Sperm Whale Research Articles

Aerial Photo-Identification of Sperm Whales (Physeter macrocephalus)

Photo-identification is a staple tool used in cetacean conservation studies since the 1970s to monitor individuals on a regional and ocean basin-wide scale to infer critical information about habitat use, suitability, and shifts. This technique has been extensively used on sperm whales globally since it was developed in 1982, initially using the tail fluke from deep diving whales and the dorsal fin when appropriate. From the mid 2010s onwards, the emergence of domestically available unoccupied aerial systems (drones) has reshaped how whale research can be conducted. Herein, we describe the suitability of aerial images to determine the identity of individual sperm whales (Physeter macrocephalus) using all available identifiable markings along their dorsal side to complement the use of fluke notches and dorsal fin scars photographed from the surface of the sea from boat-based platforms for photo-identification and to maximize opportunities to identify and monitor sperm whales. Drone data were gathered while flying over sperm whales in Andenes, Norway; Shetland, Scotland; Dursey Island, Ireland; and Faial and São Miguel Islands, Azores, Portugal, between 2017 and 2024, which enabled the entire dorsal surface of sperm whales to be captured and assessed. Aerial photographs and videos were used to differentiate between 336 individual sperm whales using physical characteristics. We identified the main features of sperm whales through aerial drone images, as well as their prevalence in Atlantic high latitude foraging grounds and lower latitude nursery grounds. We discuss the advantages of using aerial drone photographs to identify sperm whales in addition to traditional boat-based photo-identification.

Killer whales in the Gulf of Mexico and North Atlantic off the Southeastern United States

Killer whales occur in the Gulf of Mexico (GoMex) and the North Atlantic, including off the southeastern United States (SEUS). Data from cetacean surveys during 1990 – 2021 and other sources were combined to assess killer whale biology, including spatial and temporal distribution, social structure, genetics, morphology, acoustics, and predatory behavior. GoMex records occurred predominantly in oceanic waters (>200 m) during spring and summer. SEUS records occurred primarily in winter and spring off the North Carolina region along the shelf-edge and deeper waters, and off the east coast of Florida. Photo-identification analysis of GoMex killer whales resulted in 49 individuals sighted up to seven times with sighting histories up to 26 years, and social analysis provided evidence of long-term relationships up to 16 years. The GoMex genetic samples revealed two mtDNA haplotypes, one of which does not match any outside the GoMex. Most GoMex whales had wide non-faint saddle patches and many had cookiecutter shark scars while no scars were noted on SEUS whales. Three groups recorded in the GoMex made few calls, but a group harassing sperm whales produced many. Cetaceans and tuna are known prey in the GoMex and SEUS, respectively. Directed studies of killer whales in the GoMex areas would be difficult to implement as this species is very rare. It is therefore important to pursue ongoing efforts to collect behavioral, acoustic and any biological samples that will contribute to improve our understanding of the biology and ecology of killer whales in tropical and subtropical regions.

Reinforcement learning-based framework for whale rendezvous via autonomous sensing robots.

Rendezvous with sperm whales for biological observations is made challenging by their prolonged dive patterns. Here, we propose an algorithmic framework that codevelops multiagent reinforcement learning-based routing (autonomy module) and synthetic aperture radar-based very high frequency (VHF) signal-based bearing estimation (sensing module) for maximizing rendezvous opportunities of autonomous robots with sperm whales. The sensing module is compatible with low-energy VHF tags commonly used for tracking wildlife. The autonomy module leverages in situ noisy bearing measurements of whale vocalizations, VHF tags, and whale dive behaviors to enable time-critical rendezvous of a robot team with multiple whales in simulation. We conducted experiments at sea in the native habitat of sperm whales using an "engineered whale"-a speedboat equipped with a VHF-emitting tag, emulating five distinct whale tracks, with different whale motions. The sensing module shows a median bearing error of 10.55° to the tag. Using bearing measurements to the engineered whale from an acoustic sensor and our sensing module, our autonomy module gives an aggregate rendezvous success rate of 81.31% for a 500-meter rendezvous distance using three robots in postprocessing. A second class of fielded experiments that used acoustic-only bearing measurements to three untagged sperm whales showed an aggregate rendezvous success rate of 68.68% for a 1000-meter rendezvous distance using two robots in postprocessing. We further validated these algorithms with several ablation studies using a sperm whale visual encounter dataset collected by marine biologists.

AI-driven aerial robots advance whale research.

