Reproduction in Northern sea lions on Southeast Farallon Island, 1973-1985

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

NOAA Technical Memorandum
NOS MEMD 4

REPRODUCTION IN NORTHERN SEA LIONS ON
SOUTHEAST FARALLON ISLAND, 1973-1985

Harriet Huber

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

f~~~~~~

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MEMD 1 M.M. Littler, D.S. Littler and B.E. Lapointe. 1986. Baseline Studies of Herbivory and Eutrophication
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MEMD 2 M.M. Croom 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.

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

NOAA TECHNICAL MEMORANDA SERIES NOS/MEMD

Reproduction in Northern Sea Lions on Southeast Farallon Island, 1973-1985

Harriet Huber

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

Reproduction in Northern Sea Lions on
Southeast Farallon Island, 1973-1985

Harriet Huber

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

INTRODUCTION

The northern (Steller) sea lion (Eumetopias jubatus) has bred from

the Pribiloff Islands in Alaska south to the Channel Islands in California

(Scheffer 1958). In the last 50 years the populations south of Alaska have

decreased dramatically and breeding on the Channel Islands is intermittent.

By the mid 1970's, the numbers of northern sea lions in the eastern

Aleutians dropped dratically (Braham et al. 1980). In the last 10 years

pup production in the western Gulf of Alaska has decreased by 26% (Goodwin

and Calkins 1985), and the newest evidence from statewide censuses in 1984

and 1985 indicates that the decline involves the population In the rest of

the Aleutian chain and the western Gulf of Alaska as well (Merrick, pers.

comm.). The population in the Point Reyes/Farallon Island Marine Sanctuary

was as high as 900 animals in the 1920's and 1930's (Bonnot et al. 1938);

it has been stable at about 130 animals during the breeding season for the

last 15 years (Huber et al. 1985). Although a small number of northern sea

lions haul out at the Point Reyes Headlands during the breeding season,

pupping and breeding take place only at the Farallones within the Point

Reyes/Farallon Island Marine Sanctuary boundaries (Allen and Huber 1984).

The reasons for the decline within the Sanctuary are unknown but may be

associated with the low natality and high rate of premature pupping found

at the Farallones (Huber et al. 1984). Since 1973 when observations by

Point Reyes Bird Observatory began, the number of northern sea lion pups

born each year ranged from 5 to 27. At the same time the number of pups

born prematurely ranged from 1 to 14 (Table 1). Premature pups are seen as

early as February and as late as May, but the majority (53/81) occur in

April (Table 2) which indicates that abortion may occur at a specific stage

of fetal development. The abortion rate, which averaged 44% over 13 years

at the Farallones, is much higher than reported at other rookeries: about

2% at Ano Nuevo Island in central California (Gentry 1970) and 4 to 5% in

Oregon (Mate 1975), DeLong pers. comm.). In a recent study in the Gulf of

Alaska, Pitcher and Calkins (1981) found evidence of premature pupping in

at least 9% of the female northern sea lions collected between February and

September. The differences may indicate that the problem is greater at the

Farallones than elsewhere or merely reflect the fact that biologists are

present on the Farallones year round and only present May to July or August

at other rookeries.

Little is known about premature pupping in northern sea lions although

the problem is being investigated (Huber et al. 1984, Goodwin and Calkins

1985). However, in the early l970's researchers on San Miguel Island,

California, noted that 20% of the California sea lions were born

prematurely. Multiple factors appeared to be associated with the premature

pupping including a bacterium, Leptospira interrogans serovar pomona, a

calicivirus, San Miguel Sea Lion Virus (SMSV), and increased levels of

organocholorines (PCB and DDE) in various tissues (Gilmartin 1976).

