JAS 1999 Quarterly Rpt. sidebar
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(Quarterly Report for Jul-Aug-Sep 1999)
Steller Sea Lion Field Studies at Marmot
Island
Marmot Island, located 45 km northeast of
Kodiak Island in the Gulf of Alaska, has been the site of land-based studies of Steller
sea lions (Eumetopias jubatus) for more than 20 years. Most of the work has
been conducted cooperatively between the National Marine Mammal Laboratory (NMML) and the
Alaska Department of Fish and Game (ADF&G). The island once supported one of the
largest Steller sea lion rookeries in Alaska, but numbers of pups and non-pups (adults and
juveniles) counted during the breeding season have declined dramatically since the 1970s.
Marmot Island is currently considered both a trend site and a trend rookery used to
identify and monitor Steller sea lion population trends in the central Gulf of Alaska.
Researchers from the NMML Alaska Ecosystems
Program conducted studies at Marmot Island from 7 June to 11 July 1999 during the pupping
and breeding season. Objectives of the study were to continue monitoring the
population of Steller sea lions through counts by age and sex class (territorial males,
nonterritorial males, females, juveniles, and pups) and by resightings of branded and
tagged animals. The census was conducted from cliff-top sites and included daily
counts of beaches 1-4, weekly counts of beaches 5-7, weekly dawn-to-dusk hourly counts of
beach 4, plus additional, twice-daily brand observations at beaches 1-4. Currently, only
beaches 4 and 7 are rookeries, beach 3 is actively used as a male haulout, beaches 1 and
3Z are frequented by only a few males, and beaches 2, 5, and 6 have been abandoned.
The preponderance of fog this year precluded counting on 6 of 34 days and counting
beaches 5-7 during the first 3 weeks of the study. Beach 7 was counted only twice
and beaches 5 and 6 were each surveyed three times, although no sea lions were observed.
Maximum counts at beach 4 were 293 females, 269 pups, 25 juveniles, 41 territorial
males, and 6 nonterritorial males. Maximum counts at beach 7 were 213 females,
233 pups, 26 juveniles, 29 territorial males, and 5 non-territorial males. A single
day, island-wide census was possible on only two occasions. The maximum island-wide
count (3 July, all beaches combined) was 413 females, 499 pups, 37 juveniles, 52
territorial males, and 74 non-territorial males, for a total of 1,075 sea lions.
Approximately 750 pups were branded at Marmot Island during 1987 and 1988, yet only
6 of those were resighted during 1999. Five were males, and one was a female with a
pup. Two other branded males that were sighted included a subadult from Forrester
Island and another whose brand origin is presently unknown. Preliminary review of
the 1999 data suggests that the Marmot Island population is continuing to decline.
By Lisa Baraff.
Bogoslof Island
Research
The following research was conducted at
Bogoslof Island, Alaska, and en route to Adak while aboard the U.S. Fish and
Wildlife Service (USFWS) research vessel Tiglax from 31 July to 5 August 1999.
Steller sea lion counts
A census of Steller sea lions on Bogoslof Island was conducted on 31 July 1999.
Three groups of sea lions were observed on the island. The largest group was located
on the sandy beach on the east side of the island, and the two smaller groups were at the
southeast tip of the island and on the west side just south of Castle Rock. A total
of 144 sea lion pups and 281 nonpups were counted in the three groups. The nonpup
count is slightly lower than the 1998 count of 274 adult sea lions, however the pup count
shows a substantial decrease from 220 pups in 1998. This decrease is likely due to the
late date of the 1999 census (i.e., pups were no longer confined to the beach in 1999) and
does not necessarily indicate a real decline.
Northern fur seal studies
Based on descriptions provided by researchers who have visited the island in the past,
the distribution of northern fur seals (Callorhinus ursinus) on Bogoslof Island
continues to expand. Three territorial males with females and a minimum of five pups
were observed in the small cove between Kenyon Dome and the 1992 dome, where no pups have
been observed previously. Territorial males with females and pups extended far into
the sandy beach area past the end of the boulders and cobble rock, however this may also
be attributable to increased areas of sand deposited by winter storms. Approximately
40 scat samples were collected from northern fur seal haul-out areas on the north end of
the island adjacent to Kenyon Dome and behind the rookery between Kenyon Dome and Castle
Rock.