Aerial robots assisted with artificial intelligence improve real-time wildlife monitoring of sperm whales.

Utilization of stable isotopes in teeth to investigate pygmy sperm whales (Kogia breviceps) in the southeastern United States

AbstractThe pygmy sperm whale (Kogia breviceps) is currently the second‐most stranded cetacean in the southeastern United States (SEUS), but information concerning their population structure is severely limited. This study used stable isotope analysis to investigate the isotopic niches and population structure of K. breviceps among three regions in the SEUS determined by the distance of the continental shelf break and a fourth region in the Gulf of Mexico. Teeth from stranded individuals were subsampled via dental drill at four separate areas on each tooth, representing four different age classes: calf, juvenile, subadult, and adult. Stable isotope ratios of carbon and nitrogen were measured in the organic component of 42 teeth, and oxygen isotope ratios were measured in the inorganic (hydroxyapatite) component of 19 teeth. No differences were found in δ13C, δ15N, or δ18O values between regions. However, differences between age classes were significant for adults and subadults for δ13C and adults and juveniles for δ15N. Differences between males and females were also significant for δ15N. Results from this study provide the first carbon and nitrogen isotope values from different age classes of pygmy sperm whales as well as the first reported oxygen isotope values for this species.

Parallel Spectral Tuning of a Cone Visual Pigment Provides Evidence for Ancient Deep-Sea Adaptations in Cetaceans.

Dichromatic color vision is mediated by two cone visual pigments in many eutherian mammals. After reentry into the sea, early cetaceans lost their violet-sensitive visual pigment (short wavelength-sensitive 1) independently in the baleen and toothed whale ancestors and thus obtained only monochromatic cone vision. Subsequently, losses of the middle/long wavelength-sensitive (M/LWS) pigment have also been reported in multiple whale lineages, leading to rhodopsin (RH1)-mediated rod monochromatic vision. To further elucidate the phenotypic evolution of whale visual pigments, we assessed the spectral tuning of both M/LWS and RH1 from representative cetacean taxa. Interestingly, although the coding sequences for M/LWS are intact in both the pygmy right whale and the Baird's beaked whale, no spectral sensitivity was detected in vitro. Pseudogenization of other cone vision-related genes is observed in the pygmy right whale, suggesting a loss of cone-mediated vision. After ancestral sequence reconstructions, ancient M/LWS pigments from cetacean ancestors were resurrected and functionally measured. Spectral tuning of M/LWS from the baleen whale ancestor shows that it is green sensitive, with a 40-nm shift in sensitivity to a shorter wavelength. For the ancestor of sperm whales, although no spectral sensitivity could be recorded for its M/LWS pigment, a substantial sensitivity shift (20 to 30 nm) to a shorter wavelength may have also occurred before its functional inactivation. The parallel phenotypic evolution of M/LWS to shorter wavelength sensitivity might be visual adaptations in whales allowing more frequent deep-sea activities, although additional ecological differentiations may have led to their subsequent losses.

The departure of sperm whales (Physeter macrocephalus) in response to the declining jumbo squid (Dosidicus gigas) population in the central portion of the Gulf of California.

As sperm whales are important predators that control energy flux in the oceans, changes in their population can be used as a sentinel to measure of ecosystem health. The present study conducted a sperm whale survey of the eastern Midriff Islands Region in the Gulf of California over the course of nine years, recording sightings and collecting photographs of the fluke of sperm whale individuals. A photo-identification catalog was compiled, while individual recapture data were used to estimate the population size in the central portion of the Gulf of California, using a Jolly-Seber POPAN open population model. The results obtained show a yearly population of between 20 and 167 sperm whales, with a super population of 354 sperm whales observed between 2009 and 2015. However, from 2016 to 2018, no sightings of the species were recorded, which coincides with the decline observed in landings of their main prey, the jumbo squid, in the region. General additive model conducted on sperm whale sightings per unit of effort vs jumbo squid landings obtained an adjusted R2 of 0.644 and a deviance explained of 60.3%, indicating a good non-linear relationship between sightings of this odontocete and its prey availability. This evidence suggests that sperm whales departed the region between 2016 and 2018, due to a documented fishery collapse alongside changes of their main prey into its small phenotype, possibly as the result of increase warming conditions in surface and subsurface waters in the Gulf of California in the last three decades.

