NOAA Technical Memorandum NMFS-AFSC-131

U.S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Marine Fisheries Service

Alaska Fisheries Science Center

December 2002

by

J. L. Sease and C. J. Gudmundson

Aerial and Land-Based Surveys of

Steller Sea Lions (Eumetopias jubatus)

From the Western Stock in Alaska,

June and July 2001 and 2002
NOAA Technical Memorandum NMFS

The National Marine Fisheries Service's Alaska Fisheries Science Center

uses the NOAA Technical Memorandum series to issue informal scientific and

technical publications when complete formal review and editorial processing

are not appropriate or feasible. Documents within this series reflect sound

professional work and may be referenced in the formal scientific and technical

literature.

The NMFS-AFSC Technical Memorandum series of the Alaska Fisheries

Science Center continues the NMFS-F/NWC series established in 1970 by the

Northwest Fisheries Center. The new NMFS-NWFSC series will be used by

the Northwest Fisheries Science Center.

This document should be cited as follows:

Sease, J. L., and C. J. Gudmundson. 2002. Aerial and land-based

surveys of Steller sea lions (Eumetopias jubatus) from the western

stock in Alaska, June and July 2001 and 2002. U. S. Dep. Commer.,

NOAA Tech. Memo. NMFS-AFSC-131, 45 p.

 

Reference in this document to trade names does not imply endorsement by

the National Marine Fisheries Service, NOAA.
National Marine Mammal Laboratory

Alaska Fisheries Science Center

7600 Sand Point Way N.E.

Seattle, WA 98115

by

J. L. Sease and C.J. Gudmundson

December 2002

NOAA Technical Memorandum NMFS-AFSC-131

Aerial and Land-Based Surveys of

Steller Sea Lions (Eumetopias jubatus)

From the Western Stock in Alaska,

June and July 2001 and 2002

U.S. DEPARTMENT OF COMMERCE

Donald L. Evans, Secretary

National Oceanic and Atmospheric Administration

Vice Admiral Conrad C. Lautenbacher, Jr., U.S. Navy (ret.), Under Secretary and Administrator

National Marine Fisheries Service

William T. Hogarth, Assistant Administrator for Fisheries
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iii

ABSTRACT

The National Marine Fisheries Service (NMFS) conducted aerial and land-based surveys

of the western stock of Steller sea lions (Eumetopias jubatus) in Alaska during June and July of

2001 and 2002 at all sites from 144° W to 172° E, the westernmost point in the Aleutian Islands. 

Survey effort in 2001 was restricted to pup counts at selected sites in the Aleutian Islands and the

Gulf of Alaska. The 2002 survey included the entire western stock: aerial surveys of non-pups at

all sites and pup counts at all rookeries except those counted in 2001. In June 2002, a total of

26,602 non-pups were counted on all surveyed sites (n = 259). Of these non-pups, 14,320 were

on 30 trend rookeries and 5,020 were on 54 trend haul-out sites for a total of 19,340 on all 84

trend sites. This was an increase of 5.5% for all trend sites and 6.8% for trend rookeries from

June 2000, the first region-wide increase observed since standardized aerial surveys began in the

1970s. Counts were still down compared to 1998 (-5.4% for all trend sites and -1.2% for trend

rookeries) and down more than 30% since 1990. From 1991 to 2002, the population declined by

an average of 4.1% per year (P < 0.001: 95% C.I.' -2.8% to -5.5%) for all trend sites and 3.9%

per year (P' 0.002: 95% C.I.' -2.3% to -5.6%) at the trend rookeries.

The Kenai Peninsula to Kiska Island index area, a core subarea within the Alaska portion

of the western stock, included 22,221 non-pup sea lions at 220 of the 259 surveyed sites. Of

these, 12,893 were on 26 trend rookeries and 3,130 were on 44 trend haul-out sites (16,023

non-pups on all 70 trend sites). These counts represented increases from June 2000 of 4.9% and

9.8%, respectively, for all trend sites and for trend rookeries. Trend rookeries in the

Kenai-to-Kiska region also increased by 6.4% relative to 1998, although all trend sites were

down 2.4%, and both were down about 25% from 1991. From 1991 to 2002, Kenai-to-Kiska
iv

counts declined by an average of 3.1% per year (P < 0.001: 95% C.I.' -2.0% to -4.2%) for all 70

trend sites and 3.2% per year (P' 0.006: 95% C.I.' -1.4% to -5.1%) for the 26 trend rookeries

from 1991 to 1998. The 2002 aerial survey included replication of 27 sites in the Gulf of Alaska

and 30 sites in the eastern and east-central Aleutian Islands. Coefficients of variation calculated

from the replicate counts were 0.029 for all sites, 0.044 for the Gulf of Alaska sites, and 0.038

for sites in the Aleutian Islands.

Region-wide pup counts are on a 4-year schedule (including 2002), with counts at

selected sites during intervening years. During June and July 2001, NMFS personnel counted

3,837 live pups at 11 rookeries and 90 live pups at five haul-out sites in Alaska. During June

and July 2002, NMFS counted 5,472 live pups at 27 rookeries and 178 live pups at six haul-out

sites. Pups were counted in both years at Marmot, Ugamak, and Semisopochnoi Island rookeries

and at the Seguam Island, Turf Point haul-out site. Using a composite of 2001 and 2002 pup

counts, the total pup count for the western stock was 8,345 live pups at 35 rookeries and 244 live

pups at 10 haul-out sites. This represented a decline of 11.2% since 1998 for the western stock

in Alaska.
v

 CONTENTS

 Page

Abstract . . . . . . . . . . iii

Introduction . . . . . . . . . . 1

Methods . . . . . . . . . . 1

Aerial Surveys of Non-Pups . . . . . . . 3

Pup Surveys . . . . . . . . . 5

Data Analysis . . . . . . . . . 6

Results . . . . . . . . . . 6

Aerial Surveys of Non-Pups . . . . . . . 6

Kenai-to-Kiska Index Area . . . . . . 7

Counts Within Geographical Subareas . . . . 7

Counts of Non-pups on Rookeries . . . . . 8

Coefficients of Variation from Replicate Counts . . . 8

Pup Surveys . . . . . . . . . 9

Discussion . . . . . . . . . . 10

Acknowledgments . . . . . . . . . 13

Citations . . . . . . . . . . 14
INTRODUCTION

In November 1990 the National Marine Fisheries Service (NMFS) listed Steller sea lions

(Eumetopias jubatus) as “threatened” range-wide under the U.S. Endangered Species Act

(55 Federal Register 49204). Several years later, two population stocks were identified, based

on differences in genetics and population trends (Loughlin 1997). The western stock, which

occurs from 144° W (just east of Prince William Sound, Alaska) westward to Russia and Japan,

was listed as “endangered” in June 1997 (62 Federal Register 24345). The eastern stock, which

occurs from Southeast Alaska southward to California, remains classified as threatened.

The NMFS conducted aerial surveys of Steller sea lion non-pups (adults and juveniles)

and land-based surveys of pups across the range of the western stock in Alaska during June and

July 2002. These efforts extended the series of surveys in Alaska that began in the mid-1970s

(Braham et al. 1980, Calkins and Pitcher 1982, Loughlin et al. 1984, Merrick et al. 1987,

Loughlin et al. 1990, Merrick et al. 1991, Merrick et al. 1992, Sease et al. 1993, Strick et al.

1997, Sease et al. 1999, Sease and Loughlin 1999, Sease et al. 2001). This report focuses

primarily on counts of non-pup Steller sea lions at trend sites, which include both rookeries and

haul-out sites, from 1990-1991 to 2002. Longer historical perspectives are included in Merrick

et al. (1991: for 1956-90) and Sease et al. (1993: for 1976-92).

METHODS

The 2001 and 2002 surveys for western-stock sites adhered to protocols of earlier aerial

and land-based surveys (Braham et al. 1980, Calkins and Pitcher 1982, Merrick et al. 1991,

Merrick et al. 1992, Loughlin et al. 1992, Sease et al. 1993, Strick et al. 1997, Sease et al. 1999,

Sease and Loughlin 1999, Sease et al. 2001). Analyses of non-pup counts focus on “trend sites.” 
2

Trend sites are those rookeries and haul-out sites surveyed consistently from the 1970s to the

present, thus allowing analysis of population trends on a decadal scale. Trend sites include the

majority of animals observed in each survey (70-75% from 1998 to 2002). “Trend rookeries”

are a subset of all trend sites. Most non-trend sites are haulouts with few animals. The only

major rookeries not included as trend sites are located on Outer and Attu Islands. “Rookeries”

are those sites where adult males actively defend territories, pups are born, and mating takes

place. “Haul-out sites” are those where sea lions rest on land (haul out), but where few or no

pups are born (Calkins and Pitcher 1982, Loughlin et al. 1984). The distinction between

rookeries and haul-out sites has become blurred during recent years as some sites traditionally

listed as rookeries have produced few or no pups; for example, Semisopochnoi Island,

Agligadak Island, and Amchitka Island (Column Rocks). Conversely, noteworthy numbers of

pups have been counted during recent years at some haul-out sites, such as the Chiswell Islands

and Jude Island.

