Distribution of Belugas (Delphinapterus leucas) in Cook Inlet, Alaska, June 2021 and June 2022 (original) (raw)
Related papers
Aerial Surveys of Beluga in Cook Inlet , Alaska , June 2001
2000
The National Marine Fisheries Service (NMFS) conducted an aerial survey of the beluga population in Cook Inlet, Alaska, during 5-12 June 2001. The 55 hr survey was flown in a twin-engine, high-wing aircraft at an altitude of 244 m (800 ft) and speed of 185 km/hr (100 kt), consistent with NMFS’ annual surveys conducted each year since 1993. The flights in June 2001 included one or more surveys of coastal areas (flown 1.4 km offshore) around the entire Inlet and 1186 km of transects across the Inlet. Paired, independent observers searched on the coastal (left) side of the plane, where virtually all beluga sightings occur, while a single observer was on the right. A computer operator/data recorder was on the left side. After finding beluga groups, a series of aerial passes were made with two pairs of primary observers each making 4 or more counts of each group. Median counts made in optimal viewing conditions on 5 different days were 44-114 beluga in the Susitna Delta (between the Belu...
Aerial surveys of belugas in Cook Inlet, Alaska, June 2007
2007
The National Marine Fisheries Service (NMFS) conducted surveys of the beluga population in Cook Inlet, Alaska, 3-12 June 2008. The aerial surveys (47.7 flight hours) were flown in a twin-engine, high-wing Aero Commander aircraft at an altitude of 244 m (800 ft) and speed of 185 km/hr (100 kt), consistent with NMFS' surveys of Cook Inlet conducted each year since 1993. The study in June 2008 included surveys of coastal areas (flown 1.4 km offshore) around most of the Inlet and 1,776 km of transects across the Inlet, effectively searching 34% of offshore Cook Inlet and 100% of the coastline. Paired, independent observers searched on the coastal (left) side of the plane where virtually all beluga sightings occur, while a single observer and computer operator/data recorder were on the right side of the plane. After finding belugas, multiple aerial passes were made with paired observers doing four or more independent counts of each group. Daily median counts made on seven different days ranged from 34 to 103 belugas in the Susitna delta (between the Beluga and Little Susitna rivers), and 5 to 33 belugas in Chickaloon Bay. Belugas were not observed in lower Cook Inlet, which is typical of annual surveys in most of the recent years. In June 2008, the highest daily median estimate, used here as an index for relative abundance (not corrected for effort nor for estimates of missed whales), was 126 belugas. This is below index counts for all previous survey years (305 belugas in
Aerial Survey of Belugas in Cook Inlet Alaska August 2009
2009
The National Marine Fisheries Service conducted a photographic aerial survey of belugas (Delphinapterus leucas) in Cook Inlet, Alaska, 11-12 August 2005, with the express purpose of documenting the proportion of calves at a time when it was likely that all calves of the year were born. During the standard abundance surveys conducted in early June, some calves are probably not yet born. The aerial survey in August (10.1 flight hrs) was flown in a twin-engine, high-wing aircraft at an altitude of 244 m (800 ft) on a trackline 1.4 km offshore, consistent with annual surveys for beluga abundance in Cook Inlet as done since 1993. Two observers searched for whales on the left side of the aircraft, and two searched on the right; however, there was no attempt to conduct independent searches. After finding beluga groups, a series of aerial passes was made with three observers counting surfacing whales while paired video and digital still cameras captured images for analyses. The sum of the aerial counts was 236 belugas for 11 August and 277 belugas for 12 August, numbers that represent a rough index of abundance uncorrected for missed whales. The counts from August 2005 were higher than uncorrected estimates from June during the past seven years. Laboratory analyses of the video tapes will determine whether or not the number of whales actually was higher in August than in June 2005.
