National Marine Mammal Lab Quartery Rpt for Jan-March 2000

Steller Sea Lion Research in the Aleutian Islands and Gulf of Alaska

Scientists from the National Marine Fisheries Service’s Alaska Fisheries Science Center, Colorado State University, and the University of Alaska Sea Grant Program conducted Steller sea lion research in the Aleutian Islands region and Gulf of Alaska aboard the U.S. Fish and Wildlife Service vessel Tila from 24 February through 15 March 2000. The primary goal of this cruise was to capture juvenile and pup sea lions for collection of blood and other biological samples and for deployment of satellite-linked time-depth recorders. A secondary goal was to go ashore at any accessible haul-out site to collect sea lion scats (fecal material) for food habits analyses. Capture effort was concentrated in three geographical regions: Seguam Island, the Krenitzen Islands and Unimak Pass, and eastern Kodiak.

Itinerary
The scientific party boarded the Tila at Adak, Alaska, on 24 February. Most of the cruise was conducted under storm- or gale-warning flags, as a succession of low-pressure weather systems swept across the region, delivering high winds and heavy seas. Several of our intended research sites were fully exposed to weather (e.g., southwest winds and seas washing directly onto Lake Point, Adak). Other sites may have been on the leeward sides of islands, but the lack of protection from surging waves made them unworkable on most days (e.g., Seguam, Yunaska, and Jude Islands). Consequently, we spent much of our time at anchor in shelter when conditions precluded safe landings at haul-out sites, striving to be in position to go ashore and work when the weather did let up. This strategy resulted in a very successful day of work at Turf Point, Sequam Island. Even in the relative protection of the Krenitzen Islands, we constantly changed anchorages and target haul-out sites in reaction to changes in wind direction and speed. When we were able to land at haul-out sites in the Krenitzen Islands, wind direction frequently was exactly wrong for stalking sea lions. On several occasions, all animals spooked and departed from the haulout before a capture could be attempted. We were unable to get ashore at haul-out sites along the eastern coastline of Kodiak Island (Twoheaded Island, Cape Barnabas, Gull Point, Cape Chiniak) because of easterly winds and seas, but we did have one workable day at Long Island near Kodiak City and one day in the northern Archipelago (Sea Otter Island and Latax Rocks). A severe storm warning caused us to curtail our work a day early. We concluded the cruise at Homer, Alaska, on 15 March.

Results
During the Tila cruise, we visited 29 Steller sea lion rookery and haul-out sites from Lake Point, on Adak Island in the central Aleutian Islands region, to Flat Island in lower Cook Inlet. We made no attempt to land at 19 of these sites, either because conditions prohibited safe landing or there were so few animals hauled out that the low likelihood of successful results did not warrant disturbance. We successfully landed ashore at nine different sites. On one occasion we went ashore but were unable to reach the haul-out site (Silak Island in Little Tanaga Strait). We collected a total of 219 scats from ten shore visits to nine different sites: 13 scats from Seguam, 174 scats from the Krenitzen Islands (five sites), and 32 scats from the northern Kodiak Archipelago (three sites).

We captured nine pup and yearling sea lions: five at Seguam Island (Turf Point: four females, one male), two at Aiktak Island (one female, one male), and two at Long Island (two males). Mean mass was 82.2 kg (SD=14.3, range 61.8-100.2 kg) for five females and 83.6 kg (SD=23.7, range 62.2-109.0 kg) for three males. Mean mass for eight animals of both sexes was 82.7 kg (SD=16.6). We were unable to weigh one male (estimated to be 95-100 kg) because of his struggling and the difficult position where he lay. This male probably was 21!22 months old, based on the length of his canine teeth. All others were pups of the year, approximately 9!10 months old. We deployed satellite-linked time-depth recorders (SLTDRs) and VHF transmitters on eight of the nine captured sea lions, not attaching instruments to the smallest of the female pups captured at Sequam Island. Via e-mail, we were able to notify colleagues at NMML immediately after SLTDR deployment, receiving confirmation within a few hours that each instrument was working and that each animal had shown some movement.

