An Index of the Relative Abundance of Wintering Belugas, Delphinapterus leucas, and Narwhals, Monodon monoceros, off West Greenland

1993 ◽  
Vol 50 (11) ◽  
pp. 2323-2335 ◽  
Author(s):  
M. P. Heide-Jørgensen ◽  
H. Lassen ◽  
J. Teilmann ◽  
R. A. Davis
Keyword(s):  
Relative Abundance ◽  
Delphinapterus Leucas ◽  
Late Winter ◽  
The West ◽  
Baffin Bay ◽  
West Greenland ◽  
Abundance Estimate ◽  
Monodon Monoceros ◽  
Pack Ice ◽  
Ice Conditions

Systematic aerial surveys of the wintering grounds of belugas, Delphinapterus leucas, and narwhals, Monodon monoceros, in southern Baffin Bay and northern Davis Strait were conducted in late winter of 1981, 1982, 1990, and 1991. Most belugas were found between 67°N and 69°N and none were seen more than 80 km off the coast of West Greenland. Compared with the surveys in 1981 and 1982, a decline in relative abundance of belugas along West Greenland was evident in 1991. This decline was significant at a probability level of 0.13 of the bootstrapped distribution of the combined abundance estimate. Pod sizes declined significantly between the 1981–82 and 1990–91 surveys. The variations in ice conditions between years did not seem to affect the distribution, clumping, or pod sizes of the belugas. Narwhals were widely distributed in the close pack ice offshore between 65°N and 72°N. Along the West Greenland coast, narwhals were primarily seen at the mouth of Disko Bay. No change in relative abundance or pod sizes could be detected for narwhals.

Observations on Distribution and Intraspecific Variation in Pigmentation Patterns of Odontocete Cetacea in the Western North Atlantic

1973 ◽  
Vol 30 (8) ◽  
pp. 1111-1130 ◽  
Author(s):  
M. C. Mercer
Keyword(s):  
Intraspecific Variation ◽  
North Atlantic ◽  
Intraspecific Variability ◽  
Delphinapterus Leucas ◽  
Phocoena Phocoena ◽  
Western Atlantic ◽  
Stenella Coeruleoalba ◽  
West Greenland ◽  
Monodon Monoceros

This paper comprises sight records for nine species and morphometries, color descriptions, and miscellaneous notes on the food and parasites of seven species of small odontocetes observed from West Greenland to Florida 1967–72. Of interest are the first western Atlantic extralimital record of Monodon monoceros, first Newfoundland records of Stenella coeruleoalba, and extralimital records of Delphinapterus leucas from Newfoundland. Intraspecific variability is described in the pigmentation patterns of Phocoena phocoena.

scholarly journals Population size and yield of Baffin Bay beluga (Delphinapterus leucas) stocks

2002 ◽  
Vol 4 ◽  
pp. 225 ◽  
Author(s):  
Stuart Innes ◽  
Robert EA Stewart
Keyword(s):  
Population Biology ◽  
Maximum Sustainable Yield ◽  
Production Model ◽  
Delphinapterus Leucas ◽  
Sufficient Information ◽  
Stock Size ◽  
Baffin Bay ◽  
West Greenland ◽  
The North ◽  
North Water

A surplus production model within a Sampling, Importance Resampling (SIR) Bayesian analysis was used to estimate stock sizes and yields of Baffin Bay belugas. The catch of belugas in West Greenland increased in 1968 and has remained well above sustainable rates. SIR analysis indicated a decline of about 50% between 1981 and 1994, with a credibility interval that included a previous estimate of 62%. The estimated stock sizes of belugas wintering off West Greenland in 1998 and 1999 were approximately 5,100 and 4,100 respectively and were not significantly different than an estimate based on aerial surveys combined for both years. Projected to 1999 this stock can sustain median landings of 109 whales with a total kill of about 155, based on posterior estimates of struck and lost plus under-reporting. The declining stock size index series did not provide sufficient information to estimate the potential maximum rate of population growth, the number of whales struck and lost, or the shape of the production curve with precision. Estimating these parameters requires an index time series with a marked step change in catch or a series with increasing stock sizes. The stock size estimate for the belugas wintering in the North Water in 1999 was approximately 14,800 but there is no information about the population biology of these whales. The estimated maximum sustainable yield (landed) for the North Water stock was 317 belugas.

scholarly journals Vertical sonar beam width and scanning behavior of wild belugas (Delphinapterus leucas) in West Greenland

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0257054
Author(s):  
Marie J. Zahn ◽  
Kristin L. Laidre ◽  
Peter Stilz ◽  
Marianne H. Rasmussen ◽  
Jens C. Koblitz
Keyword(s):  
Beam Width ◽  
The Arctic ◽  
Delphinapterus Leucas ◽  
Recording Equipment ◽  
West Greenland ◽  
Beluga Whales ◽  
Pack Ice ◽  
Scanning Behavior ◽  
Hydrophone Array ◽  
Free Ranging