AERIAL SURVEYS OF BELUGAS IN COOK INLET, ALASKA, JUNE 2008
2000
The National Marine Fisheries Service (NMFS) conducted surveys of the beluga population in Cook Inlet, Alaska, 3-12 June 2008. The aerial surveys (47.7 flight hours) were flown in a twin-engine, high-wing Aero Commander aircraft at an altitude of 244 m (800 ft) and speed of 185 km/hr (100 kt), consistent with NMFS' surveys of Cook Inlet conducted each year since
AERIAL SURVEYS OF BELUGAS IN COOK INLET, ALASKA, September and October 2008
2000
The National Marine Fisheries Service (NMFS) conducted two aerial surveys focused primarily in lower Cook Inlet, Alaska, 19-20 September and 22 October 2008, in an exploratory effort to look for belugas in Kamishak Bay. Each survey (4 flights totaling 8.9 flight hours in September and 1 flight for a total of 3.5 flight hours in October) was flown in a
Distribution of eastern Bering Sea belugas from aerial line-transect surveys in 2024
AFSC Processed Report, 2024
The Eastern Bering Sea (EBS) beluga (Delphinapterus leucas) stock inhabits the waters of Norton Sound and the Yukon River Delta, Alaska, during the ice-free period from sea-ice breakup in spring to the beginning of freeze-up in autumn. During June, July, and August, belugas aggregate near the Yukon River Delta, where they feed on seasonally abundant anadromous fish such as Pacific herring (Clupea pallasii) and salmon (Oncorhynchus spp.). EBS belugas are an important nutritional and cultural resource for Alaska Natives, and are harvested by more than 20 communities near Norton Sound and the Yukon River. To collect data for an updated abundance estimate of EBS belugas, aerial line-transect surveys were conducted in Norton Sound and near the Yukon River Delta from 18 June through 1 July 2024. Flights were conducted on 7 days (18-21, 24, 30 June and 1 July) covering 6,934 km of transect effort. Within the study area, a high-density stratum, where belugas have been observed in large numbers during previous surveys in 2017 and 2022, was sampled multiple times. A digital camera mounted in the belly port of the aircraft collected images primarily within the high-density stratum at 3-second intervals. A total of 29,031 images were collected. Images were reviewed to determine if an observer correction factor for belugas missed along the trackline (g(0)) could be estimated. Images will also be reviewed for age class based on skin color and size (calf, juvenile (light gray), adult (white)) and group composition. Caveats to developing a g(0) correction factor based on a review of sightings within the camera and observer fields of view are discussed. Throughout the study area, 338 beluga groups totaling 1,716 belugas were sighted (328 sightings, 1,195 belugas on transect). This included 24 cow-calf pairs (23 observed on transect). Five beluga carcasses were also observed, photographed, and reported to the Alaska Marine Mammal Stranding Network. The highest densities of belugas extended along the Yukon River Delta north of Scammon Bay within the 5 m depth contour, then east into Pastol Bay, broadening northward to Unalakleet within the 5-15 m depth contours. Other marine mammal sightings included a minke whale (Balaenoptera acutorostrata), a pod of six killer whales (Orcinus orca), harbor porpoises (Phocoena phocoena, 2 sightings, 4 total), 5 small, unidentified pinnipeds, and one unidentified marine mammal. Compared to the 2017 and 2022 surveys, the encounter rate of belugas (whales/km) observed on transect in 2024 was slightly lower, though this was largely due to diverting from the trackline north of Scammon Bay, where a group of approximately 500 belugas were sighted while circling, and therefore not included in the encounter rate.
AERIAL SURVEY OF BELUGAS IN COOK INLET, ALASKA, AUGUST 2005
2000
The National Marine Fisheries Service conducted a photographic aerial survey of belugas (Delphinapterus leucas) in Cook Inlet, Alaska, 11-12 August 2005, with the express purpose of documenting the proportion of calves at a time when it was likely that all calves of the year were born. During the standard abundance surveys conducted in early June, some calves are probably not
Marine Fisheries Review
ABSTRACT—Aerial surve ys of belugas, centration of belugas (151–288 whales by Delphinapterus leucas, in Cook Inlet were aerial count) was in the northern portion flown each year ,during ,June ,and/or July ,of upper ,Cook Inlet in the ,Susitna River from 1993 to 2000. This project was ,de-,Delta and/or in Knik Arm. Another con- signed to delineate distribution and collect,centration (17–49 whales) was consistently
Distribution of Belugas, Delphinapterus leucas, in Cook Inlet, Alaska, During June/July 1993-2000
2000
ABSTRACT—Aerial surve ys of belugas, centration of belugas (151–288 whales by Delphinapterus leucas, in Cook Inlet were aerial count) was in the northern portion flown each year ,during ,June ,and/or July ,of upper ,Cook Inlet in the ,Susitna River from 1993 to 2000. This project was ,de-,Delta and/or in Knik Arm. Another con- signed to delineate distribution and collect,centration (17–49