We successfully obtained blood from all captured animals. We performed preliminary blood work onboard the ship (e.g., serum extraction, hematocrit, white cell counts). Samples retained for later analyses in the laboratory included frozen serum and plasma, hemoglobin preserved in reagent, and blood smears on slides. The white-cell counts were very low for the two smallest pups, possibly an indication of viral infection. One of these pups also had ulcers on his foreflippers, possibly indicative of calicivirus infection. The largest female captured had an ulcer on her vulva that also may have been caused by calicivirus; however, her white cell count appeared within normal limits. We collected a genetic sample (flipper punch) from each captured animal, and a blubber biopsy from all five animals captured at Seguam Island and both animals captured at Long Island. The two animals captured at Aiktak Island were marginally restrained in an awkward setting and we decided to forgo biopsy. Blubber will be used for fatty acid studies as well as other analyses. Biopsies of one of the smaller flipper ulcers on the male pup at Long Island will be used for virology analysis.

Other observations
We collected a fresh-born fetus on Sea Otter Island, at the northern end of the Kodiak Archipelago. Judging from the overall condition of the fetus, it had been born a few hours prior to our arrival. Partial inflation of the lungs implied that the pup had been born alive but had not survived more than 15-30 minutes. Dr. Terry Spraker of Colorado State University performed a postmortem examination onboard the ship and collected a full suite of formalin-preserved and frozen tissues for laboratory analyses. We also collected blood from the fetus, which we worked up according to the same protocols as for the live pups.

We had only two resightings of tagged animals. Both were tagged as new-born pups at Ugamak Island on 2 July 1998. We saw no branded sea lions during the cruise. In addition, we had surprisingly few observations of other marine mammals. We saw killer whales on only three occasions: two whales in Amukta Pass on 3 March, four whales in Tigalda Bay on 7 March, and five whales cruising processor row in Kodiak harbor on 12 March. We were unable to obtain photographs of any killer whales. On 3 March a group of 6-10 Pacific white-sided dolphins rode our bow for several minutes north of Akutan Island, near Unimak Pass.

The most notable bird observation was of a male spectacled eider off the sea lion haulout on the rocks northeast of Tigalda, a site identified as “Kaligagan Rocks” by the Alaska Maritime Wildlife Refuge biologists. It is thought that most spectacled eiders winter in polynyas (open waters in sea ice) in the Bering Sea near St. Lawrence and St. Matthews islands. The few sightings of these birds in the Aleutian Islands during winter likely is a function of low observer effort.

Summary
The capture technique of using hand-held hoop nets on land worked very well. This was only the second time we have applied this technique to Steller sea lions in Alaska. The technique does require liberal adaptation and improvisation to cope with the physiography of each site, local weather conditions, and haul-out distribution of the animals. On three occasions we experimented with using the skiff immediately in front of the haulout to herd and distract animals and drive them towards the capture team, who crept up from behind. The skiff-aided technique was successful at one haul-out site but yielded only near misses at two others. Favorable weather, of course, is key to the success of any field operations in maritime Alaska, particularly in midwinter. Captures are difficult at best when forced to approach animals from up-wind, and impossible when conditions prevent landing the scientific party on the beach.

We administered a dose of valium (1.1-2.0 cc, depending on the animal’s estimated weight) to each animal about 10 minutes before we started handling it. Each animal struggled while we attached the various restraints, but calmed down quickly thereafter, usually by the time we finished weighing and taking measurements. All animals lay still while we attached SLTDRs and took blubber biopsies; several appeared to sleep through much of the procedure. Valium greatly reduced the animals’ struggles to escape, which in turn reduced the amount of wrestling and fighting required to restrain them, and reduced total handling time. Valium undoubtedly minimized the overall stress experienced by captured animals.

As of 10 April 2000, all eight SLTDRs continue to transmit data, 36 to 43 days after deployment. Two of the sea lions have remained within about 10 km of the capture site. Four others travelled as far as 30-40 km away from their capture sites, visiting several haul-out sites. Two sea lions travelled extensively, paying extended visits to haulouts 100 km and 110 km from their capture sites at Aiktak and Long Islands. Results from analyses of dive data are not available at this time.

By John Sease.

APIS 2000 Cruise: Multidisciplinary Research into the Ecology and Behavior of Antarctic Pack Ice Seals

Background
The research described here was conducted as part of the Antarctic Pack Ice Seals (APIS) Program, an international research effort formulated by the SCAR (Scientific Committee on Antarctic Research) Group of Specialists on Seals to consider the functional significance of upper trophic level predators in the Antarctic pack ice zone and to investigate the seals’ interactions with their biological and physical environments. Recognizing the high cost and logistic difficulties in undertaking research in the pack ice on a circumpolar scale, scientists from the United States, Australia, Germany, South Africa, Norway, and the United Kingdom collaborated to implement a multi-disciplinary science program that would be far greater than the sum of its parts
( Figure 1).

