National Marine Mammal Lab quarterly research report for April-June 2000 AFSC Qrtly Rpt.

Cetacean Survey

Three marine mammal observers conducted a cetacean survey from 9 June to 2 July 2000 aboard the NOAA ship Miller Freeman. The survey was a piggyback project during a RACE Division acoustic-trawl survey for walleye pollock. The primary objective of the cetacean survey was to find northern right whales and obtain photographs for individual identification and biopsy samples. The secondary objective was to collect line-transect data for all whales, dolphin, and porpoise species for abundance estimation. Other marine mammal sightings such as walrus, sea otters, and pinnipeds, were also recorded for distribution information. The Miller Freeman is a 215 ft long research vessel and the survey was conducted while the ship was at a speed of approximately 11.8 kts. The cetacean survey included part of the transit from Kodiak Island to the first acoustic trawl line in Bristol Bay, the 18 north-south transect lines proceeding from east (long.160° 20´W) to west (long. 171° 20´W), and part of the transit to Dutch Harbor. The transect lines were 20 nautical miles (nmi) apart and ranged from approximately 85 km to 290 km in length and covered the southwestern portion of Bristol Bay and across the shelf (the southern ends of the lines along the shelf edge) to just west of the Pribilof Islands.

The cetacean survey was conducted from the flying bridge where two observers searched through 25x150 power binoculars at starboard and port stations. A data recorder also searched by equally scanning both sides of the trackline with the naked eye, using Fujinon 7x50 hand-held binoculars to confirm sightings. The observers rotated positions every half hour during a 2 hour shift, followed by a half hour break. The survey was suspended when the ship stopped for fishing operations, during inclement weather, and when light levels were too low for efficient observations.

A total of 2,598 km of trackline was surveyed. Northern right whales were not observed. The number of other recorded marine mammals are listed in here in Table 1.

By Janice Waite.

Harbor Seals in Inland Transboundary Waters

The first phase of a cooperative project on harbor seal assessment, distribution, and foraging behavior conducted by the NMML, Washington Department of Fish and Wildlife and the Canadian Department of Fisheries and Oceans was conducted 16-19 May 2000 at Boundary Bay, British Columbia. Twenty-five harbor seals were captured and released, including 15 that were fitted with time-depth recorders, VHF head mounts and VHF flipper tags. The project is part of an effort to determine if harbor seal haul-out behavior has changed in the last 10 years, or if the apparent leveling of the harbor seal population in the inland waters is real. In addition, the study will provide a comparison of methods for determining a correction factor to account for seals in the water during aerial surveys and will provide information on movements and foraging behavior in transboundary waters.

By Harriet Huber.

Pinniped-Salmonid Interactions in Ozette River and Lake

The Lake Ozette sockeye salmon (Oncorhynchus nerka) population was listed as threatened under the Endangered Species Act in March 1999. For the last 2 years, the NMML and the Makah Tribal Fisheries Service in cooperation with the National Park Service, have been conducting research on the possible impacts of pinniped predation on sockeye recovery. During May and June 2000, field research was conducted both at the mouth of the Ozette River and upriver at the fish weir to identify the quantity, timing, and location of predation. At the river mouth, 83 sockeye were captured, anesthetized, and tagged. Each fish was examined for marine mammal scars, and a digital photograph was taken of each side of the fish. Upriver at the fish weir, a fish trap was monitored 24 hours a day and all sockeye were counted and examined through a floating glass viewport. Tagged fish were removed, anesthetized, examined for scars, photographed, and then released. A sample of fish received an internal sonic tag to enable tracking of the fish on the spawning grounds in the lake.

By Jeff Laake.

Cetacean Tagging

The attachment of satellite-linked transmitters is an important technique for obtaining information on the movements and diving behavior of cetaceans. However, until recently most attachments lasted only several months, which does not provide information about seasonal and long-term movements. Using bioengineering principles, NMML researchers have studied the material properties of the dorsal fin and attachment pins of the transmitters, and the drag and load created by different tag attachments. Research has shown that a paired-side mount configuration produced the least amount of stress at the pin sites.

Scientists were able to monitor a Dall’s porpoise successfully tagged using the paired-side mount technique, from early May 1999 through May 2000, a duration of 380 days. This Dall’s porpoise was initially tagged in Haro Strait and subsequently moved to the outer coast of Vancouver Island in late spring 1999, returned to inland waters during the fall and winter of 1999/2000, and has now returned back to the outer coast.

NMML researchers have also developed a telemetry system for Keiko the killer whale using a similar approach in tag design. In May and June researchers finalized the tag configuration and custom fit the package to Keiko’s fin. Like other packages that have been developed, it incorporates a satellite-linked and VHF transmitter which will allow Keiko’s movements to be monitored if he is released.

By Brad Hanson.

