Tursiops Truncatus Research Articles

The bottlenose dolphin (Tursiops truncatus): A novel model for studying healthy vascular aging

Aging is the primary non-modifiable risk factor for the development of cardiovascular diseases (CVD). CVD are often preceded by arterial dysfunction, including endothelial dysfunction and aortic stiffening. Our preliminary results suggest that the circulating milieu is associated with differences in arterial function in young and mid-life/older (ML/O) adults. Moreover, incubation of mouse arteries with serum from young and ML/O adult humans can directly transfer arterial aging phenotypes for endothelial function and aortic stiffness. These results suggest that age-related changes in the circulating milieu are an underlying mechanism of age-related arterial dysfunction. Dolphins are mammals that have evolutionary adapted to diving, with constant cycles of tissue hypoxia/reoxygenation and disturbed shear stress -- exposures which cause arterial dysfunction in humans. Dolphins also have long lifespans and are relatively free of CVD. Taken together, dolphins may be a unique model of healthy vascular aging, with possible applications to clinical medicine. PURPOSE: To determine if the serum of bottlenose dolphins ( Tursiops truncatus) induces the same arterial aging phenotypes as the serum of age-equivalent humans. Methods: Common carotid arteries and aorta rings from young (Y; 5 mo) and old (O; 25 mo) wildtype female (F) and male (M) C57BL/6N mice were exposed ex vivo for 24 and 48h, respectively, to 5% sex-matched adult dolphin serum. Dolphin serum of Y (17 ± 4 years; n = 16: 5F / 11 M) and ML/O (29 ± 2 years; n = 4: 1F/3M) adults was obtained from the National Marine Mammal Tissue Bank. Endothelial function was assessed as carotid artery endothelium-dependent dilation (EDD) in response to increasing doses of acetylcholine. Aortic stiffness was measured as elastic modulus, a measure of intrinsic mechanical wall stiffness. Dolphin serum-mediated responses in mouse arteries were compared with that of adult human serum data (Y, 24 ± 1 years, n=10: 5F/5M; ML/O, 67 ± 3 years, n=10: 5F/5M). Differences were assessed via 2-way ANOVAs; within species post hoc analyses conducted between age groups. Results: Endothelial Function. Peak EDD in Y mouse carotid arteries was lower following exposure to serum from ML/O adult humans (ML/O, 78 ± 2 v. Y, 92 ± 2%; P < 0.001) and higher in O mouse carotid arteries after exposure to Y adult serum (92 ± 2 vs. 73 ± 5%, P = 0.001). In contrast, EDD was similarly high across all groups following dolphin serum exposure (³ 93% peak EDD), independent of the age of the serum donor or the mouse arteries (Y v. ML/O serum donor in Y arteries, P = 0.773; in O mouse arteries, P = 0.942). Aortic Stiffness. Stiffness in Y aortic rings was ~60% higher following exposure to ML/O adult human serum (P = 0.001 v. Y adult serum). In O mouse aortic rings, stiffness was 25% lower after exposure to Y adult serum (P = 0.044 v. ML/O adult serum). In contrast, stiffness was similar across all groups following dolphin serum exposure, independent of age of the serum donor or the arteries (Y v. ML/O serum donor in Y aortic rings, P = 0.974; in O aortic rings P = 0.157). CONCLUSIONS: The circulating milieu of bottlenose dolphins may be geroprotective, which could serve as a model to investigate mechanisms and potential therapies for preventing adverse vascular aging and promoting CV health and longevity in humans. FUNDING: R21 AG078408 & MSCA-IF-2019:892267. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Nursing Behavior of Bottlenose Dolphin (Tursiops truncatus) Calves from 1990-2014 at Brookfield Zoo Chicago, USA