L. pomona has since been isolated from dead premature or newborn pinniped

pups and, in each instance, the isolate was recovered from an animal having

"perinatal hemorrhagic syndrome" (Smith et al. 1974). This syndrome is now

attributed to Leptospirosis which is associated with reproductive failure

in domestic animals. SMSV has been isolated from aborted sea lion fetuses

and causes blisters on the flippers of adult animals. Viruses of this kind

are known to cause a variety of reproductive-related problems in other

species and, presumably, in pinnipeds (Smith et al. 1973). Diagnosis of

SMSV is by virus isolation and identification. The levels of PCB and DDE

were obtained from the liver, kidney, muscle, blubber and brain tissues of

both premature and full-term California sea lions. In general, rising

levels were associated with increasing reproductive problems (DeLong et al.

1973). The Individual effects and interrelationship among these three

factors is not well understood. It is likely that the effects of one

exacerbates the stresses of the others.

In 1983 we investigated the high incidence of premature pupping in

northern sea lions on the Farallon Islands by laboratory analysis of

disease pathogens and pollutants concentrated in the tissues of premature

pups (Huher et al. 1984). We found evidence of an unidentified virus in

all five of the fresh samples tested. In 1985 we hoped to isolate and

identify that virus to more clearly understand the causes of reproductive

failure in northern sea lions within the Point Reyes/Farallon Islands

National Marine Sanctuary. Unfortunately, the only fetus observed in 1985

washed away before It could be collected. Thus it was not possible to

identify the virus found in 1983.

This report will summarize sightings of naturally marked males and

females observed an the Farallones during breeding seasons 1978 to 1984,

provide updates of the 1984 and 1985 breeding seasons, and compare DDE and

PCB levels concentrated in the blubber of five premature fetuses collected

1978 to 1982 with blubber samples of seven premature fetuses collected in

1983.

METHODS

In mid-1973, Point Reyes Bird Observatory (PRBO) biologists began

weekly censuses of northern sea lions. Censuses from Lighthouse Hill

(elevation 109 m) and other vantage points were conducted between 1300 to

1600 h to obtain maximum counts; animals in the water were included.

Since 1976, censused animals were divided into five age/sex classes

whenever possible. Beginning in 1973, from February to mid-May, PRBO

biologists canvassed the major sea lion pupping areas daily, looking for

premature births. When a fetus was found we noted if an adult female was

in attendance, her behavior, and if she had a yearling with her. Fetuses

were collected for organochlorine analysis whenever it was possible to do

so without disturbing other wildlife. Between 1978 and 1982, seven

premature fetuses were collected, five were tested for organochlorine

residues in the blubber, brain, kidney, muscle and liver, and the remaining

two for pollutant residues in the pectoral muscle.

In 1983, funded by the Point Reyes/Farallon Island Marine Sanctuary,

all seven pups born prematurely were collected; five within four hours of

death. All were necropsied and tested for organochlorine residues in

blubber, brain, muscle, and liver. The five fresh fetuses were also tested

for the presence of San Miguel Sea Lion Virus (SMSV), Leptospirosis and

hemorrhagic syndrome (a symptom of Leptospirosis).

The methods used for organochlorine, viral, and bacterial analysis are

described in Huber et al. (1984).

In 1978, after the main pupping area changed from an offshore rock to

Sea Lion Cove, we began records of naturally marked animals to determine

if females giving birth to full term pups returned each year, if the same

females gave birth prematurely each year, if territorial males returned

each year and which males copulated. During the breeding season (mid-May

to mid-August), observations of identified animals were made for two to

three hours each day, weather permitting. Opportunistic sightings of

scarred individuals were made during winter and while looking for premature

births at the Farallones, at Point Reyes Headlands in 1982-1984 during

another study, and whenever North Farallones were censused. We saw many

animals only once. An animal was considered "identified" if it was

resighted at least once during a season. At least two and usually three

scars or patterns of scars were used in determining whether a rersighted

animal was the same as a known animal.

RESULTS AND DISCUSSION

Despite the decline in the population throughout its range and the high

rate of premature pupping on the Farallones, the number of northern sea

lions on the Farallones during the breeding season has been consistently

counted at about 130 animals for the past 13 years (Figure 1).

