                                              36

    Northern sea lions

       At Point Reyes, little change in the numbers of northern sea lions

    occurred between 1982-83 and 1983-84 despite great changes in the marine

    environment during the second year. The population on the mainland is

    quite small and as a result it was difficult to discover what effects, if

    any, El Nino had. In 1983-84, peak numbers of animals occurred in May,

    before the breeding season, whereas in 1982-83 the peak occurred in August,

    after the breeding season. Numbers during the rest of the year were

    similar (Figure 13).

        The mortality of northern sea lion pups born on the Farallones was

    higher in 1983 than at any time in the last 10 years but that may be

    related more to a problem of premature pupping in Eumetopias (Huber et al

    1984) than to the effects of El Nino. Although numbers during the

    breeding season in 1982-83 were higher than in 1983-84 (Figure 14), neither

    year was significantly different from the monthly means during 1972-81

    (t-test p>0.05).

         In fall 1983 the absence of immature northern sea lions and the

    extended attendance of subadult males at both coastal and off-shore sites

    may possibly be related to the El Nino conditions and their effect on prey

    availability.

        We suspect that sea lion populations within the Sanctuary will return

    to pre-1983 numbers and age-class ratios after the widespread residual

    effects of El Nino recede.

                                                                              37

                                      SUMM4ARY

    1. The California sea lion population hauling out at mainland sites in the

    Point Reyes/Farallon Islands 'National Marine Sanctuary is comprised

    primarily of migrating animals. Numbers peaked at 338 in 1982-83 and at

    1530 in 1983-84 at the Point Reyes Headlands. The northern sea lion

    population reached a maximum of 20 animals at Point Reyes. There is some

    interchange of animals between the Farallon and Point Reyes populations.

     2. Neither species gave birth nor bred at Point Reyes from 1982-84. On

    the Farallones up to three California sea lion pups and up to 27 northern

    sea lion pups have been born each year since 1974.

     3. Peak numbers of Zalophus occurred during the southern spring

    migration and northern fall migration to and from breeding rookeries in

    southern California and Mexico. The population peak of Eumetopias occurred

    during the summer breeding season.

     4. Maximum numbers of both species hauled out between 1100 h to 1600 h.

    Where high tides and large swells decreased the haul out area, the highest

    numbers were counted when low tides occurred at mid-day. Numbers decreased

    on hot, calm days when many animals went into the water.

     5. A peak in California sea lions on the coast in December corresponded

    to the herring run in Tomales Bay. A winter peak was not observed at the

    Farallones.

     6. Numbers of California sea lions within the Sanctuary were greatly

    inflated during 1983-84, due to an influx of immature animals. This was

    probably related to the warm waters of El Nino; "normal" numbers are

    probably closer to the results of censuses in 1982-83.

                                                                             38

                                 ACKNOWLEDGEMENTS

        This study was made possible under the auspices of the Sanctuary

    Programs Office of the National Oceanic and Atmospheric Administration, the

    National Park Service, the Marin County Department of Parks and Recreation,

    the Point Reyes Bird Observatory, and D. Miller. F. and R. Allen, C.

    Connors, C. Cutler, C. Depkin, J. Evens, L. Fry, C. Poulsen, S. Peaslee, A.

    Rovetta, D. Shuford, B. Stewart, S. Trivelpiece, and J. Young all spent

    long hours in the field, often under adverse weather conditions, collecting

    the information on which this report is based. D. Miller and D. Hanan of

    the California Department of Fish and Game, generously offered advice and

    information from CDFG aerial surveys. L. Amaya and M. Webber of the

    California Marine Mammal Center kindly provided us with information on the

    recovery and release of harbor seals in the region. D. DeMaster and C.

    Ribic gave guidance and assistance in the analysis of data from Double

    Point. E. Tuomi and S. Goldhaber greatly assisted in the preparation of

    this manuscript. Finally we are most grateful to D. Ainley of the Point

    Reyes Bird Obsevatory, and P. Gogan and G. Fellers of the Point

    Reyes/Farallon Islands National Marine Sanctuary for advice and

    encouragement. This is Point Reyes Bird Observatory Contribution number

    283.

                                                                              39

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    Ainley, H. R. Huber, and K. M. Bailey. 1981. Population fluctuations of
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    Allen, J. A. 1870. The eared seals (Otariadae), with detailed
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           .  1880.  History of the North American pinnipeds.  A monograph
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    Allen, S. G. 1980. Notes on the births and deaths of harbor seal pups at
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            1985.   Mating  behavior  in  the harbor seal.  J. Marine
         Mammal Science. 1:84-87.