While the common bottlenose dolphin (Tursiops truncatus) population under managed care in North American zoos and aquariums is self-sustaining, understanding normal nursing behavior can help management make informed care decisions for neonates and future births. This study examined behavioral data from the first 30 days of life collected from 14 dolphin calves born between 1990-2014 at Brookfield Zoo Chicago in Brookfield, IL. We hypothesized that surviving calves showed significantly different patterns of nursing than those that did not survive. There were no significant differences in average nursing rates or average nursing frequency between calves that did and did not survive up to 17 days old. Surviving calves up to eight days old had significantly longer average nursing performance (s/hr), and significantly longer average nursing durations (s/bout) than non-surviving calves. Shorter nursing duration early in the life of the calf may be indicative of developmental problems and may be a useful metric to inform staff when supplemental care may be needed. Calf survival improved from the first half to the second half of the study period by 150%, most likely due to improvements in animal care, medical intervention, and experience of the dams. Understanding normal nursing behavior is essential to learning when human intervention is necessary to help survival and can help guide future care and management of dolphin births under professional care.

Threatened cetaceans off the coast of Israel and long‐range movement of a sperm whale

Abstract Research in the western Mediterranean has shown that sperm (Physeter macrocephalus) and Cuvier's beaked whales (Ziphius cavirostris) are present as small, globally distinct populations that face numerous threats. The eastern Mediterranean is not well studied, and few surveys have investigated the composition of cetacean communities. In this study, visual‐acoustic surveys were conducted off the coast of Israel during April–May 2022 to characterize the cetacean community. Sperm whales (three encounters), Cuvier's beaked whales (one encounter), bottlenose dolphins (one encounter (Tursiops truncatus)) and unidentified delphinids (17 encounters) were acoustically detected. Sperm whales were foraging ~10 km off Haifa, at 370–1220 m deep and social vocalizations (codas) corresponded to the Mediterranean dialect. One immature male that was photographed is known from 12 previous encounters in the Ligurian Sea, indicating a west–east movement of approximately 2800 km. Automated passive acoustic monitoring of narrow, relatively shallow areas such as the Sicily Channel could provide an opportunity to reduce mortality of individuals making long‐distance movements within Mediterranean basins. Israeli waters provide habitat for cetaceans, with two threatened subpopulations—sperm and Cuvier's beaked whales—that are negatively impacted by anthropogenic activities, including those that introduce underwater noise. More data are needed on densities of these deep‐water species, and an evaluation of the threats faced in the wider Levantine basin.

Molecular characterization of cetacean poxviruses along the coast of mainland Portugal.

Cetacean poxvirus (CePV) is the causative agent of tattoo skin disease (TSD) in dolphins, porpoises and whales, a condition characterized by pinhole, ring-like lesions or generalized tattoo-like skin lesions. This study genetically characterized cetacean poxviruses from stranded animals along mainland Portugal. Samples from skin lesions compatible with TSD were obtained from 4 odontocete species (Delphinus delphis, Stenella coeruleoalba, Phocoena phocoena, and Tursiops truncatus) and analyzed using a conventional PCR assay targeting the DNA polymerase gene partially. Among the positive samples (n = 29, 65.9%), a larger DNA polymerase gene fragment was obtained, allowing a robust phylogenetic analysis. Nineteen samples (43.2%) were successfully amplified and sequenced using Sanger sequencing. By combining 11 of these sequences with those from public databases, a maximum likelihood phylogenetic tree was constructed, revealing high heterogeneity within the group. These findings contribute to a better understanding of the genetic diversity, epidemiology, phylogenetics, and evolution of CePV.

Highly pathogenic avian influenza A(H5N1) virus in a common bottlenose dolphin (Tursiops truncatus) in Florida.

Since late 2021, highly pathogenic avian influenza (HPAI) viruses of A/goose/Guangdong/1/1996 (H5N1) lineage have caused widespread mortality in wild birds and poultry in the United States. Concomitant with the spread of HPAI viruses in birds are increasing numbers of mammalian infections, including wild and captive mesocarnivores and carnivores with central nervous system involvement. Here we report HPAI, A(H5N1) of clade 2.3.4.4b, in a common bottlenose dolphin (Tursiops truncatus) from Florida, United States. Pathological findings include neuronal necrosis and inflammation of the brain and meninges, and quantitative real time RT-PCR reveal the brain carried the highest viral load. Virus isolated from the brain contains a S246N neuraminidase substitution which leads to reduced inhibition by neuraminidase inhibitor oseltamivir. The increased prevalence of A(H5N1) viruses in atypical avian hosts and its cross-species transmission into mammalian species highlights the public health importance of continued disease surveillance and biosecurity protocols.

