scholarly journals Fluctuations in Hawaii’s humpback whale Megaptera novaeangliae population inferred from male song chorusing off Maui

2020 ◽  
Vol 43 ◽  
pp. 421-434
Author(s):  
A Kügler ◽  
MO Lammers ◽  
EJ Zang ◽  
MB Kaplan ◽  
TA Mooney
Keyword(s):  
North Pacific ◽  
Low Frequency ◽  
Humpback Whale ◽  
Megaptera Novaeangliae ◽  
Acoustic Energy ◽  
Humpback Whales ◽  
Underwater Sound ◽  
The North ◽  
The Pacific ◽  
The North Pacific

Approximately half of the North Pacific humpback whale Megaptera novaeangliae stock visits the shallow waters of the main Hawaiian Islands seasonally. Within this breeding area, mature males produce an elaborate acoustic display known as song, which becomes the dominant source of ambient underwater sound between December and April. Following reports of unusually low whale numbers that began in 2015/16, we examined song chorusing recorded through long-term passive acoustic monitoring at 6 sites off Maui as a proxy for relative whale abundance between 2014 and 2019. Daily root-mean-square sound pressure levels (RMS SPLs) were calculated to compare variations in low-frequency acoustic energy (0-1.5 kHz). After 2014/15, the overall RMS SPLs decreased between 5.6 and 9.7 dB re 1 µPa2 during the peak of whale season (February and March), reducing ambient acoustic energy from chorusing by over 50%. This change in song levels co-occurred with a broad-scale oceanic heat wave in the northeast Pacific termed the ‘Blob,’ a major El Niño event in the North Pacific, and a warming period in the Pacific Decadal Oscillation cycle. Although it remains unclear whether our observations reflect a decrease in population size, a change in migration patterns, a shift in distribution to other areas, a change in the behavior of males, or some combination of these, our results indicate that continued monitoring and further studies of humpback whales throughout the North Pacific are warranted to better understand the fluctuations occurring in this recently recovered population and other populations that continue to be endangered or threatened.

scholarly journals Fluctuating reproductive rates in Hawaii's humpback whales, Megaptera novaeangliae , reflect recent climate anomalies in the North Pacific

2019 ◽  
Vol 6 (3) ◽  
pp. 181463 ◽  
Author(s):  
R. Cartwright ◽  
A. Venema ◽  
V. Hernandez ◽  
C. Wyels ◽  
J. Cesere ◽  
...  
Keyword(s):  
Climate Change ◽  
North Pacific ◽  
Megaptera Novaeangliae ◽  
Anthropogenic Climate Change ◽  
Humpback Whales ◽  
Encounter Rates ◽  
The North ◽  
The Impact ◽  
The North Pacific ◽  
Population Segment

Alongside changing ocean temperatures and ocean chemistry, anthropogenic climate change is now impacting the fundamental processes that support marine systems. However, where natural climate aberrations mask or amplify the impacts of anthropogenic climate change, identifying key detrimental changes is challenging. In these situations, long-term, systematic field studies allow the consequences of anthropogenically driven climate change to be distinguished from the expected fluctuations in natural resources. In this study, we describe fluctuations in encounter rates for humpback whales, Megaptera novaeangliae , between 2008 and 2018. Encounter rates were assessed during transect surveys of the Au'Au Channel, Maui, Hawaii. Initially, rates increased, tracking projected growth rates for this population segment. Rates reached a peak in 2013, then declined through 2018. Specifically, between 2013 and 2018, mother–calf encounter rates dropped by 76.5%, suggesting a rapid reduction in the reproductive rate of the newly designated Hawaii Distinct Population Segment of humpback whales during this time. As this decline coincided with changes in the Pacific decadal oscillation, the development of the NE Pacific marine heat wave and the evolution of the 2016 El Niño, this may be another example of the impact of this potent trifecta of climatic events within the North Pacific.

