NOAA Technical Memorandum NMFS-AFSC-153

U.S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Marine Fisheries Service

Alaska Fisheries Science Center

June 2005

by

L. W. Fritz and C. Stinchcomb

Aerial, Ship, and Land-based Surveys

 of Steller Sea Lions (Eumetopias jubatus) 

in the Western Stock in Alaska, 

June and July 2003 and 2004
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 NMFS-NWFSC series is currently used by 

the Northwest Fisheries Science Center. 

This document should be cited as follows: 

Fritz, L. W., and C. Stinchcomb. 2005. Aerial, ship, and land-based 

surveys of Steller sea lions (Eumetopias jubatus) in the western stock 

in Alaska, June and July 2003 and 2004. U.S. Dep. Commer., NOAA 

Tech. Memo. NMFS-AFSC-153, 56 p. 

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

the National Marine Fisheries Service, NOAA. 
NOAA Technical Memorandum NMFS-AFSC-153

Aerial, Ship, and Land-based Surveys

 of Steller Sea Lions (Eumetopias jubatus) 

in the Western Stock in Alaska,

June and July 2003 and 2004

by

 L. W. Fritz1 and C. Stinchcomb2

1

Alaska Fisheries Science Center

National Marine Mammal Laboratory

7600 Sand Point Way N.E.

Seattle, WA 98115

www.afsc.noaa.gov

2

Southwest Fisheries Science Center

Marine Mammal Division

8604 La Jolla Shores Drive

La Jolla CA 92037

U.S. DEPARTMENT OF COMMERCE

Carlos M. Gutierrez, 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 

June 2005
This document is available to the public through: 

National Technical Information Service 

U.S. Department of Commerce 

5285 Port Royal Road 

Springfield, VA 22161 

www.ntis.gov 
ABSTRACT 

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

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

July 2003 and 2004. Survey effort in 2003 consisted of sea lion pup (newborn) counts from land 

or skiff/ship at 13 sites in the eastern Aleutian Islands and in the Gulf of Alaska. Efforts in 2004 

included: (1) a medium-format (MF) photography, vertically-oriented aerial survey of adult and 

juvenile sea lions (non-pups) at 262 sites spanning the entire range of the western stock in 

Alaska, and (2) pup counts from land or skiff/ship at 20 sites in the central and eastern Aleutian 

Islands and in three sub-areas of the Gulf of Alaska. 

Non-pup sea lion population trends in the western stock were analyzed using counts at 

groups of consistently surveyed sites: (1) ‘1970s trend sites’ (n = 93) - surveyed since the mid1970s; (2) ‘1990s trend sites’ (n = 161), a group that includes all the 1970s sites and others 

surveyed since 1991; and (3) Kenai-Kiska trend sites – sites located between 150/W (Kenai 

Peninsula) and 177/E (Kiska Island). In all previous years, non-pups were counted from 

projected 35 mm slides. Comparison of non-pup counts from both 35 mm and MF images taken 

in June 2000 indicated that MF counts tended to be greater than 35 mm counts. To integrate the 

2004 MF with the long-term 35 mm data for sea lion population trend analyses, sub-area totals of 

non-pup counts in 2004 were reduced by 3.64% to account for film format differences in 

resolution and orientation. 

iii 
Non-pup counts at trend sites in the western stock increased 11-12% between 2000 and 

2004. The trend observed between 2000 and 2002 continued from 2002 to 2004. Between 2000 

and 2004, the estimated average annual rate of change at all the 1970s trend sites was +2.9%

 (P < 0.05), while at all 1990s trend sites, the annual rate of change was not significantly different 

from zero. These short-term trend data suggest that the overall decline in the western Steller sea 

lion population may have abated. However, the western population has not significantly 

increased in size and in 2004 was 28-30% smaller than in 1991, and 69% smaller than in 1985 at 

the Kenai-Kiska trend sites. 

Changes in sea lion non-pup counts between 2000 and 2004 have not been uniform across 

the range of the western stock and appear to follow the pattern in sub-area trends observed in the 

1990s. Between 1991 and 2000, the sea lion population in the core of the western stock’s range 

in Alaska (eastern and central Aleutian Islands and western Gulf of Alaska) was relatively stable, 

while the population at the eastern (eastern and central Gulf of Alaska) and western (western 

Aleutian Islands) edges declined considerably. Between 2000 and 2004, the decline in non-pup 

counts slowed at the edges, while increases were observed in the core. 

While there are no recent (2003 or 2004) data for the western and much of the central 

Aleutian Islands, recent regional trends in pup counts were generally similar to those observed in 

non-pup counts. Pup counts in the eastern Aleutian Islands and eastern Gulf of Alaska have 

increased since 1998 but have been relatively stable since 1994 in the western Gulf of Alaska. 

Pup counts have been declining unabated in the central Gulf of Alaska since the 1980s and were 

the lowest on record in 2003-2004. 

iv 
CONTENTS


ABSTRACT ................................................................. iii 


INTRODUCTION ............................................................. 1

METHODS .................................................................. 2

Aerial Survey of Non-Pups ................................................ 2

Comparison of Non-Pup Counts from Medium-


Format and 35 mm Film ............................................ 5

Pup Surveys ............................................................ 6

Pup Count Method Comparison: 1998-2002 Counts from the Beach


 and Medium-Format Film ........................................... 7

Population Trend Analyses ................................................ 8

RESULTS ................................................................... 9

Aerial Survey of Non-Pups ................................................ 9

Pup Surveys ........................................................... 12 


DISCUSSION ............................................................... 14 


ACKNOWLEDGMENTS ...................................................... 16 


CITATIONS ................................................................. 19 


v 

INTRODUCTION 

The Steller sea lion (Eumetopias jubatus) is the largest otariid pinniped species in the 

world (Loughlin et al. 1987, Hoover 1988). It inhabits coastal and continental shelf regions of 

the North Pacific Ocean. Along the eastern and northern Pacific coasts, its breeding range 

extends from central California, north through British Columbia, Canada and southeast Alaska, 

and west through the Gulf of Alaska, Bering Sea, and Aleutian Islands in the United States. 

Along the western Pacific coast, Steller sea lions breed along the Kamchatka Peninsula, on 

various Kuril Islands, and on islands within the Sea of Okhotsk in Russia (Loughlin et al. 1987, 

Hoover 1988). The National Marine Fisheries Service (NMFS) listed Steller sea lions as 

“threatened” range-wide under the U.S. Endangered Species Act (ESA) in November 1990 (55 

Federal Register 49204). Since then, two population stocks have been identified based on 

differences in genetics and population trends (Bickham et al. 1996, Loughlin 1997). The ESA 

listing for the western stock, which breeds on rookeries located from 144/ W (just east of Prince 

William Sound, Alaska) westward to Russia, was changed to “endangered” in June 1997 (62 

Federal Register 24345). The eastern stock, which breeds on rookeries in southeast Alaska 

southward to California, retained its “threatened” ESA-classification (62 Federal Register 

24345). The western stock has been further sub-divided into central and Asian stocks, with the 

boundary occurring west of Russia’s Commander Islands (Bickham et al. 1998). 

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

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

June and July 2003 and 2004. These efforts extend 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, Loughlin et al. 1992, Merrick et al. 1992, Sease 

et al. 1993, Strick et al. 1997, Sease et al. 1999, Sease and Loughlin 1999, Sease et al. 2001, 

Sease and Gudmundson 2002). This report focuses primarily on counts of pups (new-born), and 

adult and juvenile (non-pup; age 1+ years old) Steller sea lions at terrestrial rookery and haul-out 

sites from 1985 to 2004. Longer historical perspectives are included in Merrick et al. (1991: for 

1956-90) and Sease et al. (1993: for 1976-92). Rookeries are those sites where adult male sea 

lions 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). Trends in the size of the sea lion population are determined by 

analyzing time series of pup and non-pup counts at ‘trend’ sites that have been consistently 

surveyed over time. 

METHODS 

Aerial Survey of Non-Pups 

The 2004 Steller sea lion non-pup counts were, for the first time, obtained from mediumformat (MF) vertical photographs. In previous aerial surveys (e.g., Sease and Gudmundson 

2002), adult and juvenile sea lions were counted from projected images of 35 mm photographic 

slides shot obliquely from the side windows of aircraft. Alternatively, if sea lions at a site were 

not numerous (# 10), an airborne observer made only a visual count. In 2004, however, all 

counts were made from MF photographic images taken on 10-29 June 2004 at 262 Steller sea 

2 
lion terrestrial rookeries and haul-out sites from Cape St. Elias (59/ 48’N, 144/ 36’W) to Cape 

Wrangell, Attu Island (52/ 55’N, 172/ 28’E; Fig. 1). 

The 2004 MF aerial photographic survey of non-pup Steller sea lions was conducted by 

the Marine Mammal Division of the NMFS Southwest Fisheries Science Center. The survey was 

conducted with an AeroCommander aircraft (i.e., high-wing, low speed, survey plane) and 

photographs of rookeries and haulouts were taken with a MF (5-inch) military reconnaissance 

camera (with image-motion compensation) mounted in the belly of the aircraft. Photographs 

were taken vertically at altitudes of at least 700 feet between 0900 and 1700 local time when sea 

lions are most likely to be on land (Sease and Gudmundson 2002). Counts of sea lions from MF 

images were made using a dissecting scope (magnification ranging from 2X to 20X) mounted 

over a high intensity light table. 

Analyses of non-pup counts focused on ‘trend’ sites. Trend sites are those rookeries and 

haul-out sites surveyed consistently over a period of time, thus allowing analyses of population 

trends on decadal scales. Three groups of trend sites were used: 

·	 ‘1970s trend sites’ (n = 93): 30 rookeries and 63 haulouts consistently surveyed from the 

1970s to the present. The ‘1970s trend sites’ typically have 70%-80% of all animals 

observed during each survey. 

·	 ‘1990s trend sites’ (n = 161): sites consistently surveyed from 1991 to the present. This 

group includes all the ‘1970s trend sites’, but also includes 68 other rookeries and 

haulouts surveyed routinely since 1991. The ‘1990s trend sites’ typically have 91%-98% 

of all animals observed during each survey. 

3

· “Trend rookeries” (n = 30) are a subset of all rookeries, and are the 30 rookeries included 

in the ‘1970s trend sites’. The only major rookeries not included with the ‘trend 

rookeries’ are located on Outer and Attu Islands. 

The distinction between rookeries and haul-out sites has become blurred in recent years as some 

sites traditionally listed as rookeries have produced few or no pups (e.g., Semisopochnoi Island, 

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

pups have been counted at some haul-out sites (e.g., Chiswell Islands, Jude Island and Kanaga 

Island-Ship Rock). 

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, Loughlin 

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

Loughlin 1999, Sease et al. 2001, Sease and Gudmundson 2002) and those adopted in the Final 

Recovery Plan for Steller sea lions (NMFS 1992). The NMFS aerial survey effort during 2004 

covered six western-stock regions: the eastern, central, and western Gulf of Alaska and the 

eastern, central, and western Aleutian Islands (Fig. 1). Western stock terrestrial sites in the 

Bering Sea region, which contain few haul-out sites and only one rookery (Walrus Island in the 

Pribilof Islands), were not surveyed in 2004. 