The pack ice region surrounding Antarctica contains at least 50% of the world’s population of seals, comprising about 80% of the world’s total pinniped biomass. As a group, these seals are among the dominant top predators in Southern Ocean ecosystems, and the fluctuations in their abundance, growth patterns, life histories, and behavior provide a potential source of information about environmental variability integrated over a wide range of spatial and temporal scales. Variations in top predator distribution, abundance, behavior, and physiology can provide valuable insights into locations of oceanographic features and areas of high secondary production.

One of the hypotheses being explored by the APIS Program suggests that there are measurable physical and biological features in the Southern Ocean that result in areas of high biological activity by upper trophic level predators. Environmental features such as the margin of the continental shelf, the physical characteristics of sea ice, ocean fronts, and icebergs, are thought to produce conditions that lead to high biomass sites within the pack ice region. These sites may provide protection from predators, concentrated prey resources, access to water for foraging activity, and preferred sites for animals to give birth or molt. Moreover, such sites appear to be preferentially chosen depending upon species’ sex, age, physiological condition, and general health characteristics. Preliminary data indicate a strong coupling between biological characteristics of the upper trophic level species and the physical features of the pack ice environment. However, there have only been rare opportunities to make simultaneous measurements assessing in detail the processes leading to high densities of upper trophic level species associated with such features.

Scientists from the United States took a multi-disciplinary approach when developing their contribution to the international APIS Program. A group of 17 principal investigators from 12 agencies and institutions were funded by the National Science Foundation’s Office of Polar Programs to undertake the APIS 2000 cruise, which focused on the pack ice zone of the Ross Sea. The total group of 31 scientists that participated in the APIS 2000 cruise had expertise in seal abundance and distribution, seal health and nutrition, seal population genetics and immunogenetics, seabird ecology, fish and squid ecology, zooplankton and krill ecology and physiology, sea ice dynamics, and physical oceanography. The following questions formed the foundation upon which the APIS 2000 investigators formulated hypotheses within their respective disciplines:

Cruise report
The APIS 2000 cruise departed Lyttleton, New Zealand, on 20 December 1999 and ended on the morning of 10 February 2000, when we arrived at McMurdo Station, Antarctica (Figure 2). The cruise was extremely productive and allowed us to accomplish a tremendous amount of research on the ecology and behavior of Antarctic pack ice seals and their biological and physical environment. The research vessel N.B. Palmer proved to be an outstanding platform for conducting the APIS Program’s multidisciplinary research. The helicopter detail sailing with us was also terrific, and the helicopters were a research tool that we utilized to the fullest extent that weather allowed. On a typical day, it was not unusual for our science activities to include two helicopters aloft flying seal surveys, two or three Zodiac boats supporting local seal work, divers, and sea ice sampling, and a CTD cast or HTI acoustic survey conducted from the ship. Net tows were conducted in the evening when the seals went in the water to feed.

A quick look at some summary numbers provides a hint of the intensity with which the APIS cruise was conducted: 45 science days, 647 separate science events, ship track sampling of approximately 800 km along the Ross Sea polynya marginal ice zone, nearly 1,000 km along the coastal fast ice, two short transects across the ice-covered shelf slope zone, four long transects from the coast to the northern marginal ice zone (each about 600 km long), and 175 hours of helicopter flights (which yielded well over 18,000 km of aerial survey transects for seals).

By John L. Bengtson.

Gray Whale Strandings

In 1999, an unusually high number of gray whales (273) stranded along the west coast of North America (see summary by S. Moore in AFSC Quarterly Report, October-December 1999), which caused NMFS to consult the Working Group on Marine Mammal Unusual Mortality Events in July 1999. The group decided that this qualified as an unusual mortality event, and an evaluation was requested. NMFS contracted with Stephanie Norman to complete this evaluation. The draft report (Gray Whale Strandings in 1999 and a Review of Stranding Records in 1995-1998 by Stephanie A. Norman, Marcia M. Muto, David J. Rugh, and Sue E. Moore) includes a summary of all available data; a review of the stranding response; an assessment of the impact of the mortality event on the affected population; and a list of potential causes for the event.

Several factors may have contributed to the high number of gray whale strandings in 1999:

Given the expected natural mortality for a population now estimated in excess of 26,600 whales, the high number of stranded animals observed in 1999 most likely did not have a deleterious effect on the overall population.

By David Rugh and Marcia Muto.