Although numbers have remained stable, the Farallon breeding population

has undergone several shifts in location. Photographs taken in the 1930's

show large numbers of northern sea lions hauled out on Indianhead at West

End. When PRBO first began observations, all full-term pups were born on

Saddle Rock, one quarter mile offshore of Southeast Farallon, although

premature pups were seen on the main island. The seasonal pattern was

consistent in the early years of observations: resident females hauled out

at Sea Lion Cove during fall and winter but as the summer breeding season

approached they moved to Saddle Rock where they pupped. In 1976, this

pattern changed and adult males and females remained year round in Sea Lion

Cove, a more protected and.seemingly preferable area. In 1984, northern

sea lions were observed on West End for the first time since PRBO

biologists began observations, but it was not until 1985 that a pup was

born there. Northern sea lions may have moved from Sea Lion Cove to Saddle

Rock because of human disturbance during the occupation of the island by

the Navy, Coast Guard and Lighthouse personnel; they returned to Sea Lion

Cove four years after PRBO imposed restrictions on access to pinniped and

bird breeding areas, possibly because of reduced disturbance.

In looking at censuses dividing the population into age classes, we

found that adult females are resident on the Farallones year round but that

adult males are present only during the breeding season (Table 3).

Full-term pups on the Farallones were born between 27 May and 24 July which

is a slightly more extended period than at Ano Nuevo Island, California

(late-May to mid-July; Gentry 1970), or at Cape St. James, British Columbia

(28 May to 14 July; Edie 1977) or at Lewis Island, Alaska, where no pupping

was observed after 1 July (Sandegren 1970). Premature pups were born

between February and mid-May (Table 3). The proportion of premature pups

was higher on the Farallones than at Ano Nuevo, where the proportion is

about 2% (Gentry 1970) or in Oregon where it is about 4% (Mate 1975).

Seven premature fetuses were collected between 1978-1982 and seven in 1983.

Half (7/14) had evidence of perinatal hemorrhagic syndrome which is

indicative of Leptospirosis, nearly 80% (11/14) had inflated lungs

indicating they were alive at birth. In all, there were 8 males and 6

females. Fetuses collected between 1978-1982 were tested only for

organochlorines in the tissues. All seven fetuses from 1983 neretested for

organochlorines and five of these were fresh enough to be tested for the

presence of SMSV and Leptospirosis. No evidence of SMSV was found, and

only one sample had antibodies to Leptospirosis. All five samples

contained an influenza-like virus that could not be replicated because of

logistic problems causing repeated freezing and thawing and therefore not

possible to identify. This same virus was also present in premature pups

at Rogue Reef.

We had hoped to collect more samples in 1985 that would enable us to

identify the influenza virus and determine if it was responsible for the

high rate of premature pupping. However, only one premature pup was born

in 1985 and it was not available for collection.

Between 1978-1983, we identified 21 adult males by natural markings.

More than half (12/21) were seen in more than one season (Table 4). All

males resighted were seen in successive years: no resighted males

"skipped" seasons. Seven of the 12 males seen for more than one year held

territories, one for six years, one for four years, and three for three

years. The resighted males without territories were generally seen early

or late in the breeding season and may have been enroute to or from the

nearby Ano Nuevo rookery. At least two males were seen at the Point Reyes

Headlands in the same year they were present on the Farallones, but neither

held a territory at the Farallones. No males could be identified at the

North Farallones, and thus, whether there is interchange between North and

South Farallones is not known.