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

Kenai Peninsula (Outer Island) to Kiska Island. This index area includes all of the central and 

western Gulf of Alaska, and the eastern and central Aleutian Islands, and encompasses what 

historically was the heart of the Steller sea lions’ range (Merrick et al. 1987, NMFS 1992). The 

4

Kenai-to-Kiska region typically has included between 74% and 88% of the western Alaska sea 

lion population. Except for the distinction between the eastern and western stocks, the 

geographical divisions used in this report are arbitrary and may not accurately reflect the 

underlying structure of the population. We present results for each region to identify and 

highlight varying population trends. However, readers should not think that sea lion populations 

in one region are separate and independent of those in other regions. York et al. (1996), using a 

cluster analysis based on location and similarities in population trends, derived groupings of 

rookeries (from Outer to Attu Islands only; central Gulf of Alaska through western Aleutian 

Islands) that were similar to those used here to present survey results. The only differences 

between the rookery clusters identified by York et al. (1996) and those used here are as follows: 

· York et al. (1996) grouped Atkins Island with the central Gulf of Alaska instead of the 

western Gulf of Alaska, and 

· York et al. (1996) grouped Buldir Island with the central Aleutian Islands instead of the 

western Aleutian Islands. 

Comparison of Non-Pup Counts from Medium Format and 35 mm Film 

From 24 to 29 June 2000, both MF and 35 mm film were used to photograph Steller sea 

lions on 20 rookery and haul-out sites in southeast Alaska, and the eastern and central Gulf of 

Alaska. Adult and juvenile Steller sea lions were counted from both types of film images at each 

site. Photographs were taken on the same day from different aircraft; the MF photograph was 

5

always taken first, followed within minutes by the 35 mm photograph. Differences in counts at 

each site and in aggregate were determined and analyzed using a sign test (Sokal and Rohlf 

1969). 

Pup Surveys 

Pups were counted at 9 rookeries (Ugamak/North, Ugamak/Ugamak Bay, and 

Ugamak/Round were considered a single site) and 4 haul-out sites between 20 June and 5 July 

2003 and at 17 rookeries and 3 haul-out sites from 20 June to 6 July 2004. Numbers of pups on 

all rookeries in the eastern, central and western Gulf of Alaska, and in the eastern Aleutian 

Islands were counted once in either 2003 or 2004. Pups on rookeries west of Adak Island were 

not counted in either 2003 or 2004. This area included all of the western Aleutian Islands (four 

rookeries) and most of the central Aleutian Islands (7 of 11 rookeries). Most pup counts were 

performed by personnel directly on the rookery beach (beach counts), but others were made from 

a skiff or ship just offshore, or from a viewpoint overlooking the rookery beach. Beach counts 

were conducted by two or three people after most sea lions older than pups were safely cleared 

from the beach; all live pups on the beach and in the water were counted. 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, with counts at selected rookeries 

during intervening years. 

6

Pup counts made from overlooks or from a skiff are done at several sites without 

disturbing sea lions off the beach. This is done at sites where only few pups were present or 

where vantage points offered clear views of the entire rookery beach. Shore-based observers 

counted pups daily at Marmot and Ugamak Islands from overlooks in June and July 2003 and 

2004. Pups were counted on two separate beach rookeries on both Marmot and Ugamak Islands. 

Counts at each beach by separate observers were averaged, and the maximum daily sum for each 

island and year is reported here (Ugamak: 2004 only). 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). 

Pup Count Method Comparison: 1998-2002 Counts from the Beach and Medium Format Film 

Pup counts from MF photographs taken at 16 rookery and haul-out sites within the range 

of the western stock in Alaska in late June-early July in 1998, 2000, 2001, and 2002 were 

compared with beach pup counts at the same sites taken within 4 days of each other. There were 

18 comparisons of photographic counts to ground counts since two rookeries were photographed 

twice in the same year and straddled the ground count. Differences in counts at each site and in 

aggregate were determined and analyzed using a sign test (Sokal and Rohlf 1969), with particular 

attention to the order of the surveys. 

7

Population Trend Analyses 

To determine trends in the non-pup population, annual totals of non-pups at ‘1970s trend 

sites’, ‘1990s trend sites’, and trend rookeries were computed for each of the following regions: 

· the western stock in Alaska (Cape St. Elias, 144/W to Attu Island, 172/E); 

· the Kenai-to-Kiska index area (150/W to Kiska Island, 176/E); and 

· within each of the six smaller geographical sub-areas. 

Overall regional changes in numbers of non-pups for various time periods are expressed as a 

percentage of the earlier count. For instance, the percent change in numbers of non-pups at 

‘1970s trend sites’ in the Kenai-Kiska area between 1985 (n = 54,738) and 2000 (n = 15,279) is 

[(15,279-54,738)/54,738] = -72.1%. Estimates of the annual rate of change (AR) for various 

time periods are derived from regression coefficients (m) of log-linear regressions of the natural 

logarithm of the non-pup counts on the survey years; AR = em - 1. Tests of the significance of the 

regression coefficient (H0: m = 0 vs. H1: m ... 0) were done at the 95% level (P < 0.05). 

Trends in pup counts were analyzed only by calculating the percent change in numbers 

for similar time periods and regions used in the non-pup analyses. The lack of annual time series 

for any of the regions precludes further statistical analyses. 

8

RESULTS 

Aerial Survey of Non-Pups 

The June 2004 MF aerial survey resulted in a total count of 29,037 non-pup Steller sea 

lions on all surveyed sites (n = 262) in the western stock in Alaska (Table 1). Of these sites, 131 

(50%) were occupied by more than 20 sea lions, 41 sites (16%) were occupied by 1 to 20 sea 

lions, and 90 sites (34%) were unoccupied. These rates of site occupancy by sea lions in 2004 

were similar to those observed in 2002 (53% had more than 20 sea lions, 13% had 1-20, and 34% 

had none). 

The 2004 aerial survey of non-pup Steller sea lions was the first to use MF vertical 

photogrammetry to obtain counts at all sites (except one), with counts in all previous surveys 

being made visually or from projected 35 mm slide images. For trend analyses, it is necessary to 

construct a consistent time series of counts and to know if the counts from MF and 35 mm 

images are comparable. Counts of non-pup Steller sea lions from 35 mm and MF film taken in 

June 2000 at 20 terrestrial sites were compared (Table 2). As expected, counts from the two film 

formats were highly correlated (Fig. 2A; r2

 = 0.995). However, of the 20 paired counts available, 

the MF count was greater at 17 sites while the 35 mm count was greater at only 3, resulting in a 

skewed distribution of differences (MF-35 mm; Figure 2B). This result was tested against the 

hypothesis that the positive and negative differences were present in equal proportions, where p = 

proportion of differences with MF > 35 mm and q = proportion of differences with 35 mm > MF 

(H0: p = q = 0.5 vs. H1: p > q). Because of the better resolution and the vertical orientation of the 

9

MF images, it was suspected that a MF count would be greater than one from a 35 mm image. 

Therefore, a one-tailed sign test (Sokal and Rohlf 1969) on the distribution of differences was 

performed. The cumulative probability of getting 17 or more positive and 3 or fewer negative 

differences in a sample of 20 is small (0.13%; P < 0.005). Therefore, the null hypothesis is 

rejected and these results suggest that more sea lions were counted on MF than on 35 mm images 

of the same site. 

While MF counts tended to be greater than 35 mm counts, the magnitude of this 

difference was not consistent. The MF count exceeded the 35 mm count by less than 5% at 9 of 

20 sites (45%), by 5%-10% at 6 sites (30%), and by more than 10% at only 2 sites (10%; Table 

2). The average percent difference across all sites (including those where 35 mm > MF) was 

4.19%, which is slightly greater (because of the positively skewed distribution) than the percent 

difference between the 35 mm and MF totals across all sites (3.08%). The true correction factor 

for the 2004 MF counts to make them comparable with the existing time series of 35 mm counts 

may lie between 3.08% and 4.19%. Therefore, for the purposes of population trend analyses, 

2004 MF counts by sub-area and for the entire western stock were reduced by 3.64% (average of 

3.08% and 4.19%) to make them compatible with the existing 35 mm time series. Adjustments 

of 2004 MF counts were not done on a site-by-site basis because of the large range in site-by-site 

percent differences (-2.61% to +17.21%; Table 2). 

The adjusted 2004 total counts of non-pup sea lions in each group of trend sites (1970s, 

1990s, and rookeries) in the Kenai-Kiska area and the western stock were larger than their 

respective 2000 and 2002 counts (Table 3; Fig. 3). Percentage increases from 2000 to 2004 in 

the three groups of trend sites ranged from 10% to 18% in the Kenai-Kiska area, and from 11% 

10

to 16% in the entire western stock in Alaska. Estimated annual rates of change from 2000 to 

2004 were significantly different from zero for four of the six aggregate trend site groups, and 

ranged from +2.4% to +4.2% (Table 3). 

Although recent overall trends have been positive, the 2004 non-pup population is 

considerably smaller than counted in 1985, 1991 or 1996 (Table 3; Fig. 3). All of the 2004 trend 

site group totals were smaller than those of 1996, and the percent changes between 1991 and 

2004 in the Kenai-Kiska area and throughout the Alaskan western stock ranged from -18% to ­

21%, and -28% to -30%, respectively. Looking at the previous 20 years, overall changes 

between 1985 and 2004 in non-pup counts at trend rookeries and ‘1970s trend sites’ in the KenaiKiska area were -65% and -69%, respectively. 

Non-pup numbers at ‘1970s trend sites’ (Table 4; Figs. 4 and 5), ‘1990s trend sites’ 

(Table 5; Fig. 6), and trend rookeries (Table 6; Fig. 7) were greater in five of six sub-areas in 

2004 than in 2002. The only sub-area where 2004 (adjusted) non-pup trend site counts were 

lower than in 2002 was the central Gulf of Alaska. However, while recent trend site counts have 

generally increased, only 2 of 18 estimated annual rates of change between 2000 and 2004 by 

sub-area were significantly different from zero (Tables 4-6), and both were positive and in the 

western Gulf of Alaska. 

The numbers of non-pup sea lions at the edges of the western stock (eastern and central 

Gulf of Alaska and western Aleutian Islands) declined more sharply from 1991 to 2000 than in 

the central portion of its range (Tables 4-6; Fig. 5A). This pattern held for all three of the trend 

site groups and was responsible for the greater declines evident in the western stock as a whole 

than in the Kenai-Kiska index area. Since 2000, much of the central portion of the western 

11

stock’s range has shown an increase in non-pup numbers while trends at the edges have been 

more mixed (Tables 4-6; Fig. 5B). 