Killer Whale Workshop Spring 2000

On 1-2 April 2000, a killer whale workshop was held at the AFSC facilities in Seattle, Washington. Sponsors of the workshop were the NMML, Center for Whale Research, Six Flags Marine World, and the Whale Museum. Contributions were made by the Department of Fisheries and Oceans (DFO Canada) and the American Cetacean Society. The purpose of the workshop was to inform participants about the current status of southern resident killer whales and help the research community coordinate future research. The workshop focused on four areas of research:

In addition to several oral presentations covering these topics, 13 background documents were also submitted by participants.

At the conclusion of the workshop, several areas needing continued research were identified including: studies of photo-identification work; estimates of historical population levels; identification of the relation between prey base and population status; increased attention on winter feeding and feeding depths in the summer; studies of the effects of pollution on reproduction and survival; and determination of the effects of whale watching. Once existing tissue samples are analyzed and specific hypotheses are developed for contaminant and genetic investigations, additional biopsy darting may be warranted. The importance of understanding the population dynamics of transient eastern North Pacific killer whales was also recognized, as this population is more contaminated than the southern residents. Finally, a correlation in population trends between the A and J clans was reported, as these two pods are from different stocks; the population dynamics of northern residents also warrants research to help clarify what factors are contributing to the decline of southern residents.

By Christy Sims and Marilyn Dahlheim.

Alaska Killer Whale Photography and Biopsy Project

National Marine Mammal Laboratory staff working jointly with the North Pacific Groundfish Fishery Observer Program implemented a special project this year that uses selected fishery observers working aboard longline fishing vessels in the Aleutian Islands/Bering Sea to collect photographs and biopsy samples of North Pacific killer whales on an opportunistic basis. Much concern has been raised recently about the population size and stock structure of these killer whales. Minimum counts of killer whales, ranging from the western Gulf of Alaska to the Bering Sea (to include the eastern and central Aleutian Islands region) have been obtained through photo-identification studies. Photographic analyses of data collected through dedicated studies and through the efforts of the fishery observer program have resulted in the identification of 400 individual whales, to date. The data collected through the project will further aid researchers in determining killer whale stock structure, population size, and contaminant levels.

The first observer to participate in this study was selected, trained, and completed one cruise during April-June 2000.   During this cruise he successfully photographed several killer whales and collected two biopsy samples near Dutch Harbor, Alaska in June. NMML researchers are presently in the process of analyzing these new data.

By Anita Lopez.

Search for Harbor Seal Study Site in Southeast Alaska

NMML staff, along with a representative of the Alaska Department of Fish and Game (ADF&G), used the John N. Cobb during 8-14 June 2000.   The objectives of the trip were to search for a potential, long-term harbor seal study site in Southeast Alaska and to determine the stage of pupping at several selected haul-out sites. Several sites were identified as potential sites for long-term camps and observing seals and deploying remote video monitoring stations. These included Rookery, Echo, Cedar Shakes, and Beauclerc Islands, all south of Juneau and within close proximity to Petersburg or Wrangell for logistics support. Seal numbers were variable at these sites, ranging from approximately 50 to 500, and in all cases the proportion of female-pup pairs was high.

Both the Tracy and Endicott Arms glacial fjords were transited, assessed for camp/video potential, and the harbor seals were counted. In both cases floating ice that had calved from the glacier slowed the Cobb’s progress through the fjord. Six hundred to 1,000 seals were counted in Tracy Arm and roughly 700 in Endicott Arm. Again the proportion of female-pup pairs was high.  The Tracy Arm area also showed good potential for a long-term camp and remote video site.

By Dave Withrow and Jack Cesarone.

Arctic Ecosystems Program Ice Seal Surveys

NMML’s Arctic Ecosystems Program conducted aerial surveys from 21 May to 1 June 2000 to assess distribution and abundance of ringed and bearded seals in northwestern Alaska. These surveys complemented similar surveys conducted by NMML in May-June 1999. In both years, the coastline of the Chukchi Sea was surveyed east of Ikpek Lagoon (near Shishmaref) and north to Barrow. Survey lines were flown perpendicular to the coast with most lines 20 nmi in length, supplemented by a sample of longer lines (100 nmi) to assess off-shore seal densities. Ringed seal densities were highest south of Kivalina and northwest of Kotzebue. Bearded seals were generally seen at distances greater than 20 nmi from the coast, although they were present in relatively high densities within 20 nmi of shore in the area south of Kivalina.

Because the aerial surveys only observed seals on the ice surface, a correction factor is needed to account for seals that were in the water at the time of the survey. To develop this correction factor, three ringed seals were captured and instrumented with satellite tags. Data from these instruments will provide information on the amount of time the seals spend in the water and will allow NMML scientists to adjust the aerial survey numbers to account for seals not hauled out on the ice when these surveys took place.

By Lisa Hiruki.