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National Marine Mammal Laboratory

(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.

  • Other observations

    No harbor seals (Phoca vitulina) were observed on Bogoslof Island during census activities.  The usual haulout on the east side of the island was scanned on the morning of 31 July as the Tiglax  approached the island and was checked periodically during both days researchers were present on the island.

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 ship’s 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


Comment - Behavior



Helicopter sighting - resting at surface in 50% ice cover; sinks from sight on 2nd circling pass



Helicopter sighting - resting at surface in 50% ice cover; sinks from sight on 1st circling pass



Vessel sighting - juvenile (small) whale swimming cross ship’s path in 20% ice



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°14.7’N, 155°22.1’W) 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°17.7’N, 156°49.7’W) 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°15’N, then west to 125°35’W,
then east along 48°19’N

Encounter number

Time with group (in minutes)

Number in group

Number of individuals photo-

Number of whales biopsied




2 whales

2 flukes

2 biopsies




cow and calf

cow’s fluke

cow’s biopsy




1 whale

1 fluke

1 biopsy




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°10’N, west to 125°00’W, north to 48°20’N, back to Tatoosh Island

Encounter number

Time with group (in minutes)

in group

Number of individuals photo-

Number of whales biopsied




1 gray whale

ID shot

no biopsy

Not a target of the biopsy study



2 gray whales

ID shots

no biopsy

Not a target of the biopsy study



1 whale

no fluke

no biopsy

Whale was traveling, Beaufort 3



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 NMML’s 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, Dall’s 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.

  • Dall’s porpoise tagging

    As of early October, movements of two of three Dall’s 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 Dall’s 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 Niņo 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 Niņo 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 Niņo 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.