Analysis of trends in non-pup numbers at individual rookeries (Table 7) for periods 

including 2004 is confounded by the issue of counts and film format. Absolute counts 

(disregarding film format differences) increased at 20 of 31 principal rookeries between 2002 and 

2004, and each increased by a minimum of 6%. The 20 increasing rookeries were located in 5 of 

the 6 sub-areas, with none occurring in the central Gulf of Alaska. The 11 rookeries that had 

declining numbers of non-pups between 2002 and 2004 included all 4 principal rookeries in the 

central Gulf of Alaska and 7 other rookeries in the western Gulf of Alaska (n = 1), and the 

eastern (n = 1) and central (n = 5) Aleutian Islands. Each of these rookeries had smaller absolute 

non-pup counts in 2004 than in 2002 despite the difference in film format resolution (Table 2). 

The non-pup count at the Yunaska Island rookery in the central Aleutian Islands may have been 

artificially low from disturbance because the aerial survey photographs were taken on the same 

day that a beach count of pups occurred (Table 1). 

Pup Surveys 

During June and July 2003 and 2004, live pups were counted at 27 different rookeries and 

haul-out sites in the eastern and central Aleutian Islands and eastern, central and western Gulf of 

Alaska (Tables 1 and 8). This includes all sites counted from the beach, a skiff or ship offshore, 

or from an overlook by either ship-based or field camp personnel. No rookeries west of Adak 

12

Island in the central Aleutian Islands were visited in 2003 or 20041

. Trends in pup counts for the 

entire western stock in Alaska are available only through 2002 because of the lack of recent 

counts in much of the central and all of the western Aleutian Islands. Trends in pup counts by 

sub-area through 2004 are available only for the three Gulf of Alaska sub-areas and for the 

eastern Aleutians Islands (Table 9; Figs. 8 and 9). Since 1998, pup counts have increased in the 

eastern and western Gulf of Alaska and the eastern Aleutian Islands, but have continued to 

decrease in the central Gulf of Alaska and the central and western Aleutian Islands (through 

2002). 

Pup counts from MF images and from beach counts at the same location were compared 

if they were conducted no more than 4 days apart (Table 10 and Fig. 10). Paired counts were 

highly correlated (r2 = 0.99; Fig. 10A). In addition, there was little pattern associated with the 

differences between pairs of counts (Fig. 10B). A two-tailed sign test (Sokal and Rohlf 1969) 

was performed on these proportions, where p = proportion of differences with MF > beach and 

q = proportion of differences with beach > MF (H0: p = q = 0.5 vs. H1: p ... q). The cumulative 

probability of getting the observed distribution is high (48%; P > 0.5). Therefore, the null 

hypothesis cannot be rejected and these results suggest that one technique did not systematically 

yield higher sea lion pup counts than the other. 

Pup counts were also analyzed to determine if the order in which the surveys were 

conducted affected the count. Since disturbance to the animals from beach counts exceeds that 

of aerial surveys, counts may be most similar in instances when the MF survey preceded the 

1

 An incomplete beach count was conducted on Lake Point, Adak Island on 21 June 2004, and the total

 (n = 295) is considered an underestimate of the actual number of pups present and is not reported in Tables 

1 or 8. 

13 
beach count (assuming that the disturbance associated with the beach count itself did not reduce 

the number of pups on the beach). There were 14 paired observations when the MF survey 

occurred 1-4 days prior to the beach count (Table 10; MF count < beach count for 9 pairs; MF 

count $ beach count for 5 pairs). The cumulative probability of getting the observed distribution 

and the result of the two-tailed sign test (Sokal and Rohlf 1969) were similar to those when all 

the data were analyzed (42%; P > 0.5). For the four pairs of counts when the MF survey 

occurred 1-4 days after the beach count, the MF count was less than the beach count in two, 

equal in one and greater in one. Even though there are limited data to address situations where 

the MF survey occurred after the beach count, these analyses suggest that the order in which the 

surveys occurred did not affect the sign of the difference between the counts. 

DISCUSSION 

From 1989 to 2000, the western population of Steller sea lions in Alaska, as indexed by 

counts of adults and juveniles at trend sites, declined at an average rate of about 5% per year 

(Sease et al. 2001), and at rates as high as 15% per year in the late 1980s (Merrick et al. 1991). 

Since 2000, index counts of sea lions have increased. Sease and Gudmundson (2002) reported a 

5.5% increase in western stock non-pup numbers at trend sites between 2000 and 2002, and data 

reported here suggest that this trend continued between 2002 and 2004. Annual rates of increase 

between 2000 and 2004 at trend sites, while not all significantly different from zero, were in the 

range of +2.4% to +4.2%. Thus, evidence from two consecutive surveys suggests that the 

decline in the western stock of Steller sea lions as a whole has abated. 

14

While increases in non-pups between 2000 and 2002 occurred throughout the range of the 

western stock (Sease and Gudmundson 2002), 2004 counts in the central Gulf of Alaska were the 

lowest on record and those in the western Aleutian Islands and eastern Gulf of Alaska were 

largely unchanged from 2002. Therefore, the 2000-2004 increases in aggregate Kenai-Kiska or 

Alaskan western stock indices were driven by changes in the western Gulf of Alaska and eastern 

and central Aleutian Islands populations. Throughout the 1990s, non-pup counts in this central 

part of the range were generally stable or only slightly decreasing, while at the ends, they 

declined at much faster rates. While declines at the edges of the Alaskan western stock appear to 

have slowed, they do not appear to have stopped, particularly in the central Gulf of Alaska. 

Therefore, there is considerable geographic variation in the recent trends in non-pup Steller sea 

lion numbers in the Alaskan western stock, and it is not possible to make conclusions regarding 

broad-based stability or recovery of the population. 

Regional trends in pup numbers, where available, largely support the observed non-pup 

trends. Pup counts in the eastern Aleutians and at rookeries visited in the central Aleutians (east 

of Adak Island) have shown recent increases. However, pup counts in the western Gulf of 

Alaska have been largely constant since 1994, while they have continued to decline in the central 

Gulf of Alaska. 

Integration of non-pup counts from MF images into the existing time series of counts 

from 35 mm slides requires further study. The non-pup count comparisons reported here suggest 

that counts from MF images are higher, but the magnitude of the correction factor, particularly on 

a site-by-site basis is uncertain. Differences in terrain and substrate between sites may yield a 

different relationship between 35 mm and MF counts, and therefore, different correction factors. 

15

The non-pup correction factor for MF aggregate counts used in this report (-3.64%) is considered 

provisional and will be investigated further in a comparative study planned for 2005. 

In comparison to the non-pup time series, there are fewer data available for comparison of 

MF counts and beach counts of pups. However, based on these limited analyses, as well as those 

of Snyder et al. (2001), the two techniques yield similar results and neither tended to produce 

greater or smaller counts than the other. This suggests that MF photogrammetry could yield an 

index of pup counts throughout the range of the western stock in Alaska that is consistent with 

the existing beach count time series if the survey time frames are similar. Additional 

comparisons of MF and beach counts of pups are planned for 2005. 

ACKNOWLEDGMENTS 

We thank the pilots of Commander Northwest for aircraft transportation during the aerial 

survey, and M. Lynn who participated in the survey. We thank the captain and crew of the R/V 

Tiglax 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 K. Sundseth 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. Many individuals including NMFS personnel and cooperating scientists participated in 

pup counts on ship-based surveys and from field camps. T. Gelatt, E. Logerwell and R. Towell 

provided comments on early drafts of the manuscript, and G. Duker and J. Lee provided editorial 

16

support. This fieldwork was conducted 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. 

17


CITATIONS


Bickham, J. W., J. C. Patton, and T. R. Loughlin. 1996. High variability for control-region 

sequences in an marine mammal: implications for conservation and biogeography of 

Steller sea lions (Eumetopias jubatus). J. Mammal. 77(1): 95-108. 

Bickham, J. W., T. R. Loughlin, J. K. Wickliffe, and V. N. Burkanov. 1998. Genetic variation 

in the mitochondrial DNA of Steller sea lions: haplotype diversity and endemism in the 

Kuril Islands. Biosphere Conserv. 1:107-117. 

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. 

Hoover, A. A. 1988. Steller sea lion (Eumetopias jubatus), pp. 159-193. In J. W. Lentfer (ed.), 

Selected marine mammals of Alaska: Species accounts with research and management 

recommendations. U.S. Marine Mammal Commission, Washington, D. C. 275 p. 

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 (eds.), Molecular genetics of 

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

Loughlin, T. R., M.A. Perez, and R. L. Merrick. 1987. Eumetopias jubatus. Mammalian Species 

Account No. 283. Publ. By Amer. Soc. Mammalogists. 7 p. 

19

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 shipbased 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. 

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. 

20 
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 shipbased 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. 

Sokal, R. R., and F. J. Rohlf. 1969. Biometry. W.H. Freeman and Co., San Francisco. 

Snyder, G. M., K. W. Pitcher, W. L. Perryman, and M. S. Lynn. 2001. Counting Steller sea lion 

pups in Alaska: an evaluation of medium-format, color aerial photography. Mar. Mamm. 

Sci. 17: 136-146. 

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. 

21

York, A. E., R. L. Merrick, and T. R. Loughlin. 1996. An analysis of the Steller sea lion 

metapopulation in Alaska, pp. 259-292 In D. R. McCullough (ed.), Metapopulations and 

Wildlife Conservation. Island Press, Washington, D.C. 

22

Table 1.--Counts of Steller sea lions at rookery (R) and haul-out sites in Alaska, June and 

July 2003 and 2004. All adult and juvenile (non-pup) counts are from mediumformat photographs taken vertically over each site in June 2004. Pup counts are 

from on-site beach counts (B), from a skiff or ship just offshore (S), or from a 

land-based overlook (O; Type) in June and July 2003 and 2004. Trend (T) and 

1990s trend (90T) sites are those sites used for analyses of trends in survey 

counts. M = Month (June = 6, July = 7); D = Day.

 Non-Pups Pups 

Site Name M D Count M D Year Count Type 

Eastern Gulf of Alaska 

CAPE ST. ELIAS (T, 90T) 6 29 318 

HOOK POINT 6 10 96 

CAPE HINCHINBROOK (90T) 6 10 496 

SEAL ROCKS (R, T, 90T) 6 29 841 7 4 2003 543 B 

WOODED (FISH) (R, T, 90T) 6 29 523 7 3 2003 173 B 

MIDDLETON 6 10 4 

GLACIER (T, 90T) 6 10 620 

THE NEEDLE (T, 90T) 6 10 123 7 5 2003 7 S 

POINT LaTOUCHE 6 10 0 

DANGER 6 10 12 

POINT ELRINGTON (T, 90T) 6 10 132 7 5 2003 2 S 

PROCESSION ROCKS 6 10 36 

CAPE PUGET (90T) 6 10 0 

CAPE JUNKEN 6 10 0 

CAPE FAIRFIELD (90T) 6 10 0 

CAPE RESURRECTION 6 10 3 

RUGGED (T, 90T) 6 10 0 

AIALIK CAPE (90T) 6 10 1 

CHISWELL ISLANDS (T, 90T) 6 10 72 

GRANITE CAPE 6 10 1 

SEAL ROCKS (KENAI) (T, 90T) 6 10 3 

STEEP POINT 6 10 1 

RABBIT 6 10 0 

Eastern Gulf of Alaska Total 3,282 

Central Gulf of Alaska 

OUTER (PYE) (R, 90T) 6 10 222 7 5 2004 59 S,O 

NUKA POINT 6 10 0 

GORE POINT (90T) 6 11 0 

EAST CHUGACH (90T) 6 11 0 

PERL (90T) 6 10 49 

PERL ROCKS 6 11 0 

NAGAHUT ROCKS (90T) 6 11 1 

ELIZABETH/CAPE ELIZABETH (90T) 6 26 28 

23 

Table 1.--(Continued). 