An underwater survey was made on the
afternoon of 1 August to assess the suitability of Bogoslof Island as an underwater
capture site for Steller sea lions. The dive lasted 20 minutes, and the maximum
depth reached was 50 ft. Most of the dive was spent in depths of 30-40 ft among
large boulders, many of which had kelp attached. Wave surge was present even at
maximum depths reached. We were accompanied by subadult male northern fur seals
throughout the dive, although no aggressive behavior was observed. Very little
marine fauna was present in the area, and only one small school of fish, possibly
juvenile or larval greenlings, was seen.
By Bruce Robson.
Northern Fur Seal
Foraging Ecology
Scientists from the NMML conducted research
on the summer foraging ecology of juvenile male northern fur seals in the Bering Sea from
26 July to 30 August 1999 on St. Paul Island, Alaska. Juvenile males form a large
component of the population that actively forages during the summer. Recent studies
of northern fur seal foraging ecology have focused on females with pups, but little is
known about the utilization of the Bering Sea by juvenile males and whether aspects of
their foraging behavior overlap with that of female fur seals. The objectives of our
research were to investigate the travel routes, foraging habitat, and diving behavior of
these juvenile male fur seals.
Fifteen juvenile males, 3-5 years of age
(35-85 kg), were captured and instrumented with satellite transmitters to provide location
data at sea. Seven of these animals were also instrumented with time-depth
recorders for analysis of diving behavior. Multiple foraging trips were recorded for
two of the animals and, as of October 1999, some of the recorders were still transmitting
data. The maximum distance recorded at sea from the location of capture for each of
13 foraging trips (11 individuals) ranged from 88 to 1,015 km, and the mean was over
490 km. The duration of nine completed foraging trips (eight individuals) ranged
from 6 to 30 days, and the mean was 17 days. Foraging trips of six female fur seals
instrumented during summer 1998 had a mean maximum distance of 274 km and a mean foraging
duration less than 10 days. Preliminary data indicate that juvenile male foraging
behavior differs from that of females in duration of foraging trips and in utilization of
Bering Sea habitat.
Data were also collected for monitoring pup
condition and fur seal food habits during summer 1999. Pup weight, length, and sex
data were collected from 1,082 pups during 24-25 August, and scats were collected for
examining food habits of northern fur seals.
By Rolf Ream.
Tagging of Beluga
Whale in Cook Inlet, Alaska
From 24 May to 3 June 1999, biologists from
NMML and the NMFS Anchorage Field Office tested new techniques for capturing and
tagging beluga whales in upper Cook Inlet, Alaska. Animals equipped with
satellite-linked-time-depth-recorders (SLTDRs) are needed to provide data on surfacing and
dive patterns as well as distribution and movements. In particular, the surfacing
interval data are critical for developing a correction factor to account for beluga
whales not at the surface (and thus not visible) at the time of aerial surveys.
The study area encompassed the wide tidal
deltas between the Big and Little Susitna Rivers, approximately 50 km southwest of
Anchorage. A crew of seven, based in a field camp at the mouth of the Big Susitna
River, searched for beluga whales during each high tide when conditions were adequate for
small boat operation. Once animals were located in shallow water, a 125-m gill net was set
at high speed around a target whale. Despite problems with the capture net
tangling in tight, high-speed turns, four whales were caught. This marked the first
successful capture of beluga whales in Upper Cook Inlet. We equipped one of the four
animals, a 370-cm adult male, with a satellite TDR and VHF combination tag; one
230-cm immature female too small to tag was measured and released; one adult escaped
during handling; and one adult escaped at the onset of handling.
The tagged animal was tracked by boat in
early June following the VHF signal, yielding over 10 hrs of detailed observation and
surfacing interval data to be compared with the satellite-based data set. The
satellite tag transmitted location and dive data for a total of 112 days, having either
lost power or fallen off on 17 September. A larger capture effort using
further modifications of the gill-net encirclement technique are planned for May and June
2000 in the same area.
By Rich Ferrero.