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    Bartholomew, G.  1967.  Seal and sea lion populations of the California
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    Bonnot, P., G. H. Clark, and S. R. Hatton. 1938. California sea lion
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                                                                              40

    Boulva, J. and 1. A. McLaren. 1979. Biology of the harbor seal, Phoca
        vitulina, in eastern Canada. Fish. Res. Board, Can. Bulletin no.
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    Brown, R. F. and B. R. Mate. 1983. Abundance, movements, and feeding
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    Bureau of Marine Fisheries. 1947. California sea lion census for 1946.
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    Carlisle, J. G. and J. A. Alpin. 1966. Sea lion census for 1965 including
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         and J. A. Alpin. 1971.  Sea lion census for 1970 including counts off
          other California pinnipeds. Calif. Fish Game. 57:124-126.

    Caughley, G. 1977. Analysis of vertebrate populations. John Wiley and
           Sons, New York� 232 pp.

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          Headland and Bird Rock ASBS. Report to the California Department of
          Fish and Game and the State Water Resource Control Board. Report
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    Dohl, T. P., M. L. Bonnell, R. C. Guess and K. T. Briggs. 1982. Marine
         mammal and seabird study of central and northern California. POCS
          Technical Paper no. 82-1.  BLUI -YN-P/T-82-001-1792.  210pp.

    Everitt, R. D. and S. J. Jefferies.  1979.  Marine Mammal investigations
          in Washington State.  Abstract only in: Proceedings of the Third
         Conf. of the Biology of Marine Mammals.  Oct. 7-11, 1979.  Seattle,
          WA.

    Everman, B. W.  1921.  The Aio Nuevo Steller sea lion rookery.  J. Mamml.
          2:16-19.

    Fancher, L. 1979. The distribution, population dynamics, and behavior of
          the harbor seal, Phoca vitulina richardi, in south San
          Francisco Bay, California. Ms. thesis. California State University,
          Hayward, Ca. 109pp.

    Fienberg, S. E. 1981. The Analysis of Cross-classified Categorical Data.
          2nd ed. The MIT Press, Cambridge, Mass.

    Frey, H. W., and J. A. Alpin. 1970. Sea lion census for 1969, including
          counts of other pinnipeds. Calif. Fish and Game. 56:130-133.

    Hanan, D. A. 1985. California Department of Fish and Game coastal marine

                                                                               41

         mammal study, annual report for the period July 1, 1982 - June 30,
          1983. Dept. of Commerce, NMFS Adminst. Rpt. no. LJ-85-10C.

    Heath, C. B., and J. N. Francis. 1984. The California sea lion
         population on San Nicolas Island during the 1983 E1 Nino year. The
          IX Internatl. Reunion of the Mexican Soc. for the Study of Marine
         Mammals. March 29-31, 1984. La Paz, Baja California, Mexico.

    Huber, H. R., D. Skilling, R. Risebrough, and A. Smith. 1984. Premature
         pupping in northern sea lions on the Farallon Islands. Final Report
         to the U. S. Dept. of Commerce, NOAA, Sanctuary Programs Office.
         2Opp.

    Huber, H. R., C. Beckham, J. Nisbet, A. Rovetta, and J. Nusbaum. 1985.
         Studies of marine mammals at the Farallon Islands 1982-1983.   U. S.
        Dept. of Commerce, National Marine Fisheries Service. Rpt. No.
         LJ-85-OlC

    Knudtson, P. 1975. Observations on the breeding behavior of the harbor
          seal, in Humboldt Bay, California. Calif. Fish & Game. 63:66-70.

    Mate, B. R. 1977. Aerial censusing of pinnipeds in the eastern Pacific
          for assessment of population numbers, migratory distributions, rookery
          stability, breeding effort, and recruitment. N.T.I.S. no. PB-265 859.
          67pp.

    Miller, D. J. 1983. Coastal marine mammal study, annual report for the
          period of July 1, 1981 - June 30, 1982. U. S. Dept. of Commerce,
          National Marine Fisheries Service. Rpt. No. LJ-83-21C.

    Naito, Y. and S. Konno. 1979. The post-breeding distributions of
          ice-breeding harbor seals, Phoca vitulina and Ribbon seal,
          Phoca fasciata, in the southern sea of Okhotsk. Sci. Rep.
         Whales Res. Inst., 31:105-119.

    Ripley, W. E., K. W. Cox, and J. L. Baxter. 1962. California sea lion
          census for 1958, 1960, 1961. Calif. Fish and Game. 48:228-231.

    Risebrough, R. W., D. Alcorn, S. G. Allen, V. C. Alderlini, L. Booren, R.
          L. DeLong, L. E. Fancher, R. E. Jones, S. M. McGinnis and T. T.
          Schmidt. 1978. Population biology of harbor seals in San Francisco
          Bay. N.T.I.S. No. PB-81-107963.

    Rowley, J. 1929. Life history of the sea lions on the California coast.
         J. Mammal.  10:1-36.

    Scammon, C. M. 1874. The marine mammals of the northwestern coast of
          North America. Dover Publications, New York. 319 pp.

                                                                              42

    Scheffer, V. B. 1958. Seals, sea lions and walruses. Stanford Univ.
         Press, Stanford, Calif.