Non-Pups Pups 

Site Name M D Count M D Year Count Type 

Central Gulf of Alaska (continued) 

FLAT 6 10 4 

WEST AMATULI 6 11 0 

SUGARLOAF (R, T, 90T) 6 25 667 7 6 2004 488 B,S,O 

USHAGAT/NW (T, 90T) 6 25 3 

USHAGAT/SW (T, 90T) 6 25 101 

USHAGAT/ROCKS SOUTH (T, 90T) 6 25 8 

SUD 6 11 0 

LATAX ROCKS (T, 90T) 6 11 56 

SEA OTTER (90T) 6 24 127 

RK NEAR SEA OTTER (90T) 6 24 10 

AFOGNAK/TONKI CAPE (90T) 6 24 0 

SEA LION ROCKS (MARMOT) (T, 90T) 6 25 2 

MARMOT (R, T, 90T) 7 6 2003 505 O 

MARMOT (R, T, 90T) 6 26 703 6 26 2004 474 O 

LONG ISLAND (T, 90T) 6 24 32 

KODIAK/CAPE CHINIAK (T, 90T) 6 25 87 

UGAK (90T) 6 26 0 

KODIAK/GULL POINT (90T) 6 26 109 

KODIAK/CAPE BARNABAS (T, 90T) 6 26 0 

TWOHEADED (T, 90T) 6 26 266 6 29 2003 20 S 

SITKINAK/CAPE SITKINAK (T, 90T) 6 26 80 

KODIAK/SUNDSTROM 6 11 0 

KODIAK/CAPE ALITAK 6 11 0 

KODIAK/CAPE IKOLIK 6 11 108 

KODIAK/TOMBSTONE ROCKS 6 11 0 

KODIAK/CAPE KULIUK 6 11 0 

KODIAK/CAPE UGAT (90T) 6 24 2 

NOISY 6 24 0 

KODIAK/MALINA POINT 6 24 0 

KODIAK/STEEP CAPE (90T) 6 24 0 

KODIAK/CAPE PARAMANOF 6 24 0 

SHAW 6 11 81 

CAPE DOUGLAS 6 11 0 

SHAKUN ROCKS (90T) 6 11 104 

CAPE NUKSHAK 6 11 0 

CAPE UGYAK 6 11 0 

CAPE GULL 6 11 0 

TAKLI (90T) 6 11 85 

PUALE BAY (90T) 6 11 58 

KILOKAK ROCKS 6 26 85 

AIUGNAK COLUMNS 6 26 1 

 24 
Table 1. --(Continued). 

Non-Pups Pups 

Site Name M D Count M D Year Count Type 

Central Gulf of Alaska (continued) 

UGAIUSHAK (T, 90T) 6 26 0 

SUTWIK (T, 90T) 6 26 206 

AGHIYUK 6 12 27 

CHOWIET (R, T, 90T) 6 12 541 6 28 2003 368 O 

CHIRIKOF (R, T, 90T) 6 26 303 7 1 2004 189 B 

NAGAI ROCKS (90T) 6 26 330 7 1 2004 22 S 

Central Gulf of Alaska Total 4,486 

Western Gulf of Alaska 

LIGHTHOUSE ROCKS (90T) 6 12 111 

ATKULIK 6 12 0 

KAK (90T) 6 12 17 

CHANKLIUT 6 12 0 

SEAL CAPE 6 12 0 

MITROFANIA (90T) 6 12 182 

SPITZ (T, 90T) 6 12 1 

KUPREANOF POINT (90T) 6 12 53 

CASTLE ROCK (T, 90T) 6 12 70 

BIG KONIUJI 6 12 0 

ATKINS (R, T, 90T) 6 12 651 6 30 2004 266 B,O 

CHERNABURA (R, T, 90T) 6 12 828 6 27 2003 82 B 

TWINS 6 12 0 

THE HAYSTACKS (90T) 6 12 38 

THE WHALEBACK (90T) 6 12 102 

NAGAI/MOUNTAIN POINT (T, 90T) 6 12 80 

NAGAI/RK W OF CAPE WEDGE 6 12 0 

EGG (SAND POINT) 6 12 0 

SEA LION ROCKS (SHUMAGINS) (T, 

90T) 6 12 36 

UNGA/CAPE UNGA 6 12 0 

UNGA/ACHEREDIN POINT (90T) 6 12 264 

JUDE (90T) 6 12 474 6 29 2004 187 B,O 

OMEGA 6 12 0 

WOSNESENSKI 6 12 166 

OLGA ROCKS NE 6 12 11 

OLGA ROCKS SW 6 12 117 

SUSHILNOI ROCKS 6 12 290 

PINNACLE ROCK (R, T, 90T) 6 12 1,011 6 29 2004 663 B 

HUNT 6 12 0 

SOZAVARIKA 6 12 0 

UMGA 6 12 0 

 25 
Table 1. --(Continued). 

Non-Pups Pups 

Site Name M D Count M D Year Count Type 

Western Gulf of Alaska (continued) 

CLUBBING ROCKS (R, T, 90T) 6 12 911 6 26 2003 566 B 

CHERNI (90T) 6 12 0 

HAGUE ROCK 6 12 0 

CATON 6 12 109 

SOUTH ROCKS (90T) 6 12 528 

SANAK 6 12 0 

BIRD (T, 90T) 6 12 57 

ROCK (90T) 6 12 17 

Western Gulf of Alaska Total 6,124 

Eastern Aleutian Islands 

UNIMAK/CAPE LAZAREF 6 12 0 

UNIMAK/CAPE LUTKE 6 12 0 

UNIMAK/SCOTCH CAP 6 12 0 

UNIMAK/SENNETT POINT 6 12 0 

UNIMAK/CAPE SARICHEF (90T) 6 14 250 

AMAK+ROCKS (T, 90T) 6 24 733 

SEA LION ROCK (AMAK) (R, T, 90T) 6 24 456 6 27 2004 185 B 

UGAMAK/NORTH (R, T, 90T) 6 25 2003 352 B 

UGAMAK/NORTH (R, T, 90T) 6 14 644 7 3 2004 272 O 

UGAMAK/UGAMAK BAY (R, T, 90T) 6 24 2003 295 O 

UGAMAK/UGAMAK BAY (R, T, 90T) 6 14 575 7 3 2004 242 O 

UGAMAK/ROUND (R, T, 90T) 6 25 2003 39 S 

UGAMAK/ROUND (R, T, 90T) 6 14 85 6 28 2004 27 O 

AIKTAK (90T) 6 14 101 6 28 2004 7 S 

KALIGAGAN 6 14 1 

TIGALDA/ROCKS NE (90T) 6 14 141 

TIGALDA/SOUTH SIDE (90T) 6 14 46 

BASALT ROCK 6 14 1 

ROOTOK/EAST (90T) 6 14 31 

ROOTOK/NORTH (90T) 6 14 65 

TANGINAK (90T) 6 14 4 

AKUN/JACKASS POINT 6 14 0 

AKUN/AKUN BAY 

AKUN/BILLINGS HEAD (R, T, 90T) 

6 

6 

14 

14 

0 

3071 6 26 2004 85 B 

AKUN/AKUN HEAD 6 14 0 

AKUTAN/REEF-LAVA (T, 90T) 6 14 119 

AKUTAN/CAPE MORGAN (R, T, 90T) 6 14 1,021 6 22 2003 497 B 

1

 In 2004, the count from Akun/Billingshead Rookery was made from projected 35 mm image shot 

obliquely from the side window of the aircraft 

26 
Table 1. --(Continued). 

Non-Pups Pups 

Site Name M D Count M D Year Count Type 

Eastern Aleutian Islands (continued) 

AKUTAN/BATTERY POINT 6 14 0 

BABY 6 14 0 

OLD MAN ROCKS (90T) 6 14 71 

EGG (90T) 6 14 5 

OUTER SIGNAL (90T) 6 14 0 

INNER SIGNAL 6 14 38 

UNALASKA/CAPE SEDANKA (90T) 6 14 0 

UNALASKA/PRIEST ROCK 6 23 0 

UNALASKA/CAPE WISLOW 6 23 0 

UNALASKA/BISHOP POINT (90T) 6 23 265 6 20 2003 2 S 

UNALASKA/KOVRIZHKA 6 23 0 

UNALASKA/MAKUSHIN BAY (90T) 6 23 20 

UNALASKA/CAPE STARICHKOF 6 23 0 

UNALASKA/SPRAY CAPE (90T) 6 23 0 

UNALASKA/WHALEBONE CAPE 6 14 0 

UNALASKA/CAPE IZIGAN (90T) 6 14 238 

BOGOSLOF/FIRE ISLAND (R, T, 90T) 6 23 380 6 25 2004 278 B 

UMNAK/CAPE ASLIK (T, 90T) 6 14 119 

EMERALD 6 14 0 

POLIVNOI ROCK (90T) 6 14 91 

THE PILLARS (90T) 6 14 4 

OGCHUL (R, T, 90T) 6 14 139 6 21 2003 69 B 

VSEVIDOF (T, 90T) 6 14 48 

SAMALGA 6 14 1 

ADUGAK (R, T, 90T) 6 14 259 6 24 2004 185 B 

Eastern Aleutian Islands Total 6,258 

Central Aleutian Islands 

ULIAGA (T, 90T) Not surveyed 

KAGAMIL (T, 90T) 6 23 1 

CHUGINADAK (T, 90T) 6 23 129 

CARLISLE (T, 90T) 6 23 0 

HERBERT (T, 90T) 

YUNASKA (R, T, 90T) 

6 

6 

23 

23 

38 

2602

 6 23 2004 145 B 

CHAGULAK (T, 90T) 6 23 0 

AMUKTA+ROCKS (T, 90T) 6 23 2 

SEGUAM/FINCH POINT (T, 90T) 6 23 2 

SEGUAM/SW RIP (T, 90T) 6 23 40 

SEGUAM/SADDLERIDGE (R, T, 90T) 6 23 923 6 22 2004 517 B 

SEGUAM/TURF POINT (T, 90T) 6 23 58 

2

 Possibly a low non-pup count because of the on-land disturbance related to the pup count on the same 

day. 