Accounting for sperm whale population demographics in density estimation using passive acoustic monitoring

Sperm whales Physeter macrocephalus are highly sexually dimorphic, with adult males having larger bodies, more powerful echolocation clicks, and slower echolocation clicking rates compared to females. This study introduces methods for estimating sperm whale population densities in the Gulf of Mexico (GoMex) by accounting for the population demographics using passive acoustic monitoring and reveals that ignoring the differences between demographic segments can introduce bias in density estimates. Weekly densities were estimated per 3 demographic segments: social groups consisting of adult females and their offspring, mid-size animals, and adult males. Analysis revealed that the GoMex sperm whale population is primarily composed of social groups, which account for 92 to 98% of the overall population. Mid-size animals and adult males made up a small proportion of the population and were only intermittently present. Our 7 yr GoMex density estimates, including the 2010 Deepwater Horizon (DWH) oil spill period and subsequent years, revealed demographic-specific trends. Declines found at 2 north-central GoMex sites, coupled with increases at a southeastern site, may indicate population movements and potential impacts from the 2010 DWH oil spill and elevated noise levels from anthropogenic activities in the north-central GoMex.

Evidence for seasonal migration by a cryptic top predator of the deep sea

BackgroundIn 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.MethodsWe 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.ResultsWe 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.DiscussionOur 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.

Anatomical description of a pygmy sperm whale, Kogia breviceps (Cetacea: Kogiidae), pre-term calf using CT scan and 3D reconstructions.

Little is known about the biology of pygmy sperm whales, Kogia breviceps (De Blainville, 1838), being that most anatomical descriptions for the species derive from necropsy after stranding or from osteological material preserved in museums. This species is rarely seen despite its wide distribution, and its reproductive behaviour is still being investigated. The eventual occurrence of pregnant female strandings and the collection and description of foetuses can give clues about the organisms' mostly unknown early development. However, this type of biological material is extremely rare, limiting anatomical analysis due to the risk of damage or loss. Here, we describe the external and internal anatomy of an 84 cm long K. breviceps foetus. The methods utilised were non-intrusive, meaning that no incisions were made on the specimen. The foetus was analysed using computed tomography images and a three-dimensional reconstruction of the skeleton. A great number of features were observed, such as axial and appendicular skeletal structures, internal organs, echolocation apparatus and umbilical cord, as well as diagnostic characters of the species, such as the asymmetrical skull, spermaceti chamber and false gill pigmentation. We suggest that more specimens on different stages of development should be analysed by the same technique, as well as further comparison with specimens from other taxa, in order to facilitate more comparative studies on embryonic and foetal development of cetaceans.

Movement and diving behavior of satellite-tagged male sperm whales in the Gulf of Alaska

Male sperm whales (Physeter macrocephalus) are known to interact with and depredate from commercial longline fishing vessels targeting sablefish (Anoplopoma fimbria) in the Gulf of Alaska (GOA). This study aims to better understand their movement patterns and diving behavior in this region, and in relation to depredation behavior. Between 2007 and 2016 a total of 33 satellite tags were deployed on sperm whales interacting with fishing vessels in the eastern GOA. A subset of these tags also collected dive characteristics. We used state space models to interpolate hourly positions from tags and estimate behavioral state from 29 usable tag records, 14 of which had associated dive information. Whales exhibited slower horizontal movement (1.4 km/hr) within GOA waters compared to south of the GOA (5.5 km/hr), indicating tagged whales sped up when they left the region. Behavioral states indicated primarily foraging behavior (82% of locations) in the GOA and primarily transiting behavior (74% of locations) when whales left the GOA. Dive data showed average ( ± Standard Deviation) maximum dive depths of 396 m ( ± 166), and dive durations of 32 min (± 9). Generalized additive models indicated that dives were significantly deeper and longer during the daytime than dawn, dusk, or nighttime, and dives were significantly deeper and shorter during quarter moons, when tidal currents are weakest. Maximum dive depth decreased in areas of higher sablefish CPUE, suggesting a potential link between the sablefish fishery and depredation behavior. As seafloor depth increased, up to 800 m, dives became deeper, indicating that whales were likely targeting both bathypelagic and mesopelagic prey. This highlights the importance of the GOA continental slope as a foraging ground for male sperm whales. This enhanced understanding of sperm whale foraging ecology informs management and conservation efforts in high latitude foraging grounds.

Female, juvenile, and calf sperm whale Physeter macrocephalus (Linnaeus 1758) records from Ireland.