Photo-identification matches of humpback whales (Megaptera novaeangliae ) from feeding areas in Russian Far East seas and breeding grounds in the North Pacific

2017 ◽  
Vol 34 (1) ◽  
pp. 100-112 ◽  
Author(s):  
Olga V. Titova ◽  
Olga A. Filatova ◽  
Ivan D. Fedutin ◽  
Ekaterina N. Ovsyanikova ◽  
Haruna Okabe ◽  
...  
Keyword(s):  
North Pacific ◽  
Russian Far East ◽  
Far East ◽  
Megaptera Novaeangliae ◽  
Humpback Whales ◽  
Photo Identification ◽  
The North ◽  
Breeding Grounds ◽  
The North Pacific

Abundance and mtDNA differentiation of humpback whales (Megaptera novaeangliae) in the Shumagin Islands, Alaska

2004 ◽  
Vol 82 (8) ◽  
pp. 1352-1359 ◽  
Author(s):  
Briana H Witteveen ◽  
Janice M Straley ◽  
Olga von Ziegesar ◽  
D Steel ◽  
C Scott Baker
Keyword(s):  
North Pacific ◽  
Gulf Of Alaska ◽  
Megaptera Novaeangliae ◽  
Individual Identification ◽  
Humpback Whales ◽  
Small Samples ◽  
Mtdna Haplogroups ◽  
The North ◽  
Kodiak Island ◽  
The North Pacific

Despite extensive research on humpback whales (Megaptera novaeangliae (Borowski, 1781)) in parts of the North Pacific, little research has focused on the whales feeding in coastal waters west of Kodiak Island in the Gulf of Alaska. To extend research westward in the North Pacific, small-boat surveys were conducted near the Shumagin Islands during the summers of 1999–2002. Photographs of the natural markings of humpback whales were collected, representing 413 sightings of 171 individual whales. Small samples of skin tissue were collected from 20 individuals, including two mother–calf pairs, for sex identification and comparison of mtDNA haplogroups with previously published results from surveys in other regions of the North Pacific. Individual identification photographs were used in mark–recapture analysis to estimate abundance for the Shumagin Island region. The best estimate was given by a modified Jolly–Seber method: N = 410 (95% CI: 241–683) for 2002. Comparison of photographs with archived photographs from throughout the North Pacific revealed four migratory destinations for 13 of the Shumagin Islands whales: Hawai'i, Japan, offshore Mexico, and coastal Mexico. The frequencies of mtDNA haplogroups differed significantly from those in three other sampled feeding grounds: California, southeastern Alaska, and Prince William Sound. The haplogroup frequencies and migratory destinations of individuals suggested an affinity with the Hawaiian wintering ground but data are insufficient to associate whales off the Shumagin Islands with any surveyed breeding ground.

scholarly journals Distinguishing the Quasi-Decadal and Multidecadal Sea Level and Climate Variations in the Pacific: Implications for the ENSO-Like Low-Frequency Variability

2017 ◽  
Vol 30 (13) ◽  
pp. 5097-5117 ◽  
Author(s):  
Kewei Lyu ◽  
Xuebin Zhang ◽  
John A. Church ◽  
Jianyu Hu ◽  
Jin-Yi Yu
Keyword(s):  
Sea Level ◽  
Time Scales ◽  
North Pacific ◽  
Low Frequency ◽  
Tropical Pacific ◽  
The North ◽  
The Pacific ◽  
Low Frequency Variability ◽  
Sea Surface Temperature Anomalies ◽  
The North Pacific

Low-frequency sea level variations with periods longer than interannual time scales have been receiving much attention recently, with the aim of distinguishing the anthropogenic regional sea level change signal from the natural fluctuations. Based on the available sea level products, this study finds that the dominant low-frequency sea level mode in the Pacific basin has both quasi-decadal variations and a multidecadal trend reversal in the early 1990s. The dominant sea level modes on these two time scales have different tropical structures: a west–east seesaw in the tropical Pacific on the multidecadal time scale and a dipole between the western and central tropical Pacific on the quasi-decadal time scale. These two sea level modes in the Pacific basin are closely related to the ENSO-like low-frequency climate variability on respective time scales but feature distinct surface wind forcing patterns and subbasin climate processes. The multidecadal sea level mode is associated with the Pacific decadal oscillation (PDO) and Aleutian low variations in the North Pacific and tropical Pacific sea surface temperature anomalies toward the eastern basin, while the quasi-decadal sea level mode is accompanied by tropical Pacific sea surface temperature anomalies centered in the central basin along with the North Pacific part, which resembles the North Pacific Oscillation (NPO) and its oceanic expressions [i.e., the North Pacific Gyre Oscillation (NPGO) and the Victoria mode]. The authors further conclude that the ENSO-like low-frequency variability, which has dominant influences on the Pacific sea level and climate, comprises at least two distinct modes with different spatial structures on quasi-decadal and multidecadal time scales, respectively.

scholarly journals Global diversity and oceanic divergence of humpback whales ( Megaptera novaeangliae )