27 
 Table 1. --(Continued) 

Non-Pups Pups 

Site Name M D Count M D Year Count Type 

Central Aleutian Islands (continued) 

SEGUAM/LAVA COVE (T, 90T) 6 23 0 

SEGUAM/LAVA POINT (T, 90T) 6 23 5 

SEGUAM/WHARF POINT (T, 90T) 6 23 90 

AGLIGADAK (R, T, 90T) 6 15 61 6 22 2004 2 S 

AMLIA/EAST CAPE (T, 90T) 6 15 34 

AMLIA/CAPE MISTY 6 15 21 

AMLIA/SVIECH. HARBOR (R, 90T) 6 15 144 6 22 2004 28 O 

TANADAK (AMLIA) (T, 90T) 6 15 1 

SAGIGIK (T, 90T) 6 15 30 

ATKA/NORTH CAPE (T, 90T) 6 15 383 

ATKA/CAPE KOROVIN (T, 90T) 6 15 4 

SALT (T, 90T) 6 15 0 

KONIUJI/NORTH POINT 6 15 0 

KASATOCHI/NORTH POINT (R, T, 90T) 6 15 667 6 20 2004 354 B 

OGLODAK (90T) 6 15 86 

IKIGINAK (T, 90T) 6 15 0 

FENIMORE (90T) 6 15 30 

TAGALAK 6 15 91 

CHUGUL 6 15 39 

ANAGAKSIK (T, 90T) 6 15 2 

IGITKIN/SW POINT 6 15 0 

GREAT SITKIN (90T) 6 15 0 

LITTLE TANAGA STRAIT (T, 90T) 6 15 49 

SILAK 6 15 38 

KAGALASKA (90T) 6 15 48 

ADAK/CAPE MOFFET (T) 6 15 0 

ADAK/ARGONNE POINT (T) 6 15 35 

ADAK/LAKE POINT (R, T, 90T) 6 15 799 

ADAK/CAPE YAKAK (R, T, 90T) 6 15 209 6 21 2004 4 S 

ADAK/CRONE ISLAND 6 14 0 

KANAGA/N CAPE (90T) 6 15 7 

KANAGA/CAPE MIGA (90T) 6 15 0 

KANAGA/SHIP ROCK (90T) 6 15 229 

KANAGA/CAPE CHUNU 6 23 9 

BOBROF 6 23 49 

TANAGA/BUMPY POINT (90T) 6 23 33 

TANAGA/CAPE SASMIK (90T) 6 23 122 

ILAK 6 23 45 

GRAMP ROCK (R, T, 90T) 6 23 679 

UGIDAK (T, 90T) 6 23 25 

TAG (R, T, 90T) 6 23 242 

OGLIUGA 6 23 49 

 28 
Table 1. --(Continued) 

Non-Pups Pups 

Site Name M D Count M D Year Count Type 

Central Aleutian Islands (continued) 

SKAGUL/S. POINT 6 23 1 

KAVALGA (T, 90T) 6 23 56 

UNALGA+DINKUM ROCKS (T, 90T) 6 23 19 

ULAK/HASGOX POINT (R, T, 90T) 6 23 531 

AMATIGNAK/KNOB POINT (90T) 6 23 1 

AMATIGNAK/NITROF POINT (T, 90T) 6 23 76 

SEMISOPOCHNOI/POCHNOI (R, 90T) 6 20 55 

SEMISOPOCHNOI/PETREL (R) 6 20 0 

SEMISOPOCHNOI/TUMAN POINT 6 20 0 

SEMISOPOCHNOI/SW KNOB 6 20 17 

AMCHITKA/CAPE IVAKIN (T, 90T) 6 20 0 

AMCHITKA/EAST CAPE (T, 90T) 6 23 178 

AMCHITKA/OMEGA POINT 6 23 0 

AMCHITKA/ST. MAKARIUS (90T) 6 23 0 

AMCHITKA/COLUMN ROCK (R, 90T) 6 20 85 

AMCHITKA/BIRD 6 20 0 

AMCHITKA/CHITKA POINT 6 20 0 

AYUGADAK (R, T, 90T) 6 20 152 

RAT (90T) 6 20 45 

SEA LION ROCK (KISKA) (90T) 6 20 0 

TANADAK (KISKA) (90T) 6 20 34 

TWIN ROCKS (KISKA) 6 20 13 

KISKA/SOUTH HEAD 6 24 0 

KISKA/GERTRUDE-BUKHTI 6 20 0 

KISKA/SOBAKA-VEGA (90T) 6 20 101 

KISKA/CAPE ST STEPHEN (R, T, 90T) 6 20 210 

KISKA/LIEF COVE (R, T, 90T) 6 20 170 

KISKA/WITCHCRAFT POINT 6 20 0 

KISKA/PILLAR ROCK (90T) 6 20 0 

Central Aleutian Islands Total 7,552 

Western Aleutian Islands 

BULDIR/EAST CAPE (90T) 6 21 0 

BULDIR/ROOKERY (R, T, 90T) 6 21 72 

BULDIR/NW ROCKS (R, T, 90T) 6 21 36 

INGENSTREM ROCKS 6 21 0 

SHEMYA (90T) 6 16 17 

NIZKI 6 16 0 

ALAID (T, 90T) 6 16 125 

AGATTU/CAPE SABAK (R, T, 90T) 6 21 325 

AGATTU/GILLON POINT (R, T, 90T) 6 21 374 

 29 
Table 1. --(Continued). 

Non-Pups Pups 

Site Name M D Count M D Year Count Type 

Western Aleutian Islands (continued) 

DAN'S ROCKS 6 17 0 

ATTU/MASSACRE BAY (90T) 6 17 0 

ATTU/CHIRIKOF POINT (90T) 6 17 75 

ATTU/CHICHAGOF POINT (90T) 6 17 54 

ATTU/KRESTA POINT (90T) 6 17 0 

ATTU/CAPE WRANGELL (R, 90T) 6 21 257 

Western Aleutian Islands Total 1,335 

Western Stock in Alaska Total 29,037 

 30 
Table 2.--Counts of non-pup Steller sea lions from 35 mm (shot obliquely from side 

window of aircraft) and medium-format (MF; shot vertically) photographs taken 

at various sites in southeast Alaska, and eastern and central Gulf of Alaska in June 

2000. Photographs were taken on the same day, minutes apart at each site. The 

medium-format photograph was always taken first. The percent difference 

((Medium-35mm)/35 mm =% Diff) for each site is calculated along with the 

aggregate totals and percent difference for all sites. Time is Alaska Daylight 

Time, HH:MM. 

Film Format 

Location Date Time 35 mm MF % Diff 

Fish I. 6/24/2000 10:10 408 421 3.31 

Seal Rocks (PWS) 6/24/2000 10:30 820 846 3.23 

Graves Rock 6/24/2000 14:25 492 558 13.53 

White Sisters 6/24/2000 15:10 1,398 1,361 -2.61 

Jacob Rock 6/24/2000 15:52 233 228 -1.94 

Biali Rock 6/24/2000 16:10 662 669 1.13 

Sea Lion Rock (Puffin) 6/24/2000 16:38 212 213 0.71 

Cape Ommaney 6/24/2000 16:54 289 305 5.72 

West Rock 6/25/2000 11:24 625 732 17.21 

Sea Lion Rock 6/28/2000 15:25 507 557 9.86 

North Rock 6/28/2000 15:35 1,202 1,221 1.58 

East Rock 6/28/2000 15:43 193 203 5.45 

Lowrie I. 6/28/2000 15:50 1,213 1,228 1.24 

Cape Addington 6/28/2000 16:26 1,116 1,180 5.73 

Timbered I. 6/28/2000 16:50 267 287 7.69 

Hazy I. 6/28/2000 17:18 1,824 1,885 3.34 

SW Brother 6/28/2000 18:12 1,499 1,461 -2.50 

Outer I. 6/29/2000 11:37 308 328 6.67 

Sugarloaf I. 6/29/2000 12:55 746 756 1.34 

Marmot I. 6/29/2000 13:50 699 720 3.08 

Total 14,706 15,159 3.08 

Average of site by site % differences 4.19 

31 

Table 3.--Counts of adult and juvenile (non-pup) Steller sea lions observed at trend rookeries, 1970s and 1990s tr

surveyed (surv.) sites in the Kenai-to-Kiska area and throughout the western stock in Alaska during June surveys from 1985 to 2004. Also shown are overall percent changes between various pairs of years, and 

of change between 1991 and 2000 and between 2000 and 2004. Annual rates of change that are significazero (P < 0.05) are shown in bold. Totals at trend sites in 2004 (*) have been adjusted to account for film 

differences (see text). 

 Kenai-to-Kiska Index Area Western Stoc

Year 

Trend 

Rookeries 

1970s 

Trend Sites 

1990s 

Trend Sites 

All Surv. 

Sites 

Trend 

Rookeries 

1970s 

Trend Site

1985 39,390 54,738 67,336 

1990 18,791 22,754 26,219 1991 17,181 21,726 27,149 27,454 22,436 29,405 1992 16,577 20,692 25,811 26,970 20,897 27,299 1994 14,536 18,736 24,796 25,997 17,633 24,136 1996 13,902 17,891 23,091 24,603 16,855 22,210 

1998** 12,116 16,417 22,964 24,380 14,819 20,438 

2000 11,738 15,279 20,101 21,381 13,798 18,325 2002 12,893 16,023 21,018 22,221 14,716 19,340 

2004* 13,860 17,099 22,137 24,420 15,952 20,533 

Percent change 

1985-2000 -70.2% -72.1% 1985-2004 -64.8% -68.8% 1991-2000 -31.7% -29.7% -26.0% -38.5% -37.7% 1991-2004 -19.3% -21.3% -18.5% -28.9% -30.2% 2000-2004 18.1% 11.9% 10.1% 15.6% 12.1% 

Estimated annual rates of change: 1991 to 2000 

Annual Change -4.3% -3.8% -2.9% -5.2% -4.9% 

+95%CI -3.4% -3.3% -1.9% -4.1% -4.3% 

-95% CI -5.3% -4.2% -3.9% -6.3% -5.5% 

P < 0.001 < 0.001 < 0.01 < 0.001 < 0.001 

32 
Table 3. --(Continued) 

 Kenai-to-Kiska Index Area Western Stoc

Year 

Trend 

Rookeries 

1970s 

Trend Sites 

1990s 

Trend Sites 

All Surv. 

Sites 

Trend 

Rookeries 

1970s 

Trend Site

Estimated annual rates of change: 2000 to 2004 

Annual Change 4.2% 2.9% 

+95%CI 8.4% 6.2% 

-95% CI 0.2% -0.4% 

P < 0.05 > 0.05 

2.4% 

3.8% 

1.1% 

< 0.05 

3.7%

6.8% 

0.7% 

< 0.05 

2.9% 

4.0% 

1.8% 

< 0.05 

** For eastern Gulf of Alaska in 1998, counts made in 1999 were substituted for those sites not surveyed in 1998

33 
Table 4.--Counts of adult and juvenile (non-pup) Steller sea lions observed at 1970s trend 

sites in seven sub-areas of Alaska during June and July aerial surveys from 1985 

to 2004. Also shown are overall percent changes between various pairs of years 

and estimated annual rates of change between 1991 and 2000 and between 2000 

and 2004. Annual rates of change that are significantly different from zero 

(P < 0.05) are shown in bold. ND = no data. Data shown for 2004(*) have been 

adjusted to account for film format-count differences (see text). 

