Recent sightings of the bowhead whale (Balaena mysticetus) in Northeast Greenland and the Greenland Sea

By the end of the 19th century, European whalers had brought the bowhead whale (Balaena mysticetus) in the “Spitsbergen stock” ranging the waters between eastern Greenland and the western Russian Arctic to the verge of extinction. This paper presents observations of this species in Northeast Greenland and in the Greenland Sea between 1940 and 2004. The number of observations has increased in Northeast Greenland since the mid-1980s. Only three observations are known for the period 1940–1979 but during the 1980s, the 1990s and between 2000 and 2004, six, six and eight observations of bowhead whales were made, involving an absolute minimum of three, five and eight to ten different individuals, respectively. It remains uncertain whether this represents an increase in survey effort, an immigration from other areas, a recent recovery of an eastern Greenland relict “tribe” belonging to the Spitsbergen stock, or a combination of these factors.     

Serology and virology of the bowhead whale (Balaena mysticetus L.)

Sera from four bowhead whales (Balaena mysticetus L.) were examined for the presence of specific antibodies, and tissue and swab samples from six and four animals respectively were processed for isolation of viruses and for initiation of bowhead whale cell cultures. All sera were negative for antibodies to nine serovars of Leptospira interrogans and to 21 orthomyxovirus subtypes and a paramyxovirus (Newcastle disease virus). All sera were positive, however, for neutralizing antibodies to one or more calicivirus serotypes. Two untyped adenoviruses were isolated from colon samples of two different whales, but neutralizing antibodies to the agents could not be demonstrated in any sera. Three primary bowhead whale cell cultures were derived from kidney (two cultures) and testis (one culture), from three individual whales.     

Captive killer whale (Orcinus orca) survival

Killer whales (Orcinus orca) were first placed into captivity in 1961 and are now found in theme parks around the world. Despite successful breeding of captive killer whales since 1985 there is growing concern for their welfare in captivity, which often includes claims of poor survival. We employed Kaplan‐Meier and Cox Proportional hazards models and annual survival rate analyses on 201 captive killer whales to discern how sex, facility (U.S. vs. foreign), captive‐born vs. wild‐captured, pre‐ vs. post‐1 January 1985, and animal age upon entering captivity affect survival. Overall median survival estimate was 6.1 yr, with no difference between male and female survival. Killer whales in U.S. facilities (12.0 yr) demonstrated a significantly higher median survival than those in foreign facilities (4.4 yr), as did whales entering captivity post‐1 January 1985 (11.8 yr) vs. those entering prior to 1 January 1985 (3.9 yr). Median survival for captive‐born (14.1 yr) was significantly higher than wild‐captured killer whales (5.5 yr), though the two failed to differ among the post‐1 January 1985 cohort. Facility location and pre‐ vs. post‐1 January 1985 were predictors of the hazard rate. Survival of captive killer whale cohorts has generally improved through time, although survival to age milestones are poor when compared to wild killer whales.     

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.     

Microflora associated with the skin of the bowhead whale (Balaena mysticetus)

A study of the microbiological flora isolated from cultures of normal and lesional skin tissue samples collected from 19 bowhead whales (Balaena mysticetus) over a 4 yr period is presented. These cultures were obtained from 30 tissue samples (17 normal, 13 lesion) and 248 swab samples (157 normal, 91 lesion). Seven hundred-thirty bacterial and yeast isolations were made (285 normal, 445 lesion). Distribution revealed that 56% of the gram positive bacterial isolates, 75% of the gram negative bacterial isolates and 64% of the yeast isolates recovered were associated with lesional skin. It was found that 80% of one group of Corynebacterium sp. isolates, 90% of the Acinetobacter sp. isolates and 94% of the Moraxella sp. isolates were associated with lesional skin. Although the primary yeasts recovered were Candida spp., they were found on both normal and lesional skin. Enzymatic assays of isolates from normal and lesional skin demonstrated production of enzymes capable of causing necrosis. The majority of the microorganisms recovered were facultative anaerobes and many of them could be considered potential pathogens of mammalian hosts.     

Olfaction and brain size in the bowhead whale (Balaena mysticetus)

Although there are several isolated references to the olfactory anatomy of mysticetes, it is usually thought that olfaction is rudimentary in this group. We investigated the olfactory anatomy of bowhead whales and found that these whales have a cribriform plate and small, but histologically complex olfactory bulb. The olfactory bulb makes up approximately 0.13% of brain weight, unlike odontocetes where this structure is absent. We also determined that 51% of olfactory receptor genes were intact, unlike odontocetes, where this number is less than 25%. This suggests that bowheads have a sense of smell, and we speculate that they may use this to find aggregations of krill on which they feed.     