    Siniff, D. B., D. P. DeMaster, and R. J. Hlofman. 1977. An analysis of the
         dynamics of a Weddell seal population. Ecol. Monographs
         47:319-355.

    Slater, L. M. and H. Markowitz. 1983. Spring population trends in Phoca
         vitulina richardi in two central California coastal populations.
         Calif. Fish & Game. 69:217-226.

    Snedecor, G. W. and W. G. Cochran. 1967. Statistical Methods, 6th ed.
          Iowa State College Press, Ames, Iowa. 593 pp.

    Starks, E. Co. 1921. Notes on sea lions. Calif. Fish and Game.
         7:250-253.

    Stewart, B. S. 1984. Diurnal hauling patterns of harbor seals at San
         Miguel Island, California.  J. Wildl. Manage.  48:1459-1461.

                                                                            43

    Table 1. Harbor seal counts for all sites in the Point Reyes region for 1983-84. Census days during which disturbance

              occurred are noted with an asterisk. Numbers following a slash indicate pups.

                                                                        LOCATION

              Bodega  Tomales  Hog       Bird    Tomales   Point   Drakes    Limant.   Double   Duxbury   Bolinas   Total
    DATE       Rock      Bay   Island   Rock       Point    Reyes   Estero        Spit      Point     Reef      Lagoon      Pups  Totals

    1983
    March  9            146      54      123      123        92      363           0       273          99       64                1337
          25            148*    25*    162/1    252         179     414            0      404          41        76          1    1701
          31    47
    April  7    12      202/2*   0*    102/1    165          71      209*          0       313/22      101        67/1      26    1242
          21    30      189/11*  0      164/13   196/14    92/1   334/19          0       634/128      67        65/3      189    1771
           2/3                          142        56                                     104*
           9/10         148/3*   0      163/1    120                322*          0       387/33
          16/17         105/3*   0       55/7*                      168/4*        0       250/65
          21                                                                              595/144*
          23/24                         189/18                      485/36*       0       634/107*
          30/1                          193/29*                                           623/167
    May    6            275/45   0       229/42   285/78    25       461/104    141/8    820/241   116         97/17      527      2449
          20            169/34*  0      161/48   171/48    fog    218/62*        fog      551/157   122/3    70/10        362     1462
           7/8          156/24*         207/38*                     480/102*   176/20   716/226*
          12    25
          14/15          89/19*         159/48*                     370/90      122/16   267/118*
          21/22 16      152/5*          204/38                      249/71*    238/25*  567/173*
          28/29         148/23*         161/17*                      83/7*      362/28   335
    June   3              84/2*   0      137/12    70/16    69/1    71/3         340/14   463/48    166/3    67/3         102      1467
          16             93/2*   0      229/6*    74/2       50     354/8       150/10   455/103   100/2*   95/2*         135     1600
          30              --      -     269/14   122/3       74/1   270/3       350       438/91      85/3   136          115     1894
          4/5                                                        69/3*      345/6
          17    15
          18/19                                                                           583/20
          25/26         158*            132/13
          30    44

                                                                             44

            Bodega   Tomales   Hog    Bird    Tomales   Point   Drakes   Limant.   Double   Duxbury   Bolinas   Total
    DATE     Rock       Bay   island   Rock       Point    Reyes   Estero        Spit     Point      Reef      Lagoon    Pups    Totals

    1983 (cont'd)
    July   5             74       0      336      255        68      516         115      747         61      151                  2323
          18             93      0      315       265        45     422         150       316        118     174                  1898
          16/17          89*            215
          19    50
          22                                                        410
          30/31                                                     305*        250       353
    Aug    1    22        54*     0      232      131        60      324         207      301        138      122                  1591
          15            168      0      fog       fog       fog     362           0        51        fog      80                   661
          29/30         241      0       33        74        35     310          63        13         0      102                   871
           6/7                          215
          13/14         268*                                                               77*
          17    30
          27/28         213              41*                        380
          31     2
    Sept   9            --       --       19       84        16      240           0      155         92       54                   660
          19            134      0      fog        81        46     298          45        50        270       70                  994
           3/4
           6    21
          18    14*
          24/25                          26*                        252*         74
    Oct    3            113       0      48       167        65      322           0       34        .220     102                  1071
          17            122      0       38        47        58     137           0        33        254      85                   774
          15/16                                                                          32
          22/23 15       95*                                                                                   60*
          29/30  35                                                 141          40
    Nov    2               93      0*      51        15       113    415            0         0       235      107                  1029
          16             136      0       64       163         84    198          48         1         87       74                  855
           5/6                            49
          15     47
          26/27                                                      246*         59
          29     31

