Decreasing body lengths in North Atlantic right whales

Stewart, Joshua; Durban, John W.; Knowlton, Amy R.; Lynn, Morgan S.; Fearnbach, Holly; Barbaro, Jacob; Perryman, Wayne L.; Miller, Colin; Moore, Michael J.

doi:10.1016/j.cub.2021.04.067

Cited by 61 publications

(79 citation statements)

References 32 publications

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“…With limited data, Sharp et al (2019) found some evidence that whales in the 2010 decade were smaller than whales from previous decades. Those preliminary findings have since been borne out by Stewart et al (2021), who found decreasing body lengths in right whales over a three-decade period. The authors discovered that a whale born in 2019 is expected to reach a maximum length one meter less than a whale born in 1981.…”

Section: Physical Developmentmentioning

confidence: 76%

“…The genetic identifications presented here provided age for 12 whales, maternity for one, and supported the maternity assignments for another 10 (Table 4). Knowing the age of individuals allows for more precise age-specific: (1) survival and fecundity to be estimated in population models (Caswell et al 1999;Pace et al 2017), (2) growth curves to be developed (Moore et al 2004;Fortune et al 2012;Sharp et al 2019;Stewart et al 2021), and (3) mortality threats to be assessed (Knowlton et al 2016). The maternity data are used for female fitness and survival estimates and provide the possibility for paternities to be assigned (Frasier et al 2007).…”

Section: Age and Maternitymentioning

confidence: 99%

“…Two dead whales in this study were incorrectly classified as calves of the year (Table 4). Like all mammals, the length of a right whale at a given point in time is influenced by the fitness of its mother, timing of the calf's birth, their length at birth, and their growth rate after birth (Moore et al 2004;Christiansen et al 2018;Sharp et al 2019;Stewart et al 2021). For most right whales, many of these factors are unknown, or only partially known.…”

Section: Physical Developmentmentioning

confidence: 99%

“…org), which contains all known photographed sightings of right whales in the North Atlantic from 1935 to the present (Hamilton et al 2007;Pace et al 2017). The data available in the Catalog have provided information on individual movements (Kraus et al 1986a;Knowlton et al 1992;Jacobsen et al 2004;Silva et al 2012;Gowan et al 2019), age structure (Hamilton et al 1998), weaning (Hamilton et al 1995;Hamilton and Cooper 2010), reproductive success (Knowlton et al 1994;Kraus et al 2001;Frasier et al 2007), mortality (Moore et al 2004;Sharp et al 2019), growth rates (Fortune et al 2012;Stewart et al 2021), sublethal anthropogenic impacts (Kraus 1990;Knowlton et al 2012) and population dynamics (Pace et al 2017;Hayes et al 2018).…”

Section: Introductionmentioning

confidence: 99%

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Genetic identifications challenge our assumptions of physical development and mother–calf associations and separation times: a case study of the North Atlantic right whale (Eubalaena glacialis)

et al. 2022

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While photo-identification is an effective tool to monitor individuals in wild populations, it has limitations. Specifically, it cannot be applied to very young animals before their identifying features have stabilized or to dead, decomposed animals. These shortfalls leave gaps in our understanding of survival, parentage, age structure, physical development, and behavioral variability. Here we report on 13 case studies of North Atlantic right whale, Eubalaena glacialis, calves that required genetics to track their life history data. These case studies revealed unexpected variations in mother–calf associations and separation times, as well as calf physical development. Prior to this study, calves were assumed to have died if their mothers were always alone on the feeding ground in the calf’s birth year. Using genetics and photo-identification, four such calves were discovered to be alive; two of the four possibly weaned earlier than expected at 7.5–8.0 months. To put these early separations in context, photo-identification data were queried and revealed that mothers and calves are seen apart from each other on the feeding grounds in 10–40% of all spring/summer sightings; previously, there were no published data on how often pairs are seen apart in the calf’s birth year. Two dead whales initially logged as calves of the year were discovered to be juveniles, thus allowing skewed survival estimates for calves of the year to be corrected. Genetically sampling animals early in their lives before they disperse or separate from their mothers provides an important means of individual identification at a time when photo-identification is not reliable.