Cetacean Surveys
Aboard Sir Wilfrid Laurier
Sue Moore of the NMML met the Canadian
Coast Guard Icebreaker (CCGI) Sir Wilfrid Laurier in Barrow, Alaska, on 20
July 1999 where she participated in a cruise to study the ecology of marine organisms
along the ice edge and in the Beaufort Sea. Extensive sea ice caused postponement of
mooring and oceanographic work, and U.S., Canadian, and Japanese oceanographers departed
Barrow on 22 July. The ship remained in the Barrow area until 25 July, waiting for
wind conditions to induce sea ice movement offshore. On 25 July, the decision was
made to begin a crossing of the Alaskan Beaufort Sea along the only available route close
to shore. Prior to departing Barrow, a 2-hour aerial survey of the Barrow Canyon
area was conducted by helicopter, and a watch for marine mammals from the ships
bridge was initiated. Eight bowhead whales were seen during the search: two from the
helicopter and six from the ship (Table 1 below). Whales were observed resting,
swimming, or feeding. The whales seen from the helicopter (surveying at 1,000-ft altitude)
reacted to circling passes by sinking from sight (i.e., no rounding on dives). Four
of the whales seen from the ship appeared to be feeding.
Table 1. Location and behaviors of bowhead whales seen near Barrow,
Alaska, on 25 July 1999.
|
Number of whales |
Location |
Comment - Behavior |
1 |
71�.8N,
155�.7W |
Helicopter
sighting - resting at surface in 50% ice cover; sinks from sight on 2nd circling pass |
1 |
71�.0N,
155�.1W |
Helicopter
sighting - resting at surface in 50% ice cover; sinks from sight on 1st circling pass |
1 |
71�.5N,
156�.1W |
Vessel
sighting - juvenile (small) whale swimming cross ships path in 20% ice |
5 |
71�.7N,
156�.1W |
Vessel
sighting - synchronous swimming/echelon feeding behavior (4 whales); 1 juvenile (small)
whale swimming near group in 20% ice |
Two gray whales were also seen
on 25 July, just north of Dease Inlet (71�.7N, 155�.1W) in 50% ice
cover. These two whales appeared to be juveniles (small) and initially tried to
outrun the vessel while maintaining very low profiles as they surfaced to breathe.
As the ship passed the whales, one whale turned sharply and slapped its fluke on the
water. Prior to departing Barrow, gray whales had been observed from the stationary
ship (71�.7N, 156�.7W) on two occasions: a cow/calf pair was observed on
24 July, and a juvenile whale was observed on 25 July.
No other cetaceans were seen during
the remainder of the cruise, although the crew of the Laurier made several cetacean
and pinniped sightings prior to 20 July and have recorded sightings since 27 July.
These opportunistic sightings are being recorded on NMML Platform of Opportunity
data forms. Although ice conditions curtailed plans to survey the Beaufort Sea slope, it
is noteworthy that bowhead whales were seen near Barrow in July, a time of year when the
Bering-Chukchi-Beaufort stock is expected to be in the Canadian Arctic.
By Sue Moore.
Humpback
Whale Survey
A study of humpback whale
distribution in Washington State waters in the vicinity of Cape Flattery was conducted as
a collaboration between the NMML and Cascadia Research (CR), facilitated by the Olympic
Coast National Marine Sanctuary (OCNMS). Survey tracklines were proposed to
complement ongoing research conducted by CR. Survey protocol included
photo-identification and biopsy sampling. Biopsy samples were collected only after
fluke identification shots were obtained.
Surveys were conducted during
3-5 August 1999 on the OCNMS vessel OC-2, a Zodiac Hurricane 630, rigid hull inflatable,
captained by Andy Palmer, on contract to OCNMS (Tables 2 and 3 below). Six sightings
occurred of one or more humpback whales, comprising a total of seven individuals.
Two sightings of gray whales occurred comprising three individuals. Humpback whale
fluke photographs were taken of five individual whales. One adult humpback whale and
one humpback whale calf whale were not photographed. Biopsy samples were obtained
from four whales (all but one of the adult humpback whales encountered). Gray
whales were not biopsy targets during this survey but were included in this survey as
encountered and photographed for identification.