2014 ◽  
Vol 281 (1786) ◽  
pp. 20133222 ◽  
Author(s):  
Jennifer A. Jackson ◽  
Debbie J. Steel ◽  
P. Beerli ◽  
Bradley C. Congdon ◽  
Carlos Olavarría ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
North Atlantic ◽  
North Pacific ◽  
Megaptera Novaeangliae ◽  
Population History ◽  
Humpback Whales ◽  
Restricted Gene Flow ◽  
Geological Time ◽  
The North ◽  
The North Pacific

Humpback whales ( Megaptera novaeangliae ) annually undertake the longest migrations between seasonal feeding and breeding grounds of any mammal. Despite this dispersal potential, discontinuous seasonal distributions and migratory patterns suggest that humpbacks form discrete regional populations within each ocean. To better understand the worldwide population history of humpbacks, and the interplay of this species with the oceanic environment through geological time, we assembled mitochondrial DNA control region sequences representing approximately 2700 individuals (465 bp, 219 haplotypes) and eight nuclear intronic sequences representing approximately 70 individuals (3700 bp, 140 alleles) from the North Pacific, North Atlantic and Southern Hemisphere. Bayesian divergence time reconstructions date the origin of humpback mtDNA lineages to the Pleistocene (880 ka, 95% posterior intervals 550–1320 ka) and estimate radiation of current Northern Hemisphere lineages between 50 and 200 ka, indicating colonization of the northern oceans prior to the Last Glacial Maximum. Coalescent analyses reveal restricted gene flow between ocean basins, with long-term migration rates (individual migrants per generation) of less than 3.3 for mtDNA and less than 2 for nuclear genomic DNA. Genetic evidence suggests that humpbacks in the North Pacific, North Atlantic and Southern Hemisphere are on independent evolutionary trajectories, supporting taxonomic revision of M. novaeangliae to three subspecies.

Geographical restriction as a guide to the causes of extinction: the case of the cold northern oceans during the Neogene

Paleobiology ◽  
1989 ◽  
Vol 15 (4) ◽  
pp. 335-356 ◽  
Author(s):  
Geerat J. Vermeij
Keyword(s):  
Primary Productivity ◽  
North Pacific ◽  
Early Pleistocene ◽  
Northwestern Pacific ◽  
Supporting Evidence ◽  
Geographical Patterns ◽  
The North ◽  
The Pacific ◽  
Late Neogene ◽  
The North Pacific

Geographical restriction to refuges implies the regional extinction of taxa in areas of the previous range falling outside the refuge. A comparison of the circumstances in the refuge with those in areas from which the taxa were eliminated is potentially informative for pinpointing the causes of extinction. A synthesis of data on the geographical and stratigraphical distributions of cool-water molluscs of the North Pacific and North Atlantic Oceans during the late Neogene reveals four patterns of geographical restriction, at least two of which imply that climatic cooling was not the only cause of extinction during the last several million years. These four patterns are (1) the northwestern Pacific restriction, involving 15 taxa whose amphi-Pacific distributions during the late Neogene became subsequently restricted to the Asian side of the Pacific; (2) the northwestern Atlantic restriction, involving six taxa whose early Pleistocene distribution is inferred to have been amphi-Atlantic, but whose present-day and late Pleistocene ranges are confined to the northwestern Atlantic; (3) a vicariant Pacific pattern, in which many ancestral amphi-Pacific taxa gave rise to separate eastern and western descendants; and (4) the circumboreal restriction, involving six taxa whose early Pleistocene distribution, encompassing both the Atlantic and Pacific Oceans, became subsequently limited to the North Pacific. Like the Pliocene extinctions in the Atlantic, previously studied by Stanley and others, the vicariant Pacific pattern is most reasonably interpreted as having resulted from regional extinction of northern populations in response to cooling. The northwestern Pacific and Atlantic restrictions, however, cannot be accounted for in this way. In contrast to the northeastern margins of the Pacific and Atlantic, the northwestern margins are today characterized by wide temperature fluctuations and by extensive development of shore ice in winter. Northeastern, rather than northwestern, restriction would be expected if cooling were the overriding cause of regional extinction. Among the other possible causes of extinction, only a decrease in primary productivity can account for the observed northwestern and circumboreal patterns of restriction. Geographical patterns of body size and the distribution of siliceous deposits provide supporting evidence that primary productivity declined after the Miocene in the northeastern Pacific, but remained high in the northwestern Pacific, and that productivity in the Pacific is generally higher than it is in the Atlantic. The patterns of geographical restriction in the northern oceans thus provide additional support to previous inferences that reductions in primary productivity have played a significant role in marine extinctions.

