Hunting and cooperative foraging behavior of Galapagos sea lion: An attack to large pelagics
Diego Páez‐Rosas, Leandro Vaca, Roberto Pepolas, Richard Wollocombe, Tui De Roy, Gonzalo Rivas‐Torres
The Galapagos sea lion is one of the few otariids adapted to tropical ecosystems. Since this species lives in an environment with greater uncertainty in terms of marine productivity, it is constantly exposed to variation in the availability of its main prey, a condition that leads to nutritional stress scenarios. This variability in its environment has resulted in different adaptations relating to foraging strategies. Because of the high energetic demand, altruism or collaboration is scarce in these species; however, there may be occasions where these animals form groups aimed at exploiting certain resources, as reported in this work.
Unexpected mid‐winter presence of harbor porpoises (Phocoena phocoena) in Kotzebue Sound, Alaska
Alex Whiting, Manuel Castellote, Robert J. Small, Kathryn J. Frost, Robert Suydam
Arctic marine mammals are difficult to monitor. Underwater sound recordings can be used to document their presence. A study was completed in 2014-2015 in Kotzebue Sound, Alaska, using acoustic moorings. The goal was to detect beluga whales, yet unexpectedly harbor porpoise were also detected. The most notable detections occurred during winter in January, February, and March 2015 when much of Kotzebue Sound was covered in ice. This is the first instance of harbor porpoises having been reported during winter in the Alaska Arctic. Their winter presence is likely related to a dramatic declining trend in ice coverage in Kotzebue Sound.
A Southern Ocean archipelago enhances feeding opportunities for a krill predator
Lisa‐Marie K. Harrison, Kimberly Goetz, Martin J. Cox, Robert Harcourt
Marine predators including whales are often found to feed close to oceanographic and bathymetric features such as fronts and islands. We conducted a five-day visual and acoustic survey of a remote Antarctic feeding area, the Balleny Islands (67oS, 164oE), to look at the relationship between Antarctic krill (Euphausia superba) density and humpback whale (Megaptera novaeangliae) presence. We found stark differences between krill swarms near the islands and those in adjacent open water with swarms twice as dense and three times as numerous suggesting that the islands provide profitable feeding habitat for whales.
Visual and passive acoustic observations of blue whale trios from two distinct populations
Elena Schall, Lucia Di Iorio, Catherine Berchok, Diego Filún, Luis Bedriñana‐Romano, Susannah J. Buchan, Ilse Van Opzeeland, Richard Sears, Rodrigo Hucke‐Gaete
For many blue whale (Balaenoptera musculus) populations the timing and location of breeding activities still remains unclear and opportunistic breeding strategies might be common. Here, we report on a distinct vocal behavior in blue whales recorded in a reproductive context. During three encounters, three adult blue whales engaged in vigorous chasing behavior. In two cases one female and two males were involved in the behavioral events. In all three cases the acoustic behavior was highly similar, including the repetition of one specific vocalization. Our findings suggest that this commonly produced vocalization also serves a function in reproductive contexts
Intraskeletal variability in stable isotope ratios of C and N among pinnipeds and cetaceans
Maria Bas, Néstor A. García, Enrique A. Crespo, Luis Cardona
There are several unsettled issues related to bone tissue stable isotope analysis when dealing with archaeological samples from marine mammals: chemical treatments and the combination of skeletal elements. This research has allowed us to know that combined chemical treatments have a strong influence in both δ13C and δ15N values. Furthermore, the δ15N values of skeletal elements from the distal part of the appendicular skeleton may differ from those of other skeletal elements; and the δ13C values of the skeletal elements consisting of only cortical bone may differ significantly from those of the skeletal elements made up of both of cortical and trabecular bone
Evaluating the power of photogrammetry for monitoring killer whale body condition
Holly Fearnbach, John Durban, Lance Barrett-Lennard, David Ellifrit, and Kenneth Balcomb
We used aerial photogrammetry to track changes in body condition of Southern Resident killer whales. Recovery actions for this endangered population focus on restoring priority runs of Chinook salmon prey, requiring information on seasonal differences in whale body condition. We used an unmanned hexacopter to collect aerial images in alternating May and September sampling periods and compared the power of two photogrammetry metrics to infer condition changes. One of these had significantly lower measurement variability and greater power to reveal poorer condition in May, highlighting the importance of considering the power of photogrammetry metrics to fill specific data gaps.
Quantifying spatial and temporal variation of North Pacific fin whale (Balaenoptera physalus) acoustic behavior
Frederick I. Archer, Shannon Rankin, Kathleen M. Stafford, Manuel Castellote, Julien Delarue
We present a new method for analyzing fin whale calls. This method uses a machine learning algorithm to classify the unique notes that fin whales produce. A second stage then numerically describes sequences of notes by summarizing the proportion of note patterns as well as how much they are clumped in each sequence. This method allows for sequences of any length or composition to be compared to each other and avoids most of the human subjectivity of traditional acoustic analyses. We use the method to demonstrate potential connections between fin whales in several regions across the North Pacific.
