Three decades of nearshore surveys reveal long-term patterns in gray whale habitat use, distribution, and abundance in the Northern California Current

Scientific Reports, Journal Year: 2024, Volume and Issue: 14(1)

Published: April 23, 2024

Abstract The nearshore waters of the Northern California Current support an important seasonal foraging ground for Pacific Coast Feeding Group (PCFG) gray whales. We examine whale distribution, habitat use, and abundance over 31 years (1992–2022) using standardized (< 5 km from shore) surveys spanning a large swath PCFG range. Specifically, we generated density surface models, which incorporate detection probability into generalized additive models to assess environmental correlates distribution predict time. illustrate importance coastal upwelling dynamics, whereby increased only yields higher if interspersed with relaxation events, likely because this combination optimizes influx retention nutrients recruitment aggregation prey. Several features influence including substrate, shelf width, prominent capes, river estuaries. However, these differs between regions, revealing heterogeneity in preferences throughout Predicted fluctuated our study period, but without clear directional trends, unlike previous estimates based on mark-recapture models. This highlights value long-term monitoring, shedding light impacts variable conditions iconic marine predator.

Language: Английский

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Closing the air gap: the use of drones for studying wildlife ecophysiology

Biological reviews/Biological reviews of the Cambridge Philosophical Society, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 17, 2025

ABSTRACT Techniques for non‐invasive sampling of ecophysiological data in wild animals have been developed response to challenges associated with studying captive or using invasive methods. Of these, drones, also known as Unoccupied Aerial Vehicles (UAVs), and their sensors, emerged a promising tool the ecophysiology toolkit. In this review, we synthesise research scoping review on use drones wildlife PRISMA‐SCr checklist identify where efforts focused knowledge gaps remain. We these results explore current best practices provide recommendations future use. 136 studies published since 2010, aided animal body condition morphometrics, kinematics biomechanics, bioenergetics, health (e.g. microbiomes, endocrinology, disease) both aquatic terrestrial environments. Focal taxa are biased towards marine mammals, particularly cetaceans. While conducted globally, is primarily led by institutions based North America, Oceania, Europe. The obtain morphometric through standard colour sensors single camera photogrammetry predominates. such video tracking thermal imaging allowed insights into other aspects ecophysiology, when combined external techniques biologgers. most used commercially available multirotor platforms modification collect samples, integration techniques, multidisciplinary integrate suite remote sensing methods more fully. outline how technological advances will play key role delivery novel improved data. recommend that researchers prepare influx drone‐assisted advancements cross‐institutional collaborations. describe diversify across species environments sources technologies comprehensive results.

Language: Английский

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Variation in faecal testosterone levels in male gray whales on a foraging ground relative to maturity and timing

Conservation Physiology, Journal Year: 2025, Volume and Issue: 13(1)

Published: Jan. 1, 2025

Abstract Understanding wildlife reproductive seasonality is crucial for effective management and long-term monitoring of species. This study investigates the seasonal variability testosterone in male Pacific Coast Feeding Group (PCFG) gray whales, using an eight-year dataset (2016–2023) individual sightings, drone-based photogrammetry endocrine analysis faecal samples. We analyzed relationship between levels total body length (TL), condition (body area index, BAI), sexual maturity day year generalized additive mixed models. Our findings reveal a significant increase mature males (MM) towards end foraging season. was not observed JM, highlighting age-dependent development characteristics. No found TL. Additionally, BAI significantly associated with levels. results suggest that increasing MM whales may indicate preparation mating before southbound migration. These provide valuable insights into biology PCFG underscore importance non-invasive sampling studying large whales. approach only provides further reproduction but also offers tools to enhance understanding baleen broadly approaches.

