scholarly journals Do Gray Whales Count Calories? Comparing Energetic Values of Gray Whale Prey Across Two Different Feeding Grounds in the Eastern North Pacific

2021 ◽  
Vol 8 ◽  
Author(s):  
Lisa Hildebrand ◽  
Kim S. Bernard ◽  
Leigh G. Torres
Keyword(s):  
North Pacific ◽  
Prey Availability ◽  
The Arctic ◽  
Caloric Content ◽  
Amphipod Species ◽  
Gray Whale ◽  
Dungeness Crab ◽  
Gray Whales ◽  
The Mean ◽  
Feeding Grounds

Predators must consume enough prey to support costly events, such as reproduction. Meeting high energetic requirements is particularly challenging for migrating baleen whales as their feeding seasons are typically restricted to a limited temporal window and marine prey are notoriously patchy. We assessed the energetic value of the six most common nearshore zooplankton species collected within the Oregon, United States range of the Pacific Coast Feeding Group (PCFG) gray whale (Eschrichtius robustus) feeding grounds, and compared these results to the energetic value of the predominant amphipod species fed on by Eastern North Pacific (ENP) gray whales in the Arctic. Energetic values of Oregon zooplankton differed significantly between species (Kruskal–Wallis χ2 = 123.38, df = 5, p < 0.0001), with Dungeness crab (Cancer magister) megalopae displaying the highest mean caloric content of all tested species (4.21 ± 1.27 kJ g– 1). This value, as well as the mean energetic value of the mysid Neomysis rayii (2.42 ± 1.06 kJ g– 1), are higher than the mean caloric content of Ampelisca macrocephala, the predominant Arctic amphipod. Extrapolations of these results to daily energetic requirements of gray whales indicate that lactating and pregnant gray whales feeding in the PCFG range would require between 0.7–1.03 and 0.22–0.33 metric tons of prey less per day if they fed on Dungeness crab megalopae or N. rayii, respectively, than a whale feeding on A. macrocephala in the Arctic. Yet, these results do not account for differences in availability of these prey species to foraging gray whales. We therefore suggest that other factors, such as prey density, energetic costs of feeding, or natal philopatry and foraging site fidelity play a role in the differences in population sizes between the PCFG and ENP gray whales. Climate change is implicated in causing reduced body condition and increased mortality of both PCFG and ENP gray whales due to decreased prey availability and abundance. Therefore, improved understanding of prey dynamics in response to environmental variability in both regions is critical.

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.

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.

Assessment of genetic structure among eastern North Pacific gray whales on their feeding grounds

2014 ◽  
Vol 30 (4) ◽  
pp. 1473-1493 ◽  
Author(s):  
Aimée R. Lang ◽  
John Calambokidis ◽  
Jonathan Scordino ◽  
Victoria L. Pease ◽  
Amber Klimek ◽  
...  
Keyword(s):  
Genetic Structure ◽  
North Pacific ◽  
Gray Whales ◽  
Feeding Grounds

Gray whale feeding on dense ampeliscid amphipod communities near Bamfield, British Columbia

1984 ◽  
Vol 62 (1) ◽  
pp. 41-49 ◽  
Author(s):  
John S. Oliver ◽  
Peter N. Slattery ◽  
Mark A. Silberstein ◽  
Edmund F. O'Connor
Keyword(s):  
Bering Sea ◽  
Benthic Communities ◽  
Gray Whale ◽  
Gray Whales ◽  
Northern Bering Sea ◽  
Amphipod Crustacean ◽  
Different Parts ◽  
Feeding Grounds ◽  
Made In ◽  
The Bering Sea

Gray whales fed on dense populations of ampeliscid amphipods while summering along the west coast of Vancouver Island. These amphipod crustacean communities are ecological analogs of the primary feeding grounds of gray whales in the northern Bering Sea. The same major genera of amphipods dominated the Alaskan and Canadian feeding grounds, including Ampelisca, Photis, Protomedeia, Anonyx, and Orchomene, and comprised 67 to 90% of the number of infaunal crustaceans at the two locations. This is the first documented report of gray whale feeding on benthic infauna south of the Bering Sea. Feeding gray whales observed in Pachena Bay produced an extensive record of feeding excavations in bottom sediments. Excavation patterns suggest that: (i) whales used suction to extract infaunal prey and sediments; (ii) a maximum of six excavations was made in one feeding dive; (iii) excavation size was related to whale size; (iv) small and large whales fed in different parts of the bay; and (v) whales effectively located and worked the densest patches of benthic prey. We estimate that a 6-m whale consumed 116 kg of infaunal prey per 12-h day, and that a 12-m whale consumed 552 kg per 12-h day. Scavenging lysianassid amphipods were attracted to feeding disturbances within seconds and preyed on injured and dislodged infauna. Individual feeding excavations were large, deep valleys in a tube-mat plateau. In addition to the lysianassids, many other infauna undoubtedly colonize these highly modified habitats, resulting in important effects on the structure of benthic communities.