Table
2. Survey Plan: South to 48�N, then west to 125�W,
then east along 48�N |
Encounter
number |
Time with
group (in minutes) |
Number in
group |
Number of
individuals photo-
graphed |
Number of
whales biopsied |
Comments |
990803-
OC-1 |
80 |
2 whales |
2 flukes |
2 biopsies |
|
990803-
OC-2 |
36 |
cow and calf |
cows fluke |
cows biopsy |
|
990803-
OC-3 |
26 |
1 whale |
1 fluke |
1 biopsy |
|
990803-
OC-4 |
33 |
1 whale |
1 fluke |
No biopsy: individual had been
biopsied during encounter 1 |
Re-encounter of whale 1 from encounter 1 |
Table 3. Survey Plan: South to 48�N, west to 125�W,
north to 48�N, back to Tatoosh Island |
Encounter
number |
Time
with group (in minutes) |
Number
in group |
Number
of individuals photo-
graphed |
Number
of whales biopsied |
Comments |
990804-
OC-G1 |
12 |
1 gray whale |
ID shot |
no biopsy |
Not a target of the biopsy study |
990804-
OC-G2 |
21 |
2 gray whales |
ID shots |
no biopsy |
Not a target of the biopsy study |
990804-
OC-1 |
19 |
1 whale |
no fluke |
no biopsy |
Whale was traveling, Beaufort 3 |
990804-
OC-2 |
48 |
1 whale |
1 fluke |
no biopsy |
Too difficult to biopsy: whale traveling, Beaufort 3 |
The humpback whale photographs have
been printed and entered in the NMML
North Pacific humpback whale database.
Two of the five individual whales
photographed during this survey had been photographed previously. The cow on 3 August 1999
was first photographed and observed off La Perouse Bank in 1991 (NMMLID 16614 and CWR ID
14209). The whale observed on 3 August 1999 (encounter OC-3) was previously photographed
off California in 1992 and off Washington in 1995 (NMMLID 25975 and CRC ID 10654)
By Sally Mizroch.
Cetacean
Survey Aboard the John N. Cobb
NMML scientists conducted a cetacean
survey aboard the NOAA research vessel John N. Cobb 10-23 September 1999 in
Southeast Alaska. The purpose of the study was to collect information on the
distribution, abundance, and stock structure of cetaceans, particularly killer whales,
Orcinus orca, in Southeast Alaska. Biopsy samples were collected also to investigate
genetic diversity, dietary preferences, and contaminant levels of North Pacific killer
whales. Underwater recordings of cetacean sounds were made to add to NMMLs acoustic
library.
Approximately 1,930 km of trackline
were surveyed. Survey areas included all major inland waterways of Southeast Alaska
ranging from Juneau to Ketchikan. Several species of cetaceans were observed
including humpback whales, minke whales, killer whales, Dalls porpoise, and
harbor porpoise. Of particular note were the rare observations of a northern
elephant seal in Chatham Strait and a northern fur seal in Frederick Sound. Skin samples
collected from killer whales will be sent to the University of Durham (England) for
genetic analysis. Contaminant studies using killer whale blubber samples are being
conducted by NMML scientists in collaboration with the Northwest Fisheries Science Center
(NWFSC).
By Marilyn Dahlheim.
Polar
Ecosystem Program
The Harbor Seal Task of the NMML
Polar Ecosystem Program conducted an aerial assessment survey of harbor seals along the
Aleutian Islands from Unimak Pass to Attu Island during 5-15 August 1999. The survey
is the second of two surveys conducted by the NMML specifically designed to assess
harbor seal abundance along the Aleutian Islands; the first was conducted in 1994.
One aircraft, a standard Grumman Goose, and observer were stationed in Dutch Harbor,
Alaska, and surveyed east to Unimak Pass; a second aircraft, a turbo Commander, was
also stationed in Dutch Harbor and surveyed west to the Fox Islands. A third aircraft,
also a turbo Commander, was stationed in Atka and surveyed east to Amukta Pass. A fourth
aircraft, a turbine Grumman Goose, surveyed from Adak Island west to Attu Island. Seal
densities were low but similar to those in 1994. Several new haul-out sites were
discovered.
Another field project was conducted
in late August and early September from the John N. Cobb and a smaller skiff
provided by the Canadian Department of Fisheries and Oceans. The work was a
follow-up to field work conducted in April 1999, when nine TDRs were placed on seals
hauling out on the glacial ice near south Sawyer Glacier (Tracy Arm) in Southeast Alaska.