Status of Cook Inlet Beluga Whales

The National Marine Mammal Laboratory (NMML) in conjunction with other researchers conducting studies in Cook Inlet, Alaska, is preparing manuscripts summarizing available information on beluga whales (Delphinapterus leucas) from the Cook Inlet stock. Beluga whales occur in five stocks around Alaska, the most isolated of which is the Cook Inlet population. The geographic and genetic segregation of this stock, combined with their tendency toward site fidelity in summer, makes this population especially vulnerable to deleterious impacts from large or persistent harvests. Results from 6 years (1993-98) of summer aerial surveys indicated that beluga distribution within Cook Inlet was shrinking, and estimated population size has declined by nearly 50%. Point estimates of annual abundance ranged from 653 whales in 1994 to 347 whales in 1998. This meant that the average reported harvest of belugas in Cook Inlet during this period (72 whales) was 21% of the best estimate of abundance. Relative to the total number of animals that can be safely removed annually from a population of marine mammals (referred to as the Potential Biological Removal (PBR) in the Marine Mammal Protection Act (MMPA) ), the harvest rate between 1994 and 1996 was approximately 5 times the calculated PBR of 14 whales. Notably, the PBR was later reduced to 1.6 whales when the calculations incorporated revised abundance estimates from surveys completed in 1998 and a revised recovery factor to account for the observed decline in abundance.

On 19 November 1998, NMFS initiated a formal review of the status of the Cook Inlet beluga stock through a cooperative process with the Alaska Beluga Whale Committee (ABWC) and the Cook Inlet Marine Mammal Council (CIMMC). The objective of this review was to provide recommendations to the Alaska Regional Office and the NMFS Office of Protected Resources regarding the classification of this stock as endangered or threatened under the Endangered Species Act (ESA) or depleted under the MMPA. The scientific portion of the review focused on the current status of Cook Inlet belugas: distribution, abundance, trends in abundance, and habitat. The effects of the Alaska Native subsistence harvest and the potential effects of other anthropogenic impacts, as well as beluga natural mortality were also examined. Manuscripts covering these topics will be published in a special issue of Marine Fisheries Review in summer 2000.

By Sue Moore and Doug DeMaster.

Alaska Eskimo Whaling Commission’s Initial Mitigation Meeting on Bowhead Whales

On 24 February 2000, NMML held a meeting called by the Alaska Eskimo Whaling Commission (AEWC) to discuss concerns about the impacts of oil and gas development on subsistence use of bowhead whales and on the communities of the North Slope Borough in general. Participants included members of the AEWC, the Barrow Whaling Captains, representatives from the North Slope Borough, British Petroleum, ARCO Alaska, Phillips Petroleum, LGL, Clearwater Environmental, U.S. Minerals Management Service, and staff from NMFS Headquarters, NMFS’ Alaska Region, and NMML.

The focus of the meeting was to develop a process for addressing the following issues:

Preliminary meeting recommendations included convening interagency workshops to coordinate agency activities related to monitoring the impacts of oil and gas development, clarifying the legislative and administrative authorities of various agencies with respect to oil and gas development, and collecting suggestions for resolving concerns about oil and gas development from the North Slope Borough communities. A draft report of the meeting was circulated to participants in early March, and a final report will be distributed by late spring 2000.

By Robyn Angliss.

Harbor Seal Task

The Alaska harbor seal task developed procedures to digitally grab photographs taken during the Aleutian Islands assessment survey flown during late summer 1999. These images were archived on CD-ROMs, digitally enhanced, and pulled into an image analysis program. Procedures were developed to seam overlapping images into one panoramic image per haulout. Seals were first counted in all assessment images using the traditional method of projecting slides onto counting boards. A sample of these counts was compared to counts taken using the new digital method. Initial results indicate that the digital method is not always a more effective way to count seals. In particular, images of harbor seals taken during the Aleutian Island survey typically showed dark-colored seals on dark wet rocks in extremely low light conditions; under these circumstances, the seals in the digitized image were not any easier to detect, even with a variety of image enhancement tools available. However, the technique appears to work quite well for seals hauling out on other substrates, such as sand, which provides better contrast.

Last summer, nine harbor seals associated with the glacial ice in Tracy Arm, Southeast Alaska were captured and fitted with time-depth recorders (TDR). A series of three remote data collection computers (DCC) were placed in Tracy Arm to monitor the presence or absence of the tagged seals and to determine whether individual seals were in the glacial fjord or in Stephens Passage. In early 2000, programs were written to analyze the DCC data in preparation for a comparison with the haul-out and diving behavior data from the TDRs.

By Robyn Angliss.