Geographical regions used for analyzing survey results were the same as those used in

previous survey reports (Merrick et al. 1987, Loughlin et al. 1990, Merrick et al. 1991, Merrick

et al. 1992, Sease et al. 1993, Strick et al. 1997, Sease et al. 1999, Sease and Loughlin 1999,

Sease et al. 2001) and those adopted in the Final Recovery Plan for Steller sea lions (NMFS

1992). The NMFS survey effort during 2001 and 2002 covered six western-stock regions: the

eastern, central, and western Gulf of Alaska and the eastern, central, and western Aleutian

Islands (Fig. 1). The NMFS surveys did not include western stock sites in the Bering Sea region,

which contain few haul-out sites and only one rookery (Walrus Island in the Pribilof Islands), or

eastern stock sites in Southeast Alaska.
3

Another geographical region used during the analyses of survey data extends from the

Kenai Peninsula (Outer Island) to Kiska Island This index area (the central and western Gulf of

Alaska, and the eastern and central Aleutian Islands) encompasses what historically was the

heart of the Steller sea lions’ range (Merrick et al. 1987, NMFS 1992). The Kenai-to-Kiska

region typically has included about 60% of the Alaska sea lion population.

It should be noted that, except for the distinction between the eastern and western stocks,

the geographical divisions between regions are arbitrary and may not accurately reflect the

underlying structure of stocks or other subunits of the population, if they exist. We present

results for each region to identify and highlight varying population trends in the different

regions. However, readers should not think that sea lion populations in one region are separate

and independent of those in other regions.

Aerial Surveys of Non-Pups

The NMFS surveyed from Sitkagi Bluffs in the eastern Gulf of Alaska to Attu Island in

the western Aleutian Islands, from 14 June to 25 June 2002 (Table 1). Flight tracks included

traditional sea lion rookeries and haul-out sites, but potential haul-out sites along the flight path

also were examined en route. Under ideal conditions, we surveyed each site at 100-150 knots air

speed, 150-200 m (500-650 ft) altitude, and 500 m (0.25 nautical mile) offshore, depending on

the topography of the site. Strong winds occasionally required flying at higher altitudes or

farther offshore, whereas low clouds sometimes required flying at lower altitudes or closer

inshore. 
4

We photographed sea lions at most sites using 35-mm, manual-focus cameras with motor

drives and zoom lenses (80-200 mm or equivalent) and moderately fast (e.g., ISO 200 or faster)

color transparency (slide) film. Where appropriate, sequential photographs overlapped slightly

to guarantee complete coverage of a site. We also photographed each site with a miniDV digital

video camera and a high-resolution (5.3 megapixel) digital still camera to record an overview of

each site and to provide backup imagery. In the laboratory, we counted sea lions from projected

images. The final count of non-pup sea lions for each rookery or haul-out site was the mean for

two independent counters. If the individual results for a particular site differed by 10% or more,

each person re-counted the images for that site. Because all final counts from photographs were

means of two independent counts, many ended in “.5”. To avoid a systematic upward bias, we

rounded all such means up or down to the next even integer (Knuth 1981). We frequently relied

on direct visual counts instead of photographs for sites with few (e.g., #10) sea lions. 

Replication of individual site counts is the only way to measure variability of counts,

typically through a coefficient of variation (CV). The 2002 aerial survey included two sets of

replicate sites. Replicate sites in the Gulf of Alaska included 5 rookeries and 22 haul-out sites,

primarily around the Kodiak Archipelago. Replicates in the eastern Aleutian Islands included 8

rookeries and 21 haul-out sites from Amak and Sea Lion Rocks westward to Seguam Island, plus

an incidental replicate at Kagalaska Island in the central Aleutian Islands. Table 1 includes the

dates for each individual survey visit and a mean for the counts. Mean counts also were used in

the analyses. Coefficients of variation were calculated by summing the variances for individual

counts at each replicated site and dividing the square root of that sum by the sum of mean counts

for the same sites.
5

Pup Surveys

NMFS counted pups at 10 rookeries and 5 haul-out sites between 23 June and 6 July

2001 and at 28 rookeries and 8 haul-out sites from 25 June to 9 July 2002. Most pup counts

were performed by personnel on the rookery beach. As one person cleared most sea lions older

than pups from the beach, two or three others followed, counting all live pups on the beach and

in the water. The final pup count for each rookery was the mean of the two or three individual

counts. Beach counts of pups introduce disturbance to the rookeries and are logistically difficult

to conduct. Consequently, complete Alaska-wide pup counts are attempted only every 4 years

(including 2002), with counts at selected rookeries during intervening years. In a further attempt

to reduce disturbance, NMFS personnel did not count pups at 8 rookeries in 2002 that were

counted the previous year. Pup counts were made from overlooks or from a skiff without

disturbing sea lions at several sites where few or no pups were present and vantage points

offered clear views of the entire rookery beach. Shore-based observers count pups at the

Ugamak Island rookery from overlooks daily during the breeding season; for this site we used

the maximal daily count. Pups were counted from medium-format aerial photographs for two

sites (Fish and Marmot Islands) and from oblique digital aerial photographs for another site

(Sviechnikof Harbor, Amlia Island) that ship-based survey personnel were unable to count. It is

not unusual for pups to be born at haul-out sites, although the numbers typically are very small in

comparison to births at rookeries (Calkins and Pitcher 1982, Loughlin et al. 1984).
6

Data Analysis

Analyses for population trends included comparison of subtotals of non-pups for 1) all

trend sites (both rookeries and haul-out sites) and 2) rookery trend sites for a) the western stock,

b) the Kenai-to-Kiska index area, and c) within the six smaller geographical regions. Overall

changes in numbers of non-pups and pups, either regionally or for individual rookeries, are

expressed as a percentage of the earlier count. The estimated annual rate of change for 1991 to

2000 is the slope of a simple linear regression of the natural log of counts on survey year, testing

the null hypothesis of no trend using the significance of the slope for the natural-log regression.

RESULTS

Aerial Surveys of Non-pups

The June 2002 survey resulted in a total count of 26,602 non-pup Steller sea lions on all

surveyed sites (n'259) in the western stock in Alaska (Tables 1 and 2; Fig. 2). Of these sites,

137 (53%) were occupied by more than 20 sea lions, 34 sites (13%) were occupied by 1 to 20 sea

lions, and 88 sites (34%) were unoccupied. Of those sites occupied by 20 or more sea lions in

2002, 19% changed by less than 5% or by fewer than 10 animals from 2000 to 2002, 47%

increased by more than 5%, and 34% declined by more than 5%.

The western stock includes 84 trend sites; the June 2002 counts included 14,320

non-pups on the 30 trend rookeries and 5,020 non-pups on 54 trend haul-out sites. The overall

total for all 84 trend sites was 19,340 non-pups. This represented an increase of 5.5% from June

2000, but it was still 5.4% and 34.2%, respectively, below the 1998 and 1991 counts (Table 2,
7

Fig. 2). The long-term trend, based on natural log regression, was a decline of 4.1% per year

from 1991 to 2002 (P < 0.001: 95% C.I.' -2.8% to -5.5%). The trend rookery count increased

6.8% from June 2000, showed equivocal change from 1998 (-1.2%), but declined by 32.1% from

1991 (Table 2, Fig. 2). The estimated average annual rate of decline for trend rookeries from

1991 to 2002 was 3.9% per year (P' 0.002: 95% C.I.' -2.3% to -5.6%).

Kenai-to-Kiska Index Area

We counted a total of 22,221 non-pup sea lions at all surveyed sites (n'220) in the

Kenai-to-Kiska index area in June 2002 (Tables 1 and 2; Fig. 2). The Kenai-to-Kiska index area

includes 70 of the Alaskan trend sites (26 rookeries and 44 haulouts), at which we counted

16,023 non-pups in 2002. This was an increase of 4.9% from June 2000 but a decline of 2.4%

from 1998, and 26.2% since 1991. The 26 trend rookeries in the Kenai-to-Kiska area included

12,893 non-pups, representing increases of 9.8% from June 2000 and 6.4% from 1998, but an

overall decline of 25.0% from 1991. The average trends from 1991 to 2002 were a decline of

3.1% per year (P < 0.001: 95% C.I.' -2.0% to -4.2%) for the 70 trend sites and a decline of 3.2%

per year (P' 0.006: 95% C.I.' -1.4% to -5.1%) for the 26 trend rookeries. Overall declines for

Kenai-to-Kiska have been more than 80% since 1976, when there were almost 90,000 non-pups

on trend sites and more than 70,000 non-pups on trend rookeries (Fig. 2).