The purpose of the project is to develop a correction factor to account for seals in the
water and not hauled out when aerial assessment surveys take place in August. Ancillary
information on dive profiles, haul-out times, and possibly feeding can be determined from
the TDR data. The TDR units are designed to be glued onto the backs of the seals and fall
off during the late summer molt and then float, transmitting a signal that observers use
to relocate the devices. Observers recovered seven of the nine devices (only
three to five were realistically expected to be recovered). Data collection computers,
which were strategically placed along Tracy Arm in April to record presence or absence of
the tagged seals, were also recovered in early September.
By Dave Withrow.
California
Current Program Field Studies Gray Whale Surveys
From June to August 1999, vessel
surveys were conducted off the Washington coast, Vancouver Island, British Columbia, and
in the Strait of Juan de Fuca to determine the abundance and distribution of gray
whales. Surveys were conducted over 29 days, including a 14-day survey of the west coast
of Vancouver Island and a 2-day survey of the Washington coast. Whenever
possible, the whales were identified by photographs. A total of 89 gray whales were
sighted during the survey and most were successfully photographed.
Dalls porpoise tagging
As of early October, movements of two of three Dalls porpoises tagged with
satellite/VHF transmitters in inland Washington waters continue to be monitored 145 days
after tag deployment. Although the satellite transmitters on the these animals have
reached the end of their service life, tracking continues with the use of the VHF
transmitters. One of the porpoises, a subadult male, has generally remained in the Haro
Strait area, with a brief excursion into the central part of the Strait of Juan de Fuca.
Visual observations indicate that the tag attachment remains very stable. The
other porpoise, an adult female, moved to an area between La Perouse Bank and the Juan de
Fuca canyon off the west entrance to the Strait of Juan de Fuca about a month after
tagging and remained there until recently moving into the central part of the strait.
Researchers have suspected that Dalls porpoise observed in inland waters will move
to coastal areas. This project has identified that at least one animal has displayed
this type of movement pattern.
San Miguel Island pinniped
studies
Research activities at San Miguel Island, California, continued long-term studies of
survival, recruitment, and natality rates of California sea lions and northern fur seals
and branding and tagging fur seal and sea lion pups. Recent research activities
included the observation of previously branded sea lions and tagged fur seals, pup
mortality surveys, and live pup counts of both species. In general, California
sea lion and northern fur seal production increased significantly in 1999. Sea lion
production increased 77% from 1998 and exceeded the 1997 production by 2.4% indicating
that the population has recovered from the 1997-98 El Ni駉 event. Northern fur seal
production increased 72.2% from 1998 but the total production was still 64.7% below the
1997 production, indicating that this population may have suffered adult mortality as well
as juvenile mortality during the 1997-98 El Ni駉 event. Observed pup mortality
rates for sea lions (14.4%) and fur seals (21.8%) were lower than in 1997 and 1998.
Our branding study continues to provide data for estimation of age-specific
survival, natality, and recruitment rates of sea lions and will provide insight into the
impacts of and recovery from El Ni駉 events on these vital parameters. Two northern
elephant seals were also instrumented to test satellite instruments for future deployment
on cetaceans.
Harbor seal surveys
In collaboration with the Washington Department of Fish and Wildlife, NMML personnel flew
aerial surveys of the Washington coastal and inland stocks of harbor seals in June and
August. At least two surveys of each of the eight survey regions were completed.
In addition to the annual abundance surveys of the coastal stock, we reassessed the
1991-92 correction factor to account for harbor seals in the water during abundance
surveys. The reassessment was made to determine if changes in harbor seal haul-out
behavior during surveys might account for the apparent leveling of the rate of increase
for harbor seals in the coastal stock or if they have reached optimum sustainable
population. Harbor seals were captured in Grays Harbor and Willapa Bay and screened
for evidence of brucellosis and leptospirosis, diseases which can cause reproductive
failure in marine mammals. Observations of survival and reproductive success of
branded harbor seals in Puget Sound began in July.
Columbia River pinniped
predation study
Fecal samples (scats) were collected at Desdemona Sands, the largest harbor seal haul-out
site in the lower Columbia River in an effort to describe harbor seal diet throughout the
year and to assess the species impact on endangered salmon species. From June to
August, six sampling trips were conducted approximately every 2 weeks during extreme low
tides. Harbor seal abundance ranged from 100 to 850 individuals. Collectors
gathered between 58 and 125 scats per sampling period for a total of 520 samples.
By Jeff Cooke.
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