Apneustic anesthesia ventilation improves pulmonary function in anesthetized bottlenose dolphins (Tursiops truncatus).

Use of mechanical ventilation during general anesthesia is a necessary practice in the anesthetization of small cetaceans as spontaneous ventilation fails to provide adequate gas exchange. Currently available methods of ventilation do not account for the intermittent breathing strategy of representative species within this infraorder of fully aquatic mammals and may have a significant effect on cardiac and respiratory physiology. To understand the impact of mechanical ventilation on cardiopulmonary function in one small species of cetacean, the bottlenose dolphin (Tursiops truncatus), we compared controlled mechanical ventilation (CMV) to a novel ventilation method known as apneustic anesthesia ventilation (AAV). AAV simulates the normal inspiratory breath-hold pattern of dolphins. Ten anesthetic procedures (dental procedure, n = 9; bronchoscopy, n = 2) were performed on nine dolphins (age range: 10-42 years; mean = 32 years; median = 37 years; female = 3, 40%; male = 6, 60%). In a cross-over study design, dolphins were instrumented and randomly assigned to AAV or CMV as the initial mode of ventilation, then switched to the alternate mode. Baseline cardiopulmonary data were collected and again after 30 min on each mode of ventilation. Cardiac index, stroke volume index, systemic vascular resistance, alveolar dead space, alveolar-arterial oxygen tension gradient, arterial oxygen content, oxygen delivery index, and dynamic respiratory system compliance index were calculated at each of the four time points. During AAV, dolphins had higher arterial oxygen tension, higher mean airway pressure, reduced alveolar dead space ventilation and lower alveolar-arterial oxygen difference. Cardiovascular performance was not statistically different between the two modes. Our study suggests AAV, which more closely resembles the conscious intermittent respiratory pattern phenotype of dolphins, improves ventilation and pulmonary function in the anesthetized dolphin. Future studies should evaluate the cardiopulmonary effects of neutral buoyancy and cardiopulmonary sparing drug protocols to reduce the need for hemodynamic support of current protocols.

A Quantitative Analysis of Microplastics in the Gastrointestinal Tracts of Odontocetes in the Southeast Region of the United States.

Microplastics (<5 mm in diameter) are ubiquitous in the oceanic environment, yet microplastic accumulation in marine mammals is vastly understudied. In recent years, efforts have been made to document microplastic profiles in odontocetes. The objective of the present study was to describe and quantify microplastics in the gastrointestinal (GI) tracts of deceased odontocetes that stranded in the southeastern United States. Our study included 24 bottlenose dolphins (Tursiops truncatus), two pygmy sperm whales (Kogia breviceps), one pantropical spotted dolphin (Stenella attenuata), one short-snouted spinner dolphin (Stenella clymene), one Risso's dolphin (Grampus griseus), and one dwarf sperm whale (Kogia sima) obtained from stranding networks in Texas, Alabama, Florida, and Puerto Rico. Contents found in the GI tracts, namely, the stomach and portions of the intestinal tract, were subjected to a laboratory procedure to isolate microplastics. The physical characteristics of microparticles were analyzed with a stereomicroscope, and microplastics were classified by polymer type via Fourier-transform infrared spectroscopy. There was an average of 47.6 ± 41.4 microparticles, ranging from 1 to 193 items per stomach. More specifically, there was an average of 5.6 ± 4.7 microplastics per stomach. The predominant morphologies, colors, and polymer types were fibers, white-colored items, and polyester, respectively. This research contributes to the current knowledge of microplastic exposure in top marine mammal predators and sets the stage for further exploration into the associated risks of microplastics in odontocetes within the United States and worldwide. Environ Toxicol Chem 2024;43:1260-1273. © 2024 SETAC.