Counts Within Geographical Subareas

Numbers of non-pups on trend sites increased or remained stable in five of the six

western stock subregions from 2000 to 2002, although the maximal increase was only 525
8

animals (Table 3; Fig. 3). The only observed decline at trend sites was in the western Aleutian

Islands: -23.7% or -254 animals. The same general trend of increase or negligible change in

five of the six subregions and decline in the western Aleutian Islands was apparent for trend

rookeries (Table 4; Fig. 4) and for all surveyed sites (Table 5; Fig. 5). Declines in the western

Aleutian Islands were equally steep for trend rookeries, for all trend sites, and for all surveyed

sites.

Counts of Non-pups on Rookeries

Counts of non-pups at individual Alaskan rookeries from 1991 through 2000 are

presented in Table 6. Across the western stock, non-pup counts changed by less than 5% or

fewer than 25 animals from 2000 to 2002 at 12 rookeries (34%), increased by more than 5% at

13 rookeries (37%), and declined by more than 5% at 10 rookeries (29%). Distribution of

increasing and declining rookeries was not uniform across the region. Eight of 10 declining

rookeries but only 1 of 13 increasing rookeries are located from Adak (176° W) westward

(Fig. 6). That one increasing rookery, Ayugadak Island, increased from 146 non-pups in 2000 to

182 in 2002 (Table 6).

Coefficients of Variation from Replicate Counts

The 2002 aerial survey included replication of 27 sites (3 rookeries and 24 haul-out sites)

in the Gulf of Alaska and 29 sites (8 rookeries and 21 haul-out sites) in the eastern and

east-central Aleutian Islands. Coefficients of variation calculated from the replicate counts were

0.029 for all sites, 0.044 for the Gulf of Alaska sites, and 0.038 for sites in the Aleutian Islands.
9

1

Southwest Fisheries Science Center, National Marine Fisheries Service, 8604 La Jolla

Shores Drive, La Jolla, CA 92037. Unpublished data.

Pup Surveys

During 25 June to 9 July 2002, NMFS personnel counted pups at 24 rookeries and 8

haul-out sites during ship-board surveys. The pup count for Ugamak Island was the maximal

counts made by shore-based personnel on 8-9 July for the south and north sides, respectively. 

We counted pups for Amlia (Sviechnikof Harbor) from digital oblique aerial photographs taken

on 19 June. For Marmot and Fish Islands, we used counts made from medium-format aerial

photographs taken on 22 June and 4 July, respectively (SWFSC1

). All 2002 pup counts are listed

in Tables 1 and 7. Table 7 also lists pup counts made at 9 rookeries (Seal Rocks, Sugarloaf

Island, Chowiet Island, Chernabura Island, Clubbing Rocks, Ugamak Island, Akutan Island,

Ogchul Island, and Seguam Island-Saddleridge) and 2 haul-out sites (Chiswell Islands and

Seguam Island-Turf Point) during ship-board surveys between 23 June and 6 July 2001, as well

as counts made from medium-format aerial photographs for 7 sites: Fish Island, Outer Island,

Marmot Island, Nagai Rocks haul-out site, Jude Island haul-out site, Sea Lion Rocks, and

Semisopochnoi Island SWFSC1

) .

During June and July 2001, NMFS personnel counted 3,837 live pups at 11 rookeries and

90 live pups at five haul-out sites in Alaska. During June and July 2002, NMFS counted 5,472

live pups at 27 rookeries and 178 live pups at six haul-out sites. For the individual rookeries

listed in Table 7, pup counts changed from 1998 to 2001-2002 by less than 5% or fewer than 20

pups at 10 sites (29%), increased by more than 5% at 9 sites (26%), and declined by more than

5% at 15 sites (44%). All nine rookeries with increasing numbers of pups were in the central
10

portion of the range, from Chowiet Island (156°40' W) through Adak Island (177° W), whereas

declining rookeries were located east of Chowiet Island or west of Adak Island (Fig. 7).

The composite 2001-2002 pup count for the western stock, which included counts from

24 rookeries in 2002 and 7 in 2001, showed continuing decline in pup production: 10.8% from

1998 to 2001-2002 (Table 8, Fig. 8). For the Kenai-to-Kiska index area, the area with the

longest time series of region-wide counts, pup numbers were down 7.5% from 1998, 24.3% from

1994, and 42.3% from 1990-1991. Pup counts increased in one region (western Gulf of Alaska:

+5.5%) from 1998 to 2002, but declined in the five other regions. The western Aleutian Islands

experienced the worst decline (39.2%) from 1998 to 2002.

DISCUSSION

The 5.5% increase from June 2000 to June 2002 in numbers of non-pup Steller sea lions

counted at western-stock sites was the first region-wide increase observed during more than two

decades of systematic surveys. The decline had persisted at an average rate of about 5% per year

from 1989 through 2000 (Sease et al. 2001). As importantly, the observed increase was not the

result of a large increase at a few sites in one region, but rather by a geographically broad-based

increase from the eastern Gulf of Alaska through the central Aleutian Islands. Although this

observed increase certainly is a favorable change, it is premature to conclude that the

decades-long decline is over. Non-pup counts at all western-stock trend sites in 2002 still were

5.4% below the 1998 counts and 34.2% below the 1991 count.

In contrast to the observed increases in non-pup counts, numbers of pups continued to

decline across the western stock in Alaska. The combined 2001-2002 pup count was 11.2%
11

below the 1998 count for the western stock. For the Kenai-to-Kiska index area, 2001-2002 pup

counts were 7.8% below 1998 and 42.4% below the composite 1990-1991 count. Comparison of 

the observed trends for pups and non-pups is confounded by differences in survey regimen. 

Non-pups are counted biennially, whereas region-wide pups counts take place every 4 years. In

fact, non-pup counts at all trend sites and at trend rookeries showed net declines (5.4% and 7.5%,

respectively) over the same 4-year interval (1998 to 2002) available for comparing pup counts. 

The status of Steller sea lions in the western Aleutian Islands region, which includes

Buldir Island and the Near Islands, continues to be troubling. The decline in pup counts from

1998 to 2002 was greatest (down 39%) in this region, and it is the only region where non-pup

numbers continued to decrease (down 24% at trend sites) from 2000 to 2002. In fact, the relative

changes in numbers of non-pups on rookeries (Fig. 6) suggest that the region may still be

undergoing a decline that may extend as far east as Adak Island.

The distinction between rookeries and haul-out sites has become blurred during recent

years. Several sites legally defined as rookeries (50 CFR 223.202, 50 CFR 226.202) produced

few or no pups during recent years, notably Agligadak Island, Semisopochnoi Island (Pochnoi

and Petrel Points), and Amchitka Island (East Cape). These individual rookeries may recover

when and if the western stock of Steller sea lions experiences significant population recovery. 

As a case in point, Fish Island (also called Wooded Island or Lewis Island) has undergone

several changes in status. Rookery studies were conducted there during the late 1950s and 1960s

(Sandegren 1970, 1976). It was abandoned as a rookery sometime during the 1970s, perhaps as

a result of uplifting and other physiographic changes caused by the 1964 earthquake (Sandegren

1970), although it continued to be used as a haul-out. Pups (n = 514) were rediscovered on Fish
12

2

 Division of Wildlife Conservation, Alaska Department of Fish and Game, 333

Raspberry Road, Anchorage, Alaska 99518. Unpublished data.

3

 National Marine Mammal Laboratory, Alaska Fisheries Science Center, National

Marine Fisheries Service, 7600 Sand Point Way, Seattle, Washington 98115. Unpublished data.

Island in 1993 (ADF&G2

, NMML3). Pup numbers there ranged from 70 to 150 during 1997 to

2002 (Table 7).

Conversely, several haul-out sites have evolved into rookeries. White Sisters in

Southeast Alaska became established as a rookery just over 10 years ago; production has

increased from 30 pups in 1990 to over 200 by 1997 (ADF&G2). In 2001 and 2002, there were

about 400 pups at White Sisters, and increasing numbers of pups at two other traditional haul-out

sites in Southeast Alaska (SWFSC1). Table 7 includes four traditional haul-out sites within the

western stock where noteworthy numbers of pups have been observed in recent years. During

2001 and 2002, two haul-outs sites adjacent to existing rookeries (Nagai Rocks, approximately

10 km northwest of the Chirikof Rookery, and Turf Point, approximately 20 km distant from the

rookery at Saddleridge Point on Seguam Island) produced 20-30 pups per year, and the Chiswell

Islands haul-out site produced more than 50 newborn pups. At Jude Island, in the western Gulf

of Alaska, 192 and 119 pups were counted in 2001 and 2002, respectively; re-examination of

survey photographs from June 1998 and June 2000 revealed no evidence of pups. It is not

uncommon to observe low numbers of pups (e.g., fewer than 10) at haul-out sites, but the sudden

appearance of more than 100 pups certainly is unexpected.
13

ACKNOWLEDGMENTS

We thank our pilots D. Vollum and L. Teufel of Aero Planes, Hillsboro, Oregon, for

aircraft transportation during aerial surveys. We thank the captains and crews of M/V Tigla $ $x and

F/V Pacific Star for vessel support during pup counts in the Gulf of Alaska and Aleutian Islands. 

