Glycopatterns of the foregut in the striped dolphin Stenella coeruleoalba, Meyen 1833 from the Mediterranean Sea
Roberto Carlucci, Giulia Cipriano, Carmelo Fanizza, Tommaso Gerussi, Rosalia Maglietta, Antonio Petrella, Guido Pietroluongo, Pasquale Ricci, Daniela Semeraro, Marco Vito Guglielmi, Giovanni Scillitani, Donatella Mentino
We studied by histochemical and lectin-histochemical methods the carbohydrate composition of the mucus secreted by the stomach and the first tract of the duodenum of the striped dolphin, Stenella coeruleoalba. The stomach can be divided into four compartments: main stomach, two connecting chambers and a pylorus, followed by the duodenal ampulla. Mucus is secreted by both surface cells and intramucosal glands specific for each compartment. Carbohydrate complexity and sulphation is highest in the connecting chambers, probably as a defense against pathogens. The results are compared with those available in literature.
finFindR: Automated recognition and identification of marine mammal dorsal fins using residual convolutional neural networks
Jaime W. Thompson, Victoria H. Zero, Lori H. Schwacke, Todd R. Speakman, Brian M. Quigley, Jeanine S. Morey, Trent L. McDonald
Photographic identification is an essential research and management tool for marine mammal scientists. However, manual identification of individuals is time-consuming. To shorten processing times we developed finFindR, an open-source application that uses a series of neural networks to autonomously locate dorsal fins in unedited field images, quantify an individual’s unique fin characteristics, and match them to an existing photo catalog. FinFindR allows users to build a catalog of known individuals either in conjunction with, or independent from existing systems. Given training data, finFindR’s architecture can be modified to identify members of other species with various types of distinctive markings.
Behavioral responses of humpback whales to biopsy sampling on a breeding ground: the influence of age-class, reproductive status, social context, and repeated sampling
Claire Garrigue and Solène Derville
Acquiring biological samples is essential to understand and protect marine mammals, yet it is important to evaluate the disturbance that it may cause to individuals. Using over 20 years of data, we assessed the short-term response of humpback whales to remote biopsy and boat approach in a breeding ground to inform management. Among the many factors tested, our study provided new insights into the effect of age-class as we found no significant difference between the response of calves (young of the year) and that of adults, whereas juveniles responded significantly more strenuously to being biopsied.
A decade of photo-identification reveals contrasting abundance and trends of Type B killer whales in the coastal waters of the Antarctic Peninsula
Holly Fearnbach, John W. Durban, David K. Ellifrit, Alyssa Paredes, Leigh S. Hickmott, Robert L. Pitman
We assessed abundance trends of Type B1 and B2 killer whales around the Antarctic Peninsula. By identifying individuals in photographs collected during austral summers from 2008/2009 to 2017/2018, we documented site fidelity across years for both types and fit mark-recapture models to estimate the size of their wide-ranging populations. The results revealed contrasting status: a smaller (~102) and declining population of B1s had reduced survival in recent years compared to a larger (~740) and stable population of B2s. We hypothesize that B1s may be responding to declining sea-ice and resulting changes in the availability of their primary ice-seal prey.
Use of satellite imagery to identify southern right whales (Eubalaena australis) on a Southwest Atlantic Ocean breeding ground
Audrey A. Corrêa, João H. Quoos, André S. Barreto, Karina R. Groch, Patricia P. B. Eichler
Satellite imagery has been used to improve scientific research worldwide. The southern right whale was chosen to test the use of medium, high, and very high resolution (VHR) satellite images, on the Brazilian breeding ground. These images were used to identify the whales and compare to aerial survey data collected in the same area. The VHR satellite images from the Pleiades-1A, available on Google Earth, displayed the best results when compared to that of Sentinel2, Landsat8, Rapid Eye, and Planet Scope. This technique may represent an important tool for detecting right whales, especially in countries where research funding is scarce.
Age-related changes to the speckle patterns on wild Indo-Pacific bottlenose dolphins
Genfu Yagi, Mai Sakai, Kazunobu Kogi
We studied age-related changes in the speckle density and shape of Indo-Pacific bottlenose dolphins. Speckles tended to increase from the genital to the throat area along the caudal-cranial axis, and from the ventral to the lateral area along the dorsal-ventral axis. The speckles continued to increase with age and may increase throughout their lifespan. We also found no speckle area around the genital slit which differed in shape between the sexes. Our study suggests speckle can be used for visual signals of age and sexual maturity among dolphins. We also suggest the speckle can be used for noninvasive age estimation.