We identified 25 different females, 70% of which were seen for more than

one breeding season. Sixty percent were never seen with a pup; three were

seen with full-term pups and seven with premature pups (Table 5). Only two

females were observed in non-consecutive seasons and neither was ever seen

with a pup. One female raised a full-term pup successfully for three

consecutive years. Less than 20% (15/81) of the premature pups found had

females in attendance. Those females associated with premature pups were

not seen with a premature pup in more than one season, nor with a full-term

pup in any season, nor with a nursing yearling. Although no females were

seen with premature pups in more than one year, only 1/5 of premature pups

were seen with attendant females, therefore it is not possible to say

whether the same females are giving birth to premature pups year after

year. Most of the 15 females seen with premature pups were very attentive

to those pups even if the pup was dead. Some females protected their dead

pups from scavenging Western Culls. Two females even carried dead pups

into the water and swam off with them.

The majority of identified females were not seen with pups and may have

been females which gave birth at some other rookery and were seen on the

Farallones only during feeding bouts or before parturition. At least five

females were seen during the winter on the Farallones and two others at the

Point Reyes Headlands during other censuses.

Within the breeding season, resightings of males without territories

and females without pups were lower than territorial males or parturient

females. This is partially because non-breeding animals are more likely to

move out of the area than breeders and partially because the pup or

territory serves as an additional clue to the individual's identity.

Resightings also increased when the number of observers was limited to

those familiar with the scars. Resightings were a function of the

distinctiveness of marks combined with visibility, e.g., belly scars which

are visible only when a female is nursing, although distinctive, are less

useful than those which are visible from more angles. Based on sightings

of identified males and females, males copulated with females 10-14 days

after parturition; at least 20% of copulations observed were with

non-parturient females.

Robert Risebrough of Bodega Marine Laboratory analyzed DDE and PCB

levels in tissues from premature pups collected in April: 3 from 1978, 1

from 1980, and 3 from 1982 (Table 6). Samples were taken from the brain,

blubber, liver, kidney and/or pectoral muscle. Results were similar to

those in 1983 (Huber et al. 1984). At least five pups collected between

1978-1982 were born alive but died within several hours as was true for six

of seven pups in the 1983 sample (one sample was not checked). Since

organochlorines concentrate in the blubber layer, we tested the five

blubber samples from 1978-1982 against the seven blubber samples obtained

in 1983. The levels of DDE in the blubber were similar in the two sets of

samples (t=1.637, df=10, p<.20). The same was true for PCB levels

(t=.3519, df=10, p<.50). Five of seven pups in the 1978-1982 sample showed

evidence of perinatal hemorrhagic syndrome which is symptomatic of

Leptospirosis. Only two in the 1983 sample showed evidence of

Leptospirosis. No pups in the 1978-1982 sample were tested for the

influenza-like virus found in five of seven in the 1983 samples. In both

samples, DDE and PCB residues concentrated in the blubber layer and samples

with high levels of DDE also had correspondingly high levels of PCB.

However, Jones (cited in Reijnders 1980) discovered that high levels of PCB

and DDE found in fetuses are not necessarily related to correspondingly

high levels of pollutants in the maternal blubber, possibly because adult

females lose pollutant residues when their fat is metabolized during

parturition and lactation.

In 1984, six pups were born, one prematurely on 22 March. Pup

mortality was 33% that year. Between 23 April and 17 July, 1985, seven

pups were born, one prematurely. Pup mortality was 28% in that year (Table

5). It was not possible to collect either fetus for analysis.

In summary, we have determined that premature pupping is more extensive

on the Farallones than in other areas, that disease and concentrations of

PCB's or some combination of the two may be contributing to premature

pupping, and that there is a world-wide decline in the northern sea lion

population. Nonetheless, we do not yet know the cause of the decline, the

cause of the premature pupping, nor the relationship (if it exists) between

the two. Recent research has opened up more questions to be investigated.

Reijnders (1984) suggests that mercury, selenium and cadmium

concentrations, which may have severe consequences on reproductive rates in

pinnipeds, should be assessed. Goodwin and Calkins (1985) feel that

Chlamydiosis may contribute to reproductive failure in the western Gulf of

Alaska. Other researchers feel the decline may be ascribed to changes in

prey availability, entanglement of Juveniles in discarded fishing gear or

disease or some combination of these factors (Merrick, pers. comm.).

