Beluga Tagging in Cook Inlet, August 2001
During 10-20 August 2001, members of the National Marine Mammal Laboratory
(NMML), the Alaska Region Anchorage office, and the native village of
Alaska, participated in a cooperative tagging project to attach satellite
tags to seven beluga whales in Cook Inlet, Alaska. The first whale was
captured in the little Susitna River and the remaining six whales were
captured in Knik Arm. A 1,000-ft net was used to encircle the whales. Captured
whales were quickly removed from the net and placed into a sling between
rigid-hull inflatable boats. The sling was an innovation introduced this
year, which allowed the tagging team to cut handling time per whale to
less than an hour and avoid stranding the whale in shallow water. Once
a whale was secured, one or two tags were surgically attached to its back,
the animal was measured, and skin, blubber and blood samples were taken.
The whale was then released.
Two types of tags were employed, and for five of the seven whales one
of each type was attached. Each of the seven whales was tagged with a
small position-only tag (S). These tags are designed to stay on for 1-2
years but give locations only three to six times a month. Five of the whales
also were tagged with a dive tag (D), similar to the tags attached by
this project in 1999 and 2000. Along with location several times a day,
the dive tags report dive data but only last for 2-4 months. The long-term
data from the position-only tag allow us to follow movements of the whales
through an entire year and determine the distribution of the whales during
the winter months when they are difficult to spot from an airplane due
to ice cover and weather conditions. The dive tags give us more detailed
location and dive data, including depths and durations of dives. These
data are important for determining how beluga whales use the habitat of
Cook Inlet. Initial location data are shown in Figure 1 and
Figure 2. For the December
tracking map click
The biopsy samples are used for various studies. Skin samples provide
genetic information. Blubber samples are analyzed for diet and contaminant
loads. Blood samples provide information on general health, pathogens,
parasites, and hormone levels.
By Rod Hobbs.
Instrument Testing on Northern Fur Seals
NMML scientists tested remote release devices for data collection instruments
on adult female northern fur seals (Callorhinus ursinus) during 17 -31
August 2001 on St. Paul Island, Alaska. Testing of the devices was designed
for future use in studies on Steller sea lions, Eumetopias jubatus. Scientists
have deployed a number of data collection instruments on Steller sea lions;
however, recovery of these instruments is rare due to the low probability
of recapturing sea lions. The instruments are expensive to replace and
valuable dive and location data, stored in memory, are lost when the instruments
are not recovered. Consequently, a device that could release the instruments
from sea lions on land was determined desirable. Two release platforms
and a transmitter to trigger the release of the instruments were tested
on adult female fur seals, due to their higher probability of recapture.
Two adult females (38.5 and 41.5 kg) were captured and instrumented with
1) a satellite-linked depth recorder (SDR) attached to a release platform,
2) a time-depth recorder (TDR), and 3) a VHF transmitter. A single foraging
trip for each female was recorded for the purpose of testing initial durability
of the release platform and the release mechanism. Each foraging trip
lasted 7 days. Female A was the first to return to the island. Personnel
were positioned to recapture the animal prior to attempting to release
the instrument. A laser range-finder was used to estimate the distance
from which the release was triggered. Instrument A was triggered to
release from a distance of 185 m. Once personnel initiated the capture
and the animal reacted, the instrument fell off the release platform, indicating
a successful remote release. The animal was then captured and the release
platform and other instruments were removed. Instrument B was initially
triggered from 255 m, and then the animal was captured. The release platform
did not function. The animal was restrained, the release was again triggered
at distances of 175, 100, 60, 30 and 2 m. The release did not function
when triggered from any of these distances.
Once the design and performance of the release platform is improved, the
remote release instruments should prove extremely useful to Steller sea
lion and other pinniped research.
By Rod Towell.
Research: Harbor Seals
The NMML and the Washington Department of Fish and Wildlife
conducting a collaborative study to determine reproductive success, survival,
natality, and longevity of harbor seals in Washington State. Observations
of tagged and branded harbor seals began on 15 July at Gertrude Island
in south Puget Sound, Washington, where about 100 pups were born between
15 July and 1 September. Fifty harbor seals, primarily pups and
were branded on 18-19 September. In addition, blood from these branded
seals was screened for Brucella and Leptospira antibodies. Two seals tested
positive for Brucella.
Three hundred scat samples were collected between 23 July and 18 September
at the Columbia River to assess harbor seal predation on endangered
From these samples, prey species will be identified morphologically from
bones and otoliths. Unfortunately, salmonid bones can only be identified
to family using morphological characteristics. The salmonid bones will
therefore be identified to species using molecular genetics. In fall
2000, 27 percent of scat samples contained salmonid bones.