Bony labyrinths of the Blackfish (Delphinidae: Globicephalinae)
Rachel A. Racicot and V. Eve Preucil
The inner ear contains key information about hearing sensitivity and ecology. We investigated inner ear variation in melon-headed dolphins by digitally extracting ‘virtual’ inner ears using X-ray imaging technology. Analysis of measurements from melon-headed dolphin inner ears alongside a broad sampling of whales, dolphins, and their relatives, generated a visualization of hearing ‘morphospace’. In this morphospace, melon-headed whales appear in two distinct clusters, reflecting differences in environmental influences on echolocation abilities. The shape of the inner ear thus sheds light on hearing abilities related to specializations in echolocation related to habitat.
Southern right whales generally appear not to react to transiting research vessels
María Belén Argüelles, Mariano Coscarella, Carla Fiorito, Marcelo Bertellotti
Reactions of southern right whales related to whale-watching boats have been reported but there are no quantitative data showing how these whales react to boats not preforming whale-watching trips. The objective of this study was to investigate the reaction of southern right whales to transiting vessels in Puerto Madryn city, Argentina. We found that the response differed depending on the number of whales present. The lack of reaction of whales suggests that they would not consider transiting research vessel as a threat. This study represents an important piece of information for the conservation of southern right whales.
Examining shark bite scars on dolphins off Bimini, The Bahamas: Comparisons between bottlenose and Atlantic spotted dolphins
Kelly Melillo-Sweeting, Maria Maust-Mohl, Matthew J. Smukal
Since direct predation is rarely observed, researchers look for injuries on living dolphins to understand the impact of shark predation risk. Off Bimini, The Bahamas, at least 29% of bottlenose and 15% of Atlantic spotted dolphins survived a bite. For both species, bites were predominantly on the dorsal (back) side; this isn’t surprising since bites to their bellies (ventral side) may be more likely to be fatal. We did not determine the shark species responsible, but these dolphins overlap with tiger and bull sharks. This study builds on long-term research in this region, providing insight into factors influencing predation risk.
Spatiotemporal variation in harbor porpoise distribution and foraging across a landscape of fear
Laura D. Williamson, Beth E. Scott, Megan R. Laxton, Fabian E. Bachl, Janine B. Illian, Kate L. Brookes, Paul M. Thompson
Increased understanding of porpoises’ seasonal distribution, key foraging areas, and their relationship with competitors can shed light on management options and potential interactions with offshore industries. Data from an array of echolocation-click detectors were analyzed to investigate spatial and temporal variation in occurrence and foraging activity of harbor porpoises. The porpoises’ overall distribution shifted throughout the summer and autumn, likely influenced by seasonal prey availability. Probability of porpoise occurrence was lowest in areas close to the coast, where dolphin detections were highest and declined prior to dolphin detection, leading potentially to avoidance of spatiotemporal overlap between porpoises and dolphins.
Translocations maintain genetic diversity and increase connectivity in sea otters, Enhydra lutris
Shawn Larson, Roderick B. Gagne, Jim Bodkin, Michael J. Murray, Katherine Ralls, Lizabeth Bowen, Raphael Leblois, Sylvain Piry, Maria Cecilia Penedo, M. Tim Tinker, Holly B. Ernest
Sea otters were once abundant in the nearshore of the North Pacific. The international maritime fur trade left few remnant populations with low genetic diversity. Subsequent reintroductions of otters resulted in several viable populations in North America. We sampled sea otters genetically from Bering Island to California using variable markers to evaluate genetic diversity, population structure and geneflow between populations. Genetic diversity was similar within all populations with the highest found in reintroduced populations. Population structure was greatest between Northern and Southern sea otters. Population connectivity and geneflow was evident between all sampled populations except for in Bering and California.
