Observations on gray whale (Eschrichtius robustus) utilization patterns in the northeastern Chukchi Sea, July–October 1982–1987

1989 ◽  
Vol 67 (11) ◽  
pp. 2646-2654 ◽  
Author(s):  
Janet T. Clarke ◽  
Sue E. Moore ◽  
Donald K. Ljungblad
Keyword(s):  
Sexual Activity ◽  
Chukchi Sea ◽  
Open Water ◽  
Gray Whale ◽  
Gray Whales ◽  
Aerial Surveys ◽  
Abundance Estimates ◽  
Point Hope ◽  
Utilization Patterns ◽  
Cow Calf

A total of 821 gray whales were seen during aerial surveys in the northeastern Chukchi Sea from July through October 1982–1987. Gray whale distribution extended from south of Point Hope to northeast of Point Barrow, Alaska, between 0.5 and 166 km offshore. Monthly abundance estimates (number of whales/survey hour) were highest in July (6.81) and lowest in October (0.40). Gray whales were usually in open water (82%, n = 670) or in light ice (16%, n = 134) and were seldom associated with heavy ice (2%, n = 17). Most whales were feeding (63%, n = 514), with the majority of the others swimming and diving (24%, n = 193) or forming part of a cow–calf association (9%, n = 72). One group of three whales was involved in sexual activity. Feeding whales were seen most often within 40 km of the shore, but also occurred offshore. Thirty-six gray whale calves were seen. Calf abundance (number of calves/survey hour) was significantly higher (p < 0.001) in July, when 92% (n = 33) of all calves were seen, than in any other month. Most cow–calf pairs were seen nearshore between Point Hope and Point Barrow. Monthly calf ratios (number of calves/number of whales) ranged from 0.09 in July to 0.00 in October, with an overall rate of 0.04.

scholarly journals Bowhead and Gray Whale Distributions, Sighting Rates, and Habitat Associations in the Eastern Chukchi Sea, Summer and Fall 2009–15, with a Retrospective Comparison to 1982–91

ARCTIC ◽  
2016 ◽  
Vol 69 (4) ◽  
pp. 359 ◽  
Author(s):  
Janet T. Clarke ◽  
Amy S. Kennedy ◽  
Megan C. Ferguson
Keyword(s):  
Habitat Selection ◽  
Chukchi Sea ◽  
Habitat Associations ◽  
Bowhead Whale ◽  
Line Transect ◽  
Gray Whale ◽  
Depth Zone ◽  
Gray Whales ◽  
Bowhead Whales ◽  
Preferred Habitat

We analyzed data from line-transect aerial surveys for marine mammals conducted in the eastern Chukchi Sea (67˚–72˚ N, 157˚–169˚ W) in July to October of 2009–15 to investigate bowhead and gray whale distributions, behaviors, sighting rates, and habitat selection preferences, the last of which allowed direct comparison with results from data collected in this area in 1982–91. Bowhead whales use the eastern Chukchi Sea primarily for migrating between the Beaufort Sea and the Bering Sea, while gray whales use the area to feed on locally abundant benthic amphipods and other prey. Bowhead whales were observed during all survey months and were distributed up to 300 km offshore west and southwest of Point Barrow, Alaska, but without a defined migratory corridor in either summer (July-August) or fall (September-October). Bowhead whale sighting rates (whales per km on effort) were highest in the shelf/trough (51–200 m North) depth zone in the northeastern Chukchi Sea in both summer and fall. This pattern was reflected in habitat selection ratios, which found bowhead whales in summer and fall selecting primarily shelf/trough habitat in the northeastern Chukchi Sea, with shelf habitat (36 – 50 m) being preferred secondarily. Gray whales were observed in all survey months and were distributed primarily within ~95 km of shore between Point Barrow and Icy Cape in the northeastern Chukchi Sea, and about 60–115 km southwest of Point Hope in the southern Chukchi Sea. In both summer and fall, gray whale sighting rates and habitat selection ratios were highest in the shelf/trough (51–200 m South) depth zone in the southern Chukchi Sea. In the northeastern part of the study area, gray whale sighting rates and habitat selection ratios both identified coastal habitat (≤ 35 m) as preferred habitat in summer and shelf/trough (51–200 m North) as preferred habitat in fall. Distribution and habitat associations of bowhead and gray whales remained similar over the 34-year time span with one exception: gray whale preference for shelf/trough habitat in the southern Chukchi Sea is now evident throughout summer and fall, whereas three decades ago gray whale preference for that area was limited to fall only.

