Prey biomass dynamics in gray whale feeding areas adjacent to northeastern Sakhalin (the Sea of Okhotsk), Russia, 2001–2015

Blanchard, Arny L.; Demchenko, Natalia L.; Aerts, Lise A.M.; Yazvenko, Sergei B.; Ивин, В. В.; Shcherbakov, Ilya; Melton, H. R.

doi:10.1016/j.marenvres.2019.02.008

Cited by 18 publications

(54 citation statements)

References 88 publications

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“…Sightings between 51.8˚and 52.4˚N and 143.4˚and 144.0˚E were classified as offshore. Substrates in the nearshore areas include silty sands with more sandy muds in the offshore area [73]. Both feeding areas have amongst the highest primary and secondary productivity in the Sea of Okhotsk [21].…”

Section: Plos Onementioning

confidence: 99%

“…This was thought to be a more important explanatory factor for gray whale density than the taxonomic composition of the available prey. The prey resources in the nearshore area are mainly comprised of smaller amphipods (Monoporeia affinis) distributed in aggregated patches that vary significantly in biomass concentration from year to year [22], but include other prey species as well [73]. In contrast, the offshore area is comprised of a high concentration of ampeliscid amphipods (Ampelisca eschrichtii), with a mean biomass of 338.2 gr/m 2 [21,57].…”

Section: Area Usagementioning

confidence: 99%

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Site-fidelity and spatial movements of western North Pacific gray whales on their summer range off Sakhalin, Russia

Bröker

Gailey²,

Tyurneva

et al. 2020

PLoS ONE

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The Western North-Pacific (WNP) gray whale feeding grounds are off the northeastern coast of Sakhalin Island, Russia and is comprised of a nearshore and offshore component that can be distinguished by both depth and location. Spatial movements of gray whales within their foraging grounds were examined based on 13 years of opportunistic vessel and shore-based photo-identification surveys. Site fidelity was assessed by examining annual return and resighting rates. Lagged Identification Rates (LIR) analyses were conducted to estimate the residency and transitional movement patterns within the two components of their feeding grounds. In total 243 individuals were identified from 2002-2014, among these were 94 calves. The annual return rate over the period 2002-2014 was 72%, excluding 35 calves only seen one year. Approximately 20% of the individuals identified from 2002-2010 were seen every year after their initial sighting (including eight individuals that returned for 13 consecutive years). The majority (239) of the WNP whales were observed in the nearshore area while only half (122) were found in the deeper offshore area. Within a foraging season, there was a significantly higher probability of gray whales moving from the nearshore to the offshore area. No mother-calf pairs, calves or yearlings were observed in the offshore area, which was increasingly used by mature animals. The annual return rates, and population growth rates that are primarily a result of calf production with little evidence of immigration, suggest that this population is demographically self-contained and that both the nearshore and offshore Sakhalin feeding grounds are critically important areas for their summer annual foraging activities. The nearshore habitat is also important for mother-calf pairs, younger individuals, and recently weaned calves. Nearshore feeding could also be energetically less costly compared to foraging in the deeper offshore habitat and provide more protection from predators, such as killer whales.

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Section: Plos Onementioning

confidence: 99%

Section: Area Usagementioning

confidence: 99%

Site-fidelity and spatial movements of western North Pacific gray whales on their summer range off Sakhalin, Russia

Bröker

Gailey²,

Tyurneva

et al. 2020

PLoS ONE

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“…Prey of gray whales may have a similar response. Total available prey at offshore Sakhalin Island feeding grounds are positively correlated with both winter and summertime PDO (Blanchard et al, 2019). Perryman et al (2020) found a positive relationship between PDO and ENP gray whale calf production where several cold years (negative PDO and/or extensive sea ice cover) translated to lower calf estimates in the following spring.…”

Section: Comparisons Of Observations Of Body Condition With Whales Studied At Sakhalin Islandmentioning

confidence: 96%

“…In this regard, it is unsurprising that there was a significant effect of several environmental variables at one or more time lags. Whale body condition as mediated by prey availability and abundance cannot respond instantaneously to environmental factors; prey populations require time to increase reproduction and grow to body sizes suitable for gray whale foraging before the changes in environmental conditions can result in changes in the body condition of gray whales (Blanchard et al, 2019;Burnham and Duffus, 2018;Feyrer and Duffus, 2015). Gray whales in the PCFG region feed on a variety of prey taxa, including several species of mysid shrimps, crab larvae (Petrolisthes spp.)…”

Section: Factors Influencing Gray Whale Body Conditionmentioning

confidence: 99%

Body condition of gray whales (Eschrichtius robustus) feeding on the Pacific Coast reflects local and basin-wide environmental drivers

Akmajian¹,

Scordino

Gearin

et al. 2021

JCRM

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A small subset of the Eastern North Pacific gray whale population does not make the full migration from wintering grounds in Mexico to feeding grounds in the Bering, Chukchi and Beaufort seas and instead feed along the Pacific Coast between northern California and northern British Columbia â€“ this group is known as the Pacific Coast Feeding Group (PCFG). We evaluated the body condition of PCFG whales observed in northern Washington and along Vancouver Island to evaluate how body condition of gray whales changes within and between years. We found that PCFG gray whales improve body condition through the feeding season and at varying rates by year and that they have variability in their body condition at the start and end of each feeding season. The inclusion of environmental factors, particularly the Pacific Decadal Oscillation (lagged two years) and September kelp canopy cover along the Washington coast (lagged one year), drastically improved the ability of a multiple regression model to predict average whale body condition for a given year as compared to models without environmental factors included. A comparison of our findings to a previously published study on body condition of gray whales at Sakhalin Island, Russia highlight the differences of life history strategy between a group of whales with a long migration (Sakhalin whales) and those with a short migration. Whales feeding at Sakhalin Island gain body condition quicker and more predictably to a good body condition by the end of the feeding season than the whales we studied in the PCFG. Photogrammetry may be an effective method for monitoring the effects of climate change on PCFG gray whales.

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“…Macrobenthic community biomass was determined from the northeastern Sakhalin Island gray whale feeding area, Sea of Okhotsk, Russia [1] . Bottom samples were collected from 2001 to 2015 to determine prey biomass characteristics and distributions.…”

Section: Datamentioning

confidence: 99%

Data on macrobenthic prey from an essential western gray whale feeding habitat, Sakhalin Island, Russia, 2001–2015

Blanchard¹,

Demchenko

Aerts³

et al. 2019

Data in Brief

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Data in this article presents data (means and standard deviations) for prey biomass from essential feeding habitats for the endangered western gray whale. Prey include Actinopterygii (primarily the sand lance Ammodytes hexapterus ), Amphipoda, Bivalvia, Cumacea, Isopoda, and Polychaeta. Total prey biomass (sum of the six prey groups) is also presented. Statistical analyses document spatial and temporal trends in prey biomass concentrations. Multivariate analyses using canonical correspondence analysis characterize relationships of potential drivers of community changes.

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Prey biomass dynamics in gray whale feeding areas adjacent to northeastern Sakhalin (the Sea of Okhotsk), Russia, 2001–2015

Cited by 18 publications

References 88 publications

Site-fidelity and spatial movements of western North Pacific gray whales on their summer range off Sakhalin, Russia

Site-fidelity and spatial movements of western North Pacific gray whales on their summer range off Sakhalin, Russia

Body condition of gray whales (Eschrichtius robustus) feeding on the Pacific Coast reflects local and basin-wide environmental drivers

Data on macrobenthic prey from an essential western gray whale feeding habitat, Sakhalin Island, Russia, 2001–2015

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