                                                                           45

              Bodega  Tomales Hog      Bird   Tomales   Point   Drakes    Limant.  Double   Duxbury   Bolinas   Total
    DATE       Rock     Bay   Island   Rock    Point    Reyes   Estero      Spit      Point    Reef     Lagoon     Pups    Totals
    m ret none mmmmmmmm mmmmmmmmm mn mminmmmmm mmmhnmmmmmmmiiqm mm Nmmmm mmmmmmrflmmmmmmuiimmmliqmmmmm mmmm m mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm mmm mmmm mmmmwimp   mm mmm    m mm   1
    1983 (cont'd)
    Dec    1             --      --     30        67         5    243          15      136        79      46                  621
          15            135      0      46      143       fog    248          24      244        100      38                 978
          29            150      0      46       59       fog    250          25      283*       104      38                 955
           3/4                          48                                            142
          17/18         118*
          20     11
          27    49
          28                                                                          348*
          31                            71*                       368          0      281
    1984
    Jan   12           105*     250     63      129        29     313           0      267        45        2               1203
          26           226*       0     50      100       70      321          0      285*        76       26               1154
          14/15                         56*
          17                                              57
          21/22
          23     35
          28/29                                                   387/1*       0       32*                            1
          31                                              66
    Feb   10           195        0     78      192        83     363         13       395       106       73               1498
          24           202        0     60       93       34      286          0      237         91       38               1041
           3                                                      206
           8                                             100
          11/12        188*
          16    54
          18/19
          23           331        0
          25/26                         63                        250*                303
          28     41
    Mar   17           195        0
          25           100        0

                                                                             46

    Table 2.  The average number of harbor seals hauled out by season during censuses in the

               Point Reyes area in 1983-84; x is the mean number of seals, SE is the standard

               error, and n is the sample size.  Tomales Bay includes Hog Island, Tomales Point

               includes Bird Rock, and Drakes Estero includes Limantour Estero.

    rn mm mm irn mm m mmmmnmmnrra TI~ mm in mm m m in mmmminmin m mm in inmm mmmmm mm mm in mmm mmin mmm mm mm m mm mmmin min mmm mmmm In111 Ill 711Th n lni m nmnin I

                                                            LOCATION

                  Tomales     Tomales   Point   Drakes      Double   Duxbury   Bolinas         All
                    Bay        Point    Reyes   Estero       Point     Reef     Lagoon        Sites
    mm~ mm m mmmn~ mmNITT nm nn mm mm   mm   n inmmmnmT 11Th mmm mm mm mmmmm mm mm mmii  inmuum mm in in miii mm TnMn n innnnnnminini in 711 WTh mii i iimi i 1 11 11NTT1iATHNnTh ii  n mii mmuiininT T1 T ilThni

    Breeding
       x           155.7      337.1     81.5    420.2        501.9    99.7       81.9       1653.4
       SE           12.3       31.6     15.9     34.3         32.8    11.7        8.0        121.0
       n            16          9        8        17          30        9         9            9
       range       84-275    207-514   25-179  168-656      104-832   41-166    64-136     1230-2449

    Summer
       x           138.7      265.6     49.1    393.1        174.3    144.1    100.0        1270.1
       SE           19.9       77.4      6.2      41.0        53.7      34.0     12.4        210.6
       n            12          8        8        14          14         8       10            8
       range       54-268     81-591    16-68  181-631       13-747    61-270   54-174      661-2323

    Winter
       x           193.5      161.0     64.1    304.6        215.8     101.2     49.1       1089.1
       SE           84.0       21.9     10.6     16.1         32.2      17.7     11.0         70.1
       n            11          9       10        14          15         9        9            8
       range       93-355     66-270    5-113  206-415        0-395    44-235    2-107      855-1498

                                                                          47

    Table 3. Maximum number of harbor seal pups counted at each haul-out site

              by month in 1982 and 1983.

                                              LOCATION

                  Tomales   Tomales        Point      Drakes      Double      Bolinas
    Date             Bay      Point         Reyes      Estero      Point        Lagoon

    1982
       April         22         19             1        101         262           0
      May           58        135           19         170         263          17
       June          23         54           18          60          90           4

    1983
      April         11         29             1         36         186           3
       May           45       120              0        122         262          17
       June           2        28              1         18         103.          3

                                                                            48

    Table 4, The hourly presence of harbor seals at primary locations in the Point Reyes area

               on June 16, 1983. Low tide was -.7' at 1032 hr, and high tide was 5.2' at 1803

               hr. An asterisk (*) indicates disturbance.

