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Cetacean Assessment and Ecology ProgramCetacean Survey Aboard the Miller Freeman The cetacean survey was conducted from the flying bridge of the 215-ft long Miller Freeman. Two observers searched through 25x150 power binoculars at starboard and port stations. Observers were at an eye height of approximately 12 m, with ship speed roughly 11 kts during surveys. A data recorder searched the trackline with 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 for meals, fishing operations, inclement weather, and when light levels were too low for efficient observations. If time permitted, the survey was suspended when humpback whales or killer whales were sighted to conduct sampling for photo-identification and biopsy collection. The survey included the shelf waters of the eastern Bering Sea (Fig. 2 above). Analyses of data from 6 to 30 June yielded a total of 2,032 km of trackline surveyed with 93 cetacean sightings (896 individuals). An additional eight cetacean sightings were made (32 individuals) during off effort periods. Species included harbor porpoise, Dall’s porpoise, Pacific white-sided dolphins, killer whales, minke whales, fin whales, and humpback whales (Table 1, Figs. 2 and 3). Pacific white-sided dolphins were seen only once in a very large school on the north side of the Alaska Peninsula, near an area where they have been seen on past surveys. Harbor porpoise were seen only four times, in a small area in the southern middle shelf area, while Dall’s porpoise distribution was more widespread across the more southern half of the survey area. Killer whales were seen predominantly around the Pribilof Islands, or near Unimak Pass. The six minke whale sightings were spread out across the western half of the survey area near the 100 m depth contour. Fin whales were seen only near the eastern edge of the survey, with none seen along the shelf break where the species has been common during past surveys. Humpback whale sightings were spread out, with most seen near shore from Akutan Island and west along the Alaska Peninsula. The most northerly sighting was a humpback whale approximately 300 km north of the Pribilof Islands.
The ship was stopped 11 times to collect photographs and biopsy samples; seven times for killer whales and four
times for humpback whales. Photographs from these encounters will be analyzed to identify individuals and then
matched to existing catalogues to look at movements and to be included in ongoing mark/recapture studies. Biopsy
samples will be used for stock determination. |
AFSC Quarterly Research Reports Apr-June 2004 ContentsFeature ABL Reports NMML Reports RACE Reports REFM Reports Quarterly Index Quarterly Home |
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