Pregnancy rate and biomarker validations from the blubber of eastern North Pacific blue whales
Shannon Atkinson, Diane Gendron, Trevor A. Branch, Kendall L. Mashburn, Valentina Melica, Luis E. Enriquez‐Paredes, Robert L. Brownell Jr.
Hormonal biomarkers are useful indicators of mammalian reproductive and metabolic states. We used progesterone and cortisol blubber assays to assess physiological state of blue whales (53 females, 49 males) with known sighting histories from the Gulf of California, Mexico. Pregnant females had elevated progesterone concentrations. Cortisol concentrations did not differ between male and female blue whales, or among females in different reproductive states. The corrected noncalf pregnancy rate was 33.4%. Interpretation of hormone biomarkers must consider all physiological states that influence them. These results demonstrate the utility of pairing biomarkers with sighting histories to assess reproduction in blue whales.
On the size of crabeater seal, Lobodon carcinophaga, pups
Peter D. Shaughnessy, Robert Jones, Karen Viggers
Crabeater seals, Lobodon carcinophaga, breed on Antarctic pack-ice in spring, primarily in October. Mean weight of three pups at birth plus one from the literature was 30 kg; standard lengths (nose to tail in a straight line) of three of them averaged 1.29 m. Weights of 16 pups in the 1987 pupping season ranged from 27 to 139 kg, standard lengths ranged from 1.13 to 1.78 m. Two pups had weaned, they weighed 77 and 130 kg and had molted 85% of their lanugo. Weight of the unweaned pups is predicted by an equation incorporating standard length and axillary girth.
Feeding of humpback whales (Megaptera novaeangliae) on the Pacific coast of Nicaragua
Joelle De Weerdt, Eric A. Ramos
Humpback whales typically feed and breed in geographically separate areas, but sometimes they eat outside of their traditional feeding grounds. We documented Central American #humpbackwhales lunge feeding on their breeding grounds off the Pacific Coast of Nicaragua in 2017 and 2018. One identified whale fed in both years! Are shifting ocean conditions driving changes in prey distribution leading to changes in whale behavior? Do more whales mean more competition for food? Learn more about the hungry whales in Nicaragua in our new Note in Marine Mammal Science! @marinemammalogy #science
Methods in the study of marine mammal stress: Measuring binding affinity of corticosteroid binding globulin
Brendan Delehanty, Gregory D. Bossart, Cory Champagne, Daniel E. Crocker, Patricia A. Fair, Martin Haulena, Dorian Houser, Evan Richardson, Nicholas J. Lunn, Tracy Romano, Rudy Boonstra
Stress in marine mammals—anything like hunger, pollution, or competing for mates—causes the release of the hormone cortisol into the bloodstream. However, cortisol only affects animals once it leaves the bloodstream and enters tissues like brain or muscle. A protein in blood holds on to most of the cortisol being produced. Figuring out how much cortisol is getting to tissues means we need to figure out how strongly this protein holds on to cortisol. We explain a method for measuring this binding strength in a way that will help us to better understand how to measure marine mammal stress
New views of humpback whale flow dynamics and oral morphology during prey engulfment
Alexander J. Werth, Madison M. Kosma, Ellen M. Chenoweth, Janice M. Straley
GoPro cameras held by scientists on floating platforms and aerial drones provided close-up views of humpback whales feeding on juvenile salmon in Alaska. GoPro cameras were attached to poles held underwater or 2-3 meters above the surface, looking straight into mouths of whales. We saw water rushing into the mouth, causing the tongue to fold into a hollow throat space, and throat reverberations as engulfed water “bounced” before splashes of filtered water were expelled. Events happen consistently no matter how the whale’s body is turned, with the mouth filling in about two seconds and emptying in twenty seconds.