                                                                HOUR
                       i nmmmii n mm i mm mmm in n mm i miimin in mm   imn  mnmi irn in inmm ininmim  mnin in ininin m m in in  nn mm  mm   i in mm mm in i
      LOCATION        0700   0800   0900   1000   1100   1200   1300   1400   1500  1600   1700   1800

    in m nmm mn mm mini inw    l tn i mm m minm inrm   mmmninin  n immni   Tn in  n  T i  n ininn in n mmmm  inm i nnn in mm n in n ininnnirnmian imm

    Tomales Bay        91    93      77*    72*    64      81     82     85     77          70    --  --

    Bird Rock         133    169     72*   108    173    146    200    234    212   159    148    165

    Drakes Estero     151    274    343    370    430    504    491    332    316   218      39      30

    Double Point      275    318    325    330    348    375    408    434    455   426    397    212

    Duxbury Reef       84     93     95    100      82     54    95      14      0     0       0      0

    Bolinas Lagoon     51     65     76    88       91     95     86     87     80    59     43      11

    TOTALS            785   1012    988   1068   1188   1255   1362   1186   1140   932    627    418

    .mi. mm.n.mimn.n mm. mm mm mmm.mmm.im.mmiin.min imi mimmimmm nnni..................       m im mmmmi7n mm  mm   rm in i

                                                                       49

    Table 5. Freeman-Tukey deviates (FT) for the deviation of the observed from

              the expected for a log-linear model of independence of year, seal

              location, and seal reproductive status. The numbers given are the

              total number of seals counted for each zone during each season.

                                          Coastal           Estuary

            1982
              Breeding                       9299               7213
                F-T                         -1.67               1.93
              Non-breeding                   7957               7592
                F-T                          1.83              -1.85

            1983
              Breeding                       8934               5947
                F-T                          1.73              -2.09*
              Non-Breeding                   9275               8938
                F-T                         -1.68               1.73

              *F-T deviate is significant at    = 0.05.

                                                                          50

    Table 6.  The average monthly number of harbor seals hauled out at Double Point from 1976 to 1984

              for adults, subadults, and all age classes combined. Only those censuses when immatures

              were distinguished were included in the sample; x is the mean number of seals, SE is the

              standard error, and n is the sample size.

    in mm mmm mmmm mm mmmmnmmmmm mmmnmrmnmmmmmmm mmmm mm in n inminininmmm      inmin in il inrin inninrmm in inininin mm mmin mm ini

                                                         MONTII

                        J      F      M      A      M       J      J      A      S      0       N      D

            n         13     15     25      51     52     28     20     15      12     12      9     16

    All Age Classes
            x        128.2  252.2  239.0  372.8  517.9  413.3  397.2  143.6  123.3   82.2   32.7  151.9
            SE        26.4   25.4   16.7   25.8   24.4   36.4   29.3   17.2   21.5   21.1    5.2   27.0

    Adults
            x         99.5  204.9  191.9  241.5  304.7  304.3  317.2   97.6   76.7   50.2   22.7  110.5
            SE        21.9   21.9   12.7   16.0   16.3   29.6   24.7   15.1   16.9   14.8    5.4   22.3

    Subadults
            x         22.8   41.8   41.5   36.0   36.0   52.5   40.6   19.3   31.4   17.3    4.6   31.6
            SE         7.4    6.8    5.4    4.2    3.2    8.8    6.6    3.6    6.4    7.8    1.3    7.0

    % Subadult to Total
                       17.8   16.6   17.4    9.7    7.0   12.7   10.2   13.4   25.5   21.1   14.1   20.8

    % Adult to Total
                       77.6   81.3   80.3   64.8   58.8   73.6   79.9   68.0   62.2   61.1   69.4   72.8

    .m.....m...m..lm.................nl................n. ..nlwnlTH.rdTHTT.edt rm bT..w.wnlttwlvwbw.n, pllTRRWT.lT.w.lwR.llt...lU.t.tjlll. .......i...............

                                                                        51

    Table 7. The average percentage of sex and age classes of harbor seals at

              Double Point during the early, middle, and late periods of

              the breeding season, 1984; x is the mean percent of each class,

              SD is the standard deviation, and n is the sample size.

                                               CATEGORY

                     Males    Females    Females w/pups    Subadults           Pups

    EARLY     x        29.8      32.6            7.6             26.6           10.2
     n = 6    SD        5.5       2.2            9.0              6.5            9.2

    MIDDLE    x        12.8      37.9           32.7             10.0           39.3
     n = 7    SD        3.9       3.9            4.2              2.1            6.2

    LATE      x        11.9      37.9           25.3             16.9           32.9
     n = 5    SD        3.9       4.0           10.6              8.5            7.2

                                                                         52

    Table 8. The yearly changes in abundance at Double Point during

              the breeding season, 1976 to 1984; i is the average number

              of seals censused for the season and n is the sample size.

              Rate of increase is calculated from -&  =  N t+l

                                                             t

              Year                   n         x         Rate of Increase

              1976                  14       195.2

              1977                  30       304.5              1.6

              1978                  19       330.1              1.1

              1979                  10       287.7              0.9

              1980                   5       318.0              1.1

              1981                  13       383.8              1.2

              1982                  33       525.1              1.4

              1983                  29       512.7              1.0

              1984                  22       578.3              1.1

                                                                       53

    Table 9. The daily variability in the number of seals hauled out at

              Double Point and Bolinas Lagoon during the breeding season,

              the molt (July), and the end of molt (August).