scholarly journals Mesoscale Features Associated with Tropical Cyclone Formations in the Western North Pacific

2008 ◽  
Vol 136 (6) ◽  
pp. 2006-2022 ◽  
Author(s):  
Cheng-Shang Lee ◽  
Kevin K. W. Cheung ◽  
Jenny S. N. Hui ◽  
Russell L. Elsberry
Keyword(s):  
Tropical Cyclone ◽  
North Pacific ◽  
Western North Pacific ◽  
Large Scale ◽  
North Pacific Ocean ◽  
Deep Convection ◽  
Mesoscale Convective System ◽  
Convective System ◽  
Synoptic Patterns ◽  
The Mean

Abstract The mesoscale features of 124 tropical cyclone formations in the western North Pacific Ocean during 1999–2004 are investigated through large-scale analyses, satellite infrared brightness temperature (TB), and Quick Scatterometer (QuikSCAT) oceanic wind data. Based on low-level wind flow and surge direction, the formation cases are classified into six synoptic patterns: easterly wave (EW), northeasterly flow (NE), coexistence of northeasterly and southwesterly flow (NE–SW), southwesterly flow (SW), monsoon confluence (MC), and monsoon shear (MS). Then the general convection characteristics and mesoscale convective system (MCS) activities associated with these formation cases are studied under this classification scheme. Convection processes in the EW cases are distinguished from the monsoon-related formations in that the convection is less deep and closer to the formation center. Five characteristic temporal evolutions of the deep convection are identified: (i) single convection event, (ii) two convection events, (iii) three convection events, (iv) gradual decrease in TB, and (v) fluctuating TB, or a slight increase in TB before formation. Although no dominant temporal evolution differentiates cases in the six synoptic patterns, evolutions ii and iii seem to be the common routes taken by the monsoon-related formations. The overall percentage of cases with MCS activity at multiple times is 63%, and in 35% of cases more than one MCS coexisted. Most of the MC and MS cases develop multiple MCSs that lead to several episodes of deep convection. These two patterns have the highest percentage of coexisting MCSs such that potential interaction between these systems may play a role in the formation process. The MCSs in the monsoon-related formations are distributed around the center, except in the NE–SW cases in which clustering of MCSs is found about 100–200 km east of the center during the 12 h before formation. On average only one MCS occurs during an EW formation, whereas the mean value is around two for the other monsoon-related patterns. Both the mean lifetime and time of first appearance of MCS in EW are much shorter than those developed in other synoptic patterns, which indicates that the overall formation evolution in the EW case is faster. Moreover, this MCS is most likely to be found within 100 km east of the center 12 h before formation. The implications of these results to internal mechanisms of tropical cyclone formation are discussed in light of other recent mesoscale studies.

The Reproductive Biology of Ophiacantha Bidentata (Echinodermata: Ophiuroidea) From The Rockall Trough

1982 ◽  
Vol 62 (1) ◽  
pp. 45-55 ◽  
Author(s):  
P. A. Tyler ◽  
J. D. Gage
Keyword(s):  
Reproductive Biology ◽  
Deep Water ◽  
Larval Stage ◽  
North Pacific ◽  
Deep Sea ◽  
Direct Development ◽  
The Arctic ◽  
Shallow Waters ◽  
Arctic Seas ◽  
Rockall Trough

INTRODUCTIONOphiacantha bidentata (Retzius) is a widespread arctic-boreal ophiuroid with a circumpolar distribution in the shallow waters of the Arctic seas and penetrating into the deep sea of the.North Atlantic and North Pacific (Mortensen, 1927, 1933a; D'yakonov, 1954). Early observations of this species were confined to defining zoogeo-graphical and taxonomic criteria including the separation of deep water specimens as the variety fraterna (Farran, 1912; Grieg, 1921; Mortensen, 1933a). Mortensen (1910) and Thorson (1936, pp. 18–26) noted the large eggs (o.8 mm diameter) in specimens from Greenland and Thorson (1936) proposed that this species had ‘big eggs rich in yolk, shed directly into the sea. Much reduced larval stage or direct development’. This evidence is supported by observations of O. bidentata from the White and Barents Seas (Semenova, Mileikovsky & Nesis, 1964; Kaufman, 1974)..