Southern right whales (Eubalaena australis) return to a former wintering calving ground: Fowlers Bay, South Australia
Claire Charlton, Rhianne Ward, Robert D. McCauley, Robert L. Brownell Jr, Sacha Guggenheimer, Chandra P. Salgado, Kent John L. Bannister
Southern right whale (SRW) abundance increased at Fowlers Bay, South Australia between 2004 and 2016. Sighting and photo identification data were collected during annual aerial (1993-2016) and vessel surveys (2014-2016). The total number of female and calf pairs was 3 during 1993-2003 and 63 during 2004-2014. Peak relative abundance was recorded in July/August. SRW at Fowlers Bay represent an increasing proportion of the south western subpopulation. Mean occupancy was 23 d for female and calf pairs and 2 d for unaccompanied adults. Research into the movement and connectivity of SRW is needed to understand drivers of habitat dispersal in Australia.
What can cetacean stranding records tell us? A study of UK and Irish cetacean diversity over the past 100 years
Ellen J. Coombs, Rob Deaville, Richard C. Sabin, Louise Allan, Mick O’Connell, Simon Berrow, Brian Smith, Andrew Brownlow, Mariel Ten Doeschate, Rod Penrose, Ruth Williams,… See all authors
Many factors may explain why cetaceans (whales, dolphins, and porpoises) strand (beach onto land). We use 20,000+ records, collected from around the UK and Ireland since 1913, to investigate trends, and to model possible human and environmental predictors of strandings e.g., sea-surface temperature and fishing. We found no correlation between yearly cetacean strandings and our predictors, probably because our models were too coarse to detect any patterns. We suggest that an increase in strandings since the 1980s is likely due to increases in recording effort. We highlight the need to investigate other potential predictors of strandings e.g., bycatch and military sonar.
How long do dolphins live? Survival rates and life expectancies for bottlenose dolphins in zoological facilities vs. wild populations
Kelly Jaakkola, Kevin Willis
This study found that bottlenose dolphins in U.S. zoological facilities live as long or longer than those in the wild. Researchers analyzed life expectancy and survival rates for bottlenose dolphins in U.S. zoos and aquariums, examining historical trends and comparing to wild populations. They found that survival rate and life expectancies for dolphins in U.S. zoological facilities increased significantly over the past few decades, and are now as high or higher than they are for wild dolphin populations.
Drift and beaching patterns of sea otter carcasses and car tire dummies
Colleen Young, Tomoharu Eguchi, Jack A. Ames, Michelle Staedler, Brian B. Hatfield, Mike Harris, Emily A. Golson‐Fisch
We tested whether half car tires drift in the ocean like deceased sea otters. We released 33 sea otter carcasses and 33 tire “dummies” with tracking devices and monitored their movements. We found that sea otters and dummies had similar drift patterns and beaching rates, so we concluded that car tire dummies are good substitutes for replicating drifting patterns of sea otter carcasses. These dummies can be used for estimating the number of sea otters that die at sea and wash ashore, or for directing search efforts, for general population monitoring or during a catastrophic event like an oil spill.
Specialized foraging habits of adult female California sea lions, Zalophus californianus
Martha P. Rosas‐Hernández, David Aurioles‐Gamboa, Claudia J. Hernández‐Camacho
Individual foraging specialization plays an important role in population dynamics. The foraging habitat fidelity and degree of specialization of California sea lions (Zalophus californianus) were evaluated by analyzing the stable isotope values in whiskers collected from adult females from the reproductive colony on Santa Margarita Island in Magdalena Bay, Baja California Sur, Mexico. Most of the female California sea lions assessed can be considered specialist consumers, focusing either on the same prey or on different prey from the same trophic level. Individuals showed fidelity to their foraging habitat (lagoon, coast, or ocean environment) despite the increase in sea surface temperature.
Insights from 180 years of mitochondrial variability in the endangered Mediterranean monk seal (Monachus monachus)
Philippe Gaubert, Fabienne Justy, Giulia Mo, Alex Aguilar, Erdem Danyer, Asunción Borrell, Panagiotis Dendrinos, Bayram Öztürk, Roberta Improta, Arda M. Tonay, Alexandros A. Karamanlidis
Mediterranean monk seals (Monachus monachus) are among the most endangered marine mammals. We screened the mitochondrial variability of the species through historical time, combining historical specimens with extant populations. Although we detected two new, rare haplotypes, our results suggest that genetic diversity has remained extremely low in the species since at least the mid-19th century. We hypothesize that the current segregation into isolated populations in the North Atlantic and eastern Mediterranean Sea derives from the combined effects of historical extinctions, genetic drift on small breeding groups, and persistently low levels of genetic diversity.