Exploring mtDNA Databases to Evaluate the Population Structure and Genetic Diversity of Tursiops truncatus in the Atlantic Ocean: Implications for the Conservation of a Small, Offshore Population

Inshore and offshore bottlenose dolphin, Tursiops truncatus, ecotypes were distinguished through genetics, distribution, diet, morphology, diversity, and social behaviors. Although T. truncatus is a widely studied species, few studies have focused on offshore populations. Offshore biodiversity is frequently neglected due to the difficulty of data collection, and therefore, it is challenging to assess how threatened these populations are. A small, offshore population of dolphins residing around the Saint Peter Saint Paul Archipelago (SPSPA) in the middle of the Atlantic Ocean has been monitored for several years, and a decrease in the number of dolphin sightings has recently been noticed. We analyzed a comprehensive mtDNA control-region sequence dataset for this species to infer the conservation status and better understand the relationships between the SPSPA population and other offshore populations. We assessed the genetic diversity and population structure of the bottlenose dolphin from inshore and offshore populations of the Atlantic Ocean. Offshore populations are more genetically diverse and have less variation between populations than inshore populations. The offshore populations share haplotypes, indicating potential gene flow. However, the SPSPA population presented the lowest levels of genetic diversity between populations. The conservation status of the SPSPA population is concerning, and it is necessary to apply effective management strategies to guarantee its protection.

Comparison of common bottlenose dolphin whistles in tropical waters

Comparison of common bottlenose dolphin whistles in tropical waters

First description of Rhodococcus equi infection in common bottlenose dolphin (Tursiops truncatus).

Rhodococcus equi is a terrestrial bacterium and a common pathogen in foals (Equus caballus), in which causes pneumonia. This report describes for the first time the infection caused by R. equi in a common bottlenose dolphin (Tursiops truncatus) stranded in the Calabrian coast, Italy. The post mortem examination of the animal revealed lesions in lung and colon. The animal was also positive to dolphin morbillivirus. The histological study showed lesions attributable to R. equi infection, such as pyogranulomatous bacterial pneumonia and chronic granulomatous colitis. Whole genome sequencing of the isolated strain confirmed its identification as R. equi.

Bycatch and pollution are the main threats for Burmeister's porpoises inhabiting a high-industrialized bay in the Humboldt Current System

Pollution and bycatch are two of the main threats for cetaceans worldwide. These threats are exacerbated for nearshore species particularly for those in regions with intense industrial and fishing activities. Burmeister's porpoise is endemic to South America, has a Near Threatened conservation status because of long-term mortality in fisheries. Burmeister's porpoise occur in Mejillones Bay, northern Chile, a hot spot for heavy metals pollution from the mining industry and an intense industrial and artisanal purse-seine fishing area. From 2018 to 2021, we conducted systematic marine surveys to assess the abundance, distribution and habitat use of Burmeister's porpoises. We responded to stranding reports from 2018 to 2022, and necropsied nine individuals. From five of these, we analyzed the metal concentrations (As, Cd, Cr, Cu, Pb, Hg, Se and Zn) in muscle and skin tissues. Results showed an abundance of 76.17 individuals (CV = 25.9%) and an average density of 0.45 individuals/km2 (CV = 26%). Burmeister's porpoises were observed year round, 22.2% were mother-calf pairs present in austral summer at an average of 90.6 m depth in the southwestern bound of the bay. Two-thirds of stranded specimens died due to bycatch and one died due to bottlenose dolphin (Tursiops truncatus) attack. We report a dead Burmeister's porpoise positive for avian flu virus A (H5N1). Metals analyzed were found in muscle and skin tissues of stranded Burmeister's porpoises in the following order (Zn > Cu > Cr > As > Hg > Pb > Cd). Although we could not assess pollution as a cause of mortality, Cr, As and Pb concentrations exceeded the concentrations found in other porpoises species worldwide. We conclude that bycatch and pollution as the main threats for Burmeister's porpoise survival in northern Chile. Future studies should investigate the use of acoustic deterrent alarms to mitigate the bycatch in the bay and consider the Burmeister's porpoise as a sentinel species of pollution in northern Chilean coast.