Maternal attendance patterns of Steller sea lions (Eumetopias jubatus) from stable and declining populations in Alaska

2003 ◽  
Vol 81 (2) ◽  
pp. 340-348 ◽  
Author(s):  
Linda L Milette ◽  
Andrew W Trites
Keyword(s):  
Prey Availability ◽  
A Priori ◽  
Population Decline ◽  
Perinatal Period ◽  
Eumetopias Jubatus ◽  
Steller Sea Lions ◽  
Sea Lions ◽  
First Feeding ◽  
Attendance Patterns ◽  
The Mean

Maternal attendance patterns of Alaskan Steller sea lions (Eumetopias jubatus) were compared during the summer breeding seasons in 1994 and 1995 at Sugarloaf Island (a declining population) and Lowrie Island (a stable population). Our goal was to determine whether there were differences in maternal attendance between the two populations that were consistent with the hypothesis that lactating Steller sea lions in the area of decline were food-limited during summer. Our a priori expectations were based on well-documented behavioural responses of otariids to reduced prey availability. We found that foraging trips were significantly shorter in the area of population decline, counter to initial predictions. The mean length of foraging trips in the declining area was 19.5 h compared with 24.9 h in the stable area. In contrast, the mean perinatal period (time between parturition and first feeding trip) was significantly longer in the area of decline (9.9 versus 7.9 days), again countering initial predictions. The mean length of shore visits for the declining population was also significantly longer (27.0 h compared with 22.6 h where the population was stable). For both populations, the mean time that mothers foraged increased as pups grew older, whereas the time that they spent on shore with their pups became shorter. Behavioural observations of maternal attendance patterns are inconsistent with the hypothesis that lactating Steller sea lions from the declining population had difficulty obtaining prey during summer.

scholarly journals Influence of the Monsoon Trough on Westward-Propagating Tropical Waves over the Western North Pacific. Part II: Energetics and Numerical Experiments

2015 ◽  
Vol 28 (23) ◽  
pp. 9332-9349 ◽  
Author(s):  
Liang Wu ◽  
Zhiping Wen ◽  
Renguang Wu
Keyword(s):  
North Pacific ◽  
Numerical Experiments ◽  
Western North Pacific ◽  
Monsoon Trough ◽  
Water Model ◽  
Mean Flow ◽  
Horizontal Structure ◽  
Rotational Flows ◽  
The Mean ◽  
The Waves

Abstract Part I of this study examined the modulation of the monsoon trough (MT) on tropical depression (TD)-type–mixed Rossby–gravity (MRG) and equatorial Rossby (ER) waves over the western North Pacific based on observations. This part investigates the interaction of these waves with the MT through a diagnostics of energy conversion that separates the effect of the MT on TD–MRG and ER waves. It is found that the barotropic conversion associated with the MT is the most important mechanism for the growth of eddy energy in both TD–MRG and ER waves. The large rotational flows help to maintain the rapid growth and tilted horizontal structure of the lower-tropospheric waves through a positive feedback between the wave growth and horizontal structure. The baroclinic conversion process associated with the MT contributes a smaller part for TD–MRG waves, but is of importance comparable to barotropic conversion for ER waves as it can produce the tilted vertical structure. The growth rates of the waves are much larger during strong MT years than during weak MT years. Numerical experiments are conducted for an idealized MRG or ER wave using a linear shallow-water model. The results confirm that the monsoon background flow can lead to an MRG-to-TD transition and the ER wave amplifies along the axis of the MT and is more active in the strong MT state. Those results are consistent with the findings in Part I. This indicates that the mean flow of the MT provides a favorable background condition for the development of the waves and acts as a key energy source.

scholarly journals Predictors of invertebrate biomass and rate of advancement of invertebrate phenology across eight sites in the North American Arctic

Polar Biology ◽  
2021 ◽  
Vol 44 (2) ◽  
pp. 237-257
Author(s):  
Rebecca Shaftel ◽  
Daniel J. Rinella ◽  
Eunbi Kwon ◽  
Stephen C. Brown ◽  
H. River Gates ◽  
...  
Keyword(s):  
Prey Availability ◽  
Population Level ◽  
The Arctic ◽  
Environmental Drivers ◽  
Chick Survival ◽  
The North ◽  
Phenological Mismatch ◽  
Nesting Sites ◽  
North American Arctic

AbstractAverage annual temperatures in the Arctic increased by 2–3 °C during the second half of the twentieth century. Because shorebirds initiate northward migration to Arctic nesting sites based on cues at distant wintering grounds, climate-driven changes in the phenology of Arctic invertebrates may lead to a mismatch between the nutritional demands of shorebirds and the invertebrate prey essential for egg formation and subsequent chick survival. To explore the environmental drivers affecting invertebrate availability, we modeled the biomass of invertebrates captured in modified Malaise-pitfall traps over three summers at eight Arctic Shorebird Demographics Network sites as a function of accumulated degree-days and other weather variables. To assess climate-driven changes in invertebrate phenology, we used data from the nearest long-term weather stations to hindcast invertebrate availability over 63 summers, 1950–2012. Our results confirmed the importance of both accumulated and daily temperatures as predictors of invertebrate availability while also showing that wind speed negatively affected invertebrate availability at the majority of sites. Additionally, our results suggest that seasonal prey availability for Arctic shorebirds is occurring earlier and that the potential for trophic mismatch is greatest at the northernmost sites, where hindcast invertebrate phenology advanced by approximately 1–2.5 days per decade. Phenological mismatch could have long-term population-level effects on shorebird species that are unable to adjust their breeding schedules to the increasingly earlier invertebrate phenologies.

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