Swarming benthic crustaceans in the Bering and Chukchi seas and their relation to geographic patterns in gray whale feeding

1989 ◽  
Vol 67 (6) ◽  
pp. 1531-1542 ◽  
Author(s):  
Stacy L. Kim ◽  
John S. Oliver
Keyword(s):  
Bering Sea ◽  
Baja California ◽  
Prey Availability ◽  
Chukchi Sea ◽  
Gray Whale ◽  
Life Stages ◽  
Gray Whales ◽  
Feeding Ground ◽  
Geographic Patterns ◽  
Feeding Grounds

Swarming benthic crustaceans were widespread in the Chukchi and Bering seas. Swarms differed in their geographic extent, local biomass, and life stages of swarming individuals and thus in their availability to feeding gray whales (Eschrichtius robustus). Immature amphipods apparently swarmed for dispersal, whereas cumaceans probably swarmed for mating. All life stages of the hyperbenthic mysids occurred above the sea floor. Although the geographic spread of mysid swarms and shrimp communities was much greater than for the amphipod and cumacean swarms, the latter swarmed in denser patches to produce higher local biomass. Crustacean swarms are important in describing the geographic patterns of gray whale feeding from the Chukchi Sea to Baja California, including the primary, secondary, and tertiary feeding grounds. The primary feeding ground is in the southern Chukchi Sea and especially the northern Bering Sea, where gray whales suck infaunal amphipods from fine sand, producing an extensive record of feeding excavations. The primary feeding ground is divided into a relatively deep zone (> 20 m), where tube-dwelling ampeliscid amphipods are the major prey, and a shallow zone (< 20 m), where burrowing pontoporeid amphipods dominate. The secondary feeding ground is in the southern Bering Sea along the eastern Alaska Peninsula and adjacent Alaskan mainland where shrimp and mysids are the major prey. The tertiary feeding ground is at the periphery of the primary and secondary feeding grounds in Alaskan waters and south of the Bering Sea where there is a general decrease in the availability of prey and their use by gray whales from Canada to Baja California. The tertiary prey communities include swarms of amphipods, cumaceans, and mysids as well as infaunal polychaete worms, but mysids are used the most by whales. The primary gray whale feeding ground was much smaller during low sea levels when the extensive Beringian Platform was exposed to air. This shallow shelf is a unique habitat that presently harbors the largest ampeliscid amphipod community in the world. At low sea level, swarming crustaceans like those sampled in the present study may have been equally or more important to gray whales than infaunal prey. These historical changes in prey availability may account for the catholic diet of the gray whale.

First Photographic Match of an Anomalously White Gray Whale (Eschrichtius robustus) in the Northeastern Chukchi Sea, Alaska, and Baja California, Mexico

2018 ◽  
Vol 44 (1) ◽  
pp. 7-12
Author(s):  
Amy L. Willoughby ◽  
Megan C. Ferguson ◽  
Janet T. Clarke ◽  
Amelia A. Brower
Keyword(s):  
Baja California ◽  
Chukchi Sea ◽  
Gray Whale ◽  
Eschrichtius Robustus

scholarly journals N2O dynamics in the western Arctic Ocean during the summer of 2017

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jang-Mu Heo ◽  
Seong-Su Kim ◽  
Sung-Ho Kang ◽  
Eun Jin Yang ◽  
Ki-Tae Park ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Environmental Changes ◽  
Chukchi Sea ◽  
Hot Spot ◽  
Open Water ◽  
Northern Region ◽  
The Arctic ◽  
Western Arctic Ocean ◽  
Deep Layers ◽  
Western Arctic

