The extracranial arterial system in the heads of beaked whales,with implications on diving physiology and pathogenesis

Beaked whales are medium‐sized toothed whales that inhabit depths beyond the continental shelf; thus beaked whale strandings are relatively infrequent compared to those of other cetaceans. Beaked whales have been catapulted into the spotlight by their tendency to strand in association with naval sonar deployment. Studies have shown the presence of gas and fat emboli within the tissues and analysis of gas emboli is suggestive of nitrogen as the primary component. These findings are consistent with human decompression sickness (DCS) previously not thought possible in cetaceans. Because, tissue loading with nitrogen gas is paramount for the manifestation of DCS and nitrogen loading depends largely on the vascular perfusion of the tissues, we examined the anatomy of the extracranial arterial system using stranded carcasses of 16 beaked whales from five different species. Anatomic regions containing lipid and/or air spaces were prioritized as potential locations of nitrogen gas absorption due to the known solubility of nitrogen in adipose tissue and the nitrogen content of air, respectively. Attention was focused on the acoustic fat bodies and accessory sinus system on the ventral head. We found much of the arterial system of the head to contain arteries homologous to those found in domestic mammals. Robust arterial associations with lipid depots and air spaces occurred within the acoustic fat bodies of the lower jaw and pterygoid air sacs of the ventral head, respectively. Both regions contained extensive trabecular geometry with small arteries investing the trabeculae. Our findings suggest the presence of considerable surface area between the arterial system, and the intramandibular fat bodies and pterygoid air sacs. Our observations may provide support for the hypothesis that these structures play an important role in the exchange of nitrogen gas during diving. J. Morphol. 277:5–33, 2016. © 2015 Wiley Periodicals, Inc.     

Characterization of 25 microsatellite loci in bowhead whales (Balaena mysticetus)

Bowhead whales (Balaena mysticetus) experienced a severe demographic population bottleneck caused by commercial whaling that ceased in 1914. Aboriginal subsistence whale harvests have continued and are managed by the International Whaling Commission. In an effort to provide management advice for bowhead whales, 25 microsatellite loci were isolated from genomic DNA libraries. This panel of markers will be utilized to analyse stock structure hypotheses of current bowhead whale populations.     

Movements of satellite-monitored humpback whales on their feeding ground along the Antarctic Peninsula

Humpback whales were instrumented with satellite transmitters off the western Antarctic Peninsula in January of 2004–2006 to examine their movement patterns and habitat use. Whales were tracked from 4 to 80 days (mean = 36.5 days). Distance and travel rate estimates for nine individuals ranged from 223 to 4,356 km and from 17 to 75 km/day, respectively. Considerable individual variation was observed in direction, speed and range of movements. The overall pattern was characterized by short- and long-distance movements between presumed foraging areas with relatively short residency times. Travel rates were lower at these sites, characterized by erratic movements, than during traveling between them. Area usage for six individuals based on the 95% fixed kernel home range with least squares cross-validation ranged from 2,771 to 172,356 km². The management boundary between the feeding grounds associated with Breeding Stocks G and A needs revision, as current available data suggest it should be located to the east of 50°W. This study is the first to present detailed information on the movements of humpback whales in the Southern Ocean.     

KILLER WHALE ATTACKS ON MINKE WHALES: PREY CAPTURE AND ANTIPREDATOR TACTICS

We describe nine incidents of predation or attempted predation of minke whales ( Balaenoptera acutorostrata ) by mammal-hunting "transient" killer whales ( Orcinus orca ) in coastal waters of British Columbia, Washington, and southeastern Alaska. Pursuits of minke whales were characterized by prolonged chases on a straight heading at velocities of 15–30 km/h. In four of the nine cases the adultsized minke whale gradually outdistanced the killer whales, which abandoned the high-speed pursuit after 0.5–1 h. In one case the minke beached itself and died. Four attacks were successful. In one instance a subadult minke was killed in open water following a chase. In two cases the fleeing minke entered a confined bay and was killed by the killer whales. One adult minke was taken after apparently attempting to seek cover beside a large sailboat. Minke whales made no attempt to physically defend themselves and were killed by repeated ramming or by asphyxiation. Although killer whales are capable of sprinting speeds greater than those of minke whales, it appears that adult minkes can maintain higher sustained speeds and evade capture if sufficient space for an extended escape trajectory is available. Successful predation of minke whales in coastal waters is rare compared to pinnipeds and small cetaceans, the main prey of transient killer whales.     

