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"Sperm whale Migration."
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Whales
Introduces sperm whales, including their different body parts, how they travel in groups, what they eat, and how they care for their young.
Book
Beached bachelors: An extensive study on the largest recorded sperm whale Physeter macrocephalus mortality event in the North Sea
Between the 8th January and the 25th February 2016, the largest sperm whale Physeter macrocephalus mortality event ever recorded in the North Sea occurred with 30 sperm whales stranding in five countries within six weeks. All sperm whales were immature males. Groups were stratified by size, with the smaller animals stranding in the Netherlands, and the largest in England. The majority (n = 27) of the stranded animals were necropsied and/or sampled, allowing for an international and comprehensive investigation into this mortality event. The animals were in fair to good nutritional condition and, aside from the pathologies caused by stranding, did not exhibit significant evidence of disease or trauma. Infectious agents were found, including various parasite species, several bacterial and fungal pathogens and a novel alphaherpesvirus. In nine of the sperm whales a variety of marine litter was found. However, none of these findings were considered to have been the primary cause of the stranding event. Potential anthropogenic and environmental factors that may have caused the sperm whales to enter the North Sea were assessed. Once sperm whales enter the North Sea and head south, the water becomes progressively shallower (<40 m), making this region a global hotspot for sperm whale strandings. We conclude that the reasons for sperm whales to enter the southern North Sea are the result of complex interactions of extrinsic environmental factors. As such, these large mortality events seldom have a single ultimate cause and it is only through multidisciplinary, collaborative approaches that potentially multifactorial large-scale stranding events can be effectively investigated.
Journal Article
Biologically Important Areas II for cetaceans within U.S. and adjacent waters – Gulf of Alaska Region
We delineated and scored Biologically Important Areas (BIAs) for cetacean species in the Gulf of Alaska region. BIAs represent areas and times in which cetaceans are known to concentrate for activities related to reproduction, feeding, and migration, and also the known ranges of small and resident populations. This National Oceanic and Atmospheric Association (NOAA)-led effort uses structured expert elicitation principles to build upon the first version of NOAA’s BIAs for cetaceans. Supporting evidence for these BIAs came from aerial-, land-, and vessel-based surveys; satellite-tagging data; passive acoustic monitoring; Indigenous knowledge; photo-identification data; and/or prey studies. A total of 20 BIAs were identified, delineated, and scored for six species: beluga whale ( Delphinapterus leucas ), fin whale ( Balaenoptera physalus ), gray whale ( Eschrichtius robustus ), humpback whale ( Megaptera novaeangliae ), North Pacific right whale ( Eubalaena japonica ), and sperm whale ( Physeter macrocephalus ). Of the 20 total BIAs, there were two small and resident populations, one migratory, and 17 feeding areas; no reproductive BIAs were identified. An additional five watch list areas were identified, a new feature to the second version of BIAs. In addition to more comprehensive narratives and maps, the BIA II products improve upon the first version by creating metadata tables and incorporating a scoring and labeling system which improves quantification and standardization of BIAs within and across regions. BIAs are compilations of the best available science and have no inherent regulatory authority. They have been used by NOAA, other federal agencies, and the public to support planning and marine mammal impact assessments, and to inform the development of conservation measures for cetaceans.
Journal Article
Migration to breeding areas by male sperm whales Physeter macrocephalus from the Northeast Atlantic Arctic
Mature male sperm whales (
Physeter macrocephalus
) primarily inhabit high latitude regions, travelling to tropical/temperate waters for breeding, where females and juveniles reside in cohesive social groups. Though mating is known to occur at low latitudes, the timing, duration, and routes of adult male migrations between feeding and breeding areas are poorly known. To study movement patterns of adult male sperm whales, 29 individuals were equipped with satellite transmitters in the Northeast Atlantic Arctic (69–79°N). Twelve of these animals undertook southward migrations. Departures from northern latitudes occurred asynchronously from January to October, indicating that sperm whales do not have a well-defined breeding season. Migrating males travelled 40 (± 11) d to reach the breeding areas at latitudes below 45°N. They travelled distances of 3,993–7,951 km. They spent 76 (± 22) d in the south, roaming across an enormous region (˃10 million km
2
). Dives deeper than 1,000 m occurred both during migration and at the breeding grounds. Two whales were tracked back to Arctic waters. Their trips took 175 and 180 d, with cumulative distances travelled being 16,332 km and 17,669 km, respectively. This study fills important knowledge gaps in the annual cycle of these cosmopolitan giants.