We greatly appreciate the wide-ranging assistance from personnel of the Alaska Maritime

National Wildlife Refuge in Homer, Alaska, and especially J. Mueller and C. Hill of the

Refuge’s Aleutian Islands Unit on Adak Island The National Marine Fisheries Service Observer

Program, the Dutch Harbor Airport Manager, and Delta Western Fuels, provided valuable

assistance in Dutch Harbor, Alaska. J. Cesarone (NMML), W. Testa (NMML), and Brian

Mullaly (Alaska SeaLife Center, Seward, Alaska) participated in the aerial survey. Many

individuals including NMFS personnel and cooperating scientists participated in pup counts. 

B. Fadely, L. Fritz, T. Loughlin, and A. York provided comments on early drafts of the

manuscript. G. Duker and J. Lee provided editorial support. We conducted these surveys under

the authority of NOAA MMPA/ESA Permit No. 782-1532-00 and Special Use Permit

No. 51576 from the Alaska Maritime National Wildlife Refuge.
14

CITATIONS

Braham, H.W., R.D. Everitt, and D.J. Rugh. 1980. Northern sea lion population decline in the

eastern Aleutian Islands. J. Wildl. Manage. 44:25-33.

Calkins, D.G., and K.W. Pitcher. 1982. Population assessment, ecology and trophic

relationships of Steller sea lions in the Gulf of Alaska. Alaska Department of Fish and

Game, Final Report RU243. Alaska Department of Fish and Game, 333 Raspberry Road,

Anchorage, AK 99502, 76 p.

Knuth, D. E. 1981. The art of computer programming. Vol. 2. Semi-numerical algorithms.

Addison Wesley.

Loughlin, T.R. 1997. Using the phylogeographic method to identify Steller sea lion stocks, p.

159-171. In A.E. Dizon, S.J. Chivers, and W.F. Perrin (editors), Molecular genetics of

marine mammals. Soc. Mar. Mammal., Spec. Publ. No. 3.

Loughlin, T.R., A.S. Perlov, and V.A. Vladimirov. 1990. Survey of northern sea lions

(Eumetopias jubatus) in the Gulf of Alaska and Aleutian Islands during June 1989. U.S.

Dep. Commer., NOAA Tech. Memo. NMFS F/NWC-176, 26 p.

Loughlin, T.R., A.S. Perlov, and V.A. Vladimirov. 1992. Range-wide survey and estimation of

total number of Steller sea lions in 1989. Mar. Mammal Sci. 8:220-239.

Loughlin, T.R., D.J. Rugh, and C.H. Fiscus. 1984. Northern sea lion distribution and

abundance: 1956-80. J. Wildl. Manage. 48:729-740.

Merrick, R.L., D.G. Calkins, and D.C. McAllister. 1992. Aerial and ship-based surveys of

Steller sea lions in Southeast, Alaska, the Gulf of Alaska, and Aleutian Islands during

June and July 1991. U.S. Dep. Commer., NOAA Tech. Memo. NMFS-AFSC-1, 37 p.

Merrick, R.L., L.M. Ferm, R.D. Everitt, R.R. Ream, and L.A. Lessard. 1991. Aerial and

ship-based surveys of northern sea lions, (Eumetopias jubatus) in the Gulf of Alaska and

Aleutian Islands during June and July 1990. U.S. Dep. Commer., NOAA Tech. Memo.

NMFS F/NWC-196, 34 p.

Merrick, R.L., T.R. Loughlin, and D.G. Calkins. 1987. Decline in abundance of the northern

sea lion, Eumetopias jubatus, in Alaska, 1956-86. Fish. Bull., U.S. 85:351-365.

NMFS (National Marine Fisheries Service). 1992. Recovery plan for the Steller sea lion

(Eumetopias jubatus). Prepared by the Steller Sea Lion Recovery Team for the National

Marine Fisheries Service, Silver Spring, Maryland, 92 p.
15

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

jubata) in Alaska. M.S. Thesis, Univ. Alaska Fairbanks, 138 p.

Sandegren, F. E. 1976. Courtship display, agonistic behavior and social dynamics in the Steller

sea lion (Eumetopias jubatus). Behaviour 57(1-2):136-158.

Sease, J.L and T.R. Loughlin. 1999. Aerial and land-based surveys of Steller sea lions

(Eumetopias jubatus) in Alaska, June and July 1997 and 1998. U.S. Dep. Commer., 

NOAA Tech. Memo. NMFS-AFSC-100, 61 p. 

Sease, J.L., J.P. Lewis, D.C. McAllister, R.L. Merrick, and S.M. Mello. 1993. Aerial and

ship-based surveys of Steller sea lions (Eumetopias jubatus) in Southeast Alaska, the

Gulf of Alaska, and Aleutian Islands during June and July 1992. U.S. Dep. Commer., 

NOAA Tech. Memo. NMFS F/NWC-17, 57 p. 

Sease, J.L., J.M. Strick, R.L. Merrick, and J.P. Lewis. 1999. Aerial and land-based surveys of

Steller sea lions (Eumetopias jubatus) in Alaska, June and July 1996. U.S. Dep.

Commer., NOAA Tech. Memo. NMFS F/NWC-99, 43 p.

Sease, J.L., W.P. Taylor, T.R. Loughlin, and K.W. Pitcher. 2001. Aerial and land-based surveys

of Steller sea lions (Eumetopias jubatus) in Alaska, June and July 1999 and 2000. U.S.

Dep. Commer., NOAA Tech. Memo. NMFS-AFSC-122, 52 p.

Strick, J.M., L.W. Fritz, and J.P. Lewis. 1997. Aerial and ship-based surveys of Steller sea lions

(Eumetopias jubatus) in Southeast Alaska, the Gulf of Alaska, and Aleutian Islands

during June and July 1994. U.S. Dep. Commer., NOAA Tech. Memo. NMFS

F/NWC-71, 55 p.
16

Table 1.--Counts of adult and juvenile (non-pup) Steller sea lions at rookery (*) and haul-out

 sites in Alaska, June and July 2002. Trend sites (+) are those sites used for analyses of

 trends in survey counts. Counts are from photographs (P) or visual (V). 

Non-pup count Pup count

Location Date Type Count Date Count 

Eastern Gulf of Alaska

Sitkagi Bluffs + 13 June V 0

Cape St. Elias + 14 June P 574

Hook Point 14 June P 258

Cape Hinchinbrook 14 June P 107

Seal Rocks +* 14 June P 768

Fish (Wooded) + 14 June P 396 22 June 86 1

Middleton 14 June V 0

Glacier + 14 June P 435

Point Eleanor 14 June V 0

The Needle + 14 June P 115

Perry 14 June V 0

Pleiades 14 June V 0

Point LaTouche 14 June V 2

Danger 14 June V 0

Point Elrington + 14 June P 114

Procession Rocks 14 June P 147

Cape Puget 14 June V 0

Cape Junken 14 June V 0

Cape Fairfield 14 June V 2

Cape Resurrection 14 June P 84

Rugged + 14 June V 0

Aialik Cape 14 June V 6

Chiswell Islands + 14 June P 97

Granite Cape 14 June P 68

Seal Rock (Kenai) + 14 June V 1

Steep Point 14 June P 8

Rabbit 14 June V 0
Table 1.--Counts of adult and juvenile Steller sea lions in Alaska, June and July 2002, continued.

17

Non-pup count Pup count

Location Date Type Count Date Count 

Subtotals for the Eastern Gulf of Alaska

All 27 surveyed sites 3,182

10 trend rookery and haul-out sites 2,500

1 trend rookery site 768

Central Gulf of Alaska

Outer * 14 June P 226 6 July 58

Nuka Point 14 June V 0

Gore Point 14 June V 0

East Chugach 14 June V 0

Perl 14, 25 June P 98

Perl Rocks 14, 25 June V 0

Nagahut Rocks 14, 25 June V 0

Cape Elizabeth 14 June P 177

Flat 14, 25 June V 0

West Amatuli 14 June V n.s.2

Sugarloaf +* 14, 25 June P 736

Ushagat + 14, 25 June P 116

Rocks south of Ushagat + 14, 25 June P 4

Sud n.s.