              CV = coefficient of variation. All censuses were taken

              from 1200-1300 hrs and 1-3 hrs after low tide.

                            Breeding           Molt            Molt end
                               CV               CV                CV

    Double Point                .18              .07                 .45

    Bolinas Lagoon              .44              .24                 .30

                                                                        54

    Table 10. Summary of pupping success of known female harbor seals at Double

               Point first identified in 1977 or 1982 and observed over the next

               two years (Siniff et al. 1977). x is the average for the two

               three-year sets.

                                                              YEAR

    PARAMIETER                              77   78   79       82   83   84       x
    nmmmTHmmmmnnTmmmilm"rminmotmonmmnammmnnim nminmimmnnmm mmnmmmmmminiimmmzmm

    Females seen with pup                   14   14   14       16   15   11

    Females seen without pup                 2    2    1        2    1    3

    Females not seen in given year          --    0    1       --    2    4

        TOTAL                               16   16   16       18   18   18

    Proportion of total with pup            .88  .88  .88     .89  .83  .61      .83

    Proportion of those seen in
        given year that had pup            .88  .88  .93      .89  .94  .79      .89

    Proportion not seen in given
        year                                --   0   .06       --  .11  .22      .10

    nn mmmnm T immm m mnmnnmmm i mmn imm in i  mm mm imm mm i i  nNmi nn mMTn Mmnmim"ninT

                                                                                   55

    Table 11. Maximum counts of California sea lions at Pt. Reyes Headlands,
                1983-84.

    ________________________________________________________________________________
                             Adult    Subadult    Female
    Date            Total    Male         Male        Size      Immature  Unidentified
    _______________________________________________________________________________
    1983

    Mar  5           188        72         46          56           14
        11           201      101         46          44             9
        20           150        62        38          34           16
        31           112        68        25          15             4

    Apr  7           103        44         22          14           23
        12            88        14        56            9            6
        23           211        70        45          39            17         45

    May  8           547        20        121         100           16         290
        12           662      119        104         265           35         150
        18           569      114        156         227            57        128
        24           485       120       107         110            13          38

    Jun  1           587       150        148         116          130          43
         8           584       36        172          38          110         264
        23           164         2        16           78          68
        27           428        19         13          75         271           50

    Jul 15           389        28         41          46          186          88
        22           412        25        45           68         226          48
        28           499        40        31           79         310          39

    Aug  5           763        52         98         191           96         326
        11           595        23       117         206          112          57
        19           523        27       103         174            76        143
        26           460        13       123         191            38         95

    Sep  6           190        15         15          51           47          12
        12           420        35        29          69          104         183
        23           417        28       108         165            72          44
        27           489        27       104         286            45          27

    Oct  6           316        18         44         151           31          72
        14           368       86         38         116            51         77
        19           207         7        28         112            18         42
        26           176         7        43         111            15

    Nov  5           128        42         37          30           19
        15           105        27        39          23            16
        21            61        22         21          12            6

                                                                                    56

    Table 11i (cont'd)

                             Adult    Subadult    Female
    Date            Total    Male         Male        Size      Immature  Unidentified

    1983 (cont'd)

    Dec  5           103        30         29          36             8
        15           321       153         97          62            9
        20           262        49         74         126           13
        27           180       106         46          17           11

    1984

    Jan  2           228       116         40           58           14
        13            18        15          2           1
        18           110        67         20          14            9
        26            81        51         10          13            7

    Feb  1           204        79         30          48            49
        14           239        86         30          85           38
        23           304       159         69          47           29

                                                                                  57

    Table 12. Maximum counts of California sea lions at Bodega Rock, 1983-84.

    Date                  Total           Adult Males         Unidentified

    1983
    Mar  3                 198                 14                  184

    Apr  7                   84                 4                   80
        21                  13                  3                   10

    May 12                  529                 8                  521
        22                 427                19                   408

    Jun 17                   71                 9                   62
        30                  21                                      21

    Jul 19                 100                 11                   89

    Aug  1                  420                32                  388
        17                 707                15                   692
        31                 781                24                   734

    Sep  6                 864                 26                  838
        18                 685                15                   670

    Oct 22                1270                                    1270
        31                1530                                    1530

    Nov 15                 820
        29                 635

    Dec 20                1295
        27                1100

    1984
    Jan 23                 421                                     421

    Feb 16                 684                 10                  674
        28                 275                                     275

    Mar 21                  135                                    135

                                                                                       58

    Table 13. Maximum counts of northern sea lions at Pt. Reyes Headlands,
                1983-84.