Journal Article
Predicting Cetacean Habitats from Their Energetic Needs and the Distribution of Their Prey in Two Contrasted Tropical Regions
To date, most habitat models of cetaceans have relied on static and oceanographic covariates, and very few have relatedcetaceans directly to the distribution of their prey, as a result of the limited availability of prey data. By simulating thedistribution of six functional micronekton groups between the surface and .1,000 m deep, the SEAPODYM model providesvaluable insights into prey distributions. We used SEAPODYM outputs to investigate the habitat of three cetacean guildswith increasing energy requirements: sperm and beaked whales, Globicephalinae and Delphininae. We expected HighEnergy Requirements cetaceans to preferentially forage in habitats of high prey biomass and/or production, where theymight easily meet their high energetic needs, and Low Energy Requirements cetaceans to forage in habitats of either highor low prey biomass and/or production. Cetacean sightings were collected from dedicated aerial surveys in the South WestIndian Ocean (SWIO) and French Polynesia (FP). We examined cetacean densities in relation to simulated distributions oftheir potential prey using Generalised Additive Models and predicted their habitats in both regions. Results supported theirknown diving abilities, with Delphininae mostly related to prey present in the upper layers of the water column, andGlobicephalinae and sperm and beaked whales also related to prey present in deeper layers. Explained deviances rangedfrom 9% for sperm and beaked whales in the SWIO to 47% for Globicephalinae in FP. Delphininae and Globicephalinaeappeared to select areas where high prey biomass and/or production were available at shallow depths. In contrast, spermand beaked whales showed less clear habitat selection. Using simulated prey distributions as predictors in cetacean habitatmodels is crucial to understand their strategies of habitat selection in the three dimensions of the ocean.
Journal Article
The Impact of Predation by Marine Mammals on Patagonian Toothfish Longline Fisheries
Predatory interaction of marine mammals with longline fisheries is observed globally, leading to partial or complete loss of the catch and in some parts of the world to considerable financial loss. Depredation can also create additional unrecorded fishing mortality of a stock and has the potential to introduce bias to stock assessments. Here we aim to characterise depredation in the Patagonian toothfish (Dissostichus eleginoides) fishery around South Georgia focusing on the spatio-temporal component of these interactions. Antarctic fur seals (Arctocephalus gazella), sperm whales (Physeter macrocephalus), and orcas (Orcinus orca) frequently feed on fish hooked on longlines around South Georgia. A third of longlines encounter sperm whales, but loss of catch due to sperm whales is insignificant when compared to that due to orcas, which interact with only 5% of longlines but can take more than half of the catch in some cases. Orca depredation around South Georgia is spatially limited and focused in areas of putative migration routes, and the impact is compounded as a result of the fishery also concentrating in those areas at those times. Understanding the seasonal behaviour of orcas and the spatial and temporal distribution of \"depredation hot spots\" can reduce marine mammal interactions, will improve assessment and management of the stock and contribute to increased operational efficiency of the fishery. Such information is valuable in the effort to resolve the human-mammal conflict for resources.
Journal Article
Solar storms may trigger sperm whale strandings: explanation approaches for multiple strandings in the North Sea in 2016
The Earth's atmosphere and the Earth's magnetic field protects local life by shielding us against Solar particle flows, just like the sun's magnetic field deflects cosmic particle radiation. Generally, magnetic fields can affect terrestrial life such as migrating animals. Thus, terrestrial life is connected to astronomical interrelations between different magnetic fields, particle flows and radiation. Mass strandings of whales have often been documented, but their causes and underlying mechanisms remain unclear. We investigated the possible reasons for this phenomenon based on a series of strandings of 29 male, mostly bachelor, sperm whales (Physeter macrocephalus) in the southern North Sea in early 2016. Whales’ magnetic sense may play an important role in orientation and migration, and strandings may thus be triggered by geomagnetic storms. This approach is supported by the following: (1) disruptions of the Earth's magnetic field by Solar storms can last about 1 day and lead to short-term magnetic latitude changes corresponding to shifts of up to 460 km; (2) many of these disruptions are of a similar magnitude to more permanent geomagnetic anomalies; (3) geomagnetic anomalies in the area north of the North Sea are 50–150 km in diameter; and (4) sperm whales swim about 100 km day−1, and may thus be unable to distinguish between these phenomena. Sperm whales spend their early, non-breeding years in lower latitudes, where magnetic disruptions by the sun are weak and thus lack experience of this phenomenon. ‘Naïve’ whales may therefore become disoriented in the southern Norwegian Sea as a result of failing to adopt alternative navigation systems in time and becoming stranded in the shallow North Sea.