From July to September 2001, gray whale surveys were conducted with a small
vessel along the northern Washington coast, Strait of Juan de
the west coast of Vancouver Island, Canada. These surveys covered 1,046
nautical miles and took 76 hours. One hundred fourteen gray whales were
sighted and 54 of those were photographed for later identification. Skin
biopsy samples were collected from four gray whales. One survey extended
as far south as Tillamook Bay along the northern Oregon coast. Only one
gray whale was sighted in Oregon; it was off the mouth of the Nehalem River.
No gray whales were sighted in the Strait of Juan de
Fuca. Sightings of
gray whales increased along the northern Washington coast at the end of
August and the beginning of September. The greatest number of gray whales
was seen off the southwest coast of Vancouver Island in early July.
Steller Sea Lions
As part of a larger study on food habits and assessment of Steller sea
lions in Washington, Oregon, and California, NMML staff collected scat
twice a month from haul-out sites on the northern Washington coast and
conducted bimonthly aerial and vessel surveys in collaboration with the
WDFW from July through September. In late June, 180 Steller sea lion
pups were tagged and branded at Rogue Reef, Oregon, in a cooperative study
between NMML and the Oregon Department of Fish and Wildlife. This is the
beginning of a long-term project to estimate survival and natality for
the Oregon population of Steller sea lions.
California Sea Lions and Northern Fur Seals
Population assessment studies of California sea lions and northern fur
seals were conducted at San Miguel Island, California, from 18 May to 8
August 2001. California sea lion pup production increased 2.0 percent from pup
production in 2000. The observed sea lion pup mortality rate through the
first 4 months of life was 44.2 percent. The high pup mortality is associated
with a high incidence of hookworm infections in young pups. Northern fur
seal pup production increased 23.7 percent from pup production in 2000,
but still remains 33.7 percent below 1997 pup production, indicating that
the 1997-98 El Niño event has had a long-term impact on this species.
A total of 6,799 sightings of branded California sea lions was recorded,
representing 1,522 individuals. Four hundred sixty-five California sea
lion females from 4 to 14 years old were sighted with pups. Observations
of marked California sea lions will be used to estimate survival and natality
rates for the population. Five hundred California sea lions were branded
at San Miguel Island to continue studies of survival and natality of the
population. A study comparing foraging ecology of California sea lions
and northern fur seal females was initiated in summer 2001. Preliminary
results indicate that both species feed along the central California coast,
however, northern fur seals forage farther off shore, along the continental
slope, while California sea lions forage over the continental shelf.
By Harriet Huber.
Killer Whales in Central and Western Alaska:
Population Size and Stock
The documented decline of Steller sea lions, harbor seals, and sea otters
in the western Gulf of Alaska and the Bering Sea has raised questions about
the potential impact that killer whale predation may have on these populations.
Although killer whale population size and stock structure is well documented
for the waters of Southeast Alaska and Prince William Sound, this is not
so for killer whales inhabiting central and western Alaskan waters. Dedicated
surveys for killer whales in central and western Alaska occurred only in
1992 and 1993. Minimum counts of killer whales, ranging from the western
Gulf of Alaska to the Bering Sea (including the eastern and central Aleutian
Islands) were obtained through photo-identification studies. In addition
to the photographic data collected during dedicated surveys, fisheries
observers working with the Centers RACE Division also collect photographic
data of killer whales. Analyses of photographic data collected through
these combined efforts have resulted in the identification of approximately
400 individual whales from central and western Alaska. Based on the preliminary
analyses of photographic and behavioral data, it is apparent that both
resident (primarily fish-eating) and transient (primarily mammal-eating)
forms of killer whales inhabit central and western Alaskan waters. A third
ecotype of killer whale (first described in Canadian waters) also has been
observed in Alaska and is termed the offshore type. In Alaska, offshore
killer whales have been seen only as far north as the inland waterways
of Southeast Alaska. Most of the killer whale information available from
central and western Alaska pertains to the resident form. Large aggregations
of resident whales have been observed and are frequently reported off
the eastern side of Kodiak Island, waters surrounding the Trinity Islands,
Unimak Pass, and the north side of Unalaska Island. Transient whales,
typically occurring in smaller groups, have been observed throughout the
study area. Out of the 400 photo-identified whales, approximately 40 whales
have been provisionally classified as transients (less than 10% of total
2001 Research Activities
In an effort to expand upon the killer whale work described above, NMML
initiated a 3-year study aimed at killer whale population size and stock
structure in central and western Alaskan waters. Scientists conducted
dedicated killer whale studies aboard the chartered fishing vessel Aleutian
Mariner from Resurrection Bay (Seward, Alaska) to Seguam Pass (Central
Aleutian Islands) between 17 July and 25 August 2001. The survey objectives
Estimate abundance of central and western Alaskan killer whales ranging
from Resurrection Bay to the central Aleutian Islands (Seguam Pass) using
line transect, photo-identification,
and mark/recapture photographic techniques.