Population dynamics of sperm whales (Physeter macrocephalus) in Guadeloupe, French Caribbean: A mark-recapture study from 2001 to 2013
Caroline Rinaldi, Renato Rinaldi, Juliette Laine, Christophe Barbraud
We conducted a study in Guadeloupe from 2001 to 2013 to gain better knowledge of the demography and population trends of sperm whales present yearlong in the eastern Caribbean waters. We identified the whales from photographs using marks on the trailing edge of the fluke. From 1,492 photographs collected, we identified 109 individuals. Demographic analyses suggest a population decline from 75 to 35 individuals over the years. These results highlight the vulnerability of this sperm whale population as it faces growing threats such as pollution, marine traffic, whale watching, and entanglements.
Behavioral context of echolocation and prey-handling sounds produced by killer whales (Orcinus orca) during pursuit and capture of Pacific salmon (Oncorhynchus spp.)
Brianna M. Wright, Volker B. Deecke, Graeme M. Ellis, Andrew W. Trites, John K. B. Ford
We used acoustic tags to analyze the echolocation behavior of fish-eating killer whales during pursuit and capture of salmon prey. Whales produced more echolocation trains and had faster clicking rates prior to catching salmon versus afterward, confirming the importance of echolocation in prey detection and tracking. Extremely rapid click sequences (buzzes) occurred in the lead-up to salmon captures at depths typically exceeding 50 m, and were likely used for close-range prey targeting. Distinctive crunching sounds related to prey handling occurred at shallow depths following captures, matching observations that whales surfaced with salmon prior to eating them and often shared prey.
Epidemiological features of the first Unusual Mortality Event linked to cetacean morbillivirus in the South Atlantic (Brazil, 2017–2018)
Haydée A. Cunha, Elitieri B. Santos-Neto, Rafael R. Carvalho, Joana M. P. Ikeda, Katia R. Groch, Josué Díaz-Delgado, Emi B. Guari, Juliana A. Brião, Raissa B. Oliveira, Leonardo Flach, Tatiana L. Bisi, José L. Catão-Dias, Alexandre F. Azevedo, José Lailson-Brito Jr.
In late 2017/early 2018 the first unusual mortality event (UME) linked to cetacean morbillivirus (CeMV) ever recorded in the South Atlantic took place in southeastern Brazil. The UME accounted for the death of at least 277 Guiana dolphins (Sotalia guianensis). Females and calves had higher mortality rates during the UME, indicating that they were more vulnerable to morbilliviral infection. The arrival of CeMV may be an additional threat for the conservation of endangered Guiana dolphins.
Characterization of the cardiac phospholipidome of small cetaceans provides adaptational insight and a foundation for indirect population health screening
J. P. Monteiro, E. Maciel, R. Maia, A. T. Pereira, R. Calado, P. Domingues, T. Melo, C. Eira, and M. R. Domingues
The habitat evolutionary divergence that marine mammals underwent occasioned several reported morphological and physiological adaptations in cetacean hearts. We thoroughly studied the hearts of small cetaceans (Delphinus delphis, Phocoena phocoena and Stenella coeruleoalba) in terms of lipid composition in order to disclose and understand differences towards terrestrial mammals. The cardiac lipid profile of the three studied cetacean species is somewhat similar, and differs significantly from the ones reported for terrestrial mammals, namely presenting a remarkably higher content in lipid species with esterified n-3 fatty acids. These differences imply evolutionary adaptation to the molecular level in mammalian heart. Moreover, this study opens the possibility of using lipidomics tools to remotely monitor cetacean population health.
Ice seals as sentinels for algal toxin presence in the Pacific Arctic and subarctic marine ecosystems
Alicia M. Hendrix, Kathi A. Lefebvre, Lori Quakenbush, Anna Bryan, Raphaela Stimmelmayr, Gay Sheffield, Gabriel Wisswaesser, Maryjean L. Willis, Emily K. Bowers, Preston Kendrick, Elizabeth Frame, Thomas Burbacher, David J. Marcinek
Domoic acid and saxitoxin, two algal-produced neurotoxins, are present in Alaskan seas. Marine mammal exposures to these toxins may be increasing due to warming ocean conditions. Samples from almost one thousand Alaskan ice seals harvested over fifteen years for subsistence purposes were analyzed for both toxins. Though no clinical signs of health impacts were reported in harvested seals, one or both toxins were found in all four species studied. Furthermore, the number of ice seal stomach content samples containing DA increased over time in seals collected in the Bering Sea, suggesting an increase in toxin prevalence in the region.