AbstractThe western Arctic Ocean (WAO) has experienced increased heat transport into the region, sea-ice reduction, and changes to the WAO nitrous oxide (N2O) cycles from greenhouse gases. We investigated WAO N2O dynamics through an intensive and precise N2O survey during the open-water season of summer 2017. The effects of physical processes (i.e., solubility and advection) were dominant in both the surface (0–50 m) and deep layers (200–2200 m) of the northern Chukchi Sea with an under-saturation of N2O. By contrast, both the surface layer (0–50 m) of the southern Chukchi Sea and the intermediate (50–200 m) layer of the northern Chukchi Sea were significantly influenced by biogeochemically derived N2O production (i.e., through nitrification), with N2O over-saturation. During summer 2017, the southern region acted as a source of atmospheric N2O (mean: + 2.3 ± 2.7 μmol N2O m−2 day−1), whereas the northern region acted as a sink (mean − 1.3 ± 1.5 μmol N2O m−2 day−1). If Arctic environmental changes continue to accelerate and consequently drive the productivity of the Arctic Ocean, the WAO may become a N2O “hot spot”, and therefore, a key region requiring continued observations to both understand N2O dynamics and possibly predict their future changes.

scholarly journals Arctic Fog Detection Using Infrared Spectral Measurements

2019 ◽  
Vol 36 (8) ◽  
pp. 1643-1656
Author(s):  
Li Yi ◽  
King-Fai Li ◽  
Xianyao Chen ◽  
Ka-Kit Tung
Keyword(s):  
Sea Ice ◽  
Chukchi Sea ◽  
Open Water ◽  
Detection Algorithm ◽  
Probability Of Detection ◽  
Satellite Observations ◽  
The Arctic ◽  
Water Surface Area ◽  
Infrared Spectral ◽  
Fog Detection

AbstractThe rapid increase in open-water surface area in the Arctic, resulting from sea ice melting during the summer likely as a result of global warming, may lead to an increase in fog [defined as a cloud with a base height below 1000 ft (~304 m)], which may imperil ships and small aircraft transportation in the region. There is a need for monitoring fog formation over the Arctic. Given that ground-based observations of fog over Arctic open water are very sparse, satellite observations may become the most effective way for Arctic fog monitoring. We developed a fog detection algorithm using the temperature difference between the cloud top and the surface, called ∂T in this work. A fog event is said to be detected if ∂T is greater than a threshold, which is typically between −6 and −12 K, depending on the time of the day (day or night) and the surface types (open water or sea ice). We applied this method to the coastal regions of Chukchi Sea and Beaufort Sea near Barrow, Alaska (now known as Utqiaġvik), during the months of March–October. Training with satellite observations between 2007 and 2014 over this region, the ∂T method can detect Arctic fog with an optimal probability of detection (POD) between 74% and 90% and false alarm rate (FAR) between 5% and 17%. These statistics are validated with data between 2015 and 2016 and are shown to be robust from one subperiod to another.

Migration and Feeding of the Gray Whale (Eschrichtius gibbosus)

1962 ◽  
Vol 19 (5) ◽  
pp. 815-838 ◽  
Author(s):  
Gordon C. Pike
Keyword(s):  
British Columbia ◽  
Bering Sea ◽  
Chukchi Sea ◽  
Close Contact ◽  
Gulf Of Alaska ◽  
Bering Strait ◽  
Visual Contact ◽  
Gray Whales ◽  
Baleen Whales ◽  
The Bering Sea

Observations of gray whales from the coasts of British Columbia, Washington, and Alaska are compared with published accounts in order to re-assess knowledge of migration and feeding of the American herd. Source of material is mainly from lighthouses and lightships.The American herd of gray whales retains close contact with the shore during migration south of Alaska. Off Washington and British Columbia the northward migration begins in February, ends in May, and is at a peak during the first two weeks in April; the southward migration occurs in December and January, and is at a peak in late December. Northward migrants stop occasionally to rest or feed; southward migrants are travelling faster and appear not to stop to rest or feed during December and January. Gray whales seen off British Columbia, sometimes in inside protected waters, from June through October, probably remain in this area throughout the summer and fall months.Available evidence suggests that gray whales retain contact with the coast while circumscribing the Gulf of Alaska, enter the Bering Sea through eastern passages of the Aleutian chain, and approach St. Lawrence Island by way of the shallow eastern part of the Bering Sea. Arriving off the coast of St. Lawrence Island in May and June the herd splits with some parts dispersing along the Koryak coast and some parts continuing northward as the ice retreats through Bering Strait. Gray whales feed in the waters of the Chukchi Sea along the Siberian and Alaskan coasts in July, August and September. Advance of the ice through Bering Strait in October initiates the southern migration for most of the herd. In summering areas, in northern latitudes, gray whales feed in shallow waters on benthic and near-benthic organisms, mostly amphipods.There is no evidence to indicate that gray whales utilize ocean currents or follow the same routes as other baleen whales in their migrations. Visual contact with coastal landmarks appear to aid gray whales in successfully accomplishing the 5000-mile migration between summer feeding grounds in the Bering and Chukchi Seas and winter breeding grounds in Mexico.Reconstruction of the migration from all available data shows that most of the American herd breeds and calves in January and February, migrates northward in March, April and May, feeds from June through October, and migrates southward in November and December.

