National Marine Mammal Lab quarterly research report for Oct-Decebmer'99

1999 On-Ice Monitoring and Research Workshop

The National Marine Mammal Laboratory (NMML), in cooperation with the NMFS Office of Protected Resources, has hosted annual workshops for several years with representatives from industry, federal agencies, research groups, and other interested parties to discuss and evaluate the potential impacts of oil and gas exploration and development in the Beaufort Sea on marine mammals. Prior to 1998, the majority of these discussions focused on monitoring and research associated with industrial activities during open water periods in the spring, summer, and fall. Most of the monitoring efforts were related to possible impacts on bowhead whales. However, in May 1998 and October 1999, the NMML hosted workshops to specifically address monitoring and research efforts associated with industrial activities conducted on the sea ice during winter. The main goals of the May 1998 workshop were to consider the status of on-ice seismic activities and incidental harassment authorization, to identify information needed to conduct meaningful impact assessments of such work, and to recommend future actions. Most of the discussion at this workshop focused on monitoring efforts related to possible impacts on bearded and ringed seals. Objectives of the October workshop were to review recent on-ice research and monitoring programs, identify data gaps, and suggest possible improvements for future short- and long-term research that will assist in assessing the impacts of on-ice industrial activities on marine mammals. The workshop was chaired by Robyn Angliss of NMML. A draft workshop report was circulated to participants in November 1999; a final workshop report is expected to be available during the first quarter of 2000.

By Robyn P. Angliss

Alaska Scientific Review Group Meeting

The 10th meeting of the Alaska Scientific Review Group (AKSRG) was held at the NMFS Alaska Regional Office in Juneau from 6 to 8 October 1999. Staff from both the NMML and the Regional Office presented fisheries and marine mammal data and facilitated the meeting. The purposes of the meeting were to review the revised 2000 Stock Assessment Reports (SARs) for marine mammal stocks in Alaska, to discuss current data on Cook Inlet beluga whales, and to review NMFS and U.S. Fish and Wildlife Service plans for marine mammal research and management. Special attention was given to updated assessment information on harbor porpoise, Pacific white-sided dolphin, Dall’s porpoise, and gray whale. Additional discussions addressed a broader range of issues including subsistence harvest monitoring strategy, incidental take monitoring programs, ringed seal incidental harassment authorizations, and progress on the development of comanagement agreements with Alaska Natives. The draft 2000 SAR is expected to be available for public comment in January 2000.

By Rich Ferrero

The 13th Biennial Meeting of Society for Marine Mammalogy

National Marine Mammal Laboratory scientists participated in the 13th Biennial Meeting of the Society for Marine Mammalogy held in Maui, Hawaii, from 28 November to 3 December 1999. Oral presentations and posters presented at the meeting by NMML staff (in bold) are listed below.

In addition , the presidential address was given by Doug DeMaster, president of the Society for Marine Mammalogy and the financial report was presented by John Bengston, treasurer of the Society.

By Anita Lopez.

Low Frequency Active (LFA) Noise and Marine Mammals

The significant increase of noise in the world’s oceans has been a subject of concern among marine mammal scientists for the last two decades. Vessel traffic, geophysical exploration, long-range sonar, and other sources of underwater anthropogenic noise are often regarded as a source of potential disturbance to aquatic animals. Of particular concern is the U.S. Navy’s use of the SURTASS LFA (Surveillance Towed Array Sensor System Low Frequency Active sonar). SURTASS broadcasts low frequency sounds (100-500 Hz) at levels often in excess of 200 dB re 1 uPa. On 5 October 1999, the NMML and the Navy cohosted a meeting in Seattle at which Navy representatives and scientists demonstrated the LFA program to interested public. The Navy has also drafted an Environmental Impact Statement (EIS) to document the potential effects of this project (Navy DEIS, 1999).

There have been a number of studies addressing the impact of LFA on selected species of mysticete whales (e.g., blue whales, fin whales, humpback whales, and gray whales). Recently researchers from the NMML undertook a study to determine if sperm whale signals changed in the presence of LFA broadcasts. The call rates of specific sperm whale underwater vocalizations (referred to as “clicks”) were compared prior to, during, and after the projection of LFA signals. Although statistical analysis yielded no significant change in the structure of sperm whale clicks during the projection of LFA, the overall pattern documented decreased calling rates during LFA transmissions followed by periods of silence and then a notable increase in calling immediately following LFA broadcasts. An experiment with an adequate number of treatments and replications along with concurrent surface behaviors and acoustic monitoring is required prior to making final conclusions on the effect of LFA on sperm whale behavior.

By Marilyn Dahlheim and Sue Moore.