Language: Английский

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Comprehensive assessment of the physical and health features of the threatened Araguaian River dolphin Inia araguaiaensis

PLoS ONE, Journal Year: 2025, Volume and Issue: 20(3), P. e0319212 - e0319212

Published: March 31, 2025

The Araguaia River dolphin is endemic to the Tocantins-Araguaia Basin and under severe anthropogenic threats. Given species’ vulnerability historical neglect, preliminary data on its health physical parameters are presented, along with an evaluation of potential differences between individuals from areas varying human activity. A comparison these closely related species, Amazon I. geoffrensis , was also aimed. Twenty-four dolphins were captured released in Cantão State Park (protected area, n = 10), Tocantins state; Luiz Alves (exposed fishing activities, 14), Goiás state. Preliminary indicates no significant body morphology two areas. tended show larger grey their bodies than counterparts, river dolphins. Cardiac rate, respiratory frequency, oral temperature did not vary different areas, sex, or age classes. Hematological serum chemistry variables observed among classes, mainly immune system development. Dolphins had higher AST urea/creatinine lower GGT, total bilirubin, creatinine Alves. Such variations may reflect prey types, intensities muscle extenuation during capture, subclinical diseases. Most hematological for outside reference intervals described but inside minimum maximum ranges. Conversely, values both species overlap values. highest testosterone detected adult males progesterone estradiol females. Correlations reproductive hormones measurements demonstrated hormonal variation according body’s development as reach sexual maturity. Understanding current status activity crucial drive management efforts toward conservation.

Language: Английский

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Automated body length and body condition measurements of whales from drone videos for rapid assessment of population health

Marine Mammal Science, Journal Year: 2024, Volume and Issue: 40(4)

Published: May 10, 2024

Abstract Monitoring body length and condition of individuals helps determine overall population health assess adaptation to environmental changes. Aerial photogrammetry from drone‐based videos is a valuable method for obtaining measurements cetaceans. However, the laborious manual processing select frames measure animals ultimately delays assessment hinders conservation actions. Here, we apply deep learning methods expedite improve efficiency important morphological whales. We develop two user‐friendly models automatically (1) detect output containing whales (“DeteX”) (2) extract input (“XtraX”). use gray compare versus automated ( n = 86). Our results show reduced times by one‐ninth, while achieving similar accuracy as (mean coefficient variation <5%). also demonstrate how these are adaptable other species identify remaining challenges help further in future. Importantly, tools greatly speed up key data maintaining accuracy, which critical effectively monitoring health.

Language: Английский

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Growing into it: evidence of an ontogenetic shift in grey whale use of foraging tactics

Animal Behaviour, Journal Year: 2024, Volume and Issue: 214, P. 121 - 135

Published: July 4, 2024

Individual specialization may occur relative to diet, behaviour or spatial distribution, potentially leading differential resource and space use within a population. While specializations have been documented across many animal populations, the underlaying causes of individual (e.g. morphology, age sex) are not always identified. Causes can be especially challenging uncover for large, long-lived marine animals. We used Bayesian multilevel, multinomial logistic regression model study relationships between grey whale, Eschrichtius robustus, foraging tactics morphology (body length condition), while accounting habitat characteristics variation in tactic use. The was informed by 7-year longitudinal data set concurrent collected using drones. found evidence an ontogenetic shift associated with body (a proxy age). also water depth habitat. After effects these covariates, there some residual level different tactics. Our findings demonstrate baleen whale population at habitat, suggesting that distribution access prey vary class. results applied investigate whether juveniles adults differ their success resilience stressors.

Language: Английский

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Shaped by Their Environment: Variation in Blue Whale Morphology across Three Productive Coastal Ecosystems

Integrative Organismal Biology, Journal Year: 2023, Volume and Issue: 5(1)

