Tomoko Narazaki

Tomoko Narazaki
Meijo University · Department of Environmental Bioscience

BA Science, PhD Environmental Science

About

44
Publications
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Introduction
Skills and Expertise

Publications

Publications (44)
Article
Full-text available
Aim Quantifying the importance of habitat areas for conservation of highly migratory marine species with complex life histories can be challenging. For example loggerhead turtles (Caretta caretta) nesting in Japan forage both oceanically and neritically after their reproductive period. Here, we aimed to quantify the proportions of turtles using the...
Article
Full-text available
Advances in biologging technology have enabled 3D dead-reckoning reconstruction of marine animal movements at spatiotemporal scales of meters and seconds. Examining high-resolution 3D movements of sharks (Galeocerdo cuvier, N = 4; Rhincodon typus, N = 1), sea turtles (Chelonia mydas, N = 3), penguins (Aptenodytes patagonicus, N = 6), and marine mam...
Article
Full-text available
Monitoring the body condition of free-ranging marine mammals at different life-history stages is essential to understand their ecology as they must accumulate sufficient energy reserves for survival and reproduction. However, assessing body condition in free-ranging marine mammals is challenging. We cross-validated two independent approaches to est...
Article
Animals with high resting metabolic rates and low drag coefficients typically have fast optimal swim speeds in order to minimise energy costs per unit travel distance. The cruising swim speeds of sea turtles (0.5–0.6 m s ⁻¹ ) are slower than those of seabirds and marine mammals (1–2 m s ⁻¹ ). This study measured the resting metabolic rates and drag...
Article
In order to achieve 3D tracking of swimming organisms by an AUV (Autonomous Underwater Vehicle), we proposed a method to simultaneously estimate the position and vertical motion of sea turtles from multibeam imaging sonar images using deep learning. We trained the CNN based detector using not only the sonar images but also information about vertica...
Article
Full-text available
Over the past decade, measurements from the climate-oriented ocean observing system have been key to advancing the understanding of extreme weather events that originate and intensify over the ocean, such as tropical cyclones (TCs) and extratropical bomb cyclones (ECs). In order to foster further advancements to predict and better understand these...
Article
Full-text available
Impact assessments for sonar operations typically use received sound levels to predict behavioural disturbance in marine mammals. However, there are indications that cetaceans may learn to associate exposures from distant sound sources with lower perceived risk. To investigate the roles of source distance and received level in an area without frequ...
Article
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Green turtles in year-round neritic foraging habitats are widely considered to have small home ranges and to mainly feed on plant-based diets. In contrast, few studies have examined the summer-restricted habitats to which these turtles seasonally migrate. In this study, we investigated the foraging habits of green turtles migrating to the Sanriku C...
Article
We demonstrate that assimilation of water temperature measurements by sea turtles into an operational ocean nowcast/forecast system improves representation of mesoscale eddies and front variations in the Kuroshio-Oyashio Confluence region. For a period from August to December in 2009, vertical ranges of the measurements by six turtles covered from...
Article
Full-text available
Many baleen whales undertake annual fasting and feeding cycles, resulting in substantial changes in their body condition, an important factor affecting fitness. As a measure of lipid-store body condition, tissue density of a few deep diving marine mammals has been estimated using a hydrodynamic glide model of drag and buoyancy forces. Here, we appl...
Data
Examples of linear regression of speed over time to estimate acceleration during 5s sub-glides. Linear regression of speed over time was conducted at each 5s sub-glide to estimate acceleration as a slope of the regression line. Top and bottom panels show examples from 3MPD3GT and DTAG deployments, respectively. (TIF)
Data
Data of all 5-s sub glides performed by tagged humpback whales. This file includes all 5-s sub glides data used in this study. (CSV)
Article
The metabolic rate and activity of sea turtles generally decreases with decreasing seasonal ambient temperature. Juvenile loggerhead turtles in the Mediterranean Sea made prolonged inactive dives (>400 min), indicating a state of dormancy during the cold winter period. However, seasonal differences in dive duration were not detected in juvenile log...
Article
Full-text available
To maximize foraging duration at depth, diving mammals are expected to use the lowest cost optimal speed during descent and ascent transit and to minimize the cost of transport by achieving neutral buoyancy. Here, we outfitted 18 deep-diving long-finned pilot whales with multi-sensor data loggers and found indications that their diving strategy is...
Article
There was an error published in J. Exp. Biol. 219, 2458-2468. Eqn 1 was presented incorrectly. A '-1' was missing after the ratio of densities, and the subscript of the first instance of the density of seawater (Psw) was given incorrectly as 'w' instead of 'sw'. The original equation was: (Formula presented) The correct equation is as follows (Form...