Defining areas of intensive foraging activity for a top marine predator, the Antarctic fur seal: Compromises between effort and accuracy
Fabien Vivier, Christophe Guinet, Tiphaine Jeanniard‐du‐Dot
Conservation of species requires knowing where animals feed and breed to implement effective zoning and protection plans. Progress in biologging brings increasingly finer-scale of such information but with the compromise of greater resource costs. Do more detailed information result in more accurate Areas of Intensive Foraging Activity (AIFA) than traditional tracking? We tested this on 18 Antarctic fur seals. AIFA were spatially determined from geographical occupancy (GPS), dive (dive depth), and feeding event (acceleration) locations, i.e. increasingly detailed but costly information. Comparisons between all AIFA revealed that simpler geographical occupancy were sufficient to establish efficient AIFA for the marine predator.
Food for thought: Harbor porpoise foraging behavior and diet inform vulnerability to disturbance
Cormac G. Booth
Porpoises are thought to be vulnerable to starvation when disturbed due to their need for regular food. This study used data from novel tags put on wild animals and information on porpoise diet (like calories in different fish species they eat), to explore whether animals obtained enough energy. In all but the worst-case scenarios, harbor porpoises got the required energy due to their broad diet (consisting of many medium and high energy fish) and high feeding rates. If animals can find suitable prey, porpoises may be capable of recovering from some disturbances.
The Antillean manatee (Trichechus manatus manatus) in the southern Caribbean: A compilation and review of records for the Dutch Leeward islands and the central Venezuelan coast
Adolphe O. Debrot, Luigi Eybrecht, Emily Dawson, Jenny Cremer, Ruud Stelten
We report the first-known Antillean manatee sighting record for Bonaire and an early Dutch colonial reference to this species for Curaçao, southern Caribbean. We also update manatee records for the adjacent central coast of Venezuela. The relatively high concentration of manatee records in the Leeward Dutch islands suggests nonrandom dispersal of straying animals. The documented existence of counter currents, wind-induced upwelling, and off-shore transport of waters along this section of the Venezuelan coast likely play a role. The Lake Maracaibo population seems to be the most likely nearby source of the manatees seen in the Dutch Leeward islands.
Insights into the use of an unmanned aerial vehicle (UAV) to investigate the behavior of (Megaptera novaeangliae) in Vava’u, Kingdom of Tonga
Lorenzo Fiori, Emmanuelle Martinez, Martin K.‐F. Bader, Mark B. Orams, Barbara Bollard
Multi-rotor drones can be used to measure whales and investigate their behavior. However, the potential disturbance for the targeted whales have been investigated only recently. We compared drone and boat-based observations of humpback whales in Vava’u, Kingdom of Tonga. Interestingly, behaviors such as socializing and nurturing were not detected by observers onboard the research vessel, but were evident from the drone. The drone flying at 30 m altitude appeared to did not appear to elicit changes of whale respiration and diving parameters. These results suggest that drones can be a noninvasive tool to gather morphometric and behavioral data on baleen whales.
Risky business? A note on repeated live strandings of common bottlenose dolphins (Tursiops truncatus) while foraging in a shallow water environment
Barry McGovern, Tess Gridley, Bridget S. James, Simon Elwen
Namibia is home to a population of fewer than 100 bottlenose dolphins which regularly hunt in very shallow waters. Since 1991, there have been 13 live strandings, all within a shallow tidal lagoon often used for foraging. Human intervention occurred in ten of these, assisting 47 dolphins. At least 96% of identified individuals were alive 1 year after refloating and 60% alive more than five years later. The lagoon is silting up due to human and natural changes. We discuss the role of human intervention in strandings and environmental risk assessment by wild animals in a changing environment
Age and growth analyses for the endangered belugas in Cook Inlet, Alaska
Daniel J. Vos, Kim E. W. Shelden, Nancy A. Friday, Barbara A. Mahoney
Belugas in Cook Inlet, Alaska, (CIBs) are endangered and isolated from other beluga populations. It is important to understand how long CIBs live and at what age they mate and calve. Belugas have only one set of teeth in their lifetime. Similar to rings in a tree, CIB teeth add a line of dentine each year. Teeth from dead CIBs were thin-sectioned, viewed under a microscope, and the lines counted. We found teeth from the back of the lower jaw (position 8-9) provided the best ages. Comparing ages and body lengths showed sexual dimorphism, with male CIBs larger than females
Serum antibodies against Toxoplasma gondii and Neospora caninum in southeast Queensland dugongs
Arthur Wong, Janet M. Lanyon, Ryan O’Handley, Richard Linedale,Lucy Woolford, Trevor Long, Graham R. Leggatt
Dugongs are vulnerable to pollutants and terrestrial pathogens that enter seagrass systems in terrestrial runoff, particularly near urban agricultural and industrial center. This study investigated whether dugongs along the urbanized south-east Queensland Australia, had been exposed to the terrestrial pathogens, T. gondii and N. caninum. Over the period 2008 to 2014, blood from wild dugongs was tested for the presence of IgG antibodies specific to these pathogens. A rise in antibody levels to T. gondii occurred in dugongs after a major Queensland flood event in 2011, suggesting that risk of exposure to this pathogen coincides with coastal runoff events.