Published: Jan. 1, 2023

Synopsis Species ecology and life history patterns are often reflected in animal morphology. Blue whales globally distributed, with distinct populations that feed different productive coastal regions worldwide. Thus, they provide an opportunity to investigate how regional ecosystem characteristics may drive morphological differences within a species. Here, we compare physical biological oceanography of three blue whale foraging grounds: (1) Monterey Bay, California, USA; (2) the South Taranaki Bight (STB), Aotearoa New Zealand; (3) Corcovado Gulf, Chile. Additionally, morphology from these using unoccupied aircraft imagery. Bay Gulf seasonally support migratory strategy Eastern North Pacific (ENP) Chilean populations, respectively. In contrast, Zealand population remains less STB year-round. All were indistinguishable total body length. However, significantly higher condition despite lower productivity, potentially attributable their non-migratory facilitates risk spatiotemporal misalignment more consistently available opportunities. Alternatively, ENP be successful when presence on grounds temporally aligns abundant prey availability. We document skull fluke between which relate feeding behaviors adapted region-specific habitat characteristics. These features represent trade-off maneuverability for capture efficient long-distance migration. As oceanographic shift relative long-term means under climate change, show vulnerabilities due phenology behavior regions. Spanish abstract La ecología y patrones de historia vida las especies menudo se reflejan en la morfología animal. Las ballenas azules están distribuidas globalmente, con poblaciones separadas que alimentan diferentes regiones costeras productivas todo el mundo. Por lo tanto, brindan oportunidad investigar cómo características regionales los ecosistemas pueden impulsar diferencias morfológicas dentro una especie. Aquí, comparamos oceanografía física biológica tres zonas alimentación ballena azul: Bahía Monterey, EE. UU., del sur (BST), Nueva Zelanda, Golfo Corcovado, Adicionalmente, estas utilizando imágenes aeronaves no tripuladas. son estacionalmente productivos apoyan estrategia migratoria azul chilena Pacífico Norte Oriental (PNO), respectivamente. contrario, población Zelanda permanece menos productiva BST durante año. eran indistinguibles cuanto longitud corporal total. Sin embargo, tenían condición significativamente mayor pesar menor productividad regional, potencialmente atribuible su facilita un riesgo desalineación espaciotemporal oportunidades disponibles manera más consistente. Alternativamente, PNO puede tener éxito cuando presencia alinea temporalmente abundante disponibilidad presas. Documentamos cráneo aleta caudal entre poblaciones, estar relacionadas comportamientos adaptados hábitat presas específicas para cada región. Estas representar compensación maniobrabilidad captura migración eficiente larga distancia. A medida oceanográficos cambian términos mediano largo plazo debido al cambio climático, mostrar vulnerabilidades fenología comportamiento regiones.

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Bubble blasts! An adaptation for buoyancy regulation in shallow foraging gray whales

Ecology and Evolution, Journal Year: 2024, Volume and Issue: 14(8)

Published: Aug. 1, 2024

Abstract Foraging efficiency is key to animal fitness. Consequently, animals evolved a variety of kinematic, morphological, physiological, and behavioral adaptations for efficient locomotion reduce energy expenditure while moving find, capture, consume prey. Often suited specific habitat prey types, these correspond the terrain or substrate moves through. In aquatic systems, focus on overcoming drag, buoyancy, hydrostatic forces. Buoyancy both benefits hinders diving animals; in particular, shallow divers constantly contend with costs buoyancy dive maintain position. Pacific Coast Feeding Group (PCFG) gray whales forage habitats where they work against feed using various foraging tactics. Bubble blasts (underwater exhalations) have been observed during several tactics performed by PCFG whales. As exhalations aid regulation other animals, we hypothesize that bubble are longer, more buoyant shallower water increase duration accounting size tactic. We test our hypotheses Bayesian linear mixed effects models 7‐year dataset drone footage containing concurrent individual morphological data. find headstanding – stationary, head‐down tactic extend duration, whereas forward‐swimming less likely blast. Our results suggest may use as adaption mitigate cost energetically expensive their niche.

Language: Английский

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Using accelerometry tags to quantify gray whale foraging behavior

Marine Mammal Science, Journal Year: 2024, Volume and Issue: unknown

Published: Nov. 29, 2024

Abstract High‐resolution tri‐axial accelerometry biologging tags have quantitatively described behaviors in baleen whale species that forage using lunges and continuous ram filtration. However, detailed quantitative descriptions of foraging do not exist for gray whales, a unique primarily uses benthic suction feeding with rolling component. We deployed cup on Pacific Coast Feeding Group (PCFG) whales to quantify behavior at the broad state (dive) tactic (roll event) scales. Hidden Markov models were used describe three distinct states turn angle, dive duration, pseudotrack tortuosity, presence roll events can be interpreted as forage, search, transit behavior. Classification Regression Tree best tactics (headstands, digs, side swims) median pitch, depth total length ratio, absolute value roll. On average, PCFG spent more time searching performed left‐rolled shallower depths night compared during day, potentially track prey above them water column. Describing enables examination links between behavioral budgets, energetics, physiological impact threats facing this group.

Language: Английский

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Performance of a Drifting Acoustic Instrumentation SYstem (DAISY) for characterizing radiated noise from marine energy converters

Journal of Ocean Engineering and Marine Energy, Journal Year: 2024, Volume and Issue: unknown

Published: Dec. 12, 2024

Language: Английский

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