Plot distribution and determine home ranges of identified pods of Alaska
Determine the ecotype (resident, transient, and offshore) of killer
whale pods by examining differences in morphology from photographs, genetics
from biopsy sampling, and analyses of acoustic recordings.
During the 40-day survey (17 July to 25 August 2001), 1,937 nmi of on-effort
trackline were completed. There were 19 encounters with killer whales (Figure
1) with provisional groupings as follows: 10 groups of resident whales
(approximately 290 whales), 8 groups of transient whales (approximately
30 whales), and 1 group of 40 offshore whales. Photographs were collected
for 18 of 19 encounters on 138 rolls of black and white Fuji 1600 film.
Frame by frame photographic analyses will yield a count of all individual
whales observed. A total of 17 biopsy samples were collected from 11 different
killer whale groups. Genetic studies will be used to verify the pods ecotype
as resident, transient, or offshore. Tissue samples will also be analyzed
for contaminant levels and compared to killer whale tissue samples collected
from California to Alaska. Underwater recordings were attempted on six
occasions with killer whale calls recorded in four cases. Whenever possible,
acoustic analyses will also be used to confirm the identification of resident
versus transient pods. Despite the number of encounters of killer whales
seen during the survey, predation by killer whales on a marine mammal
was only observed once. They were noted attacking and subsequently killing
a small minke whale near a Steller sea lion rookery in the Shumagin Islands.
Numerous other cetacean species were observed during the survey. Total
group sightings included humpback whales (152), fin whales (86), gray
whales (22), minke whales (33), sperm whales (7), beaked whales (1), Dalls
porpoise (156), and harbor porpoise (9).
Photographs of humpback whale flukes were collected whenever possible on
a not-to-interfere basis with the killer whale studies. Biopsy samples
were collected from humpback whales, fin whales, and gray whales.
By Marilyn Dahlheim.
Harbor Seal Survey in Gulf of Alaska
The Polar Ecosystems Program conducts counts of harbor seals in Alaska
for estimation of population abundance and long-term trends. The harbor
seal population is divided into five counting regions, one of which is
surveyed annually during August when seals molt and spend more time ashore.
The Gulf of Alaska (GOA) region, which includes the south side of the Alaska
Peninsula and runs from Unimak Pass to Kayak Island east of Prince William
Sound, is of particular concern because harbor seals have declined as much
as 85 percent since the mid-1970s in some parts of the region.
The region was divided into routes that could be surveyed by aerial observers
within the 4-hour period around low tide, which is best for counting harbor
seals on shore. The survey counts on these routes are replicated 4-5 days
for acceptable precision of the estimates. The most recent survey of
the GOA region required 13 routes using 13 separate aircraft with observers
from NMML and the Alaska Department of Fish and Game. Eleven routes were
surveyed during 14-25 August 2001, and in anticipation of the logistical
complexity of the 2001 survey season, surveys of the other two routes were
conducted during August 2000 in conjunction with surveys of the Bristol
Bay region. Observers spent the first 3-5 days in reconnaissance of the
entire coastline along their survey routes. Locations of all seal haul-out
sites were recorded and mapped using a global positioning system (GPS).
The remaining surveys were flown from site to site when the timing of
the low tide was appropriate for counting harbor seals. Visual counts
were conducted for small groups of seals (<10), and aerial photgraphs were
made of larger groups for subsequent counting at the NMML facilities in
The GOA region is large and complex and difficult to survey adequately
for harbor seal abundance. Harbor seals haul out on sand or rock, and
as many as 20 percent of the GOA seals haul out on ice calved from glaciers.
Seals hauled out on glacial ice pose special difficulties for surveys.
Ice is dispersed and in constant motion throughout glacial fjords, making
it difficult to track what ice and seals have been surveyed. Moreover,
glacial ice frequently contains dirt and rocks, which complicates detecting
and counting seals.
The GOA region contains at least 14 glacial haul-out sites. During the
2001 survey, NMML contracted with Aero Map of Anchorage, Alaska, to photograph
these sites using a GPS-linked large-format aerial mapping system. Photos
of the glacial sites were taken at various altitudes between 600 and 1,600
m (2,000 and 5,000 feet) during the same time as our regular aerial abundance
surveys described above. Future plans are to repeat the large format surveys
in the spring during the pupping period and to use a second contractor
to photograph the glacial sites using an infrared system that may aid in
discriminating between seals and rocks on the ice.
By David Withrow and Peter Boveng.
quarterly Jul-Sept 2001 sidebar
Auke Bay Lab