Fine‐scale sociality reveals female–male affiliations and absence of male alliances in bottlenose dolphins (Tursiops truncatus) in the Shannon Estuary, Ireland
Isabel Baker, Joanne O’Brien, Katherine McHugh, Simon Berrow
This is the most detailed study so far of the sociality of a population of wild bottlenose dolphins in the Shannon Estuary, Ireland. It examines associations between members of the whole population and between specific female and male dolphins. Average group size was seven, with groups changing composition roughly three times an hour. Pairs of dolphins were most frequently female-male; males spent more time with female nearest-neighbors. Female and male dolphin activity budgets were similar. There was no evidence for male alliance formation. This research reveals a distinct bottlenose dolphin society with female-male affiliations and an absence of male alliances.
Differences in regional oceanography and prey biomass influence the presence of foraging odontocetes at two Atlantic seamounts
Miriam Romagosa Carlos Lucas, Sergi Pérez‐Jorge, Marta Tobeña, Patrick Lehodey, Jesus Reis, Irma Cascão, Marc O. Lammers, Rui M. A. Caldeira, Mónica A. Silva
Seamounts can be foraging hotspots for cetaceans by concentrating prey through different oceanographic process that are still unclear. Results from this comparative study find more detections of cetaceans and predicted prey biomass in Atlantis than in Irving (two seamounts of the Northeast Atlantic) that can be explained by their different oceanographic settings. Atlantis is in a colder and less saline water mass than Irving and is affected by the Azores current, while Irving is only affected by transient features that temporarily enhance productivity. These conditions translate into more productive waters at Atlantis than at Irving, that ultimately attract top predators.
Behavioral responses of satellite tracked Blainville’s beaked whales (Mesoplodon densirostris) to mid‐frequency active sonar
Trevor W. Joyce, John W. Durban, Diane E. Claridge, Charlotte A. Dunn, Leigh S. Hickmott, Holly Fearnbach, Karin Dolan, David Moretti
Beaked whales have shown particular vulnerability intense sound exposure, which has led to interest in how they respond behaviorally to naval sonar. We tracked seven individual Blainville’s beaked whales (Mesoplodon densirostris) during a series of naval training exercises in the Bahamas using satellite transmitting tags. Most of these individuals moved away from the sonar sources (e.g., surface ships and helicopter-dipped sonars) and as a result of their movements experienced declines in sound intensity levels. Individuals continued to undertake deep dives suggestive of foraging during these displacements, but with some suggestion of a reduction in deep dives during initial exposure.
Morphometric analysis of Chilean blue whales and implications for their taxonomy
Luis A. Pastene, Jorge Acevedo, Trevor A. Branch
Southern Hemisphere blue whales are divided into two subspecies, Antarctic and pygmy blue whales. The name ‘pygmy blue whales’ was originally proposed in the 1960’s based on biological analyses of whales caught in the southern Indian Ocean. Several morphometric measurements of Chilean blue whales in this study are intermediate between pygmy and Antarctic blue whales. Furthermore, fluke-anus lengths of Chilean blue whales are significantly different from pygmy blue whales. These data confirm that Chilean blue whales are a distinct population or subspecies that require separate management from other blue whale populations and should not be called ‘pygmy blue whales’.
Estimating narwhal (Monodon monoceros) age using tooth layers and aspartic acid racemization of eye lens nuclei
Cortney A. Watt, Barbara E. Stewart, Lisa Loseto, Thor Halldorson, Steven H. Ferguson
In this study we compared the ages of narwhals using two methods 1) traditional tooth counting growth layer groups (GLG) in embedded tusks present in both males and females, and 2) new eye aspartic acid racemization estimating changes in the ratio of two forms of aspartic acid (D and L) in the eye lens nucleus. Estimated tooth ages for 7 narwhals ≤15 yr significantly correlated with aspartic acid D/L ratios. Our study included more younger GLG-aged animals than previously evaluated and supports the novel use of aspartic acid racemization for aging narwhal.
Killer whales (Orcinus orca) feeding on lumpfish (Cyclopterus lumpus) in northern Norway
Eve Jourdain, Richard Karoliussen, Jacques de Vos, Stanislav E. Zakharov, Christelle Tougard
Five years of observations revealed the lumpfish (or lumpsucker) as an additional seasonal prey to killer whales in northern Norway. Also known as herring-eaters, 75 individual killer whales repeatedly returned to the same habitat during spring and showed specialized behavior for feeding on lumpfish, after the herring had departed south to their spawning areas. This study shows that Norwegian killer whales switch prey depending on what is available. Our findings add to the knowledge about important prey and habitat to killer whales in this region and are therefore relevant to conservation
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.