Relationships between boat harbors, fish processing, contaminants, and 

wintering Steller’s eiders and Harlequin Ducks in the Eastern Aleutian 

Islands. 

 

2004 PROGRESS REPORT 

 Photo by Jeff Wasley 

United States Department of the Interior 

U.S. Geological Survey 

Alaska Science Center 

1011 East Tudor Road

Anchorage, Alaska 99503 
Wintering Steller’s Eiders at Dutch Harbor 2

INTRODUCTION 

Declines of Steller’s eiders (Polysticta stelleri) on their breeding areas in Alaska have resulted in 

the North American breeding population being listed as Threatened under the provisions of the 

Endangered Species Act (Fox et al. 1997, Flint et al. 2000). Activities such as small boat harbor 

developments and increased seafood processing may impact eiders that winter along the Alaska 

Peninsula and eastern Aleutian Islands. Adverse effects may include: displacement from foraging 

sites, destruction of foraging habitat, and exposure to petroleum products or seafood processing 

wastes. However, information on Steller’s eiders and their wintering site fidelity, home range, 

and migration patterns is limited. Understanding patterns of site fidelity, home range, and 

habitat use by wintering populations is essential to predicting the effect of disturbance, habitat 

loss, or exposure to contaminants. 

Steller’s eiders tend to winter in areas of industrial development, particularly near seafood 

processing plants and associated boat harbors (Hoffman 2000, 2001). Eiders may be attracted to 

these areas because of the presence of ice-free waters and the increased primary productivity 

resulting from eutrophication associated with seafood processing wastewater (Persson et al. 

1995, Dachs et al. 2000, Gunnarsson et al. 2000, Skei et al. 2000.) However, industrial activities 

around these areas also increase the probability of exposure to contaminants, particularly 

petroleum-based products. Further, past military activity along the Alaska Peninsula and 

Aleutian Islands may be another source of organic contamination, particularly PCBs or DDT. 

Given the historical background and the possibility of increased eutrophication, these industrial 

areas may function as ‘traps’ that attract large concentrations of wintering seaducks, which are 

then exposed to harmful levels of contaminants. 

OBJECTIVES 

(1) Radio-mark 30 Steller’s eiders and 30 Harlequin ducks (Histrionicus histrionicus) from 

several locations around Dutch Harbor and track individuals to assess site fidelity, behavior, and 

patterns of movement. 

(2) Determine patterns of habitat use and foraging locations in relation to discharged wastewater 

from sewage, fish processing, and harbor developments. 
Wintering Steller’s Eiders at Dutch Harbor 3

(3) Obtain blood serum, whole blood, cloacal swabs, and fecal samples from wintering sea ducks 

to determine exposure to contaminants, viruses, and to assess general health indices. 

(4) Determine concentrations of bacteria, viruses, and trace elements in water and Blue mussels 

collected at several locations around Dutch Harbor used by wintering sea ducks. 

Figure 2. Floating mist net capture setup. 

METHODS Figure 1. Location of study. 

Captures 

From 23 January to 31 March 2004, a study 

team consisting of 1-3 research biologists and 1-

2 biological technicians conducted fieldwork at 

Amaknak/Unalaska Islands, (Dutch Harbor) 

Alaska (Figure 1). Between 26 January and 3 

February, we captured ducks at five sites around 

Dutch Harbor. Sites included: 1) the south end 

of Hog Island, 2) Airport Beach just south of the 

runway, 3) a bay along Airport Beach Road at 

the outflow for processing waste from Unisea 

and the municipal sewage system, 4) Little 

South America (just south of the bridge 

connecting Amaknak and Unalaska Islands), and 

5) inner Captain’s Bay by the islands at the south 

end of the Bay. The Little South America 

location is one of the proposed sites for a new 

harbor development. 

As in previous years, we used floating mist nets 

with decoys sets to capture wintering sea ducks 

(Figure 2). We used two inflatable boats and a 

skiff to drive rafting birds towards the net, to 

remove captured individuals, and to transport 
Wintering Steller’s Eiders at Dutch Harbor 4

birds for immediate processing. 