Gulf of Alaska Aleutian Islands Western 

Kenai to Stock in 

Year Eastern Central Western Eastern Central Western Kiska AK 

1985*** ND 19,002 6,275 7,505 21,956 4,526 54,738 

1990 5,444 7,050 3,915 3,801 7,988 ND 22,754 

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 

2004* 2,536 2,944 3,512 4,707 5,936 898 17,099 20,533 

Percent change 

1985-2000 -83.3% -54.7% -48.8% -75.3% -76.3% -72.1% 

1985-2004 -84.5% -44.0% -37.3% -73.0% -80.2% -68.8% 

1991-2000 -57.0% -49.3% -23.9% -9.2% -27.7% -65.3% -29.7% -37.7% 

1991-2004 -44.8% -53.0% -5.9% 11.3% -20.8% -70.9% -21.3% -30.2% 

2000-2004 28.4% -7.4% 23.7% 22.6% 9.5% -16.1% 11.9% 12.1% 

Estimated annual rates of change: 1991 to 2000 

Rate -9.3% -7.4% -2.7% -1.8% -2.9% -9.5% -3.8% -4.9% 

+95% CI -5.1% -5.7% 0.2% 1.1% -0.3% -4.0% -3.3% -4.3% 

-95% CI -13.3% -9.1% -5.5% -4.7% -5.4% -14.6% -4.2% -5.5% 

P < 0.01 < 0.001 > 0.05 > 0.10 < 0.05 < 0.01 < 0.001 < 0.001 

Estimated annual rates of change: 2000 to 2004 

Rate 6.3% -1.9% 5.3% 5.1% 2.3% -4.4% 2.8% 2.8% 

+95% CI 59.8% 39.2% 13.3% 37.0% 16.0% 87.0% 6.2% 4.0% 

-95% CI -29.1% -30.9% -1.9% -19.2% -9.8% -51.0% -0.4% 1.8% 

P > 0.30 > 0.60 > 0.05 > 0.20 > 0.20 > 0.50 > 0.05 < 0.05 

** For eastern Gulf of Alaska in 1998, counts made in 1999 were substituted for those 

sites not surveyed in 1998. 

*** For western Aleutian Islands in 1985, counts made in 1988 were substituted for 

Buldir. 

34 

Table 5.--Counts of adult and juvenile (non-pup) Steller sea lions observed at 1990s trend 

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

2004. Also shown are overall percent changes between various pairs of years 

and estimated annual rates of change between 1991 and 2000 and between 2000 

and 2004. Annual rates of change that are significantly different from zero 

(P < 0.05) are shown in bold. Data shown for 2004(*) have been adjusted to 

account for film format-count differences (see text). 

Gulf of Alaska Aleutian Islands Western 

Kenai to Stock in 

Year Eastern Central Western Eastern Central Western Kiska Alaska 

1991 4,812 7,872 5,338 5,283 8,656 4,601 27,149 36,562 

1992 3,981 7,358 5,112 5,707 7,633 4,199 25,811 33,991 

1994 3,612 6,505 5,718 5,664 6,909 3,114 24,796 31,522 

1996 2,450 5,400 5,356 5,967 6,368 3,334 23,091 28,875 

1998** 2,158 4,806 5,367 5,774 7,017 2,786 22,964 27,908 

2000 2,102 4,555 3,996 4,990 6,560 1,633 20,101 23,836 

2002 2,615 4,594 4,617 5,261 6,547 1,196 21,018 24,829 

2004* 3,015 4,028 5,233 5,991 6,885 1,286 22,137 26,438 

Percent change 

1991-2000 -56.3% -42.1% -25.1% -5.5% -24.2% -64.5% -26.0% -34.8% 

1991-2004 -37.3% -48.8% -2.0% 13.4% -20.5% -72.0% -18.5% -27.7% 

2000-2004 43.4% -11.6% 31.0% 20.1% 5.0% -21.2% 10.1% 10.9% 

Estimated annual rates of change: 1991 to 2000 

Annual Rate -9.2% -6.2% -2.2% -0.4% -2.5% -9.3% -2.9% -4.2% 

+95% CI -5.9% -5.0% 1.9% 2.2% 0.3% -4.3% -1.9% -3.2% 

-95% CI -12.4% -7.4% -6.0% -2.9% -5.2% -14.1% -3.9% -5.2% 

P < 0.05 < 0.001 > 0.20 > 0.60 > 0.05 < 0.01 < 0.01 < 0.001 

Estimated annual rates of change: 2000 to 2004 

Annual Rate 9.4% -3.0% 7.0% 4.7% 1.2% -5.8% 2.4% 2.6% 

+95% CI 25.8% 25.4% 10.8% 20.6% 11.4% 90.6% 3.8% 6.8% 

-95% CI -4.8% -25.0% 3.3% -9.1% -8.0% -53.4% 1.1% -1.4% 

P > 0.05 > 0.30 < 0.05 > 0.10 > 0.30 > 0.40 < 0.05 > 0.05 

** For eastern Gulf of Alaska in 1998, counts made in 1999 were substituted for those 

sites not surveyed in 1998. 

35 

Table 6.--Counts of adult and juvenile (non-pup) Steller sea lions observed at trend 

rookeries in seven subareas of Alaska during June-July aerial surveys from 1985 

to 2004. Also shown are overall percent changes between various pairs of years 

and estimated annual rates of change between 1991 and 2000 and between 2000 

and 2004. Annual rates of change that are significantly different from zero 

(P < 0.05) are shown in bold. ND = no data. Data shown for 2004(*) have been 

adjusted to account for film format-count differences (see text). Number of 

rookeries in each subarea (n) used in the analysis is shown. 

Gulf of Alaska Aleutian Islands Western 

Eastern Central Western Eastern Central Western Kenai to Stock in 

Year n = 2 n = 4 n = 4 n = 7 n = 11 n = 3 Kiska Alaska 

1985** ND 12,379 4,888 6,406 15,717 4,526 39,390 

1990 2,703 5,140 3,496 3,417 6,738 ND 18,791 

1991 2,570 4,336 3,234 3,516 6,095 2,685 17,181 22,436 

1992 1,789 4,308 3,313 3,712 5,244 2,531 16,577 20,897 

1994 1,284 3,098 3,155 3,514 4,769 1,813 14,536 17,633 

1996 1,046 2,795 3,029 3,538 4,540 1,907 13,902 16,855 

1998 1,060 2,255 2,948 2,719 4,194 1,643 12,116 14,819 

2000 1,145 2,157 2,613 2,731 4,237 915 11,738 13,798 

2002 1,164 2,486 2,920 3,271 4,216 659 12,893 14,716 

2004* 1,314 2,133 3,277 3,725 4,725 778 13,860 15,952 

Percent change 

1985-2000 -82.6% -46.5% -57.4% -73.0% -79.8% -70.2% 

1985-2004 -82.8% -33.0% -41.8% -69.9% -82.8% -64.8% 

1991-2000 -55.4% -50.3% -19.2% -22.3% -30.5% -65.9% -31.7% -38.5% 

1991-2004 -48.9% -50.8% 1.3% 6.0% -22.5% -71.0% -19.3% -28.9% 

2000-2004 14.8% -1.1% 25.4% 36.4% 11.5% -15.0% 18.1% 15.6% 

Estimated annual rates of change: 1991 to 2000 

Annual Rate -8.2% -8.2% -2.3% -3.4% -3.7% -9.7% -4.3% -5.2% 

+95% CI -0.7% -5.8% -1.1% -0.6% -1.6% -4.3% -3.4% -4.1% 

-95% CI -15.1% -10.5% -3.4% -6.1% -5.8% -14.8% -5.3% -6.3% 

P < 0.05 < 0.001 < 0.01 < 0.05 < 0.01 < 0.01 < 0.001 < 0.001 

Estimated annual rates of change: 2000 to 2004 

Annual Rate 3.5% -0.3% 5.8% 8.1% 2.8% -4.0% 4.2% 3.7% 

+95% CI 25.4% 71.3% 6.7% 18.5% 27.8% 137.5% 8.4% 6.8% 

-95% CI -14.6% -41.9% 5.0% -1.5% -17.4% -61.2% 0.2% 0.7% 

P > 0.20 > 0.90 < 0.01 > 0.05 > 0.30 > 0.60 < 0.05 < 0.05 

** For western Aleutian Islands in 1985, counts made in 1988 were substituted for Buldir 

Island. 

36 

Table 7.--Counts of Steller sea lion non-pups (adults and juveniles) at principal western stock rookeries in Alaska 

surveys, 1985-2004. Counts from 1985 to 2002 were made from 35 mm slides. All counts in 2004 (exce

Head: 35 mm) were made from medium-format photographs. Counts in 2004 should not be used for trend individual sites because of differences in resolution between film formats (see text). Data for haul-out sitnumber of pups were counted are also shown (*). Italicized rookery names are trend rookeries whose couTable 5. 

Sub-Area and Rookery 1985 1989 1990 1991 1992 1994 1996 1997 1998 1999 200Eastern Gulf of Alaska Seal Rocks 2,159 1,471 1,220 784 636 544 730 624 74Fish (Wooded) 1,333 1,232 1,350 1,005 648 502 330 311 39Chiswell Islands* 456 408 383 240 180 115 79 5Central Gulf of Alaska Outer (Pye) 1,127 589 489 378 406 318 224 278 26Sugarloaf 2,991 2,164 1,416 1,216 1,186 976 741 624 748 70Ushagat (NW, SW, & Rocks S) * 1,813 273 496 284 519 228 137 117 98 23Marmot 4,983 2,331 1,766 1,458 1,581 1,091 1,102 780 726 67Two-headed* 1,240 479 268 382 330 364 216 308 378 25Chowiet 2,059 737 897 716 771 599 592 538 515 50Chirikof 2,346 1,278 1,061 946 770 432 360 294 266 27Nagai Rocks* 798 233 196 245 362 331 180 204 312 22Western Gulf of Alaska Lighthouse Rocks Atkins 1,562 755 728 616 792 571 624 544 602 53Chernabura 487 544 442 650 459 676 422 729 624 49The Haystacks 0 0 0 0 0 60 6The Whaleback 355 419 411 395 324 288 316 16Jude* 315 200 363 352 410 355 434 450 39Pinnacle Rock 1,588 1,366 1,305 1,048 1,092 977 1,026 1,007 864 86Clubbing Rocks 1,251 856 1,021 920 970 931 957 934 858 71South Rocks 892 332 290 232 342 345 402 408 16

37

Table 7. --(Continued). 