                                 Adult       Subadult        Female
    Date             Total       Male           Male           Size        Immature

    1983
    Mar  5             3                          2              1
        11            5                           1             4
        20            4                           1             3
        31            3                                         3

    Apr  7             3                          1              1              1
        12            1                           0             1              0
        23            4                           2             2              0
        30            3                           2              1             0

    May  8            20            2              7             7              4
        12           19            5              9             5              0
        18           17            2              6              5             4
        24           19            2              6              6             5

    Jun  1            11            4             1              1              5
         8            9            1              1             4              3
        23            9            0              3              4             1
        27           16            3              3              7             3

    Jul  7            13            2             3              6              2
        15           10            0              3              4             3
        22           13            1              2              5             5
        28           11            1              1              7             2

    Aug  5            13            1              3             7              2
        11            8            1              2              5             0
        19            9            0              3              5             1
        26            8            1              3              4             0

    Sep  6             3                                         3
        12            2                                          2
        23            7                           4             3
        27           14                           4              9

    Oct  6             6                          2              4
         14            4                           2             2
         19            1                           1
         26           10            1              1             8

    Nov  3             1                                         1
          5            2                                         2
         15            2                                         2
         21            4                                          1

                                                                                   59

    Table 13.  (cont'd)

                               Adult       Subadult       Female
    Date            Total      Male          Male           Size        Immature

    1983 (cont'd)

    Dec  5            2                                       2
        15            4                                      4
        20            5                        2             3
        27            2                                      2

    1984

    Jan  2            2                                       2
        13            1                                      1
        18            2                                      2
        26            3                                       3

    Feb  1            5                         1             4
        14            7          1             1             5
        23            5                         1

                                                                                  60

    Table 14. Hourly counts of California sea lions at Pt. Reyes Headlands,
               1982-83 and 1983--84.

                           1982-83                           1983-84

                        x     S.D.    n                  x      S.D.    n

    0700                59.0   17.4    4                 66.7    40.6    4

    0800                67.2   61.8    9               176.6   160.1   11

    0900                91.5   71.6   11               199.4   177.8   12

    1000                94.6   72.8   12               216.4   181.4   12

    1100              116.5   70.6   13                229.9   156.3   12

    1200              121.3   60.5   13                256.0   171.1   12

    1300              115.5   66.4   12                260.3   166.1   12

    1400              104.4   65.6   13                267.6   184.4   12

    1500              102.9   67.4   10                270.1   177.7   11

    1600              102.1   71.9    8                248.4   176.1   12

    1700                75.4   21.8    7               208.3   179.9    9

    1800                69.2   18.5    6               239.6   162.5    5

                                                                             61

    Table 15. Hourly counts of northern sea lions at Pt. Reyes Headlands,
               1982-83 and 1983-84.

                            1982-83                        1983-84

                       x     S.D.    n                x     S.D.    n

    0700               1.0    0.0     3               2.2    2.6     4

    0800               3.3    2.1     6               3.1    3.4     9

    0900               4.1    2.9     8               3.5    5.0   12

    1000               6.4    4.8     9               4.0    5.2   12

    1100               7.7    3.9     9               4.5    5.1   12

    1200               7.5    5.2    10               4.3    4.4   12

    1300               7.8    5.6    10               4.4    5.3   12

    1400               7.0    4.8    10               4.3    5.4   12

    1500               7.3    5.9     9               4.5    5.2    10

    1600               7.3    5.7     7               4.4    5.8    10

    1700               5.6    4.8     6               3.0    5.0     9

    1800               5.2    4.1     6               3.2    4.1     5

    _______________________________________________________________________

    FIGURE I

    20'

                     Bodegaa

                     Tomnales Point-,

                        Tomnales Bay

                      Drake's Ester

                    Point Reyes-
        38000        ~Headland~

                             Limantor Estero
                                          Double Point-.

                                               Duxbury Reef
                                                      Bolinos Logoon

    50)

                                                                     San Francisco

                     Farallon
                         Islands
            4d~~~~~~~~~~'

                                                   Approximate scaie, miles
                                              5         0         5          10

                    lo, 1123000                          5d 01

            FIGURE 2

           MAXIMUM NUMBER OF HARBOR SEALS BY MONTH

                         POINT REYES,  1983-84
      All Age Clado   Pup.

         am

         200
           -

           - 0

                N _   _,  J           \ A   2   0   v   0          F
                                    MONTH

    X                                     \                     /

            1000   .   ..-.                %..-..-   ~  ~  ~
    .<

           mm

           m-    VI I         ,
              m    J ^ | O
                 ~= = ~ ~~~~OT

     FIGURE 3                                                          FGR

    Monthly Mean Number of Harbor  Seals  1982-84                     Monthly  Mean Number of Harbor Seals  1gB2-84
                           Tomales Bay                                                      Tomales Point

                                                                              m..

                  C.                                               ~~~~~~~~~~C.

    *                                                               I)     -
    n~~~�tII44& ���!
        *~~~~~~~~ot                                                6ot

       -                                                                mm.

                  C                                                ~~~~~~~~~~~~C

    *                                                               I2~~~~
                                                                           m m..