Latax Rocks + 14, 25 June P 144

Sea Otter 14, 25 June P 45

Afognak/Tonki Cape 14 June V 0

Sea Lion Rocks (Marmot) + 14, 25 June V 0

Marmot +* 14, 15, 25 June P 848 22 June 515 1

Long + 14, 15, 25 June P 80

Kodiak/Cape Chiniak + 15, 25 June P 102

Ugak 15 June V 0

Kodiak/Gull Point 15, 25 June P 99

Kodiak/Cape Barnabas + 15, 25 June V 0

Twoheaded + 15, 25 June P 227

Cape Sitkinak + 16, 25 June P 91

Sundstrom 16 June V 0
Table 1.--Counts of adult and juvenile Steller sea lions in Alaska, June and July 2002, continued.

18

Non-pup count Pup count

Location Date Type Count Date Count 

Kodiak/Cape Alitak 16 June V 0

Cape Ikolik 16, 25 June P 74

Tombstone Rock 16 June V 0

Kodiak/Sturgeon Head 16 June V 0

Kodiak/Cape Uyak 16 June V 0

Kodiak/Cape Kuliuk 16 June V 0

Kodiak/Cape Ugat 16, 25 June P 104

Noisy 15 June V 0

Kodiak/Malina Point 15 June V 0

Kodiak/Steep Cape 15 June P 28

Kodiak/Cape Paramanof 15 June V 0

Cape Shaw 15 June P 52

Cape Douglas 15 June V 0

Shakun Rocks 15, 25 June P 45

Cape Nukshak 15 June V 0

Cape Ugyak 15 June V 0

Cape Gull 15 June V 0

Cape Kuliak 15 June V 0

Takli 15, 25 June P 79

Puale Bay 15, 25 June P 94

Kilokak Rocks 15 June P 88

Aiugnak Columns 16 June P 0

Ugaiushak + 16 June V 2

Sutwik + 16 June P 114

Aghiyuk n.s.

Chowiet +* 16, 24 June P 582

Chirikof +* 16 June P 320 1 July 225

Nagai Rocks 16, 24 June P 230 1 July 19

Subtotals for the Central Gulf of Alaska

All 52 surveyed sites 4,805

15 trend rookery and haul-out sites 3,366

4 trend rookery sites 2,486
Table 1.--Counts of adult and juvenile Steller sea lions in Alaska, June and July 2002, continued.

19

Non-pup count Pup count

Location Date Type Count Date Count 

Western Gulf of Alaska

Lighthouse Rocks 16, 24 June P 84 30 June 7

Atkulik 16 June V 0

Kak 16 June P 108

Chankliut 16 June P 28

Seal Cape 16 June V 0

Mitrofania 16 June P 150

Spitz + 16 June P 0

Kupreanof Point 16 June P 64

Castle Rock + 16 June P 75

Big Koniuji 16 June V 0

Atkins +* 16 June P 560 30 June 224

Chernabura +* 16 June P 496

Twins 16 June V 0

The Haystacks 16 June P 50 29 June 0

The Whaleback 16 June P 116 29 June 16

Nagai

 Mountain Point + 16 June P 105

 Rocks west of Cape Wedge 16 June V 0

Egg (Sand Point) 16 June V 0

Sea Lion Rocks (Shumagins) + 16 June P 26

Unga

 Cape Unga 16 June V 0

 Acheredin Pt. 17 June P 188

Jude 17, 24 June P 374 29 June 119

Omega 17 June V 0

Wosnesenski 17 June V 2

Olga Rocks 17 June P 164

Sushilnoi Rocks 17 June P 110

Pinnacle Rock +* 17 June P 1,034 28 June 769

Rocks 1.5 nm NW of Pinnacle Rk 17 June P 12

Hunt n.s.

Sozavarika n.s.
Table 1.--Counts of adult and juvenile Steller sea lions in Alaska, June and July 2002, continued.

20

Non-pup count Pup count

Location Date Type Count Date Count 

Umga n.s.

Clubbing Rocks +* 17 June P 830

Cherni 17 June V 0

Hague 17 June V 1

Caton 17 June P 89

South Rock 17 June P 262

Sanak n.s.

Bird + 17 June P 95

Rock 17 June V 0

Subtotals for the Western Gulf of Alaska

All 35 surveyed sites 5,023

9 trend rookery and haul-out sites 3,221

4 trend rookery sites 2,920

Eastern Aleutian Islands

Unimak

 Cape Lasaref 17 June V 0

 Cape Lutke 17 June V 0

 Scotch Cap 17 June V 0

 Sennett Point 17 June V 0

 Cape Sarichef 17, 24 June P 320

 Cave Point 17 June V 0

 Oksenof Point 17 June V 0

Amak + 17, 24 June P 563 25 June 3

Sea Lion Rocks (Amak) +* 17, 24 June P 507 25 June 160

Ugamak and Round +* 17, 24 June P 1044 8, 9 July 482 3

Aiktak 17, 24 June P 75 27 June 10

Kaligigan 17 June V 2

Tigalda/NE Rocks 17, 24 June P 134

Tigalda/South side 17, 24 June P 38

Basalt Rock 17 June V 0

Rootok 17, 24 June P 84

Tanginak 17, 24 June P 3
Table 1.--Counts of adult and juvenile Steller sea lions in Alaska, June and July 2002, continued.

21

Non-pup count Pup count

Location Date Type Count Date Count 

Akun

 Jackass Point 17 June V 0

 Akun Bay 17 June V 0

 Round Head 17 June V 0

 Billings Head +* 17, 24 June P 275 25 June 55

 Akun Head 17 June V 0

Akutan

 North Head 17 June V 0

 Reef Point/Lava Bight + 17, 24 June P 36

 Cape Morgan +* 17, 24 June P 783

 Battery Point n.s.

Baby Islands n.s.

Old Man Rocks 17, 18, 24 June P 25

Egg 17 June V 1

Outer Signal 18, 24 June V 0

Inner Signal 17, 18, 24 June V 5

Unalaska

 Cape Sedanka 18 June V 106

 Priest Rock 17, 18, 24 June V 2

 Cape Wislow 18 June V 0

 Bishop Point 18, 24 June P 122

 Point Kadin 18 June P 41

 Cape Kovrizhka 18 June V 0

 Makushin Bay/North Side 18, 22 June P 46

 Makushin Bay 18, 22 June P 6

 Cape Starichikof 18 June V 0

 Spray Cape 18 June V 67

 Whalebone Cape 18 June V 0

 Cape Izigan 18, 24 June P 211

Bogoslof +* 18, 24 June P 356 9 July 180

Umnak

 Cape Idak 18 June V 0

 Reindeer Point 18 June V 0
Table 1.--Counts of adult and juvenile Steller sea lions in Alaska, June and July 2002, continued.

22

Non-pup count Pup count

Location Date Type Count Date Count 

 Cape Chagak 18 June V 0

 Aguliuk Point 18 June V 0

 Cape Aslik + 18, 22 June P 52

Emerald 18 June V 0

Polivnoi Rock 18, 24 June P 98

The Pillars 18 June P 14

Ogchul +* 18, 24 June P 105

Rocks 2.7 nm west of Ogchul 24 June V 2

Vsevidof + 18, 24 June P 34

Samalga 18 June V 0

Adugak +* 18, 22 June P 201 25 June 160

Subtotals for the Eastern Aleutian Islands

All 55 surveyed sites 5,358

11 trend rookery and haul-out sites 3,956

7 trend rookery sites 3,271

Central Aleutian Islands

Uliaga 18 June P 121

Kagamil + 18 June P 12

Chuginadak + 18 June P 62

Carlisle + 18 June P 0

Herbert + 18 June P 2

Yunaska +* 18 June P 276 25 June 145

Chagulak + 18 June P 5

Amukta + 18 June P 42

Seguam

 Saddleridge +* 18, 22 June P 666

 Other + 18, 22 June P/V 220 26 June 23

Agligadak +* 19 June P 82

Amlia

 East Cape + 19 June P 82

 Sviechnikof Harbor * 19 June P 98 19 June 18 4

 Cape Misty 19 June 42
Table 1.--Counts of adult and juvenile Steller sea lions in Alaska, June and July 2002, continued.

23

Non-pup count Pup count

Location Date Type Count Date Count 

Tanadak + (Amlia) 19 June P 32

Sagigik + 19 June P 40

Amatagis n.s.

Sagchudak n.s.

Atka

 North Cape + 19 June P 224

 Cape Korovin + 19 June V 1

Salt + 19 June V 0

Koniuji 19 June V 0

Kasatochi +* 19 June P 529 28 June 302

Oglodak 21 June P 76

Ikiginak + 21 June P 8

Fenimore 21 June P 22

Tagalak 21 June P 28

Chugul 21 June P 52

Anagaksik + 21 June P 40

Igitkin n.s.