First Report of Organochlorine Pesticides and Heavy Metals in a Stranded Bottlenose Dolphin Off the Central Coast of Veracruz State: A Warning to Assess Pollution in a Reef Marine Ecosystem from the Gulf of Mexico

Live-strandings of cetaceans are uncommon in the southwestern Gulf of Mexico. However, an adult female bottlenose dolphin (Tursiops truncatus) with normal body condition was recorded at Pelicano’s Beach on the coast of Veracruz State. Health assessment showed multiple external injuries, possibly caused by the stranding event, as well as potential bacterial infection, and, thus, the individual was held in temporary facilities for rehabilitation. Blood samples were taken to assess the health status of the individual and were also analyzed for concentrations of 20 pollutants (14 organochlorine pesticides [OCPs] and six heavy metals [HMs]). The animal was released and found dead within a few days. The concentration of OCPs and HMs were close or above the government limits. Although these were lower than those reported in other living, free-ranging bottlenose dolphins, there are well-known negative effects for health. Low OCP values were attributed to an offloading process through lactation or mobility of the lipophilic OCPs that pass from blood to fat. Whereas HM concentrations (mainly non-essential metals: mercury [Hg], lead [Pb], and cadmium [Cd]—2.73, 21.13, and 12.67 µg L-1, respectively) were probably linked to the diet and the possible distribution of the specimen (possibly offshore). This is the first report on pollutants from anthropogenic origin in the area where uncontrolled activities are of major concern within a protected national reef park. Since marine ecosystems are under continuous pressure, several health issues for top predators are being noticed; therefore, this study underlines the relevance of studying health status of marine mammals in the Mexican waters of the Gulf of Mexico.

Mitochondrial Variation of Bottlenose Dolphins (Tursiops truncatus) from the Canary Islands Suggests a Key Population for Conservation with High Connectivity within the North-East Atlantic Ocean.

In recent decades, worldwide cetacean species have been protected, but they are still threatened. The bottlenose dolphin (Tursiops truncatus) is a vulnerable keystone species and a useful bioindicator of the health and balance of marine ecosystems in oceans all over the world. The genetic structure of the species is shaped by their niche specialization (along with other factors), leading to the classification of two ecotypes: coastal and pelagic. In this study, the genetic diversity, population structure, and ecotypes of bottlenose dolphins from the Canary Islands were assessed through the analysis of 49 new samples from biopsies and from stranded animals using the 636 bp portion of the mitochondrial control region and 343 individuals from databases (n = 392). The results reveal high genetic diversity in Canarian bottlenose dolphins (Hd = 0.969 and π = 0.0165) and the apparent lack of population genetic structure within this archipelago. High genetic structure (Fst, Φst) was found between the Canary Islands and coastal populations, while little to no structure was found with the pelagic populations. These results suggest that Canarian bottlenose dolphins are part of pelagic ecotype populations in the North Atlantic. The studied Special Areas of Conservation in the Canary Islands may correspond to a hotspot of genetic diversity of the species and could be a strategic area for the conservation of the oceanic ecotype of bottlenose dolphins.

Training the Concept of Innovate in Dolphins (Tursiops truncatus) Is Both Creative and Cognitively Stimulating.

Creative or novel behaviors in bottlenose dolphins (Tursiops truncatus) can be indicators of flexible thinking and problem solving. Over 50 years ago, two rough-tooth dolphins demonstrated creative novel behaviors acquired through reinforcement training in human care. Since this novel training, a variety of species have been trained to respond to this conceptual cue. The current study assessed the creativity of 12 bottlenose dolphins (5 females, 7 males) housed at the Roatan Institute for Marine Sciences (RIMS) in Roatan, Honduras. Individual differences were found across four constructs measured for creativity: fluency, flexibility, elaboration, and originality. Variability in performance occurred across test sessions. Animals with less experience with this task performed fewer "innovative" behaviors as compared to more experienced animals. Despite errors, dolphins continued to attempt the task during test sessions, suggesting the concept of "innovate" was intrinsically rewarding and cognitively engaging. This task may be utilized across species to promote the comparative study of innovative or creative behavior as well as to promote cognitive welfare.