Passive acoustic monitoring predicts daily variation in North Atlantic right whale presence and relative abundance in Roseway Basin, Canada
Delphine Durette-Morin, Kimberley T. A. Davies, Hansen D. Johnson, Moira W. Brown, Hilary Moors-Murphy, Bruce Martin, Christopher T. Taggart
Passive acoustic monitoring is a useful tool to survey for right whales, especially in areas where visual monitoring is limited by weather and funding. We compared the information obtained from two overlapping monitoring methods, visual and acoustic, for a total of 23 days over four summers on the Roseway Basin Right Whale Critical Habitat, Canada. Acoustic analyses revealed we can predict the presence of high numbers of right whales, male dominated groups and sexual behavior in the absence of visual monitoring. While visual surveys implied a decline in right whale presence, this was not supported by the acoustic data.
Influence of occupation history and habitat on Washington sea otter diet
Jessica R. Hale, Kristin L. Laidre, M. Tim Tinker, Ronald J. Jameson, Steven J. Jeffries, Shawn E. Larson, James L. Bodkin
doi.org/10.1111/mms.12598 Sea otters are voracious predators and over time they can cause declines in abundance of their prey.
As a result, sea otters have different diets in long-occupied, high-density areas than in newly occupied, low-density areas. Previous research also shows that sea otter diet varies by habitat type. The goal of our study was to determine whether habitat type or sea otter density was more important in determining Washington sea otter diet. We observed sea otters feeding in areas with a range sea otter densities and habitat types and found that sea otter diet was most influenced by habitat type.
Chronic stress from fishing gear entanglement is recorded in baleen from a bowhead whale (Balaena mysticetus)
Rosalind M. Rolland, Katherine M. Graham, Raphaela Stimmelmayr, Robert S. Suydam, John C. George
We analyzed stress hormones at intervals along the length of a baleen plate from a bowhead whale that endured a severe, prolonged entanglement in fishing rope. This data was compared with baleen stress hormones from healthy, non-entangled bowhead whales. Hormones in the entangled whale were highly elevated over many months before death demonstrating that chronic stress was recorded in baleen. This study shows that baleen hormone analysis is a promising approach for long-term monitoring of stress physiology, with potential for assessing responses of bowheads to environmental changes and increased human activity occurring in the Arctic ecosystem.
Entanglement‐scar acquisition rates and scar frequency for Bering‐Chukchi‐Beaufort Seas bowhead whales using aerial photography
John C. “Craig” George, Barbara Tudor, Geof H. Givens, Julie Mocklin, Linda Vate Brattström
Our past studies of bowhead whales harvested by Alaskan Native hunters indicated that about 12% carry entanglement scars from Bering Sea crab and cod fisheries. This was higher than expected as they have only limited overlap with fisheries during winter. In our current study, we used aerial photo-recaptures spread over 26 years of live bowheads to determine how often they acquire scars. We found that a bowhead has a ~2.2% chance of hitting gear, escaping, and obtaining a scar each year. Since entanglements now pose the greatest threat to whales worldwide, we are working with fisheries to address this problem.
Bayesian estimation of group sizes for a coastal cetacean using aerial survey data
Charlotte Boyd, Roderick C. Hobbs, André E. Punt, Kim E. W. Shelden, Christy L. Sims, Paul R. Wade
Many marine mammal species aggregate in groups. Accurate estimation of group sizes is essential for estimating their abundance and distribution, but is challenging because individuals may be submerged or difficult to detect. We developed a new approach for estimating group sizes using aerial photographic or video imagery, and applied it to aerial survey data for beluga whales in Cook Inlet, Alaska. The role of aerial photographic and video data is expected to increase with the use of drones for wildlife assessment. Key aspects of our approach are relevant to a range of marine, freshwater, and terrestrial mammal and bird species.