Further investigations of the problem should concentrate on these questions

and determine if there are different causes in different areas for the

overall population decline.

ACKNOWLEDGEMENTS

Members and donors to the Point Reyes Bird Observatory have contributed

generously to support Farallon marine mammal research. The contract

support provided by U. S. Fish and Wildlife Service, Marine Mammal

Commission, National Marine Fisheries Service, and National Marine

Sanctuary Office has been indispensible. This report is in fulfillment of

contractual responsiblities to National Marine Sanctuary Office.

Permission to work on the Farallones, aid in transport and help in

maintaining island facilities was given by U. S. Coast Guard, Twelfth

District and U. S. Fish and Wildlife Service, Farallon Refuge. Charlie

Merrill and Oscar Fisher of the Oceanic Society's San Francisco Bay Chapter

"Farallon Patrol" arranged transportation for which we are most grateful.

We are also thankful that Sarah Allen assumed many of the mainland

responsibilities involved in running the Farallon field station.

Doug Skilling and Alvin Smith of Oregon State University, Corvallis,

Oregon, analyzed samples for evidence of Leptospirosis and influenza.

Farallon bilogists B. Boekelheide, P. Henderson, J. Nusbaum, T. McElroy,

and K. Schafer helped with identification and resighting observations. J.

Kelly, J. Oppenheimer, and P. Lemon volunteered time and energy to

identification and resighting of animals during the breeding season.

Thanks also to Gary Fellers of the Point Reyes/Farallon Island National

Marine Sanctuary and Bob DeLong of National Marine Fisheries Service for

their support of the project.

This is contribution number 321 of Point Reyes Bird Observatory.

LITERATURE CITED

Allen, S. G. and H. R. Huber. 1984. Pinniped Assessment in Pt. Reyes,

Calif. 1983-1984. Final report to Pt. Reyes/Farallon Islands Marine

Sanctuary Ovfice. 71 pp.

Bonnot, P., G.H. Clark, and S.R. Hatton. 1938. California sea lion census

for 1938. Calif. Fish and Game. 24(4):415-419.

Braham, H. W., R. D. Everitt, D. J. Rugh. 1980. Northern sea lion

population decline in the eastern Aleutian Islands. J. Wildl.

Manage. 44(1):25-33.

DeLong, R. L., W. G. Gilmartin, and J. G. Simpson. 1973. Premature births

in California sea lions associated with high organochlorine pollutant

residue levels. Science 181:1168-1170.

Edie, A.G. 1977. Distribution and movements of Steller sea lion cows

(Eumetopias jubata) on a pupping colony. Ms. thesis, Univ. Brit.

Columbia. 81 pp.

Gentry, R.L. 1970. Social behavior of the Steller sea lion. Ph.D.

dissertation. Univ. Calif., Santa Cruz. 113 pp.

Geraci, J. R., D. S. St. Aubin, and I. K. Barker. 1982. Mass mortality of

harbor seals: pneumonia associated with Influenza A Virus. Science

215:1129-1131.

Gilmartin, W. G., R. L. DeLong, A. W. Smith, J. C. Sweeny, B. W. deLappe,

R. W. Risebrough, L. A. Griner, M. D. Dailey, and D. B. Peakall.

1976. Premature parturition in the California sea lion. J. Wildl.

Diseases 12:104-115.

Goodwin, E. A. and D. G. Calkins. 1985. Preliminary results of ongoing

investigations of San Miguel sea lion virus, leptospirosis, and

chlamydiosis in Alaska Steller sea lions and their relationship to

declining pup counts. Presented at the Sixth Bienn. Conf. Bio. Mar.

Mammals, Vancouver, B.C. Nov. 1985.

Huber, H.R., C. Beckham, J. Nisbet, A. Rovetta, and J. Nusbaum. 1985.