Echolocation signals of wild beluga whales (Delphinapterus leucas) were recorded in 2013 using a vertical, linear 16-hydrophone array at two locations in the pack ice of Baffin Bay, West Greenland. Individual whales were localized for 4:42 minutes of 1:04 hours of recordings. Clicks centered on the recording equipment (i.e. on-axis clicks) were isolated to calculate sonar parameters. We report the first sonar beam estimate of in situ recordings of wild belugas with an average -3 dB asymmetrical vertical beam width of 5.4°, showing a wider ventral beam. This narrow beam width is consistent with estimates from captive belugas; however, our results indicate that beluga sonar beams may not be symmetrical and may differ in wild and captive contexts. The mean apparent source level for on-axis clicks was 212 dB pp re 1 μPa and whales were shown to vertically scan the array from 120 meters distance. Our findings support the hypothesis that highly directional sonar beams and high source levels are an evolutionary adaptation for Arctic odontocetes to reduce unwanted surface echoes from sea ice (i.e., acoustic clutter) and effectively navigate through leads in the pack ice (e.g., find breathing holes). These results provide the first baseline beluga sonar metrics from free-ranging animals using a hydrophone array and are important for acoustic programs throughout the Arctic, particularly for acoustic classification between belugas and narwhals (Monodon monoceros).

scholarly journals Oceanic Boundary Conditions for Jakobshavn Glacier. Part II: Provenance and Sources of Variability of Disko Bay and Ilulissat Icefjord Waters, 1990–2011

2015 ◽  
Vol 45 (1) ◽  
pp. 33-63 ◽  
Author(s):  
Carl V. Gladish ◽  
David M. Holland ◽  
Craig M. Lee
Keyword(s):  
Atlantic Water ◽  
Temperature Cycle ◽  
Freshwater Flux ◽  
The West ◽  
Baffin Bay ◽  
West Greenland ◽  
Water Fraction ◽  
West Greenland Current ◽  
Current Water ◽  
Polar Water

AbstractJakobshavn Glacier, west Greenland, has responded to temperature changes in Ilulissat Icefjord, into which it terminates. Basin waters in this fjord exchange with neighboring Disko Bay waters of a particular density at least once per year. This study determined the provenance of this isopycnic layer for 1990–2011 using hydrographic data from Cape Farewell to Baffin Bay. The warm Atlantic-origin core of the West Greenland Current never filled deep Disko Bay or entered the fjord basin because of bathymetric impediments on the west Greenland shelf. Instead, equal parts of Atlantic water and less-saline polar water filled the fjord basin and bathed Jakobshavn Glacier. The polar water fraction was often traceable to the East/West Greenland Current but sometimes to the colder Baffin Current. The huge annual temperature cycle on West Greenland Current isopycnals did not propagate into deep Disko Bay or the fjord basin because isopycnals over the west Greenland shelf were depressed during the warm autumn/winter phase of the cycle.Ilulissat Icefjord basin waters were anomalously cool in summer 2010. This was not because of the record low NAO index winter of 2009/10 or atmospheric anomalies over Baffin Bay but, possibly, because of high freshwater flux through the Canadian Arctic and a weak West Greenland Current in early 2010. Together, this caused cold Baffin Current water to flood the west Greenland shelf. Subpolar gyre warming associated with the NAO anomaly in winter 2009/10 was more likely responsible for the record warm Disko Bay and Ilulissat Icefjord basin waters of 2011/12.

scholarly journals Tectonostratigraphy and evolution of the West Greenland continental margin

2020 ◽  
Vol 67 ◽  
pp. 1-21 ◽  
Author(s):  
Ulrik Gregersen ◽  
Paul C. Knutz ◽  
Henrik Nøhr-Hansen ◽  
Emma Sheldon ◽  
John R. Hopper
Keyword(s):  
Oceanic Crust ◽  
Continental Margin ◽  
Volcanic Rocks ◽  
Sedimentary Basins ◽  
Magnetic Data ◽  
The West ◽  
Seismic Reflection Data ◽  
Baffin Bay ◽  
West Greenland ◽  
North East