Great Sitkin 19 June P 106

Little Tanaga + (including

Silak I.) 21 June P 82

Kagalaska 19, 21 June P 34

Adak

 Argonne Point/Cape Moffet + 19 June P/V 99

 Cape Yakak/Lake Point +* 21 June P 821 29 June 363

Crone 21 June V 2

Kanaga

 North Cape/Cape Miga 19 June P 12

 Ship Rock 19 June P 242

 Cape Chunu 19 June V 62

Bobrof 19 June V 28

Tanaga

 Bumpy Point 19 June P 26

 Cape Sasmik 19 June P 148
Table 1.--Counts of adult and juvenile Steller sea lions in Alaska, June and July 2002, continued.

24

Non-pup count Pup count

Location Date Type Count Date Count 

Ilak 19 June P 46

Gramp Rock +* 19 June P 600 30 June 444

Ugidak + 19 June P 23

Tag +* 19 June P 279 30 June 153

Ogliuga 19 June V 34

Skagul n.s.

Gareloi 19 June V 0

Kavalga + 19 June P 18

Unalga and Dinkum Rocks + 19 June P 46

Ulak/Hasgox Point +* 21 June P 481 30 June 331

Amatignak

 Knob Point + 21 June V 0

 Nitrof Point + 21 June P 40

Semisopochnoi

 Pochnoi Point * 20 June P 70 7 July 0

 Petrel Point 20 June P 18

 Tuman Point 20 June V 0

 Southwestern point 20 June P 18

 Southern tip 20 June P 11

Amchitka

 Ivakin Point + 20 June V 0

 East Cape + 20 June P 186 1 July 0

 Omega Point 20 June V 0

 Cape St. Makarias 20 June V 0

 Column Rocks * 20 June P 71 1 July 52

 Bird 20 June V 0

 Chitka Point 20 June P 21

Ayugadak +* 20 June P 182 1 July 90

Rat 20 June P 28

Little Sitkin 20 June V 0

Segula 20 June V 0

Sea Lion Rocks (Kiska) 20 June P 1

Tanadak (Kiska) 20 June P 54
Table 1.--Counts of adult and juvenile Steller sea lions in Alaska, June and July 2002, continued.

25

Non-pup count Pup count

Location Date Type Count Date Count 

Kiska

 Twin Rocks 20 June P 23

 South Head 20 June V 0

 Gertrude-Bukhti Pt. 20 June V 0

 Sobaka-Vega Pt. 20 June P 54

 Cape St. Stephen +* 20 June P 126 2 July 71

 Lief Cove +* 20 June P 174 2 July 158

 Witchcraft Point 20 June V 0

 Wolf Point 20 June V 4

 Sirius Point 20 June V 0

 Pillar Rock 20 June P 3

Subtotals for the Central Aleutian Islands

All 78 surveyed sites 7,035

35 trend rookery and haul-out sites 5,480

11 trend rookery sites 4,216

Western Aleutian Islands

Buldir +* 20 June P 94 3 July 42

Ingenstrem Rocks 20 June V 0

Shemya 20 June P 34

Nizki 20 June V 0

Alaid + 20 June P 158

Agattu

 Cape Sabak +* 20 June P 307 4 July 212

 Gillon Point +* 20 June P 258 4 July 159

Attu

 Massacre Bay and ‘Dan’s

Rocks’ 20 June V/P 3

 Chirikof Point 20 June P 19

 Chichagof Point 20 June P 62

 Kresta Point 20 June V 0

 Cape Wrangell * 20 June P 264 3 July 75
Table 1.--Counts of adult and juvenile Steller sea lions in Alaska, June and July 2002, continued.

26

Non-pup count Pup count

Location Date Type Count Date Count 

Subtotals for the Western Aleutian Islands

All 12 surveyed sites 1,199

4 trend rookery and haul-out sites 817

3 trend rookery sites 659

Totals for Kenai-to-Kiska index area

All 220 surveyed sites 22,221

70 trend rookery and haul-out sites 16,023

26 trend rookery sites 12,893

Totals for the western stock (west of 144° W)

All 259 surveyed sites 26,602

84 trend rookery and haul-out sites 19,340

30 trend rookery sites 14,320

1

 Pup counts for Fish (Wooded) and Marmot Islands from medium-format, vertical photographs:

Southwest Fisheries Science Center, National Marine Fisheries Service, 8604 La Jolla

Shores Drive, La Jolla, CA 92037. Unpublished data.

2

 “n.s.” indicates sites not surveyed in 2002.

3

 Pup count for Ugamak Island made from observation points at periphery of rookery.

4

 Pup count for Sviechnikof Harbor, Amlia Island, made from oblique digital aerial photographs.
27

Table 2.--Counts of adult and juvenile (non-pup) Steller sea lions at trend rookeries, at all trend

 sites, and at all surveyed sites in the Kenai-to-Kiska index area and Alaska-wide for 

 June-July aerial surveys from 1991 to 2002, including the number of sites (n) surveyed

 in each region in 2002, the percent change from 1991 or 2000 to 2002, estimated

 annual rates of change, upper and lower 95% confidence intervals, and significance (P)

 for the linear regressions.

Kenai-to-Kiska index area Western stock in Alaska

Year

Trend

rookeries

(n=26)

All trend

sites

(n=70)

All surv.

Sites

(n=220)

Trend

rookeries

(n=30)

All trend

sites

(n=84)

All surv.

Sites

(n=259)

1991 17,181 21,726 27,454 21,086 29,405 37,186

1992 16,593 20,692 26,970 19,908 27,299 35,887

1994 14,534 18,736 25,997 16,983 24,136 33,353

1996 13,902 17,891 24,603 16,353 22,210 30,595

1998 12,116 16,417 24,380 14,489 20,438 * 29,475 *

2000 11,738 15,279 21,381 13,402 18,325 25,384

2002 12,893 16,023 22,221 14,320 19,340 26,602

Percent change

2000 to 2002 + 9.84 + 4.87 + 3.93 + 6.85 + 5.54 + 4.80

1998 to 2002 + 6.41 - 2.40 - 8.86 - 1.17 - 5.37 - 9.75

1991 to 2002 - 24.96 - 26.25 - 19.06 - 32.09 - 34.23 - 28.46

Estimated annual rates of change: 1991 to 2002

Annual 

change - 3.24 - 3.09 - 2.20 - 3.94 - 4.15 - 3.43

Upper 

95 % C.I. - 1.42 - 1.99 - 1.40 - 2.32 - 2.78 - 2.45

Lower 

95 % C.I. - 5.05 - 4.18 - 3.00 - 5.55 - 5.52 - 4.41

 P 0.006 < 0.001 < 0.001 0.002 < 0.001 < 0.001

*

 Includes 1999 counts substituted for incomplete 1998 counts in the eastern Gulf of Alaska.
28

Table 3.--Counts of adult and juvenile (non-pup) Steller sea lions observed at rookery and

haul-out trend sites in seven subareas of Alaska during June and July aerial surveys

from 1991 to 2002, including overall percent change from between 1991, 1998, and 2000

to 2002 and estimated annual rates of change from 1991 to 2002.

Gulf of Alaska Aleutian Islands

Kenai to

Kiska

(n=70)

Western

 stock

(n=84) Year Eastern

(n=10)

Central

(n=15)

Western

(n=9)

Eastern

(n=11)

Central

(n=35)

Western

(n=4)

 1991 4,596 6,270 3,732 4,228 7,496 3,083 21,726 29,405

 1992 3,738 5,739 3,716 4,839 6,398 2,869 20,692 27,299

 1994 3,365 4,516 3,981 4,419 5,820 2,035 18,736 24,136

 1996 2,132 3,913 3,739 4,715 5,524 2,187 17,891 22,210

 1998 2,110 * 3,467 3,360 3,841 5,749 1,911 16,417 20,438 *

 2000 1,975 3,180 2,840 3,840 5,419 1,071 15,279 18,325

 2002 2,500 3,366 3,221 3,956 5,480 817 16,023 19,340

Percent change

2000-200

2 + 26.6 + 5.8 + 13.4 + 3.0 + 1.1 - 23.7 + 4.87 + 5.54

1998-200

2 + 18.5 - 2.9 - 4.1 + 3.0 - 4.7 - 57.2 - 2.40 - 5.37

1991-200

2 - 45.6 - 46.3 - 13.7 - 6.4 - 26.9 - 73.5 - 26.25 - 34.23

Estimated annual rates of change: 1991 to 2002

Annual

change -6.6 -6.2 -2.2 -1.6 -2.3 -11.4 -3.1 -4.1

Upper

95 % -1.3 -3.7 -0.2 +0.4 -0.4 -7.1 -2.0 -2.8

Lower

95 % -11.9 -8.7 -4.2 -3.6 -4.2 -15.7 -4.2 -5.5

 P 0.024 0.001 0.038 0.090 0.025 0.001 < 0.001 < 0.001

*

 1999 counts substituted for sites in the eastern Gulf of Alaska not surveyed in 1998. 
29

Table 4.--Counts of adult and juvenile (non-pup) Steller sea lions observed at rookery trend

sites in seven subareas of Alaska during June-July aerial surveys from 1991 to 2002,

including overall percent change from 1991, 1998, and 2000 to 2002 and estimated

annual rates of change from 1991 to 2002.