Studies of Marine Mammals at the Farallon Islands, 1982-1983.

NMFS/SWFC Admin. Rpt. LJ-85-01C. 57 pp.

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 Marine Sanctuary Office. 20 pp.

Mate, B.R. 1975. Annual migrations of the sea lions Eumetopias jubatus

and Zalophus californianus along the Oregon coast. Rapp. P.-V.

Reun. Cons. Int. Explor. Mer. 169:455-461.

Merrick, R., National Marine Mammal Laboratory, 7600 Sand Point Way N.E.,

Seattle. Pers. comm. April 1986.

Pitcher, K. W. and D. G. Calkins. 1981. Reproductive biology of Steller

sea lions in the Gulf of Alaska. J. Mamm. 62(3):599-605.

Reijnders, P. J. H. 1984. Man-induced environmental factors in relation

to fertility changes in pinnipeds. Environ. Conserv. 11(1):61-65.

Reijnders, P. J. H. 1980. Organochlorine and heavy metal residues in

harbour seals from the Wadden Sea and their possible effects on

reproduction. Neth. 3. of Sea Res. 14:30-65.

Sandegren, F.E. 1970. Breeding and maternal behavior of the Steller sea

lion (Eumetopias jubata) in Alaska. Ms. thesis. Univ. Alaska.

~~~~~~~~~~~~~~~~~~~14~~~~~~
14

138 pp.

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

Stanford, CA.

Smith, A. W., T. G. Akers, S. H. Madin, and N. A. Vedros. 1973. San

Miguel Sea Lion Virus isolation, preliminary characterization and

relationship to vesicular exanthema of swine virus. Nature

244:108-110.

Smith, A. W., R. J. Brown, D. E. Skilling, and R. L. DeLong. 1974.

Leptospira pomona and reproductive failure in California sea

lions. J. Amer. Vet. Med. Assoc. 1965:996-998.

Table 1. Reproductive success of female northern sea lions on Southeast

Farallon Island, 1973-1985.

HIGHEST NUMBER NUMBER NUMBER OF PUP DEATHS

OF FEMALES OF PUPS PERCENT PREMATURE - OTHER PERCENT

YEAR PRESENT BORN NATALITY BIRTHS CAUSES MORTALITY

1973 73 9 12 3 - 33

1974 110 10 9 4 - 40

1975 98 19 19 4 5 47

1976 98 14 14 5 1 43

1977 111 27 24 11 - 41

1978 103 18 17 10 - 56

1979 96 15 15 3 3 40

1980 91 26 29 14 2 61

1981 86 17 20 11 - 64

1982 99 12 12 7 1 67

1983 79 10 13 7 2 90

1984 90 6 7 1 1 33

1985 80 7 8 1 1 28

Table 2. Number of premature northern sea lion pups born on Southeast
Farallon by month, 1973-1985.

YEAR FEB MAR APR MAY

1973 1 1 1

1974 3 1

1975 4

1976 3 2

1977 3 6 2

1978 3 6 1

1979 3

1980 7 7

1981 4 7

1982 6 1

1983 6 1

1984 1

1985 1

Total 1 12 53 15

Table 3. Reproductive chronology in northern sea lions on South Farallon Islands, 1973-1985.

BULLS PREMATURE FULL-TERM COPULATIONS

YEAR PRESENT PUPS BORN PUPS BORN OBSERVED

1973 16 Apr-<17 Jul 7 Feb- 9 Apr <17 July --