Large structural highs and sedimentary basins are identified from mapping of the West Greenland continental margin from the Labrador Sea to the Baffin Bay. We present a new tectonic elements map and a map of thickness from the seabed to the basement of the entire West Greenland margin. In addition, a new stratigraphic scheme of the main lithologies and tectonostratigraphy based on ties to all offshore exploration wells is presented together with seven interpreted seismic sections. The work is based on interpretation of more than 135 000 km of 2D seismic reflection data supported by other geophysical data, including gravity- and magnetic data and selected 3D seismic data, and is constrained by correlation to wells and seabed samples. Eight seismic mega-units (A–H) from the seabed to the basement, related to distinct tectonostratigraphic phases, were mapped. The oldest units include pre-rift basins that contain Proterozoic and Palaeozoic successions. Cretaceous syn-rift phases are characterised by development of large extensional fault blocks and basins with wedge-shaped units. The basin strata include Cretaceous and Palaeogene claystones, sandstones and conglomerates. During the latest Cretaceous, Paleocene and Eocene, crustal extension followed by oceanic crust formation took place, causing separation of the continental margins of Greenland and Canada with north-east to northward movement of Greenland. From Paleocene to Eocene, volcanic rocks dominated the central West Greenland continental margin and covered the Cretaceous basins. Development of the oceanic crust is associated with compressional tectonics and the development of strike-slip and thrust faults, pull-apart basins and inversion structures, most pronounced in the Davis Strait and Baffin Bay regions. During the late Cenozoic, tectonism diminished, though some intra-plate vertical adjustments occurred. The latest basin development was characterised by formation of thick Neogene to Quaternary marine successions including contourite drifts and glacial related shelf progradation towards the west and south-west.

scholarly journals Early Tertiary, low-potassium tholeiites from exploration wells on the West Greenland shelf

1987 ◽  
Vol 136 ◽  
pp. 1-25
Author(s):  
N Hald ◽  
J.G Larsen
Keyword(s):  
Baffin Island ◽  
Quaternary Sediments ◽  
The South ◽  
The West ◽  
Baffin Bay ◽  
West Greenland ◽  
Early Tertiary ◽  
Davis Strait ◽  
Low Potassium

Data on the Tertiary basalts in the Davis Strait region are reported from two exploration wells drilled by Arco and Mobil on the West Greenland shelf. Hellefisk 1 (67°53 'N, 56°44'W), situated only 60 km east of the mid-line in Davis Strait, penetrated the upper 690 m of a subaeriallava sequence continuous with the onshore volcanics of Disko and situated beneath 2.3 km of Paleocene to Quaternary sediments. The lavas are feldspar microporphyritic tholeiites and mostly unmetamorphosed despite the presence of laumontite and prehnite in the vesicular top zones. Nukik 2 (65°38'N, 54°46'W) penetrated 150 m of hyaloclastites and tholeiitic olivine dolerite sheets, presumably sills, some 200 km further to the south. These vo1canics are also deeply buried and are of unknown extension. The drilled rocks, except for the much altered hyaloclastites in the Nukik 2 well, have low contents of Ti02 (0.99-2.03%), K2O (0.09-0.18%) and P2O5 (0.08-0.21%), La/Sm ratios less than one and 87Sr/86Sr ratios of 0.7032 to 0.7044. Chemically they are related to the MORB-like picrites of Baffin Island rather than the less depleted tholeiites of West Greenland. In both areas the MORB affinity may be related to eruptions through a strongly attenuated lithosphere associated with the opening of Baffin Bay and Davis Strait.

scholarly journals A seismic and gravity study of the western part of the Cretaceous-Tertiary sedimentary basin of central West Greenland

1975 ◽  
Vol 69 ◽  
pp. 5-9
Author(s):  
J.W Elder
Keyword(s):  
Sea Level ◽  
Distinctive Feature ◽  
Strong Evidence ◽  
Sedimentary Basin ◽  
The West ◽  
Baffin Bay ◽  
West Greenland ◽  
Reflection And Refraction ◽  
Seismic Methods ◽  
Refraction Seismic

In the summer of 1972 a GGU seismic group working on land measured the thickness of sediments in the western part of the Nugssuaq peninsula, West Greenland, by explosion reflection and refraction seismic methods. In the region crudely bounded by Ikorfat, Ubekendt Bjland and Hareøen Cretaeeous-Tertiary sediments extend about 1-3 km below sea level and rest on the granodioritie gneiss basement. The basin shallows gradually toward the west where it is sharply hidden beneath Tertiary basalts. There is strong evidence for continuity of the Cretaeeous-Tertiary sediments aeross Umanak Fjord as far as Ubekendt Bjland. The most distinctive feature of the basement strueture is a ridge, running roughly N-S through the western part of the area, and rising about 2 km above the deeper parts of the basin. This ridge appears as a northerly continuation of the Disko gneiss ridge. The gravity pattern over a 100 km X 50 km strip centred on the western part of the basin shows rapid westward thinning of the earth's crust, and suggests that the basin has its origin in an incompletely rifted structure marginal to the crustal rifting responsible for Baffin Bay.

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