Journal Article
Where are Solar storm-induced whale strandings more likely to occur?
Whale strandings occur in many places worldwide and numerous possible explanations for this phenomenon have been proposed, including the effects of astronomical events such as Solar eruptions on the Earth's magnetic field. Whales use the geomagnetic field for navigation, and its distortion can therefore result in whale strandings in certain regions. However, Solar storms do not have the same impact on the geomagnetic field across the whole of the Earth's surface, and positions nearer to the equator are less exposed to this phenomenon. It is therefore plausible that Solar storms can explain whale strandings at high latitude at least, but not necessarily worldwide. This review considers strandings in relation to the geographical and geomagnetic properties of locations at higher latitudes and to changes in the magnetic field over recent centuries. It also focuses on a Solar storm in December 2015. These considerations suggest that navigation errors due to Solar storms are more likely to occur at higher latitudes, particularly in sea areas where the animals might subsequently swim into a geographic trap and become stranded. For sperm whales ( Physeter macrocephalus ), the southern Norwegian Sea in conjunction with the shallow North Sea represents such an area.
Journal Article
A link between male sperm whales, Physeter macrocephalus, of the Azores and Norway
Little is known about the movements of male sperm whales, Physeter macrocephalus, in the North Atlantic. Recoveries of traditional harpoons and tags during commercial whaling indicated movements from Nova Scotia to Spain and from the Azores to Iceland and Spain. We compared collections of photo-identification images from different areas using the North Atlantic and Mediterranean Sperm Whale Catalogue and the Eurphlukes Phlex/Match programs. The largest collections of identified males (number of individuals, start and end date for data collection shown in parentheses) are for the Azores (297, 1987–2008), Andenes (375, 1988–1996 and 2008), Tromsø (84, 2005–2008). There were six matches between Andenes and Tromsø (~25 nm), with three of these re-sighted in multiple years and three photo-identification matches from the Azores to Norway (~2400 nm). In all cases individuals first photographed in the Azores (in 1993, 1999 and 2003) were matched to images collected later in Tromsø (in 2007 and 2008). In 1997 a photo-identification image from Andenes matched a male stranded on the west coast of Ireland. No matches were made to images in smaller collections from Iceland, Nova Scotia, Greenland, Dominica, Guadeloupe, Gulf of Mexico and the Mediterranean. These findings show the value of data collected from whale watching vessels and the importance of collaboration between groups to allow investigation on an ocean basin scale. It is hoped that with the coordinated collection of more images from around the Atlantic, further insight might be gained into the movements of these widely ranging animals.
Journal Article
Evidence for seasonal migration by a cryptic top predator of the deep sea
Background
In ecosystems influenced by strong seasonal variation in insolation, the fitness of diverse taxa depends on seasonal movements to track resources along latitudinal or elevational gradients. Deep pelagic ecosystems, where sunlight is extremely limited, represent Earth’s largest habitable space and yet ecosystem phenology and effective animal movement strategies in these systems are little understood. Sperm whales (
Physeter macrocephalus
) provide a valuable acoustic window into this world: the echolocation clicks they produce while foraging in the deep sea are the loudest known biological sounds on Earth and convey detailed information about their behavior.
Methods
We analyze seven years of continuous passive acoustic observations from the Central California Current System, using automated methods to identify both presence and demographic information from sperm whale echolocation clicks. By integrating empirical results with individual-level movement simulations, we test hypotheses about the movement strategies underlying sperm whales’ long-distance movements in the Northeast Pacific.
Results
We detect foraging sperm whales of all demographic groups year-round in the Central California Current System, but also identify significant seasonality in frequency of presence. Among several previously hypothesized movement strategies for this population, empirical acoustic observations most closely match simulated results from a population undertaking a “seasonal resource-tracking migration”, in which individuals move to track moderate seasonal-latitudinal variation in resource availability.
Discussion
Our findings provide evidence for seasonal movements in this cryptic top predator of the deep sea. We posit that these seasonal movements are likely driven by tracking of deep-sea resources, based on several lines of evidence: (1) seasonal-latitudinal patterns in foraging sperm whale detection across the Northeast Pacific; (2) lack of demographic variation in seasonality of presence; and (3) the match between simulations of seasonal resource-tracking migration and empirical results. We show that sperm whales likely track oceanographic seasonality in a manner similar to many surface ocean predators, but with dampened seasonal-latitudinal movement patterns. These findings shed light on the drivers of sperm whales’ long-distance movements and the shrouded phenology of the deep-sea ecosystems in which they forage.
Journal Article