Behaviour and kinematics of continuous ram filtration in bowhead whales (Balaena mysticetus)

Balaenid whales perform long breath-hold foraging dives despite a high drag from their ram filtration of zooplankton. To maximize the volume of prey acquired in a dive with limited oxygen supplies, balaenids must either filter feed only occasionally when prey density is particularly high, or they must swim at slow speeds while filtering to reduce drag and oxygen consumption. Using digital tags with three-axis accelerometers, we studied bowhead whales feeding off West Greenland and present here, to our knowledge, the first detailed data on the kinematics and swimming behaviour of a balaenid whale filter feeding at depth. Bowhead whales employ a continuous fluking gait throughout the bottom phase of foraging dives, moving at very slow speeds (less than 1 m s⁻¹), allowing them to filter feed continuously at depth. Despite the slow speeds, the large mouth aperture provides a water filtration rate of approximately 3 m³ s⁻¹, amounting to some 2000 tonnes of water and prey filtered per dive. We conclude that a food niche of dense, slow-moving zooplankton prey has led balaenids to evolve locomotor and filtering systems adapted to work against a high drag at swimming speeds of less than 0.07 body length s⁻¹ using a continuous fluking gait very different from that of nekton-feeding, aquatic predators.     

Nursing parameters in captive killer whales (Orcinus orca)

We examined nursing behaviors for a population of captive‐born killer whales (four females, three males) at SeaWorld parks from birth until 90 days of age. Nursing parameters examined included cumulatives of suckles per day, bouts per day, and suckle duration (seconds) per day. Daily cumulatives of all nursing parameters peaked within the first 2 days after birth then decreased through time. For the ages from birth until 42 days, data were converted using log_e‐log_e transformations to allow linear regression modeling. Since these parameters were characterized by autocorrelation, bootstrapping was used to obtain parameter estimates for comparisons between sexes and cow parity. Both males and females, as well as calves born to primiparous and multiparous cows, exhibited similar nursing patterns. However, there were statistically significant differences (α < 0.05) between the regression equations among most of the nursing parameters examined. Cumulative frequencies and amounts from birth through 42 days of age for all nursing parameters were examined. Means were statistically similar (α > 0.05) between genders (means[sd] for males and females, respectively; suckles 3,772.7[412.4] and 3,276.3[1,226.5]; bouts 1,238.3[189.0] and 1,103.3[96.4]; suckle duration [seconds] 28,990.7[5,861.9] and 29,233.0[5,255.0]) and cow parity (means[sd] for primiparous and multiparous, respectively; suckles 4,459.0[606.7] and 3,101.0[753.8]; bouts 1,240.0[243.3] and 1,129.6[116.2]; suckle duration [seconds] 32,415.0[5,212.8] and 27,814.8[4854.5]). Equal amounts of nursing occurred from both left and right mammary glands for the 42‐day time period (means[sd] [seconds] for left and right, respectively; 13,800.4[2,787.0] and 15,328.7[2,471.0]; P = 0.30). Zoo Biol 18:373–384, 1999. © 1999 Wiley‐Liss, Inc.     

Dental care for a captive killer whale,Orcinus orca

The crowns of several teeth of a captive killer whale, particularly on the mandible, were worn to the level of the pulp cavities by biting a cement structure in the pool. Food plugging partially vacant pulp cavities created intense vascularization, inflammation, and eventually a systemic focus for infection. This trauma correlated with an elevated white blood cell count. Haematology was restored to normal following regular care for the worn teeth. Patent drainage of the pulp cavity was maintained through routine brushing with a large-scale toothbrush. Administration of antibiotics was not necessary in controlling the white blood cell count.     

Observations on the anatomy of the stomach and duodenum of the bowhead whale, Balaena mysticetus