Gulf of Alaska Aleutian Islands Kenai to

Kiska

(n=26)

Western

stock

(n=30) Year Eastern

(n=1)

Central

(n=4)

Western

(n=4)

Eastern

(n=7)

Central

(n=11)

Western

(n=3)

 1991 1,220 4,336 3,234 3,516 6,095 2,685 17,181 21,086

 1992 784 4,308 3,313 3,712 5,260 2,531 16,593 19,908

 1994 636 3,098 3,155 3,514 4,767 1,813 14,534 16,983

 1996 544 2,795 3,029 3,538 4,540 1,907 13,902 16,353

 1998 730 1 2,255 2,948 2,719 4,194 1,643 12,116 14,489 1

 2000 749 2,157 2,613 2,731 4,237 915 11,738 13,402

 2002 768 2,486 2,920 3,271 4,216 659 12,893 14,320

Percent change

2000-2002 + 2.5 + 15.3 + 11.7 + 19.8 < 1 - 28.0 + 9.84 + 6.85

1998-2002 + 5.2 + 10.2 < 1 + 20.3 < 1 - 59.9 + 6.41 - 1.17

1991-2002 - 37.0 - 42.7 - 9.7 - 7.0 - 30.8 - 75.5 - 24.96 - 32.09

Estimated annual rates of change: 1991 to 2002

Annual

change -2.2 -6.3 -1.6 -2.1 -3.1 -12.1 -3.2 -3.9

Upper

95 % C.I. -- 2 -2.8 -0.4 +0.6 -1.3 -7.5 -1.4 -2.3

Lower

95 % C.I. -- 2 -9.8 -2.8 -4.8 -4.8 -16.6 -5.1 -5.6

P 0.427 0.006 0.020 0.104 0.006 0.001 0.006 0.002

1

 1999 counts substituted for sites in the eastern Gulf of Alaska not surveyed in 1998.

2

 No C.I. reported for P' 0.427.
30

Table 5.--Counts of adult and juvenile (non-pup) Steller sea lions observed at all surveyed

rookery and haul-out sites for seven subareas of Alaska during June and July aerial

surveys from 1991 to 2002, including overall percent change from 1991, 1998, and 2000

to 2002 and estimated annual rates of change from 1991 to 2002.

Gulf of Alaska Aleutian Islands Kenai to

Kiska

(n=220)

Western

 stock

(n=259) Year Eastern

(n=27)

Central

(n=52)

Western

(n=35)

Eastern

(n=55)

Central

(n=78)

Western

(n=12)

 1991 4,812 7,872 5,338 5,285 8,959 4,920 27,454 37,186

 1992 4,386 7,462 5,495 5,711 8,302 4,531 26,970 35,887

 1994 3,989 6,788 5,717 5,875 7,617 3,367 25,997 33,353

 1996 2,585 5,744 5,722 5,967 7,170 3,407 24,603 30,595

 1998 2,230 1 5,022 5,850 5,837 7,671 2,865 24,380 29,475 1

 2000 2,353 4,817 4,568 4,996 7,000 1,650 21,381 25,384

 2002 3,182 4,805 5,023 5,358 7,035 1,199 22,221 26,602

Percent change

2000-2002 + 35.2 < 1 + 10.0 + 7.2 < 1 - 27.3 + 3.92 + 4.80

1998-2002 + 42.7 - 4.3 - 14.1 - 8.2 - 8.3 - 58.2 - 8.86 - 9.75

1991-2002 - 33.9 - 39.0 - 5.9 + 1.4 - 21.5 - 75.6 - 19.06 - 28.46

Estimated annual rates of change: 1991 to 2002

Annual

change -5.7 -5.0 -1.1 -0.5 -1.9 -12.2 -2.2 -3.4

Upper

95 % C.I. +0.1 -3.6 +1.1 -- 2 -0.7 -8.1 -1.4 -2.4

Lower

95 % C.I. -11.5 -6.4 -3.2 -- 2 -3.2 -16.2 -3.0 -4.4

P 0.054 < 0.001 0.263 0.489 0.012 < 0.001 < 0.001 < 0.001

1

 1999 counts substituted for sites in the eastern Gulf of Alaska not surveyed in 1998.

2

 No 95% C.I. reported for P' 0.489.
Table 6.--Counts of Steller sea lion non-pups (adults and juveniles) at principal western stock rookeries in Alask

June and July surveys, 1991 though 2002, including the Chiswell Islands, Nagai Rocks, Jude Island, and Island (Turf Point), haul-out sites where noteworthy numbers of pups have been counted during recent ye

Rookery 1991 1992 1994 1996 1997 1998 1999 2000 Eastern Gulf of Alaska Seal Rocks 1,220 784 636 544 730 624 749 Fish ( Wooded) 1,350 1,005 648 502 330 311 396 Chiswell Islands * 383 240 180 115 79 54 Central Gulf of Alaska Outer 489 378 406 318 224 278 262  Sugarloaf 1,216 1,186 976 741 624 748 706  Marmot 1,458 1,581 1,091 1,102 780 726 671  Chowiet 716 771 599 592 538 515 504  Chirikof 946 770 432 360 294 266 276  Nagai Rocks * 245 362 331 180 204 312 228 Western Gulf of Alaska Atkins 616 792 571 624 544 602 537  Chernabura 650 459 676 422 729 624 496 
Table 6.--Non-pup counts at selected rookeries, 1991-2002, continued.

Rookery 1991 1992 1994 1996 1997 1998 1999 2000  Jude * 363 352 410 355 434 450 391  Pinnacle Rock 1,048 1,092 977 1,026 1,007 864 868  Clubbing Rocks 920 970 931 957 934 858 712 Eastern Aleutian Islands Sea Lion Rock 300 329 480 590 452 444 258  Ugamak (and Round) 1,062 954 971 854 840 742 746  Akun (Billings Head) 156 271 220 346 247 212 254  Akutan (Cape Morgan) 818 1,061 908 934 760 681 739  Bogoslof 558 540 413 382 274 347  Ogchul 228 235 208 155 166 136 117  Adugak 394 322 314 277 230 270 Central Aleutian Islands Yunaska 398 394 462 340 210 241  Seguam (Saddleridge) 684 696 658 553 586 570  Seguam (Turf Point) * 101 146 0 0 82 
Table 6.--Non-pup counts at selected rookeries, 1991-2002, continued.

Rookery 1991 1992 1994 1996 1997 1998 1999 2000  Kasatochi 466 376 288 330 350 390  Adak (Lake Point-Cape Yakak) 847 615 765 618 683 874  Gramp Rock 773 691 537 582 570 580  Tag 440 370 309 320 370 301  Ulak (Hasgox Point) 1,046 1,059 866 844 698 663  Amchitka (Column Rocks) 233 194 188 137 112 92  Ayugadak 324 313 284 281 179 146  Kiska (Lief Cove) 506 357 358 341 284 272  Kiska (Cape St. Stephen) 380 248 232 258 224 152 Western Aleutian Islands Buldir 587 454 344 312 336 129  Agattu (Cape Sabak) 1,428 1,304 961 1,001 826 480  Agattu (Gillon Point) 670 773 508 594 481 306  Attu (Cape Wrangell) 736 754 839 721 584 310 

* Haul-out sites where pups have been observed.
34

Table 7.--Counts of Steller sea lion pups at western stock rookeries and other sites in Alaska

during June and July surveys, 1990 to 2002, including several haul-out sites where

noteworthy numbers of pups have been counted during recent years. Pup counts are

beach counts unless indicated otherwise. Underlined bold face counts are included in

the 2001-2002 regional totals in Table 8.

Rookery 1990 1994 1996 1997 1998 2000 2001 2002

Eastern Gulf of Alaska

 Seal Rocks 571 598 352 487 542 500

 Fish (Wooded) 305 232 123 1 147 2 149 85 1 86 1

 Chiswell Islands 3 58 54

Central Gulf of Alaska

 Outer 363 119 114 106 1 113 108 104 1 58

 Sugarloaf 1,638 958 673 703 490

 Marmot 1,611 804 632 642 466 1 515 1

 Chirikof 607 325 184 187 225

 Nagai Rocks 3 35 1 19

 Chowiet 582 4 625 234 278

Western Gulf of Alaska

 Lighthouse Rocks 3 7

 Atkins 433 324 366 352 262 224

 Chernabura 197 139 54 92

 The Haystacks 3 0

 The Whaleback 3 16

 Jude 3 192 1 119

 Pinnacle Rock 794 5 652 639 634 769

 Clubbing Rocks 547 448 490

Eastern Aleutian Islands

 Sea Lion Rocks (Amak) 134 165 1 160
Table 7.--Counts of Steller sea lion pups in Alaska, 1990-2002, continued.