Sustaining ecological and subsistence functions in conservation areas: eider habitat and access by Native hunters along landfast ice

2018 ◽  
Vol 45 (4) ◽  
pp. 361-369 ◽  
Author(s):  
JAMES R. LOVVORN ◽  
AARIEL R. ROCHA ◽  
ANDREW H. MAHONEY ◽  
STEPHEN C. JEWETT
Keyword(s):  
Chukchi Sea ◽  
Open Water ◽  
The Arctic ◽  
Cash Income ◽  
Migration Route ◽  
Conservation Areas ◽  
Subsistence Hunting ◽  
Industrial Activities ◽  
Landfast Ice ◽  
Ice Edge

SUMMARYIn the Arctic, rapid climate change has kindled efforts to delineate and project the future of important habitats for marine birds and mammals. These animals are vital to subsistence economies and cultures, so including the needs of both animals and hunters in conservation planning is key to sustaining social-ecological systems. In the northeast Chukchi Sea, a nearshore corridor of open water is a major spring migration route for half a million eider ducks that are hunted along the landfast ice. Zoning areas for industrial activities or conservation should consider both eider habitat and hunter access to those habitats from the variable ice edge. Based on benthic sampling in 2010‒2012, a model of eider foraging energetics and satellite data on ice patterns in April and May 1997‒2011, we mapped the range of positions of the landfast ice edge relative to a given dispersion of habitat suitable for eider feeding. In some sectors, feeding areas were too limited or too far from landfast ice to provide regular hunting access. In other sectors, overlap of the ice edge with eider feeding habitat was quite variable, but often within a consistent geographic range. Areas accessible to hunters were a small fraction of total eider habitat, so areas adequate for conserving eiders would not necessarily include areas that meet the hunters’ needs. These results can inform spatial planning of industrial activities that yield cash income critical to subsistence hunting in less developed locations. Our study provides an approach for mapping ‘subsistence conservation areas’ throughout the Arctic and an example for such efforts elsewhere.

scholarly journals New fossil remains of the commensal barnacle Cryptolepas rhachianecti provide evidence of gray whales in the prehistoric South Pacific

2021 ◽  
pp. 1-8
Author(s):  
Larry Taylor ◽  
Juan Abella ◽  
Jorge Manuel Morales-Saldaña
Keyword(s):  
North Atlantic ◽  
North Pacific ◽  
Evolutionary History ◽  
South Pacific ◽  
Isotopic Analysis ◽  
Gray Whale ◽  
Gray Whales ◽  
The North ◽  
The North Pacific ◽  
Historical Range

Abstract We report the finding of two partial specimens of Cryptolepas rhachianecti (Cirripedia, Coronulidae), a coronulid barnacle known only to inhabit the skin of gray whales (Eschrichtius robustus), in Pleistocene-aged sediments from the Canoa Basin, Ecuador. While the historical range of gray whales includes the North Pacific and North Atlantic, to our knowledge this is the first inferred evidence of a gray whale population having resided within the South Pacific. We describe the two Cryptolepas rhachianecti fossils, use isotopic analysis to investigate evidence of migration in their host whales, and discuss their implications for our understanding of gray whale evolutionary history.

Distribution maps and minimum abundance estimates for wintering auks in the Bay of Biscay, based on aerial surveys

2004 ◽  
Vol 17 (3) ◽  
pp. 353-360 ◽  
Author(s):  
Vincent Bretagnolle ◽  
Grégoire Certain ◽  
Sylvie Houte ◽  
Michel Métais
Keyword(s):  
Bay Of Biscay ◽  
Distribution Maps ◽  
Aerial Surveys ◽  
Abundance Estimates
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