Sperm whales spatially segregate by sex and social behavior as they mature. In the North Atlantic, male whales move to higher latitudes as far as Svalbard at 80° N, while females and young whales typically remain around lower latitudes below 40-45° N. The Azores, Madeira, and the Canary Islands constitute important nursery grounds for female and young sperm whales. Irish waters represent a midpoint for this species' spatial segregation in the Northeast Atlantic, where the species occurs along the submarine canyon systems to the west of the country. Historically, just male whales were thought to be found in this region between 51 and 55° N, but one adult female was caught by commercial whalers in 1910, and a 5.49 m calf was found stranded in 1916. Between 1995 and 2023, 10 female sperm whales have been stranded around the coast of Ireland. Eight of these whales have been stranded since 2013, and there has been at least one stranding per year between 2019 and 2023. Four of these strandings have occurred in Donegal in the northwest of Ireland, indicating the presence of female whales along the continental shelf off this region. Two females were stranded within a day of each other and were found in similar states of decomposition in February 2022, indicating that they may have been part of the same group rather than being lone vagrant individuals. Sperm whale calves and juveniles were also sighted in Irish waters in 2001, 2004, and 2010 in the Rockall Trough, along the Porcupine Bank and Goban Spur, where between 1 and 3 individuals were observed on four occasions while one calf live stranded in 2004. These records indicate a historical presence of female and young sperm whales in this region but that an apparent increase in occurrence has taken place over the past decade.

Morphological and morphometric sperm analysis of dwarf sperm whale (Kogia sima)

Nowadays, an increase in the number of marine species at risk of extinction has been observed. Therefore, studies on the reproductive characteristics of these animals are essential. This animal is considered relatively rare, and there is scarce information regarding its reproductive biology and physiology. Thus, this study aims to describe the morphology and morphometry of sperm obtained from dwarf sperm whale. The material used in this work was collected during the necropsy of a dwarf sperm whale specimen. Thus, seminal samples were fixed and stained with panoptic stain. In morphometric analysis, the results obtained were: acrosome length of 0.83±0.01 μm, head length of 1.5±0.02 μm, intermediate part of 0.4±0.00 μm and total length of 27.3±0.51 μm. In terms of morphology, the defects observed were double head, heavily curled tail, abnormal small head, simply bent tail, piriform head, heavily bent tail and specimens within the normal range. In this context, the morphometric and morphological sperm analysis of Kogia sima described in this study can assist future studies regarding the reproductive physiology of these animals.

Passive acoustic surveys demonstrate high densities of sperm whales off the mid-Atlantic coast of the USA in winter and spring

Oceans are increasingly crowded by anthropogenic activities yet the impact on Outer Continental Shelf (OCS) marine life remains largely unquantified. The MAPS (Marine Mammal Acoustic and Spatial Ecology) study of 2019 included passive acoustic and visual vessel surveys over the Mid-Atlantic OCS of the USA to address data gaps in winter/spring for deep-diving cetaceans, including sperm whales. Echolocation clicks were used to derive slant ranges to sperm whales for design- and model-based density estimates. Although more survey effort was realised in the spring, high densities of whales were identified in both winter and spring (10.46 and 8.89 per 1000 km2 respectively). The spring model-based abundance estimate of 1587 whales (CI 946–2663) was considered the most representative figure, in part due to lower coefficients of variation. Modelling suggested that high densities of whales were associated with warm core rings, eddies and edges. As OCS waters provide an important foraging habitat for North Atlantic sperm whales, appropriate mitigation is required to ensure commercial pressures to develop offshore energy do not negatively affect this endangered species.

Age and interpulse interval relation from newborn to adult sperm whale (Physeter macrocephalus) off Mauritius

Sperm whales (Physeter macrocephalus) have been studied for decades, but the development of their clicks during the animal growth is not yet well known. The click they emit during socialization and echolocation contains information about the length of their acoustic organs and, therefore the length of the body through the interpulse interval (IPI). This paper provides the first IPI/age relationship for juvenile male and female sperm whales (Physeter macrocephalus) based on field recordings of individuals whose age is largely known. Across 9 years, audiovisual recordings of a Mauritian sperm whale social unit were carried out. Adult female and juvenile sperm whales were identified and aged. The dataset made from those recordings is publicly available. The interpulse interval was measured for individuals whose ages ranged from 7 days to around 38 years. The growth of the acoustic organ of juveniles showed an early inter-individual variability as well as sexual dimorphism. Usual growth models were also fitted, predicting a mean IPI∞\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$IPI_\\infty$$\\end{document} of 3.5 ms for adults and a physical maturity reached at around 30 years old. The use of passive acoustic monitoring (PAM) is one of the main tools used to study sperm whales. This IPI-age relationship may aid demographic studies on sperm whales by enabling PAM to assess the ages of recorded sperm whales.