ANALYSIS OF MITOCHONDRIAL DNA DIVERSITY WITHIN AND BETWEEN NORTH AND SOUTH ATLANTIC RIGHT WHALES

DNA sequences of the mitochondrial control region of 180 North Atlantic right whales ( Euhalaena glacialis ) and 16 South Atlantic right whales ( E. australis ) have been determined using a combination of direct DNA sequencing and single stranded conformation polymorphism (SSCP) analysis. Five haplotypes were found in E. glacialis , and 10 in E. australis , but none were shared, supporting the reproductive isolation and separate species status of the North and South Atlantic right whales. One haplotype in E, glacialis was found in only three males born before 1982 and this matriline will likely be lost soon. The nucleotide diversity estimates for the five North Atlantic right whale haplotypes was 0.6% and 2.0% for the 10 haplotypes found in the South Atlantic right whales. The average haplotypic diversity was 0.87 in E. glacialis and 0.96 in E. australis , which is consistent with other studies showing a lower level of genetic variation in the North Atlantic right whale. Phylogenetic analysis identified two major assemblages of haplotypes in E. australis from the samples collected from Peninsula Valdes, suggesting a mixing of two historically divergent populations. Using genetic distance measurements with a divergence rate of 0.5%–1.0%/myr, we estimate E. glacialis diverged from E. australis 3–12.5 mya.     

Confirmation of right whales near a nineteenth-century whaling ground east of southern Greenland

North Atlantic right whales (Eubalaena glacialis) were found in an important nineteenth century whaling area east of southern Greenland, from which they were once thought to have been extirpated. In 2007-2008, a 1-year passive acoustic survey was conducted at five sites in and near the 'Cape Farewell Ground', the former whaling ground. Over 2000 right whale calls were recorded at these sites, primarily during July-November. Most calls were northwest of the historic ground, suggesting a broader range in this region than previously known. Geographical and temporal separation of calls confirms use of this area by multiple animals.     

Species recognition as a possible function for variations in position and shape of the sexually dimorphic tusks of Mesoplodon whales

Beaked whales of the genus Mesoplodon are characterized by the presence of a single pair of sexually dimorphic tusks. Variation in the position and shape of these tusks was examined in four sympatric species and was found to be consistent with the hypothesis that these differences may have evolved to aid species recognition between sympatric and otherwise morphologically similar species of this genus.     

Sperm whales (Physeter macrocephalus), found stranded along the Adriatic coast (Southern Italy,Mediterranean Sea), as bioindicators of essential and non-essential trace elements in the environment

In September 2014, a pod of seven sperm whales (Physeter macrocephalus) was stranded along the Adriatic coast of Southern Italy. Concentrations of 20 essential and non-essential trace elements were quantified in the brain, muscle, liver and kidneys of three female sperm whales, which died in this event.The essential elements copper, iron, manganese and zinc showed low ranges of variability, suggesting a homeostatic physiological control, while selenium concentrations were associated with age. Molybdenum, nickel and chromium showed low ranges of concentrations and no evidence of preferential accumulation in selected organs. Very low concentrations of the non-essential elements cadmium, lead, tin and vanadium were detected in all tissues, suggesting a minor impact of these pollutants on the sperm whale populations of the Mediterranean Sea. Aluminum was revealed to have relatively high concentrations, together with a high variability between tissues and individuals, reaching the highest values in the kidneys and muscle of the oldest female, which was pregnant; the rare earth elements – lanthanum and cerium – were also detected in the kidneys of this female, indicating that pregnancy probably influenced metal concentrations in body tissues.