First record of an unsuccessful parturition of a southern right whale (Eubalaena australis) at Península Valdés, Argentina
Mariano Sironi, Carina F. Marón, Luis Pettite, Justa Guevara, Juan Pablo Martorel, and Victoria Rowntree
We report a likely unsuccessful parturition of a southern right whale (Eubalaena australis) at Península Valdés, Argentina. Observations were made during a whale watch trip. During labor, the calf’s tailstock emerged from its mother, but later most of its body returned back inside. The calf did not move and the mother´s behavior could be described as unusual. The cow was later seen alone and then, in a mating group. We presume her calf was born dead or died shortly after birth. This is the first known observation of an apparent unsuccessful birth in a mysticete species in the wild
Phocoena sinus: A new hope?
Barbara L. Taylor, Randall S. Wells, Paula A. Olson, Robert L. Brownell Jr., Frances M. D. Gulland, Andrew J. Read, Francisco J. Valverde‐Esparza, Oscar H. Ortiz‐García,… See all authors
Photographs of vaquita taken in the falls of 2017 and 2018 reveal an identifiable individual that was mostlikely the mother of different calves each year. Historical data that were used to suggest that vaquitas calved every two years were reexamined and found not inconsistent with annual calving. All vaquitas seen in 2017 and 2018 were robust and several were calves. With fewer than 30 vaquitas remaining, the potential for higher birth rates provides new hope that if the accidental killing of vaquitas in illegal fisheries can be halted, the species can recover.
Unoccupied aerial system assessment of entanglement in Northwest Atlantic gray seals (Halichoerus grypus)
Maria Clara Iruzun Martins Lisa Sette Elizabeth Josephson Andrea Bogomolni Kathryn Rose Sarah M. Sharp Misty Niemeyer Michael Moore
Entanglement prevalences in hauled-out gray seals were estimated using Unmanned Aerial Systems (UAS) for the first time. In Massachusetts and Maine, U.S.A. Prevalences ranged from 0.83% to 3.7% which is high compared to other pinniped populations. The only identifiable material causing these entanglements was monofilament net, which reflects the presence of gillnet fisheries in New England waters. Gillnet ligatures around the necks of growing seals lacerate underlying vital structures and are a severe animal welfare concern. UAS are an important tool for detecting entanglements. This study advances our understanding of the conservation and animal welfare aspects of fisheries entanglements.
Taxonomic revision of the dolphin genus Lagenorhynchus
Nicole L. Vollmer, Erin Ashe, Robert L. Brownell Jr., Frank Cipriano, James G. Mead, Randall R. Reeves, Melissa S. Soldevilla, Rob Williams
Since the initial naming of the dolphin genus Lagenorhynchus over 150 years ago, evidence has been gradually building to suggest that the six species currently within this genus are not closely related to one another, and taxonomic revision is needed. Here we summarize evidence from morphology, genetics, historical biogeography, and acoustics supporting that this one genus should be split up into three: Lagenorhynchus, Leucopleurus, and Sagmatias. Renaming these genera will help to highlight the differences among them and provide a better understanding of their evolutionary relationships with other dolphin species.
A comparison of image and observer based aerial surveys of narwhal
Koen C. A. Bröke, Rikke G. Hansen, Kathleen E. Leonard, William R. Koski, Mads Peter Heide‐Jørgensen
A 1,932 km long aerial survey was conducted over Melville Bay, home to one of two summering narwhal populations off West Greenland. In addition to using observers, the aircraft was equipped with two cameras. Images were reviewed for narwhal sightings, which were then matched to observer sightings. The objective was to determine if both data sets would result in similar population abundance estimates. The abundance estimate based on the image sightings was 2,536, which was not significantly different from the aerial observers estimate of 2,596 individuals. This study supports the potential of using UAS for marine mammal abundance studies.