                              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~I I  I  I  I  I I  I I  I I  I
              P    W   �   � U     J   �2  �  � S     �                        J   �a  J m  �  g  j       � �   S   �  *
                                Month                                                             Month
        F~IGR  5                                                        FIGRE

       FIGURE 7                                              FIGURE 8

       Monthly Mean Number of Harbor Seals 1982-84          Monthly Mean Number of Harbor Seals 1982-84
                         Ouxbury Reef                                        Bolinas Lagoon

         1                                                                           _    __1
                                                          =                      ,                          i~~~~~~~~~~~~~~~~~~~~~~~

                       .~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~C

      i                                                  C
                                                               L
                                                               0

                   a                          X            a~~~~~~~~

         �  I                            I I  I  I  I  I  I  I  I  I I  e_ I I     I  I I  I
             d     , a   *        � d  d   U *  S #  *            d  P     a  a   d  J  a  a  g  *
                              Month                                                Month
       FIGURE 9
       Monthly Mean Number of Harbor Seals 1976-84
                         Double Point

    L
    m
        -
    Z
        c~~
        - _.

          m    ,    ,  . I  .  . � *    . *  ,
         a  l'm   I    I  I    I  '''tonth
               �      a  a         d &  � a  a  a
                              Month

    FIGURE 1o

       MONTHLY MEAN NUMBER OF CALIFORNIA SEA LIONS
                        AT BODEGA ROCK

    1        10 0
    t.   lZOO_                               ,, \

           <0I                                 \,/   \

    I 1

        2wI
    Z                  /
                          Z / \/ '

             0o~~~~~~~  I   I     I   I   ! \
            ONR  APR my  f   L  A    P  OCt  WOV MC  JAM  FM
                             MONTHS

    FIGURE 11 ,
       MONTHLY MEAN NUMBER OF CALIFORNIA SEA LIONS
                          AT POINT REYES

                              fA
                    m,?     ,/  '\

    U. I
                   /

    LL                        ,, /           \
                  I                  \
        20          I0
                 I
    Z~m,    I
        SW -

             A   am  MAY  m   nl    AUM EP OCT m    C    JAm    FEn
                              MONTHS

    FIGURE 12

       MONTHLY MEAN NUMBER OF CALIFORNIA SEA LIONS
                          AT THE FARALLONES
      11172-77   1978-81    19g2-83   1J93-S4

        5000

    LL
    O

    W

    m    0   ANJ

              AR      AY   N   L  Al  EP  OCT  HV  DEC  JAN  FEB
                                 MONTHS

    FIGURE 13

        MONTHLY MEAN NUMBER OF NORTHERN SEA LIONS
                          AT POINT REYES
      1l92-99   13-94

         20

    UI--

    LLt              /

                               MONTHS
                               MONTHS

    FIGURE 14
        MONTHLY  MEAN  NUMBER  OF  NORTHERN  SEA  LIONS
                        AT THE FARALLONES
      1X72-81    1082-83     1983-84

        20D

    z
    Z/

    LL

    ,. ..  '..,,...

         o    I   I   I    I   I   I   'I  I         I   I J
             MAR  APR  MAY  JU  .  AUG  SP  ocT  NoV     J ^N  DCMN
                               MONTHS

                                                                                  71
           Appendix 1.

    Table 2.    The average number of harbor seals hauled out by season during

                 simultaneous censuses in the Point Reyes/Farallon Islands

                 Marine Sanctuary in 1982 - 83; x is the mean number of seals,

                 SE is the standard error, and n is the sample size. Tomales Bay

                 includes Rog Island, Tomales Point includes Bird Rock, and Drakes

                 Estero includes Limantour Spit.

                                                    LOCATION

                  Tomales   Tomales   Point   Drakes   Double   Duxbury   3olinas             A.ll
                   Bay        Point    Reyes   Estero   Point         Reef       Lagoon      Sites

    Breeding

       :x         213.0      376.2       104.5   436.7    517.5        82.6       73.8       1839.4
       SE          13.3       50.8        16.8    25.3      30.6        9.5        9.6        150.1
       n           10          10         10       30        33        10         10           10
       range    149-285   151-563    44-232 116-726  228-851   19-109    30-126

    Smmer

       x          191.6      242.9        71.7   331.1    246.5        62.3       83.3        1191.5
       SE          21.5       45.5        18.4    39.1      46.1       23.8       10.3         108.5
       n            8           8          6       12         8         8          3              8
       range    102-281    L37-454    13-149 146-469   69-469    0-164    24-138

    Winter

                   92.3      158.3       49.1   257.4    142.9        49.5       56.4           692.4
       SE          30.7       22.2        17.9    34.5      47.7      21.5         6.1          164.1
       n            8          8           8       12        8          8          8               8
       range       31-271  30-240       8-155  93-421   30-359    0-148         29-83