Sub-Area and Rookery 1985 1989 1990 1991 1992 1994 1996 1997 1998 1999 20Eastern Aleutian Islands Sea Lion Rock (Amak) 410 344 286 300 329 480 590 452 444 2Amak 430 98 273 610 869 681 980 919 946 9

Aiktak 0 0 12 60 63 93 52 52 102 

Ugamak (and Round) 1,503 945 1,062 954 971 854 840 742 7Akun (Billings Head) 435 150 118 156 271 220 346 247 212 2Akutan (Cape Morgan) 1,269 578 765 818 1,061 908 934 760 681 7Bogoslof 1,287 682 713 558 540 413 382 274 3Ogchul 547 217 240 228 235 208 155 166 136 1Adugak 955 392 350 394 322 314 277 230 2

Central Aleutian Islands Yunaska 1,071 466 391 398 394 461 340 210 2Seguam (Saddleridge) 2,942 602 833 684 696 658 553 586 5Seguam (Turf Point)* 101 146 0 0 

Agligadak 514 132 274 231 125 8 73 40 Amlia (Sviechnikof Harbor)* 376 50 214 200 103 116 86 117 1Kasatochi 1,170 659 641 466 376 288 330 350 3Adak (Lake Point-Cape Yakak) 1,289 424 592 847 615 765 618 683 8Kanaga (Ship Rock)* 314 0 92 93 175 146 164 1Gramp Rock 1,290 747 712 773 691 537 582 570 5Tag 944 590 478 440 370 309 320 370 3Ulak (Hasgox Point) 2,729 1,123 1,324 1,046 1,059 866 844 698 6Semisopochnoi 443 372 363 166 143 1Amchitka (East Cape) 1,005 20 106 150 162 89 122 148 1Amchitka (Column Rocks) 728 197 233 194 188 137 112 Ayugadak 702 389 401 324 313 285 281 179 1Kiska (Lief Cove) 1,715 510 528 506 357 359 341 284 2Kiska (Cape St. Stephen) 1,351 464 564 380 248 233 258 224 1

38

Table 7. --(Continued). 

Sub-Area and Rookery 1985 1989 1990 1991 1992 1994 1996 1997 1998 1999 2000 Western Aleutian Islands Buldir** 1,396 1,058 587 454 344 312 336 129 

Agattu (Cape Sabak) Agattu (Gillon Point) 3,130 2,486 1,428 670 1,304 773 961 508 1,001 594 826 481 480 306 

Attu (Cape Wrangell) 736 754 839 721 584 310 * Haul-out sites where pups have been observed. ** 1988 Buldir Island count used for 1985.  39 
Table 8.--Counts of Steller sea lion pups at principal western stock rookeries in Alaska during June and July surv

Count-type refers to method of counting pups: OS = on-site - pups counted after adults moved from area, nearby, or from an observation point on-land; MF= pups counted from medium-format aerial photographrookeries highlighted in bold were used for time period/sub-area summaries in Table 9. Data for haul-out significant numbers of pups have been counted are also shown (*). 

Sub-Area and Rookery 1985 1986 1989 1990 1991 1992 1994 1996 1997 1998 

Count type OS OS OS OS OS OS OS OS OS OS Eastern Gulf of Alaska Seal Rocks 553 571 657 598 352 542 Fish (Wooded) 305 232 147 Chiswell Islands* Central Gulf of Alaska Outer (Pye) 557 363 180 119 113 

Sugarloaf 2,109 1,683 1,000 958 673 703 

Ushagat (NW, SW, and Rocks S) * Marmot 4,381 2,199 1,611 804 632 762 642 Two-headed* 

Chowiet 1,731 820 343 636 625 234 Chirikof 1,476 607 656 325 184 Nagai Rocks* Western Gulf of Alaska Lighthouse Rocks* Atkins 433 485 324 366 352 

Chernabura 379 197 211 139 54 The Haystacks* The Whaleback* Jude* Pinnacle Rock 794 652 639 

Clubbing Rocks 433 547 448 

South Rocks* 

40

Table 8. --(Continued). 

Sub-Area and Rookery 2000 2000 2001 2001 2002 2002 2003 2004 Count type OS MF OS MF OS MF OS OS Eastern Gulf of Alaska Seal Rocks 522 500 475 543 Fish (Wooded) 149 97 85 86 173 

Chiswell Islands* 58 54 45 52 Central Gulf of Alaska Outer (Pye) 108 148 104 58 92 59 Sugarloaf 645 490 419 444 488 Ushagat (NW, SW, and Rocks S)* 54 24 42 Marmot1 514 466 515 505 474 

Two-headed* 16 8 20 20 Chowiet 278 387 368 Chirikof 187 90 225 189 Nagai Rocks* 31 19 26 22 Western Gulf of Alaska Lighthouse Rocks* 5 4 7 4 Atkins 262 172 224 274 266 Chernabura 92 138 115 82 The Haystacks* 0 0 The Whaleback* 12 13 16 16 Jude* 182 119 130 187 Pinnacle Rock 634 501 769 466 663 Clubbing Rocks 490 417 566 South Rocks* 36 

 41 
Table 8. --(Continued). 

Sub-Area and Rookery 1985 1986 1989 1990 1991 1992 1994 1996 1997 1Count type OS OS OS OS OS OS OS OS OS 

Eastern Aleutian Islands 

Sea Lion Rock (Amak) Amak* Aiktak* Ugamak (and Round) 1,635 1,386 847 813 574 706 589 Akun (Billings Head) 60 63 69 Akutan (Cape Morgan) Bogoslof 2 

1,130 

1,109 

442 

461 501 

631 

302 281 

Ogchul 172 94 Adugak 844 262 180 Central Aleutian Islands Yunaska 1,026 230 217 192 Seguam (Saddleridge) 2,635 529 684 444 463 Seguam (Turf Point)* 

Agligadak 0 

Amlia (Sviechnikof Harbor)* 26 

Kasatochi 892 178 215 268 Adak (Lake Point-Cape Yakak) 558 137 327 Kanaga (Ship Rock)* 

Gramp Rock 909 448 425 Tag 703 357 234 

Ulak (Hasgox Point) 1,236 790 638 Semisopochnoi 21 

Amchitka (East Cape) 6 

Amchitka (Column Rocks) 148 114 

Ayugadak 329 163 142 Kiska (Lief Cove) 882 293 221 233 Kiska (Cape St. Stephen) 258 212 120 

 42 
Table 8. --(Continued). 

Sub-Area and Rookery 2000 2000 2001 2001 2002 2002 2003 2004 Count type OS MF OS MF OS MF OS OS Eastern Aleutian Islands Sea Lion Rock (Amak) 161 160 138 185 Amak* 0 3 1 Aiktak* 21 10 5 7 Ugamak (and Round) 570 686 541 

Akun (Billings Head) 41 55 85 

Akutan (Cape Morgan) 508 497 Bogoslof 249 256 180 219 278 

Ogchul 47 57 53 69 Adugak 153 172 160 151 185 

Central Aleutian Islands Yunaska 136 96 145 145 Seguam (Saddleridge) 468 410 517 Seguam (Turf Point)* 24 23 Agligadak 2 Amlia (Sviechnikof Harbor)* 22 28 Kasatochi 258 302 300 354 Adak (Lake Point-Cape Yakak) 395 363 370 Kanaga (Ship Rock)* 92 113 Gramp Rock 430 444 432 Tag 155 153 148 Ulak (Hasgox Point) 332 331 322 Semisopochnoi 2 24 Amchitka (East Cape) 5 16 Amchitka (Column Rocks) 52 43 Ayugadak 90 85 Kiska (Lief Cove) 158 136 Kiska (Cape St. Stephen) 71 62 

 43 
Table 8. --(Continued). 

Sub-Area and Rookery Count type Western Aleutian Islands Buldir3 

Agattu (Cape Sabak) Agattu (Gillon Point) 

Attu (Cape Wrangell) 

1985 1986 1989 1990 1991 1992 1994 1996 1997 

OS OS OS OS OS OS OS OS OS 

494 381 120 120 

379 907 1,127 258 

222 

199

O

12

31

21

15

Sub-Area and Rookery Count type 

Western Aleutian Islands 

Buldir Agattu (Cape Sabak) 

Agattu (Gillon Point) 

Attu (Cape Wrangell) 

2000 2000 2001 2001 2002 2002 2003 2004 

OS MF OS MF OS MF OS OS 

42 42 

212 

159 

75 

1 Maximum daily field camp counts for Marmot in 2003 and 2004. 2 1994 Bogoslof count is mean of 1993 and 1995 counts. 3 1995 Buldir count reported for 1994.  44 
Table 9.-- Counts of Steller sea lion pups at selected rookeries (italicized in Table 7) in seven sub-areas of the we

from 1985-89 to 2003-2004. The maximum count during each period at the selected rookeries (n) was usTable 8). Blank cells indicate incomplete counts in the period and sub-area. Percentage change in counts 

also shown. 

Gulf of Alaska Aleutian Islands Western 

 Eastern Central Western Eastern Central Western Kenai to Stock in 

Period n = 2 n = 5 n = 4 n = 5 n = 11* n = 4 Kiska Alaska 

1985-1989 10,254 4,778 9,428 

1990-1992 4,904 1,923 2,115 3,568 12,510 

1994 903 2,831 1,662 1,756 3,109 9,358 1997 611 979 1998 689 1,876 1,493 1,474 2,834 803 7,677 9,169 

2001-2002 586 1,721 1,671 1,561 2,612 488 7,565 8,639 2003-2004 716 1,609 1,577 1,731 

Percent Change 

1985-89 to 2001-2002 -83.2% -67.3% -72.3% 1990-92 to 2001-2002 -64.9% -13.1% -26.2% -26.8% -39.5% 

1998 to 2001-2002 -14.9% -8.3% 11.9% 5.9% -7.8% -39.2% -1.5% -5.8% 1998 to 2003-2004 3.9% -14.2% 5.6% 17.4% 

2001-2002 to 2003-2004 22.2% -6.5% -5.6% 10.9% 

* 1985-89 CAI count does not include Amchitka/Column Rocks (n = 10). 

45 
Table 10.--Steller sea lion pup counts from medium-format (vertical) photographs and from the beach at the sam

Counts were made 1-4 days apart (Time Diff relative to the beach count). The percent difference (Percen

calculated with the medium-format count relative to the beach count. 

Time 

Diff (days) Medium Format (MF) Beach (B) 

SITENAME (MF-B) Year Month Day 

Count Year Month Day Coun

ADAK/LAKE POINT -4 2002 6 25 379 2002 6 29 36GRAMP ROCK -4 2002 6 26 432 2002 6 30 44OUTER (PYE) -4 2000 6 29 148 2000 7 3 10TAG -4 2002 6 26 148 2002 6 30 15ULAK/HASGOX POINT -4 2002 6 26 322 2002 6 30 33CHERNABURA -3 2001 6 27 138 2002 6 30 9KASATOCHI/NORTH POINT -3 2002 6 25 311 2002 6 28 30KISKA/CAPE ST STEPHEN -3 2002 6 29 62 2002 7 2 7KISKA/LIEF COVE -3 2002 6 29 136 2002 7 2 15MARMOT -3 1998 6 28 624 1998 7 1 64SEA LION ROCK (AMAK) -3 2002 6 23 138 2002 6 26 16SEAL ROCKS -2 1998 6 27 542 1998 6 29 54CLUBBING ROCKS -2 2001 6 27 417 2001 6 29 49ADUGAK -1 2002 6 24 151 2002 6 25 16ADAK/LAKE POINT 1 2002 6 30 354 2002 6 29 36KASATOCHI/NORTH POINT 2 2002 6 30 289 2002 6 28 30THE WHALEBACK 3 2002 7 2 16 2002 6 29 1OGCHUL 4 2001 6 29 57 2001 6 25 4

46

Figure 1.--Map of Alaska showing the seven population sub-areas used to compile western Steller sea li

survey data, 1970s trend sites used for population analyses, and the principal rookeries (named). 