Radio Tracking 

All captured birds were banded, weighed, sexed, and aged. We attached 10 g radio transmitters 

using the sub-cutaneous prong and suture transmitter attachment described by Peitz et. al (1995). 

We tracked radio-marked ducks from 26 January through 26 March with telemetry receiving 

equipment mounted in pick-up trucks. We scanned for all transmitters multiple times per day 

from several locations around Dutch Harbor. For every transmitter detected, we recorded the 

time, location, strength of signal, and activity (diving or roosting). Between 22 February and 26 

March we collected simultaneous bearing from trucks in two locations for all radios that 

provided clear signals to both trucks. We then used the bearing data to calculate more precise 

locations using simple triangulation. 

Sampling for Associated Studies. 

Blood samples and cloacal swabs were taken using standard techniques. Blood was transferred 

to non-heparin tubes for serum and to heparin tubes for whole blood. Serum samples were 

centrifuged (10 minutes) 1-6 hours after collection, transferred to cryovials, and frozen in 

nitrogen dry shippers. Whole blood samples were frozen in a conventional freezer and cloacal 

swab samples were transferred to virus storage media and frozen with the serum samples. 

Additionally, we collected fecal samples from most birds. These were preserved in 10% 

Formalin solution for parasite analysis. We also collected water and Blue mussels at each of the 

five capture sites. 

RESULTS 

Captures 

Between 26 January and 3 February we caught 88 birds including Steller’s Eiders, Harlequin 

Ducks, Black Scoters, White-winged Scoters, and Long-tailed Ducks from five sites around 

Dutch Harbor (Figure 1, Table 1). We radio-marked 28 Steller’s eiders (8 male, 20 female) and 

32 Harlequin ducks (22 male, 10 female). 
Wintering Steller’s Eiders at Dutch Harbor 5

Table 1. Sample sizes of birds captured in Dutch Harbor 2004 by location. 

Species Sex Age Hog Island Airport Sewage 

Outflow 

Little South 

America 

Captain’s 

Bay 

Steller’s eider Male AHY 2 1 2 5 

juv 

Female AHY 9 4 1 6 

juv 1 

Harlequin duck Male AHY 5 2 3 4 4 

juv 1 4 1 2 2 

Female AHY 1 4 2 2 

juv 2 1 1 2 

Black scoter Male AHY 1 1 

juv 

Female AHY 1 1 

juv 1 

White-winged Male AHY 1 1 

scoter juv 2 

Female AHY 1 

juv 2 

Long-tailed duck Male juv 1 

Female juv 1 

Radio Tracking 

We detected all 60 radio-marked ducks after release. During February we recovered twelve 

transmitters (six per species) from dead birds (see Mortality section) or shed from live birds. Of 

the remaining transmitters all Steller’s eiders were detected through February and all but four 

were detected through 20 March. Only two Harlequin ducks were not heard through 20 March. 

The mean number of detections per Steller’s eider was 214.4 (s.e. = 25.4) and per Harlequin 

duck was 192.3 (s.e.=21.7) (Table 2). 
Wintering Steller’s Eiders at Dutch Harbor 6

Mortality 

While radio tracking, we detected the mortality of four Steller’s eiders and six Harlequin ducks. 

We recovered four fresh carcasses (3 eider, 1 Harlequin duck) from fox caches. The recovered 

carcasses were frozen in a conventional freezer and then shipped to Dr.Tuula Holmen at the 

Alaska SeaLife Center for necropsies. Additionally, one fresh Common murre (Uria aalge) 

carcass was recovered. Six of the mortalities (1 eider, 5 Harlequin duck) were likely killed or 

scavenged by eagles. 

Contaminants, Health, and Virus samples 

All blood and cloacal samples were sent to Dr. Tuula Hollmén (Alaska SeaLife Center) for 

analyses (Table 3). 

Table 3. Summary of blood and cloacal samples collected at Dutch Harbor 2004. 

Species Serum Whole 

Blood 

Virus 

Swab 

Fecal 

Sample 

Steller’s eider 25 17 27 25 

Harlequin 38 28 19 17 

Black scoter 2 0 1 5 

White-winged scoter 7 6 2 4 

Long-tailed duck 2 1 1 1 

Table 2. Telemetry effort and detection success from locations around Dutch Harbor 2004. 