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Section: Physical Developmentmentioning

confidence: 76%

Section: Age and Maternitymentioning

confidence: 99%

Section: Physical Developmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Genetic identifications challenge our assumptions of physical development and mother–calf associations and separation times: a case study of the North Atlantic right whale (Eubalaena glacialis)

et al. 2022

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“…Under these conditions, the right whale population can only grow if there are no deaths from ship strikes or from entanglements in fishing ropes (Corkeron et al, 2018;Meyer-Gutbrod and Greene, 2018). Sublethal entanglements make it harder for right whales to grow, potentially contributing to lower reproductive success (Stewart et al, 2021). Humans now have a strong influence on the potential fitness in a habitat (black arrows in Figure 1b), and unanticipated shifts in the whales' habitat preferences challenge the effectiveness of conservation measures (Davies and Brillant, 2019;Record et al, 2019;Meyer-Gutbrod et al, 2021).…”

mentioning

confidence: 99%

Can Right Whales Out-Swim Climate Change? Can We?

Pershing¹,

Pendleton²

2021

Oceanog

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The article by Meyer-Gutbrod and colleagues in this issue demonstrates that the endangered North Atlantic right whale’s preferred prey has declined as the Northwest Atlantic has warmed. Right whales are now spending more time foraging in historically colder habitats, but they are producing fewer calves. The low calf production could reflect a delay between the decline in the potential productivity of their traditional habitats and its increase in their new habitats. This delay would result in a “climate deficit” in their fitness. Right whales must also learn to forage successfully in their new habitats, creating an additional loss of fitness termed an “adaptation deficit.” Humans will also face unavoidable climate deficits, but we have more options for minimizing adaptation deficits.

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Quantifying uncertainty in anthropogenic causes of injury and mortality for an endangered baleen whale

Linden,

Hostetler,

Pace

et al. 2024

Ecosphere

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Understanding the causes of mortality for a declining species is essential for developing effective conservation and management strategies, particularly when anthropogenic activities are the primary threat. Using a competing hazards framework allows for robust estimation of the cause‐specific variation in risk that may exist across multiple dimensions, such as time and individual. Here, we estimated cause‐specific rates of severe injury and mortality for North Atlantic right whales (Eubalaena glacialis), a critically endangered species that is currently in peril due to human‐caused interactions. We developed a multistate capture–recapture model that leveraged 30 years of intensive survey effort yielding sightings of individuals with injury assessments and necropsies of carcass recoveries. We examined variation in the hazard rates of severe injury and mortality due to entanglements in fishing gear and vessel strikes as explained by temporal patterns and the age and reproductive status of the individual. We found strong evidence for increased rates of severe entanglement injuries after 2013 and for females with calves, with consequently higher marginal mortality. The model results also suggested that despite vessel strikes causing a lower average rate of severe injuries, the higher mortality rate conditional on injury results in significant total mortality risk, particularly for females resting from a recent calving event. Large uncertainty in the estimation of carcass recovery rate for vessel strike deaths permeated into the apportionment of mortality causes. The increased rates of North Atlantic right whale mortality in the last decade, particularly for reproducing females, has been responsible for the severe decline in the species. By apportioning the human‐caused threats using a quantitative approach with estimation of relevant uncertainty, this work can guide development of conservation and management strategies to facilitate species recovery. Our approach is relevant to other monitored populations where cause‐specific injuries from multiple threats can be observed in live and dead individuals.

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Decreasing body lengths in North Atlantic right whales

Cited by 61 publications

References 32 publications

Genetic identifications challenge our assumptions of physical development and mother–calf associations and separation times: a case study of the North Atlantic right whale (Eubalaena glacialis)

Genetic identifications challenge our assumptions of physical development and mother–calf associations and separation times: a case study of the North Atlantic right whale (Eubalaena glacialis)

Can Right Whales Out-Swim Climate Change? Can We?

Quantifying uncertainty in anthropogenic causes of injury and mortality for an endangered baleen whale

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