Gray Whale Strandings: January - October 1999

The NMML in conjunction with other NMFS research centers is preparing a report summarizing available information on gray whale (Eschrichtius robustus) strandings in 1999. A total of 273 gray whale strandings were reported from 1 January to 15 October 1999, roughly five times higher than the total reported for any year since 1995. Strandings were documented all along the gray whale migration route, with highest numbers reported for Mexico and Alaska. The northernmost stranding was reported at the mouth of the Yukon River in Alaska, while the southernmost was in Bahia de Banderas, Mexico.

Most strandings occurred during late spring and summer, with a peak in number (72 whales) in March. Sex of the stranded animals often could not be determined due to inaccessibility or decomposition. Of the 109 whales (40%) of known sex, 74 (68%) were females and 35 (32%) were males. Similarly, age at death based on length could not be determined for many of the strandings, particularly in Alaska where carcasses were seldom measured. Of the 178 whales where age class was assigned, 94 (53%) were adults, 34 (19%) were juveniles/subadults, 36 (20%) were yearlings, and 14 (8%) were calves.

While the number of stranded gray whales reported in 1999 was higher than previous years, the total number may have been influenced upwardly by increased aerial surveys in Alaska and greater research efforts in Mexico, both areas where high stranding numbers were reported. Of note, the total number of stranded animals represents only about 1% of the Eastern North Pacific population, estimated to number 26,635 (CV = 10.06%) whales from a census done during winter 1997/98. As reported in the recent Status Review of the Eastern North Pacific Stock (Rugh et al. 1999; NOAA Tech. Memo NMFS-AFSC-103), this stock appears to be approaching carrying capacity and therefore may be reaching the limits of available resources. The gray whales’ annual migrations along the coastline of western North America make them particularly vulnerable to potential impacts from offshore human activities or catastrophic events. As recommended in the Status Review, continued monitoring and research on potential human impacts to critical habitats is required to aid interpretation of mortality rates such as those reported in 1999.

By Sue Moore.

Depths at Sighting Sites of Harbor Porpoise and Dall’s Porpoise in Gulf of Alaska and Adjacent Inland Waters

Harbor porpoise (Phocoena phocoena) and Dall’s porpoise (Phocoenoides dalli) occur in Alaskan waters but appear to occupy different habitats, as indicated by differences in distribution. For example, water depth can indicate habitat preference. The NMML conducted 19,335 km of line-transect aerial survey for small cetaceans in June and July of 1997 and 1998. Surveys included Gulf of Alaska waters out to a water depth of 1,830 m from Dixon Entrance to just west of Kodiak Island, and adjacent inland bodies of water. Surveys were flown in a DeHavilland Twin Otter aircraft at 152.5 m (500 ft) and 185 km/hr (100 kts). Porpoise sighting locations were determined from GPS (geographic positioning systems) locations and plotted. Depths at sighting locations were subsequently obtained from NOAA nautical charts. A significant difference (t-test, p < 0.0001) was found between the mean depths of harbor porpoise (mean = 99 m, SE = 4.8 m, n = 220) and Dall’s porpoise (mean = 258 m, SE = 8.6 m, n=287) sightings. Depth comparisons were also made among five regions: 1) inside southeastern Alaska, 2) offshore southeastern Alaska, 3) inside southcentral Alaska, 4) offshore southcentral Alaska, and 5) Shelikof Strait and inlets of Kodiak Island and Kenai Peninsula. Mean depths for both porpoise species varied by region, but differences in all regions were highly significant with harbor porpoise always in shallower water. Logistic regression showed that the point where equal numbers of harbor porpoise and Dall’s porpoise were present was 125 m. Eighty-eight percent of harbor porpoise were found at depths shallower than 125 m, and 73% of Dall’s porpoise were found at depths deeper than 125 m. Although harbor porpoise and Dall’s porpoise are both found in inside and offshore waters of Alaska, they appear to occupy different habitat, which may be related to differences in diving capabilities or preferred prey. This difference in habitat preference might also be reflected in the degree to which these two porpoise species interact with various commercial fisheries in Alaska.

By Janice Waite

U.S.-Russian Marine Mammal Cooperative Agreement

Tom Loughlin attended the 15th annual meeting of the U.S.-Russian Marine Mammal Cooperative Agreement on the Environment (Project .02.05-61 “Marine Mammals” under Area V of the U.S./Russia Environmental Agreement”) in Petropovlosk Kamchatsky, Russia, during 6-17 November 1999. He presented results of U.S.-Russian cooperative research on Steller sea lions and northern fur seals. Dr. Loughlin is the co-chairman of this working group

By Tom Loughlin.

California Current Ecosystems

The California Current Ecosystems program is responsible for assessing the status and trends of marine mammals in Washington waters and the ecological impact of their involvement with fisheries along the coasts of Washington, Oregon, and California.