Telemetry Search Area 

Airport 

Beach1

Sewage 

Outflow

Inner 

Harbor

Mid Captain’s 

Bay2

South Captain’s 

Bay

# Telemetry searches 246 80 38 167 111

# Detections 

 Steller’s eider 2485 511 221 1946 678

 Harlequin duck 2794 585 266 1273 894

# Definite Locations

 Steller’s eider 889 189 58 841 292

 Harlequin duck 869 100 83 330 553

# Triangulation searches 90 35 - 78 75 

# Triangulation fixes 

 Steller’s eider 170 3 - 225 68 

 Harlequin duck 260 6 - 83 142

1

 includes birds near Hog Island

2

 includes South Eastern edge of Little South America 
Wintering Steller’s Eiders at Dutch Harbor 7

DISCUSSION 

Capture Success 

Our 88 total captures compares well to capture success in previous years at Dutch Harbor. 

Conditions during the capture period in 2004 favored our success. We had several days with 

sunny weather and stiff southerly breezes that worked well for the floating mist net set. 

Additionally, the Steller’s eider flocks tended to be smaller in size than some years, consequently 

our decoy spreads proved to be more attractive to small groups of birds looking for locations to 

settle. 

Site Fidelity, choice, and Movement 

For several birds, detection was intermittent, i.e., ‘present’ one day, absent the second, and then 

‘re-appeared’ several days later. These birds may have made daily movements to areas outside 

our range of reception. Concentrations of radio-marked Steller’s eiders and Harlequin ducks 

were consistently heard and seen in three main areas: 1) along the Airport Beach (between the 

runway and the Post Office), 2) Hog Island, and 3) Little South America. Harlequin ducks also 

used the south end of Captain’s Bay, while only a few Steller’s eiders were detected in this area. 

We observed that a few times per day the sewage outflow area was visited for short periods (<1 

hr) by large numbers of sea ducks. All but four of the radio-marked Steller’s eiders and twothirds of the Harlequin ducks were detected around the sewage outflow area on multiple 

occasions. 

As we have seen in previous years of telemetry, wintering Steller’s eider and Harlequin ducks 

showed fairly strong site fidelity. Most birds were continually detected near their original 

banding site. However, we did detect a substantial amount of movement, both daily and through 

the sampling period. By and large, Steller’s eiders had larger home ranges than Harlequin ducks 

and were more likely to make large-scale (>3 km) movements. It appears that many ducks 

concentrated at night near the runway, Hog Island, and Little South America and then dispersed 

at sunrise. During periods of strong winds (esp., North winds) ducks concentrated in protected 

areas near the airport and Little South America. For short periods each day many ducks gathered 

to feed in the sewage outflow area and then during low tide hauled out to preen on the points 
Wintering Steller’s Eiders at Dutch Harbor 8

near the entrance to Captain’s Bay and at the west end of Airport Beach (near the Post Office). 

Results from radio tracking in 2001 and 2002 indicated that birds routinely moved between the 

Little South America, the ‘Inner Harbor’ (at the mouth of the Iliuliuk River), and southwestern 

Iliuliuk Bay (In front of Unalaska proper). By contrast, in 2004 only a few of our radio-marked 

birds used the Inner Harbor and none were detected by Iliuliuk Bay. 

For further information contact: 

US Geological Survey 

Alaska Biological Science Center 

1011 East Tudor Road 

Anchorage, Alaska 99503 

Paul L Flint 

907-786-3608 

Paul_flint@usgs.gov

John Reed 

907-786-3485 

John_Reed@usgs.gov

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exchange, vertical fluxes, and phytoplankton concentrations of persistent organic pollutants. 

Environmental Science and Technology. 34:1095-1102. 

Flint, P.L., Petersen, M.R., Dau, C.P., Hines, J.E., and Nichols, J.D. 2000. Annual survival and 

site fidelity of Steller’s eiders molting along the Alaska Peninsula. Journal of Wildlife 

Management. 64 (1): 261-268. 

Fox, A.D., Mitchell, C., Henriksen, G., Lund, E., and Frantzen, B. 1997. The conservation of 

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