1974 29 Apr- 8 Aug 10 Apr-15 May 3 Jun-11 Jul --

1975 10 Apr-22 Aug 11 Apr-18 May 6 Jun-12 Jul

co 1976 18 Apr-29 Jul 17 Apr-19 May 5 Jun-28 Jun --

1977 15 Apr-11 Aug 29 Mar- 5 May 27 May- 5 Jul 11 Jun

1978 18 Apr- 3 Aug 11 Feb-12 May 3 Jun-30 Jun 18 Jun-12 Jul

1979 2 May-15 Aug 17 Apr-28 Apr 12 Jun-12 Jul 27 Jun- 3 Jul

1980 4 May- 6 Aug 3 Apr-ll May 12 Jun-24 Jul 11 Jun-29 Jun

1981 28 Apr-10 Aug 17 Mar-28 Apr 10 Jun- 7 Jul 28 Jun

1982 1 May-30 Jul 1 Apr-18 May 16 Jun- 3 Jul 24 Jun

1983 2 May- 1 Aug 7 Apr-11 May 22 Jun-26 Jul 20 Jun

1984 5 May-28 Jul 22 Mar 15 Jun-28 Jun 27 Jun

1985 6 May- 8 Aug 23 Apr 7 Jun-26 Jun 18 Jun

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Table 4. Adult male northern sea lions identified by natural markings at
Southeast Farallon Island 1978-1983. (T indicates territory
held, X indicates present during breeding season.)

IDENTIFIED
MALE 1978 1979 1980 1981 1982 1983

1 T T T T T T
2 T T T
3 T T T
4 T
5 X
6 X
7 X
8 X X
9 X X X
10 T T T T
11 X
12 T T T
13 T T
14 T T
15 X X X
16 X
17 X X X
18 X
19 X X
20 T
21 T

Table 5. Adult female northern sea lions identified by natural markings at
Southeast Farallon Island, 1978-1983 (F - full-term pup, N - not
observed with pup, P - premature pup).

IDENTIFIED
FEMALE 1978 1979 1980 1981 1982 1983

1 N N
2 N N
3 N N
4 N N
5 N N
6 F F
7 F F F
8 N N N N
9 N N
10 N N
11 N P
12 P N
13 N P N N
14 N N
15 N N N N N
16 N N
17 N P
18 P
19 N N
20 N N N
21 P
22 P
23 F N
24 N N
25 N N

Table 6. DDE and PCB levels in tissues of premature fetuses of the
northern sea lion from the Southeast Farallon Island, 1978-1982.

BML DATE % P,P'-DDE PCB
ID COLLECTED TISSUE H O PPM DRY PPM DRY

82-58 6 Apr 1980 Blubber 65 13 9.5
82-55 Brain 36 0.7 0.9
82-56 Liver 74 0.3 0.4
82-57 Pectoral muscle 85 11.8 9.6
82-59 Kidney 82 0.5 0.6
82-18 1 Apr 1982 Blubber 64 31 18
82-18 Brain 91 4 1.9
82-18 Liver 76 0.4 0.6
82-18 Pectoral muscle 81 17.6 10
82-18 Kidney 81 1.3 0.9
82-19 12 Apr 1982 Pectoral muscle 90 8.3 3.9
82-60 13 Apr 1978 Blubber 69 83 76
82-60 Liver 82 4.4 4
82-60 Pectoral muscle 82 6.5 5.4
82-61 11 Apr 1978 Blubber 75 40 33
82-61 Brain 95 13 13
82-61 Liver 81 9.6 7.1
82-61 Pectoral muscle 89 15 14
82-61 Kidney 95 6.7 16
82-66 April 1978 Blubber 79 6.6 2.3
82-66 Brain 91 0.5 0.4
82-66 Liver 76 0.7
82-66 Pectoral muscle 94 7.5 3.1
82-66 Kidney 82 0.5 0.1
82-65 7 Apr 1982 Pectoral muscle 82 15 4.6

Fig. 1. The occurrence of northern sea lions (Eumetopias jubatus) on the
Farallones, 1971-1985.

250

, 200- Eumetoplas lubatus

50I-

'~.... . . . ............ - - ,

1971 1972 1973 1974 1975 19T6 1977 1978
o

250 '

200'

o 150 .

too00 -

14950