Article
Full-text available
Ingestion of artificial debris is considered as a significant stress for wildlife including sea turtles. To investigate how turtles react to artificial debris under natural conditions, we deployed animal-borne video cameras on loggerhead and green turtles in addition to feces and gut contents analyses from 2007 to 2015. Frequency of occurrences of...
Article
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Diving lung volume and tissue density, reflecting lipid store volume, are important physiological parameters which have only been estimated for a few breath-hold diving species. We outfitted 12 northern bottlenose whales with data loggers which recorded depth, 3-axis acceleration and speed either with a fly-wheel or from change of depth corrected b...
Article
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Measuring the energy requirements of animals under natural conditions and determining how acquired energy is allocated to specific activities is a central theme in ecophysiology. Turtle reproductive output is fundamentally linked with their energy balance so a detailed understanding of marine turtle energy requirements during the different phases o...
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Although northern bottlenose whales were the most heavily hunted beaked whale, we have little information about this species in its remote habitat of the North Atlantic Ocean. Underwater anthropogenic noise and disruption of their natural habitat may be major threats, given the sensitivity of other beaked whales to such noise disturbance. We attach...
Article
Endangered loggerhead turtles (Caretta caretta) are highly migratory marine reptiles that spend extended maturation periods at sea. Although an understanding of the biology and ecology of juveniles is essential for effective conservation of this species, such information is still limited, especially for the North Pacific population. The first quant...
Article
Full-text available
The foraging habitats of green turtles Chelonia mydas range from tropical to temperate areas. Previous studies have generally been biased toward tropical and sub-tropical areas; hence, available data do not accurately describe the species' foraging activity in temperate areas. To reveal seasonal patterns of habitat use in temperate areas, we conduc...
Article
Understanding the dispersal pathway and connectivity of an endangered species plays an essential role in the development of strategies for its effective conservation and management. By using mtDNA control region sequences, we identified the genetic composition and estimated the origin of the northernmost feeding aggregation of green turtles Cheloni...
Article
Full-text available
The loggerhead turtle Caretta caretta is highly migratory and undertakes trans - oceanic migrations. In the North Pacific, loggerhead turtles that hatch on Japanese beaches reach the vicinity of Baja California in the eastern Pacific. As they grow, they return and recruit to the feeding areas around Japan. By using mtDNA control-region sequences, w...
Article
Full-text available
Identifying characteristics of foraging activity is fundamental to understanding an animals' lifestyle and foraging ecology. Despite its importance, monitoring the foraging activities of marine animals is difficult because direct observation is rarely possible. In this study, we use an animal-borne imaging system and three-dimensional data logger s...
Data
GLMM models with factors affecting foraging depth, presence of turning point and approach distance. (DOCX)
Data
Histogram of foraging depth showed unimodal pattern with peak at near 20 m. (TIF)
Data
A loggerhead turtle foraged on a chain of siphonophores. (MP4)
Data
An encounter with a plastic bag by a loggerhead turtle. (MP4)
Data
A loggerhead turtle foraged on a sea nettle, Chrysaora melanaster . (MP4)
Article
Full-text available
Ontogenetic studies of vertebrate feeding performance can help address questions relevant to foraging ecology. Feeding morphology and performance can either limit access to food resources or open up new trophic niches in both aquatic and terrestrial systems. Loggerhead sea turtles are long-lived vertebrates with complex life histories that are mark...
Article
1. Breath-hold divers are widely assumed to descend and ascend at the speed that minimizes energy expenditure per distance travelled (the cost of transport (COT)) to maximize foraging duration at depth. However, measuring COT with captive animals is difficult, and empirical support for this hypothesis is sparse. 2. We examined the scaling relations...
Article
Full-text available
Tri-axis magnetism and acceleration data loggers have recently been used to obtain time-series headings and, consequently, the 3-dimensional dive paths of aquatic animals. However, problems may arise in the resulting calculation process with multiple parameters. In this study, the dive paths of loggerhead turtles and emperor penguins were reconstru...
Article
Full-text available
Air-breathing marine animals, including sea turtles, utilise two fundamentally different environments (i.e. sea surface and underwater) during migration. Many satellite telemetry studies have shown travel paths at relatively large spatio-temporal scales, discussing the orientation and navigation mechanisms that guide turtles. However, as travel pat...

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