Novel processing and staining methodology of bottlenose dolphin (Tursiops truncatus) teeth for age determination

ABSTRACT Age determination of bottlenose dolphins (Tursiops truncatus) is a critical tool in understanding both individual and population health. There are many methods of aging bottlenose dolphins including analysis of teeth, pectoral flipper radiographs, and epigenetics. The most common and oldest method for aging toothed cetaceans is the counting of growth layer groups (GLGs) in the teeth. Current techniques have technical and repeatability challenges. Therefore, a processing technique that results in better resolution of GLGs is needed. This study compares different decalcifications and different histochemical staining techniques. Decalcification was done using 10% EDTA, Kristensen’s decalcification, and Rapid Decalcification Solution (RDO). Following decalcification and routine processing, GLGs were assessed using Hematoxylin and Eosin (H&E), hematoxylin, Giemsa, Wright-Giemsa, Toluidine Blue (T-Blue), Masson’s Trichrome, and Congo Red staining techniques. Decalcification with Kristensen’s and staining with Masson’s Trichrome and Congo Red were determined to best highlight GLGs. This processing and staining was then applied to a sample population of 102 bottlenose dolphins that were evaluated independently and blindly by two observers. Of the 102 dolphin samples, 13 (12.7%) were unable to age due to no clear distinction or distortion between GLGs.

Observational study on the non-linear response of dolphins to the presence of vessels

With the large increase in human marine activity, our seas have become populated with vessels that can be overheard from distances of even 20 km. Prior investigations showed that such a dense presence of vessels impacts the behaviour of marine animals, and in particular dolphins. While previous explorations were based on a linear observation for changes in the features of dolphin whistles, in this work we examine non-linear responses of bottlenose dolphins (Tursiops Truncatus) to the presence of vessels. We explored the response of dolphins to vessels by continuously recording acoustic data using two long-term acoustic recorders deployed near a shipping lane and a dolphin habitat in Eilat, Israel. Using deep learning methods we detected a large number of 50,000 whistles, which were clustered to associate whistle traces and to characterize their features to discriminate vocalizations of dolphins: both structure and quantities. Using a non-linear classifier, the whistles were categorized into two classes representing the presence or absence of a nearby vessel. Although our database does not show linear observable change in the features of the whistles, we obtained true positive and true negative rates exceeding 90% accuracy on separate, left-out test sets. We argue that this success in classification serves as a statistical proof for a non-linear response of dolphins to the presence of vessels.

Potential Residence and Coexistence Strategy of Tursiops truncatus in a Coastal Lagoon in the Southern Gulf of Mexico: Ecological Inferences Using Stable Isotopes

The Terminos Lagoon Flora and Fauna Protection Area is the largest coastal lagoon in the southern Gulf of Mexico and has the largest population of bottlenose dolphins, Tursiops truncatus, reported in the region. Photo identification studies have reported permanent and seasonal residence of dolphins; however, how dolphins coexist ecologically is unknown. In the present study, from 17 dead specimens stranded on the coast of Isla del Carmen (barrier island) between 2014 and 2016, stable isotopes in the liver, heart, and muscle, which represent different time scales, were analyzed to determine residence through δ13C values and niche width and trophic coexistence through δ15N values. Differences between sexes (δ13C liver: p = 0.009; heart: p = 0.01) and age classes (δ15N muscle: p = 0.02) were found, which indicated trophic sexual segregation and changes in resource use during growth, respectively. The lack of significant differences in δ13C values indicated isotopic equilibrium between the tissues, indicating the possible permanent residence of 12 dolphins in Terminos Lagoon as a coastal ecotype (− 16‰) and a second group (five dolphins) as an oceanic ecotype (− 18‰). In conclusion, most dolphins stranded in the Terminos Lagoon are potential permanent residents of this habitat, with evidence of resource partitioning as a coexistence strategy.