Intercorrelations of Chlorinated Paraffins, Dechloranes, and Legacy Persistent Organic Pollutants in 10 Species of Marine Mammals from Norway, in Light of Dietary Niche.

Short-, medium-, and long-chain chlorinated paraffins (CPs) (SCCPs, MCCPs, and LCCPs) and dechloranes are chemicals of emerging concern; however, little is known of their bioaccumulative potential compared to legacy contaminants in marine mammals. Here, we analyzed SCCPs, MCCPs, LCCPs, 7 dechloranes, 4 emerging brominated flame retardants, and 64 legacy contaminants, including polychlorinated biphenyls (PCBs), in the blubber of 46 individual marine mammals, representing 10 species, from Norway. Dietary niche was modeled based on stable isotopes of nitrogen and carbon in the skin/muscle to assess the contaminant accumulation in relation to diet. SCCPs and dechlorane-602 were strongly positively correlated with legacy contaminants and highest in killer (Orcinus orca) and sperm (Physeter macrocephalus) whales (median SCCPs: 160 ng/g lw; 230 ng/g lw and median dechlorane-602: 3.8 ng/g lw; 2.0 ng/g lw, respectively). In contrast, MCCPs and LCCPs were only weakly correlated to recalcitrant legacy contaminants and were highest in common minke whales (Balaenoptera acutorostrata; median MCCPs: 480 ng/g lw and LCCPs: 240 ng/g lw). The total contaminant load in all species was dominated by PCBs and legacy chlorinated pesticides (63-98%), and MCCPs dominated the total CP load (42-68%, except 11% in the long-finned pilot whale Globicephala melas). Surprisingly, we found no relation between contaminant concentrations and dietary niche, suggesting that other large species differences may be masking effects of diet such as lifespan or biotransformation and elimination capacities. CP and dechlorane concentrations were higher than in other marine mammals from the (sub)Arctic, and they were present in a killer whale neonate, indicating bioaccumulative properties and a potential for maternal transfer in these predominantly unregulated chemicals.

The voyage of the London whaler Lusitania, 1826–1829

The British whaling ship Lusitania left London in 1826 on a three-year voyage to the South Seas. During the course of its long voyage, the vessel spent much of its time in the waters off the Indonesian archipelago and among the islands of western Melanesia. British whalers had been driven to this challenging region because sperm whales had been severely depleted in other less difficult whaling grounds. In those tropical waters, the hot climate, endemic diseases and high death rate among the crew, as well as the routine dangers of the trade, were to try the Lusitania and her crew to the utmost. One of them kept a journal during the voyage. It chronicles the many challenges faced by this and other vessels working this whaling ground, which until recent times has been poorly documented.

The active space of sperm whale codas allows for communication within and between social units.

The active space of sperm whale codas allows for communication within and between social units.

The Strait and the Sea Unsettling Scores

In this inquiry I build on my previous work on contemporary aesthetics to engage the media practices and bio-acoustic mappings of cetacean scientists, as well as fishers’ video diaries and sound cartographies of interactions with cetaceans. To these, I also juxtapose a contemporary composer, sound engineer, and media artist’s sonographic records of encounters with these decidedly intriguing marine mammals alas too often reduced to the moniker “charismatic”. Concretely, I zoom in on three media practices: the sound compositions of Ariel Guzik, founder of the Nature Expression and Resonance Lab, who designs and engineers instruments to communicate with grey whales, sperm whales, and bottle nose dolphins in the Sea of Cortez; the hydrophone recordings, spectrograms, drone footage, and photo-identifications by a team of cetacean ethologists and communication scientists who run a research vessel and a marine ecology lab in the Tyrrhenian Sea; and the multimedia online platforms of fishers who produce video diaries of potentially fatal interactions with orcas in the Strait of Gibraltar. These carefully selected and juxtaposed audiovisual practices are the graphic, acoustic, and musical fragments that compose the de-territorialized cartography I am calling The Strait and The Sea.

The occurrence of ambergris in sperm whales caught by Soviet whaling flotillas

The occurrence of ambergris in sperm whales caught by Soviet whaling flotillas