47

35 mm Non-Pup Count 

2,000 

1,800 

1,600 

1,400 

1,200 

1,000 

800 

600 

400 

200 

-

A. 

- 200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000 

0 

20 

40 

60 

80 

- 200 600 800 

B.

Medium Format - 35 mm Non-Pup

Count 

-60 

-40 

-20 

100 

120 

400 1,000 1,200 1,400 1,600 1,800 2,000 

Medium Format Non-Pup Count 

Figure 2.—Comparison of counts of adult and juvenile (non-pup) Steller 

sea lions made from medium-format and 35 mm images taken at the 

same site on the same day (Table 2). A. 35 mm count plotted 

against medium-format count; 1:1 line also shown. B. Difference 

of medium-format and 35 mm counts plotted against the mediumformat count; line = medium-format count x 3.64%. 

48

Number of Non-Pup Steller Sea Lions 

80,000 

70,000 

60,000 

50,000 

40,000 

30,000 

20,000 

10,000 

-

A. Kenai-to-Kiska 

All Surveyed Sites 

1990s Trend Sites 

1970s Trend Sites 

Trend Rookeries 

1980 1985 1990 1995 2000 2005 

80,000 

70,000 

60,000 

50,000 

40,000 

30,000 

20,000 

10,000 

-

B. Western Stock in Alaska 

1980 1985 1990 1995 2000 2005 

Year 

Figure 3.--Number of adult and juvenile (non-pup) Steller sea lions at all 

surveyed sites, 1970s and 1990s trend rookery and haul-out sites, 

and trend rookeries in the Kenai-Kiska area (A) and throughout the 

range of the western stock in Alaska (B). Legend in A also applies 

to B. Data are in Table 3. 

49

Number of Non-Pup Steller Sea Lions 

25,000 

A. Gulf of Alaska 

20,000 

15,000 

10,000 

5,000 

Eastern 

Central 

Western 

0


1980 1985 1990 1995 2000


25,000 

B. Aleutian Islands 

20,000 

15,000 

10,000 

5,000 

0 

1980	 1985 1990 1995 2000


Year 


Figure 4.--Number of adult and juvenile (non-pup) Steller sea lions at 1970s 

trend rookery and haul-out sites in three sub-areas of the Gulf of Alaska 

(A) and Aleutian Islands (B). Legend in A also applies to B. Data are in 

Table 4. 

50


2005 

2005 
50% A. 1991 to 2000 

25% 

0% 

-25% 

-50% 

-75% Aleutian Islands Gulf of Alaska 

Western Central Eastern Western Central Eastern 

50% B. 2000 to 2004 

25% 

0% 

-25% 

-50% 

-75% Aleutian Islands Gulf of Alaska 

Western Central Eastern Western Central Eastern 

Figure 5.—Percent change in number of adult and juvenile (non-pup) Steller 

sea lions at 1970s trend rookery and haul-out sites by sub-area between 

1991 and 2000 (A) and between 2000 and 2004 (B). Data are in 

Table 4. 

51

9,000 A. Gulf of Alaska 

Eastern 8,000 

7,000 

6,000 

5,000 

4,000 

3,000 

2,000 

1,000 

0 

Central 

Western 

1990 1992 1994 1996 1998 2000 2002 2004


9,000 B. Aleutian Islands 

8,000 

7,000 

6,000 

5,000 

4,000 

3,000 

2,000 

1,000 

0 

1990 1992 1994 1996 1998 2000 2002 2004 

Year 

Figure 6.--Number of adult and juvenile (non-pup) Steller sea lions at 1990s 

trend rookery and haul-out sites in three sub-areas of the Gulf of 

Alaska (A) and Aleutian Islands (B). Legend in A also applies to B. 

Data are in Table 6. 

Number of Non-Pup Steller Sea Lions 

52

Number of Non-Pup Steller Sea Lions 

18,000 

16,000 A. Gulf of Alaska 

14,000 

12,000 

10,000 

8,000 

6,000 

4,000 

2,000 

0 

Eastern 

Central 

Western 

1980 1985 1990 1995 2000


18,000 

16,000 

14,000 

12,000 

10,000 

8,000 

6,000 

4,000 

2,000 

0 

B. Aleutian Islands 

1980 1985 1990 1995 2000 

Year 

Figure 7.--Number of adult and juvenile (non-pup) Steller sea lions at trend 

rookeries in three sub-areas of the Gulf of Alaska (A) and Aleutian 

Islands (B). Legend in A also applies to B. Data are in Table 5. 

53


2005 

2005 
Number of Steller Sea Lion Pups 

12,000 

10,000 

8,000 

6,000 

4,000 

2,000 

0 

Eastern 

Central 

Western 

A. Gulf of 

1985 1990 1995 2000 2005


12,000 

10,000 B. Aleutian Islands 

8,000 

6,000 

4,000 

2,000


0


1985 1990 1995 2000 2005 

Year 

Figure 8.--Number of Steller sea lion pups counted at rookeries in each 

of three sub-areas of the Gulf of Alaska (A) and Aleutian Islands 

(B). Legend in A also applies to B. Data are in Table 9. Data 

for pooled groups of years are plotted at the mid-point (e.g., 1985 

to 1989 plotted at 1987; 2001 and 2002 plotted at 2001.5). 

54

25% 

A. 1990-92 to 2001-2002 

0% 

-25% 

-50% 

-75% Aleutian Islands Gulf of Alaska 

Western Central Eastern Western Central Eastern 

25% 

B. 2001-2002 to 2003-2004 

0% 

-25% 

-50% 

-75% Aleutian Islands Gulf of Alaska 

Western Central Eastern Western Central Eastern 

Figure 9.—Percent change in number of Steller sea lion pups at rookeries 

by sub-area between 1990-92 and 2001-2002 (A) and between 

2001-2002 and 2003-2004 (B). Data are in Table 9. 

55

0 

100 

200 

300 

400 

500 

600 

700 

Ground Pup Count 

0 100 200 300 400 500 600


60 

40 

20 

MF Survey First 

Beach Count First 

0 

-20 

-40 

-60 

-80 

0 100 200 300 400 500 600 700 

Medium-Format Pup Count 

Figure 10.—Comparison of Steller sea lion pup counts from mediumformat (MF) photographs and from the beach at the same site 

within 4 days of each other (Table 9). A. Beach count plotted 

against MF count; 1:1 line also shown. B. Difference between MF 

and beach counts plotted against the MF count for pairs where the 

MF survey occurred first (solid squares) and the beach count 

occurred first (open squares). 

Medium Format - Ground Pup Count 

56


700 
RECENT TECHNICAL MEMORANDUMS


Copies of this and other NOAA Technical Memorandums are available from the 

National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22167 

(web site: www.ntis.gov). Paper and microfiche copies vary in price. 

AFSC152 AMES, R. T., G. H. WILLIAMS, and S. M. FITZGERALD. 2005. Using digital video monitoring systems 

in fisheries: Application for monitoring compliance of seabird avoidance devices and seabird mortality in 

Pacific halibut longline fisheries, 93 p. NTIS number pending. 

151 TESTA, J. W. (editor). 2005. Fur seal investigations, 2002-2003, 72 p. NTIS number pending. 

150 GULLAND, F. M. D., H. PÉREZ-CORTÉS M., J. URBÁN R., L. ROJAS-BRACHO, G. YLITALO, J. WEIR, 

S. A. NORMAN, M. M. MUTO, D. J. RUGH, C. KREUDER, and T. ROWLES. 2005. Eastern North Pacific 

gray whale (Eschrichtius robustus) unusual mortality event, 1999-2000: A compilation, 33 p. NTIS number 

pending. 

149 RUGH, D. J., K. E. W. SHELDEN, C. L. SIMS, B. A. MAHONEY, B. K. SMITH, L. K. LITZKY, and R. C. 

HOBBS. 2005. Aerial surveys of belugas in Cook Inlet, Alaska, June 2001, 2002, 2003, and 2004, 71 p. 

NTIS No. PB2005-103921. 

148 EILER, J. H., T. R. SPENCER, J. J. PELLA, M. M. MASUDA, and R. R. HOLDER. 2004. Distribution and 

movement patterns of chinook salmon returning to the Yukon River basin in 2000-2002, 99 p. NTIS No. 

PB2005-100707. 

147 MCELDERRY, H., J. SCHRADER, D. MCCULLOUGH, J. ILLINGWORTH, S. FITZGERALD, and S. 

DAVIS. 2004. Electronic monitoring of seabird interactions with trawl third-wire cables on trawl vessels ­

a pilot study, 39 p. NTIS No. PB2005-100243. 

146 WING, B. L., and D. R. BARNARD. 2004. A field guide to Alaskan corals, 67 p. NTIS No. PB2005-100429. 

145 RUGH, D. J., B. A. MAHONEY, and B. K. SMITH. 2004. Aerial surveys of beulga whales in Cook Inlet, 

Alaska, between June 2001 and June 2002, 26 p. NTIS No. PB2004-106479. 

144 ANGLISS, R. A., and K. L. LODGE. 2004. Alaska marine mammal stock assessments, 2003, 224 p. 

NTIS No. PB2005-100248. 

143 ZENGER, H. H. JR. 2004. Data report: 2002 Aleutian Islands bottom trawl survey, 247 p. NTIS No. 

PB2004-105068. 

142 STEVENSON, D. E. 2004. Identification of skates, sculpins, and smelts by observers in North Pacific 

groundfish fisheries (2002-2003), 67 p. NTIS No. PB2004-105817. 

141 HOFF, G. R., and L. L. BRITT. 2003. The 2002 eastern Bering Sea upper continental slope survey of 

groundfish and invertebrate resources, 261 p. NTIS No. PB2004-101668. 

140 STONE, R. P., and M. M. MASUDA. 2003. Characteristics of benthic sediments from areas open and 

closed to bottom trawling in the Gulf of Alaska., 40 p. + Appendices (111 p.). NTIS No. PB2004-100650 

139 JOHNSON, S. W., M. L. MURPHY, D. J. CSEPP, P. M. HARRIS, and J. F. THEDINGA. 2003. A survey 

of fish assemblages in eelgrass and kelp habitats of southeastern Alaska, 39 p. NTIS No. PB2004­

100139. 

138 PEREZ, M. A. 2003. Compilation of marine mammal incidental take data from the domestic and joint 

venture groundfish fisheries in the U.S. EEZ of the North Pacific, 1989-2001, 145 p. NTIS No. PB2004­

100649