Gastric and cranial duodenal structure of the bowhead whale (Balaena mysticetus) was examined grossly and microscopically. The stomach was arranged in a series of four compartments. The first chamber, or forestomach, was a large nonglandular sac lined by a keratinized stratified squamous epithelium. It was followed by the fundic chamber, a large, somewhat globular and entirely glandular compartment. At the entrance of the fundic chamber, a narrow cardiac gland region could be defined. The remaining mucosa of the chamber contained the proper gastric glands. A narrow, tubular connecting channel, the third distinct gastric division, was lined by mucous glands and joined the fundic chamber with the final stomach compartment, or pyloric chamber. This fourth chamber was also tubular and lined by mucous glands but was of a diameter considerably larger than the connecting channel. The stomach terminated at the pyloric sphincter which consisted of a well-developed band of circular smooth-muscle bundles effecting a division between the pyloric chamber and small intestine. The small intestine began with the duodenal ampulla, a dilated sac considerably smaller than the fundic chamber of the stomach. The mucosa of this sac contained mucous glands throughout. The ampulla led without a separating sphincter into the duodenum proper which continued the intestine in a much more narrow tubular fashion. The mucosal lining of the duodenum was composed of villi and intestinal crypts. Although their occurrence varied among whales, enteroendocrine cells were identified within the mucous glands of the cardiac region, connecting channel, pyloric chamber, and cranial duodenum. The hepatopancreatic duct entered the wall of the duodenum shortly after the termination of the duodenal ampulla and continued intramurally along the intestine before finally joining the duodenal lumen.     

Fractured mandible and associated oral lesions in a subsistence-harvested bowhead whale (Balaena mysticetus)

A fractured right mandible with midlength nonunion and oral lesions were noted in a subsistence-harvested female bowhead whale (Balaena mysticetus) near Wainwright, Alaska (USA). The cause of the fracture was not apparent. The fracture resulted in misalignment of the mandible. The abnormal mobility at the fracture site probably caused irregular baleen stowage within the oral cavity, leading to breakage of many baleen plates and extensive ulceration of the tongue and lips. Good body condition suggested the fracture was not debilitating.     

Survival of bowhead whales,Balaena mysticetus,estimated from 1981-1998 photoidentification data

Annual survival probability of bowhead whales, Balaena mysticetus, was estimated using both Bayesian and maximum likelihood implementations of Cormack and Jolly-Seber (JS) models for capture-recapture estimation in open populations and reduced-parameter generalizations of these models. Aerial photographs of naturally marked bowheads collected between 1981 and 1998 provided the data. The marked whales first photographed in a particular year provided the initial 'capture' and 'release' of those marked whales and photographs in subsequent years the 'recaptures'. The Cormack model, often called the Cormack-Jolly-Seber (CJS) model, and the program MARK were used to identify the model with a single survival and time-varying capture probabilities as the most appropriate for these data. When survival was constrained to be one or less, the maximum likelihood estimate computed by MARK was one, invalidating confidence interval computations based on the asymptotic standard error or profile likelihood. A Bayesian Markov chain Monte Carlo (MCMC) implementation of the model was used to produce a posterior distribution for annual survival. The corresponding reduced-parameter JS model was also fit via MCMC because it is the more appropriate of the two models for these photoidentification data. Because the CJS model ignores much of the information on capture probabilities provided by the data, its results are less precise and more sensitive to the prior distributions used than results from the JS model. With priors for annual survival and capture probabilities uniform from 0 to 1, the posterior mean for bowhead survival rate from the JS model is 0.984, and 95% of the posterior probability lies between 0.948 and 1. This high estimated survival rate is consistent with other bowhead life history data.     

Stomach contents of bowhead whales (Balaena mysticetus) from four locations in the Canadian Arctic

The stomach contents of four bowhead whales (Balaena mysticetus) harvested between 1994 and 2008 from the Canadian Arctic were examined to assess diet composition. Three samples were collected from bowhead whales of the Eastern Canada–West Greenland (EC–WG) population and represent, according to our knowledge, the first diet analysis from this bowhead whale stock. We also examined the stomach content of one bowhead whale from the Bering-Chukchi-Beaufort (BCB) population hunted in 1996. All four whales had food in their stomachs and their diet varied from exclusively pelagic (BCB whale), with Limnocalanus macrurus being the main prey, to epibenthic and benthic (EC–WG) with Mysis oculata playing an important role. These results indicate broad foraging spectrum of the bowhead whales and add to a basic knowledge of their diet.     

Salmonella Newport omphaloarteritis in a stranded killer whale (Orcinus orca) neonate

Salmonella enterica serovar Newport (Salmonella Newport) was isolated from multiple tissues in a neonate killer whale (Orcinus orca) that stranded dead in 2005 along the central coast of California, USA. Necrotizing omphaloarteritis and omphalophlebitis was observed on histologic examination suggesting umbilical infection was the route of entry. Genetic analysis of skin samples indicated that the neonate had an offshore haplotype. Salmonellosis has rarely been identified in free-ranging marine mammals and the significance of Salmonella Newport infection to the health of free-ranging killer whales is currently unknown.