35

Rookery 1990 1994 1996 1997 1998 2000 2001 2002

 Amak 3 3

 Aiktak 3 10

 Ugamak (including Round) 847 574 706 589 558 570 482 2

 Akun (Billingshead) 63 69 56 41 55

 Akutan (Cape Morgan) 442 631 505 508

 Bogoslof 461 302 6 281 220 249 180

 Ogchul 94 42 47

 Adugak 262 180 135 153 160

Central Aleutian Islands

 Yunaska 230 217 192 161 136 145

 Seguam (Saddleridge) 684 444 463 479 468

 Seguam (Turf Point) 3 30 7 24 23

 Amlia (Sviechnikof Harbor) 26 13 18 8

 Kasatochi 178 215 268 247 302

 Adak (Lake Point) 327 340 363

 Gramp 448 425 456 444

 Tag 357 234 238 153

 Ulak (Hasgox Point) 790 638 521 331

 Semisopochnoi 21 6 3 1 0

 Amchitka (East Cape) 6 9 0

 Amchitka (Column Rocks) 148 114 70 52

 Ayugadak 163 142 89 90

 Kiska (Cape St. Stephen) 212 120 54 71

 Kiska (Lief Cove) 221 233 179 158
Table 7.--Counts of Steller sea lion pups in Alaska, 1990-2002, continued.

36

Rookery 1990 1994 1996 1997 1998 2000 2001 2002

Western Aleutian Islands

 Buldir 381 120 9 120 122 42

 Agattu (Cape Sabak) 379 314 212

 Agattu (Gillon Point) 258 213 159

 Attu (Cape Wrangell) 222 154 75

1

 Count from medium-format photographs: Southwest Fisheries Science Center, National

Marine Fisheries Service, 8604 La Jolla Shores Drive, La Jolla, CA 92037 and Division

of Wildlife Conservation, Alaska Department of Fish and Game, 333 Raspberry Road,

Anchorage, Alaska 99518. Unpublished data.

2

 Counts from observation points at periphery of rookery.

3

 Haul-out sites where pups have been observed.

4

 Mean of 1989 and 1990 counts at Chowiet.

5

 1991 count at Pinnacle Rocks.

6

 Mean of 1993 and 1995 counts at Bogoslof.

7

 1999 count for Seguam (Turf Point).

8

 Count from 35-mm oblique aerial photographs for Amlia (Sviechnikof Harbor) in 2002.

9

 1995 count at Buldir.
Table 8.--Counts of Steller sea lion pups at rookeries in six subareas of the western stock in Alaska from 1990-19

The 2001-2002 composite pup count included 7 counts from 2001and 24 counts from 2002. The 1990-19count included 2 counts from 1991 and 1 from 1992. Blank cells indicate incomplete counts in a region.

Count

year(s)

Gulf of Alaska Aleutian Islands

Kenai

to Kiska

(n=25)

W

s

(

Eastern

(n=2)

Central

(n=5)

Western

(n=4)

Eastern 1

(n=5)

Central 2

(n=11)

Western

(n=4)

1990-1991 4,801 1,857 2,075 3,568 12,301

1994 903 2,831 1,662 1,776 3,109 9,3781996 5841997 610 9791998 689 1,876 1,493 1,474 2,834 803 7,677 9

2001-2002 586 1,566 1,575 1,385 2,577 488 7,103 8

Percent change

1990-1991 to

2001-2002 -67.4% -15.2% -33.3% -27.8% -42.3%

1994 to

2001-2002 -35.1% -44.7% -5.2% -22.0% -17.1% -24.3%

1998 to

2001-2002 -14.9% -16.5% 5.5% -6.0% -9.1% -39.2% -7.5% -1

1 Does not include Sea Lion Rocks (Amak) or Ogchul.2 Does not include Semisopochnoi, Amchitka (East Cape), or Amlia (Sviechnikof Harbor).
38

Figure 1.--Map of Alaska, showing seven geographical regions used for analyses of aerial survey

results and major rookeries. The dashed line indicates 140° W, the demarcation between

the eastern and western stocks of Steller sea lions.
39

Figure 2.--Counts of non-pup (adult and juvenile) Steller sea lions at all surveyed sites, all trend

sites (rookeries and major haulouts), and trend rookeries for the western stock in Alaska,

mid-1970s to 2002. All counts are from aerial surveys.
40

Figure 3.--Numbers of non-pup (adult and juvenile) Steller sea lions counted on rookery and

haul-out trend sites in the Gulf of Alaska (top) and the Aleutian Islands (bottom), 

1990 to 2002.
41

Figure 4.--Numbers of non-pup (adult and juvenile) Steller sea lions counted on trend rookery

sites in the Gulf of Alaska (top) and the Aleutian Islands (bottom), 1990 to 2002. 
42

Figure 5.--Numbers of non-pup (adult and juvenile) Steller sea lions counted on all surveyed

rookery and haul-out sites in the Gulf of Alaska (top) and the Aleutian Islands (bottom),

1990 to 2002. 
43

Figure 6.--Percent change in numbers of non-pup Steller sea lions at western stock rookeries

from 2000 to 2002. Rookeries are arranged geographically from west (left) to east

(right). 
44

Figure 7.--Percent change in numbers of Steller sea lion pups at western stock rookeries from

1998 to 2001-2002. Rookeries are arranged geographically from west (left) to east

(right). 
45

Figure 8.--Counts of Steller sea lion pups at rookeries in Alaska, by region, 1990-1991 to

2001-2002. Counts for individual rookeries and for regional subtotals are provided in

Tables 7 and 8, respectively.
RECENT TECHNICAL MEMORANDUMS

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AFSC130 AYDIN, K. Y., V. V. LAPKO, V. I. RADCHENKO, and P. A. LIVINGSTON. 2002. A comparison of the

eastern and western Bering Sea shelf and slope ecosystems through the use of mass-balance food web

models, 78 p. NTIS No. PB2003-100518.

129 FERRERO, R. C., and L. W. FRITZ. 2002. Steller sea lion research coordination: a brief history and

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128 WEINBERG, K. L., M. E. WILKINS, F. R. SHAW, and M. ZIMMERMANN. 2002. The 2001 Pacific west

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age composition, 140 p. + Appendices. NTIS No. PB2002-108221.

127 MARQUETTE, W. M. 2002. Annotated bibliography of the bowhead whale, Balaena mysticetus, 1767-

1983, 325 p. NTIS No. PB2002-108033.

126 HONKALEHTO, T., W. PATTON, S. DE BLOIS, and N. WILLIAMSON. 2002. Echo integration-trawl

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summer 2000, 66 p. NTIS No. PB2002-104686.

125 HONKALEHTO, T., N. WILLIAMSON,and S. DE BLOIS. 2002. Echo integration-trawl survey results for

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NTIS No. PB2002-104686.

124 ANGLISS, R. P., D. P. DEMASTER,and A.L.LOPEZ.2001. Alaska marine mammal stockassessments,

2001, 203 p. NTIS No. PB2002-105390.

123 ROBSON , B. W. (editor). 2001. Fur seal investigations, 1999, 52 p. NTIS No. PB2002-100418.

122 SEASE, J. L., W. P. TAYLOR, T. R. LOUGHLIN, and K. W. PITCHER. 2001. Aerial and land-based

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No. PB2001-107277.

121 BRITT, L. L., and M. H. MARTIN. 2001. Data report: 1999 Gulf of Alaska bottom trawl survey, 249 p. 

NTIS No. PB2001-105324

120 LAUTH, R. R. 2001. The 2000 Pacific west coast upper continental slope trawl survey of groundfish

resources off Washington, Oregon, and California: Estimates of distribution, abundance, and length

composition, 284 p. NTIS No. PB2001-105327.

119 FERRERO, R. C., HILL, D. P. DEMASTER, P. S. HILL, M. M. MUTO, and A. L. LOPEZ. 2000. Alaska

marine mammal stock assessments, 2000, 191p. NTIS No. PB2001-102015.

118 WILSON, C. D., M. A. GUTTORMSEN, K. COOKE, M. W. SAUNDERS, and R. KIESER. 2000. Echo

integration-trawl survey of Pacific hake, Merluccius productus, off the Pacific coast of the United States

and Canada during July-August, 1998, 103 p. NTIS No. PB2000-108482.

117 ORR, J. W., M. A. BROWN, and D. C. BAKER. 2000. Guide to rockfishes (Scorpaenidae) of the

genera Sebastes, Sebastolobus, and Adelosebastes of the northeast Pacific Ocean, second edition,

47 p. NTIS No. PB2001-100757.

116 WION, D. A., and R. A. MCCONNAUGHEY (editors). 2000. Mobile fishing gear effects on benthic

habitats: A bibliography, 163 p. NTIS No. PB2000-108106.