Critically endangered western gray whales migrate to the eastern North Pacific

Mate, Bruce R.; Ilyashenko, V. Yu.; Bradford, Amanda L.; Vertyankin, Vladimir V.; Tsidulko, Grigory A.; Рожнов, В. В.; Irvine, Ladd M.

doi:10.1098/rsbl.2015.0071

Cited by 73 publications

(69 citation statements)

References 14 publications

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“…Individual tracks can also provide significant information with conservation implications. For example, the track of a single grey whale (Eschrichtius robustus) tagged within the feeding grounds of the critically endangered western stock off Sakhalin Island, Russia, and migrating to the breeding lagoons of the eastern stock in Baja California, Mexico, questioned whether these two stocks were indeed distinct (Mate et al 2015). This individual whale also broke the world record (previously held by a humpback whale) for the longest known mammalian migration at 22,511 km.…”

Section: Fig 2 Examples Of Tracking Studies Using Various Sample Simentioning

confidence: 99%

The importance of sample size in marine megafauna tagging studies

Sequeira

Heupel

Lea

et al. 2019

Ecological Applications

103

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Telemetry is a key, widely used tool to understand marine megafauna distribution, habitat use, behavior, and physiology; however, a critical question remains: “How many animals should be tracked to acquire meaningful data sets?” This question has wide‐ranging implications including considerations of statistical power, animal ethics, logistics, and cost. While power analyses can inform sample sizes needed for statistical significance, they require some initial data inputs that are often unavailable. To inform the planning of telemetry and biologging studies of marine megafauna where few or no data are available or where resources are limited, we reviewed the types of information that have been obtained in previously published studies using different sample sizes. We considered sample sizes from one to >100 individuals and synthesized empirical findings, detailing the information that can be gathered with increasing sample sizes. We complement this review with simulations, using real data, to show the impact of sample size when trying to address various research questions in movement ecology of marine megafauna. We also highlight the value of collaborative, synthetic studies to enhance sample sizes and broaden the range, scale, and scope of questions that can be answered.

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Section: Fig 2 Examples Of Tracking Studies Using Various Sample Simentioning

confidence: 99%

The importance of sample size in marine megafauna tagging studies

Sequeira

Heupel

Lea

et al. 2019

Ecological Applications

103

View full text Add to dashboard Cite

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“…), although satellite data have shown that the western whales migrate to Mexico, where they may mix with individuals from the eastern population (Mate et al. ).…”

Section: Mediterranean Fin Whale Migration In Contextmentioning

confidence: 99%

“…Opportunistic feeding along their entire range from Baja California to Alaskan waters has been documented in eastern Pacific grey whales, as well as year-round presence in the northern Gulf of Alaska ). Comparatively less is known of the migration paths and winter grounds of the north-western Pacific Ocean grey whales along the east coast of Asia (Swartz et al 2006), although satellite data have shown that the western whales migrate to Mexico, where they may mix with individuals from the eastern population (Mate et al 2015).…”

Section: Mysticete Migration Revisitedmentioning

confidence: 99%

Mysticete migration revisited: are Mediterranean fin whales an anomaly?

2016

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1.The generally accepted model of Mysticete whale migration is that most individuals undertake seasonal migrations between high and low latitudes. Although numerous exceptions have been described in the literature, the traditional model remains unexamined. This paper represents the first 'official' challenge to the traditional model of Mysticete migration. 2. We set out to review the current state of knowledge on the Mediterranean fin whale migratory pattern, and to examine whether the small, resident population in the Mediterranean is an anomaly within the framework of the traditional model of Mysticete migration. We investigated the prevalence of alternative migratory strategies among the Mysticete whales, reviewing the migratory habits of the Mediterranean fin whales and those of other fin whale and baleen whale populations. 3. We reach three main conclusions. First, the seasonal behaviour of the resident Mediterranean fin whales is highly dynamic, and a decade of research has not clarified prevailing uncertainties regarding migration patterns. Second, migration strategies similar to those observed in the Mediterranean fin whales are commonly seen in other populations of baleen whales. Third, the traditional model of whale migration is too simplified to describe the repertoire of Mysticete migratory behaviours accurately. 4. We argue that the paradigm of baleen whale migration warrants further scrutiny to account for more complex movement strategies. We suggest that Mysticete migration should be thought of as a continuum of different strategies that have evolved in the face of different selective pressures. Instead of representing an exception to the rule, the resident Mediterranean fin whales may in fact fall towards one end of a larger spectrum of migratory behaviours. A greater knowledge of ecological factors, reproductive patterns, and local adaptations will be needed to understand the evolutionary mechanisms behind the diversity of migratory habits. bs_bs_banner

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“…Apart from the rich benthic prey biomass (average of 35.2 and 18.5 g m −2 for amphipods and isopods, respectively; Fadeev 2011), the Piltun feeding area is of particular importance to nursing/weaning gray whale calves, probably due at least in part to the relatively sheltered and shallow nature of the area . The location or locations of this population's wintering grounds are not well understood, but the whales are clearly migratory; at least some of them migrate from Sakhalin to low-latitude areas along the Baja California Peninsula, Mexico, where early calf rearing and courtship activity occur (Urban et al 2013, Mate et al 2015, and others possibly migrate to historical wintering grounds in the South China Sea (Weller et al 2002). The whales return to the Piltun feeding area in the period from June to July and remain until November.…”

Section: Introductionmentioning

confidence: 99%

Monitoring and impact mitigation during a 4D seismic survey near a population of gray whales off Sakhalin Island, Russia

Bröker¹,

Gailey²,

Muir³

et al. 2015

Endang. Species. Res.

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A 4D seismic survey was conducted in 2010 near the feeding grounds of gray whales off Sakhalin Island, Russia. To minimize disruptions to the whales' feeding activity and enhance understanding of the potential impacts of seismic surveys on gray whales Eschrichtius robustus, an extensive monitoring and mitigation plan (MMP) was developed. Typically, mitigation plans involve observers on seismic vessels to monitor for the presence of marine mammals in an exclusion zone so as to prevent physical injury to the animals. Due to the protected status of western gray whales, an additional protection zone based on a behavioural disturbance threshold of exposure of 156 dB re μPa 2 -s per pulse was applied for whales within their feeding habitat defined by the estimated 95% abundance contour. Real-time radio-transmitting acoustic recorders were deployed along this contour to verify modelled acoustic footprints within the feeding grounds. Shore-and vessel-based observation teams monitored for the presence and activity of whales. A real-time GIS workflow tracking procedure was developed that integrated acoustic and whale positioning data to determine if sound levels at a whales' position within the feeding area exceeded the behavioural threshold, in which case a shut-down of the seismic source was implemented. Additionally, behaviour and distribution surveys were conducted before, during and after the seismic survey to evaluate the effectiveness of the MMP. No large changes in whale movement, respiration, or distribution patterns were observed during the seismic survey. This could be interpreted to mean that the MMP was effective in reducing the sound exposure and behavioural responses of gray whales to seismic sounds.

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Critically endangered western gray whales migrate to the eastern North Pacific

Cited by 73 publications

References 14 publications

The importance of sample size in marine megafauna tagging studies

The importance of sample size in marine megafauna tagging studies

Mysticete migration revisited: are Mediterranean fin whales an anomaly?

Monitoring and impact mitigation during a 4D seismic survey near a population of gray whales off Sakhalin Island, Russia

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