Evaluating the current condition of a threatened marine mammal population: estimating northern sea otter (Enhydra lutris kenyoni) abundance in southwest Alaska
William S. Beatty, Michelle St. Martin, Ryan R. Wilson
Sea otter aerial surveys were conducted in southwest Alaska in 2016. In Bristol Bay, sea otters have slightly increased in abundance since the last survey in 2000. In areas south of the Alaska Peninsula from Sanak Island to Unga Island, the population has remained stable at best or has decreased since the last survey in the area in 2001.
Common dolphins form unexpected strong social bonds: insights into social plasticity of delphinids
Suzanne Mason, Chandra Salgado Kent, Kerstin Bilgmann
Common dolphins (Delphinus delphis) are considered a wide-ranging offshore species whose social groups frequently form, break-up, and reform. In most regions of the world, they occur in large schools with weak social bonds. In Port Phillip, southeastern Australia, this species is, against expectations, resident to an embayment and forms smaller schools with stable bonds. Analyses of the social interactions of resident adult bay dolphins revealed that they have preferred companions and form several strong social bonds. The study highlights that common dolphins can show extreme differences in social structure and reveals the importance of the environment for social bonds.
CpG methylation frequency of TET2, GRIA2, and CDKN2A genes in the North Atlantic fin whale varies with age and between populations
Raquel García‐Vernet, Berta Martín, Miguel A. Peinado, Gísli Víkingsson, Marta Riutort, Alex Aguilar
Age determination is critical to understand whale population dynamics. However, determining age in free-ranging animals still remains a challenge. DNA methylation of selected genes has been proposed as a tool for age determination in wild animals. Here, we analyze the methylation levels of three different genes (TET2, CDKN2A and GRIA2) in skin samples of fin whales from two North Atlantic populations. We found significant correlations between age and methylation, but our model underestimated the age of older whales. The methylation levels of one gene (TET2) differed between populations due to differences in either the genetic background or the environment.
Seasonal and diel changes in cetacean vocalizations monitored by passive acoustic methods in Nemuro Strait adjacent to the Shiretoko World Natural Heritage Site
Mayuko Otsuki, Tomonari Akamatsu, Takahiro Nobetsu, Yoko Mitani
The coexistence of humans and marine mammals is an important issue in Nemuro Strait. However, the temporal habitat use of cetaceans in this area is unknown. We document seasonal and diel changes in cetacean vocalizations collected using passive acoustic devices. Killer whale, sperm whale, and Pacific white-sided dolphin sounds were recorded during the ice-free period. No cetaceans were recorded during the sea ice period. The dolphin calls and unknown click trains were more frequent at night, and marginal diel changes in killer whale calls were detected. We provide new insights into the habitat use of marine mammals in the Strait.
Diel and lunar variation in diving behavior of rough‐toothed dolphins (Steno bredanensis) off Kauaʻi,
Jacquelyn F. Shaff and Robin W. Baird
Diving behavior of rough-toothed dolphins has only previously been described based on tagged and released rehabilitated individuals. We combined observational work with satellite tag data from free-ranging individuals to investigate rough-toothed dolphin diving behavior off Kauaʻi, Hawaiʻi across different solar (daily and seasonal) and lunar cycles. While generally remaining in near-surface waters (maximum dive depth of 399 m), dives were deepest and longest at dusk, suggesting they may dive to meet the rising mesopelagic layer. Diving occurred most often at dusk and night compared to dawn and day, and dive depth and duration varied with lunar cycle These variations in dive behavior indicate diving patterns shift based on the distribution of prey, and suggest that rough-toothed dolphins may be feeding on both epipelagic and mesopelagic prey.
Under pressure: Effects of instrumentation methods on fur seal pelt function
Paige Nankey, Nadine Filippi, Carey E. Kuhn, Bobette Dickerson, Heather E. M. Liwanag
Tracking marine mammals with electronic devices enables researchers to better understand animal movements and at-sea behavior. For pinnipeds, instruments are typically glued to the animal’s hair, either directly to the pelage or via a fabric patch. These instruments are retrieved by cutting the pelage or cutting through the patch. This study examined effects of instrument attachment on northern fur seal pelts, and found that the use of neoprene better maintained the insulation in water and reduced air loss under pressure (as during a dive). Our results suggest the use of neoprene may reduce negative consequences of instrumentation in fur seals.