scholarly journals Synoptic–Dynamic Climatology of Large-Scale Cyclones in the North Pacific

2006 ◽  
Vol 134 (12) ◽  
pp. 3567-3587 ◽  
Author(s):  
Linda M. Keller ◽  
Michael C. Morgan ◽  
David D. Houghton ◽  
Ross A. Lazear
Keyword(s):  
North Pacific ◽  
Large Scale ◽  
The United States ◽  
Height Anomaly ◽  
Maximum Frequency ◽  
Mean Flow ◽  
Central Pacific ◽  
The North ◽  
The Pacific ◽  
The North Pacific

Abstract A climatology of large-scale, persistent cyclonic flow anomalies over the North Pacific was constructed using the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) global reanalysis data for the cold season (November–March) for 1977–2003. These large-scale cyclone (LSC) events were identified as those periods for which the filtered geopotential height anomaly at a given analysis point was at least 100 m below its average for the date for at least 10 days. This study identifies a region of maximum frequency of LSC events at 45°N, 160°W [key point 1 (KP1)] for the entire period. This point is somewhat to the east of regions of maximum height variability noted in previous studies. A second key point (37.5°N, 162.5°W) was defined as the maximum in LSC frequency for the period after November 1988. The authors show that the difference in location of maximum LSC frequency is linked to a climate regime shift at about that time. LSC events occur with a maximum frequency in the period from November through January. A composite 500-hPa synoptic evolution, constructed relative to the event onset, suggests that the upper-tropospheric precursor for LSC events emerges from a quasi-stationary long-wave trough positioned off the east coast of Asia. In the middle and lower troposphere, the events are accompanied by cold thickness advection from a thermal trough over northeastern Asia. The composite mean sea level evolution reveals a cyclone that deepens while moving from the coast of Asia into the central Pacific. As the cyclone amplifies, it slows down in the central Pacific and becomes nearly stationary within a day of onset. Following onset, at 500 hPa, a stationary wave pattern, resembling the Pacific–North American teleconnection pattern, emerges with a ridge immediately downstream (over western North America) and a trough farther downstream (from the southeast coast of the United States into the western North Atlantic). The implications for the resulting sensible weather and predictability of the flow are discussed. An adjoint-derived sensitivity study was conducted for one of the KP1 cases identified in the climatology. The results provide dynamical confirmation of the LSC precursor identification for the events. The upper-tropospheric precursor is seen to play a key role not only in the onset of the lower-tropospheric height falls and concomitant circulation increases, but also in the eastward extension of the polar jet across the Pacific. The evolution of the forecast sensitivities suggest that LSC events are not a manifestation of a modal instability of the time mean flow, but rather the growth of a favorably configured perturbation on the flow.

scholarly journals Mass Footprints of the North Pacific Atmospheric Blocking Highs

2015 ◽  
Vol 28 (12) ◽  
pp. 4941-4949 ◽  
Author(s):  
Tae-Won Park ◽  
Yi Deng ◽  
Wenhong Li ◽  
Song Yang ◽  
Ming Cai
Keyword(s):  
Mass Loss ◽  
North Pacific ◽  
Three Dimensional ◽  
Low Frequency ◽  
Lower Troposphere ◽  
Decay Stage ◽  
The North ◽  
Detection And Attribution ◽  
Blocking High ◽  
The North Pacific

Abstract The mass footprints associated with atmospheric blocks over the North Pacific are evaluated by constructing daily tendencies of total mass over the blocking domain from three-dimensional mass fluxes throughout the life cycle of a composite blocking event. The results highlight the major role of mass convergence driven by low-frequency (with periods >1 week) atmospheric disturbances during both the development and decay stage of a block. Specifically, low-frequency eddies are responsible for the accelerated mass buildup 4 days prior to the peak intensity of a block, and they also account for the rapid mass loss afterward. High-frequency, subweekly scale disturbances have statistically significant positive contributions to the mass loss during the decay stage, and also show weak negative contributions to the development of the blocking high prior to the peak of the high. The majority of the mass convergence (divergence) responsible for the intensification (decay) of the blocking high occurs in the middle-to-lower troposphere and is largely attributed to mass flux driven by low-frequency meridional (zonal) winds. Also discussed are the implications of this new mass perspective of atmospheric blocks for understanding dynamics of blocking highs and for model bias detection and attribution.

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