Employing an innovative underwater camera to improve electronic monitoring in the commercial Gulf of Mexico reef fish fishery.

Vessel electronic monitoring (EM) systems used in fisheries around the world apply a variety of cameras to record catch as it is brought on deck and during fish processing activities. In EM work conducted by the Center for Fisheries Electronic Monitoring at Mote (CFEMM) in the Gulf of Mexico commercial reef fish fishery, there was a need to improve upon current technologies to enhance camera views for accurate species identification of large sharks, particularly those that were released while underwater at the vessel side or underneath the hull. This paper describes how this problem was addressed with the development of the first known EM system integrated underwater camera (UCAM) with a specialized vessel-specific deployment device on a bottom longline reef fish vessel. Data are presented based on blind video reviews from CFEMM trained reviewers of the resulting UCAM video footage compared with video from only the overhead EM cameras from 68 gear retrievals collected from eight fishing trips. Results revealed that the UCAM was a successful tool for capturing clear underwater video footage of released large (>2m) sharks to enable reviewers to improve individual species identification, determination, and fate by 34.4%. This was particularly important for obtaining data on incidental catches of large protected shark species. It also provided clear underwater imagery of the presence of potential predators such as marine mammals close to the vessel, more specifically bottlenose dolphin (Tursiops truncatus) during gear retrieval, which often damaged or removed catch. This information is intended to assist researchers in need of gathering critical data on bycatch in close proximity to a vessel in which conventional overhead EM cameras are limited.

Evidence of geographic variation in the non-signature whistle repertoires of two isolated populations of New Zealand common bottlenose dolphin

ABSTRACT Dolphins are social animals that depend on sound to communicate, navigate, and find food. The aim of our research was to describe dolphin whistle characteristics and compare whistles between two isolated populations of bottlenose dolphins in New Zealand. We focused on three aspects of dolphin bioacoustics (1) classification of whistles; (2) comparison of the whistles of two discrete bottlenose dolphin populations; and (3) comparison of whistles of dolphin populations from around the world. At Great Barrier Island, the most common type of whistle was upsweep followed by sine, while at Doubtful Sound, convex and sine whistles were the most common whistle types. Random Forest models discriminated between whistles from the two populations with an estimated accuracy of 90%. The key differences were whistle-type contour, duration, and end frequency. Linear Mixed models show that whistle acoustic parameters were influenced by location but not by group size or the presence of immatures. Whistle parameters of both populations fell within the range of multiple populations from around the world. This studyprovides a benchmark for future research into drivers of geographic variation in dolphin vocal communication.

Blubber biopsy in common bottlenose dolphins using a novel biopsy puncher: Evaluation of the impact on living individuals and possibility of applications in cetacean research.

Biopsy has recently become a preferred protocol for sampling the skin and blubber of many cetacean species, although it is desirable to collect as minimally invasive as possible. Here, the effect of biopsy sampling on the captive common bottlenose dolphins was evaluated by analyzing the process of wound healing and changes in hematological and blood biochemical parameters after biopsy using a puncher developed to collect up to the inner layer of the dolphin blubber. Results showed that the wounds caused by biopsy were closed in as early as 1 day and completely covered with the epidermis within 5-11 days. Blood fibrinogen, which generally increases due to a wound-induced inflammatory response or activation of the coagulation system, was significantly elevated after the biopsy indicating ongoing tissue repair, while other parameters did not exhibit significant differences. Furthermore, histological observation and RNA extraction of samples were performed to investigate the versatility of this method to cetacean research. Histological examination revealed three distinct layers of the blubber in the biopsy samples. Moreover, total RNA extracted from biopsy samples exhibited sufficient quality and quantity for gene expression analyses. Overall, the puncher utilized in our study represents a valuable and minimally invasive tool for investigating various aspects of small cetacean studies.