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Cetacean Assessment & Ecology Program

Cook Inlet Beluga Whale Aerial Surveys, September–October 2008

figure 5, click image to enlarge
Figure 5.  Click image to enlarge.

figure 6, click image to enlarge
Figure 6.  Click image to enlarge.

figure 7, click image to enlarge
Figure 7.  Click image to enlarge.

Scientists from the National Marine Mammal Laboratory's (NMML) Cetacean Assessment and Ecology Program (CAEP), along with colleagues from the NMFS Alaska Regional Office conducted two aerial surveys focused in Cook Inlet, Alaska, on 19-20 September and 22 October 2008. These surveys were an exploratory effort to look for beluga whales (Delphinapterus leucas) in Kamishak Bay, with a secondary objective to test paired video cameras during the September survey.

We flew a total of 8.9 flight hours during four flights in September and 3.5 flight hours during one flight in October. The survey on 19 September included a coastal trackline (1.4 km offshore) down the western side of the inlet from the Little Susitna River to Cape Douglas, mid-inlet tracklines, and a coastal trackline along Kachemak Bay (Fig. 5).

On 20 September, we flew a coastal trackline of the upper inlet north of Point Possession and the Beluga River tidal flats (Fig. 6). During the October survey, the team transited to Cape Douglas and began a coastal survey north to the Little Susitna River (Fig. 7). Poor sighting conditions and high winds precluded any exploration of the smaller bays along Kamishak Bay in October.

Belugas were not observed in lower Cook Inlet (south of lat. 60°43'N) during either the September or October surveys. Marine mammals observed on 19 September included 25 harbor seals (Phoca vitulina) hauled out in Tuxedni Bay, 317 sea otters (Enhydra lutris kenyoni) in groups (average group size = 7; median = 3) in Kachemak Bay, 12 harbor seals in Kachemak Bay, 15 Steller sea lions (Eumetopias jubatus) hauled out north of Cape Douglas, 15 sea otters in scattered small groups (average group size = 1.4; median = 1) from Cape Douglas to Iniskin Bay in Kamishak Bay, a dead beluga stranded in Turnagain Arm, and a small group of belugas swimming near McHugh Creek in Turnagain Arm (Fig. 5).

Samples from the dead beluga were collected later that evening. During the upper inlet survey on 20 September, belugas were found in Turnagain Arm (three groups: ranging from 17 to 29 whales), Chickaloon Bay (one group: 11 whales), and Knik Arm (two groups: a single whale and a group of 5 whales) (Fig. 6). No marine mammals were observed during the 22 October survey.

Wide-angle video footage of beluga groups in Turnagain Arm (15 video passes) was collected on 20 September for testing purposes. For 3 years (2003–05), Cook Inlet beluga abundance surveys relied on a mini-digital video camera with a resolution of 720 x 480 pixels (a Sony DVCAM, DSR-PDX10 Model L10A). However, with advancements in technology, we replaced this camera in 2006 with a new HD (high-definition) digital video camera (JVC GR-HD1), which provided a higher resolution of 1280 x 720 pixels.

The Sony DVCAM video camera was placed alongside the HD JVC video camera in order to collect comparable video footage on both cameras. The video footage will be analyzed at NMML to determine if the change in resolution influences the detection of beluga whales.

The September and October 2008 surveys continued the time series documenting beluga distribution in months other than June, with a primary objective to document beluga whale presence in lower Cook Inlet. Although no belugas were sighted in lower Cook Inlet during the September and October 2008 aerial surveys, opportunistic sightings of belugas in Bruin Bay on 17 September and in Iliamna Bay in October indicate that, at times, belugas are using the lower inlet bays during the fall.

Continued monitoring of opportunistic sightings and follow-up exploratory surveys of the lower inlet will be needed to confirm the presence and extent of use of these lower inlet bays by Cook Inlet belugas.

By Christy Sims, Kim Shelden, and Kim Goetz

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