Bowhead Research Articles

Estimating abundance of Eastern Canada-West Greenland bowhead whales using genetic mark-recapture analyses

The Eastern Canada-West Greenland (EC-WG) bowhead whale (Balaena mysticetus) population is widely distributed across the eastern Canadian Arctic and across Baffin Bay to the western coast of Greenland. Their vast distribution makes obtaining population estimates via aerial surveys difficult, as coverage over their entire range is not possible. Genetic mark recapture analyses address this issue, as biopsy samples can be collected at various locales across the EC-WG bowhead whale population’s distribution and microsatellites can be analyzed to identify unique individuals. EC-WG bowhead whales were subject to intense commercial whaling pressure between the early 1700 s and early 1900 s, after which a moratorium on commercial whaling was put in place in 1915. We used available genetic samples from EC-WG bowhead whales in mark recapture models to estimate population abundance from 2012 to 2021 to gain insight on population dynamics ∼100 years post commercial whaling. The preferred model, using a Jolly-Seber structure, estimated the total abundance as 5173 individuals (CI: 3436–7788). Since the cessation of commercial whaling, the population has been thought to be rebounding, which is reflected by gradually increasing abundance estimates, from the low hundreds in the 1970 s and 1980 s, to ∼6000 in the early 2000 s, but our present estimate suggests population abundance may be plateauing well below the pre-commercial whaling carrying capacity estimate. This population estimate for EC-WG bowhead whales is required to update the population dynamics for conservation efforts.

First filter feeding in the Early Triassic: cranial morphological convergence between Hupehsuchus and baleen whales

Modern baleen whales are unique as large-sized filter feeders, but their roles were replicated much earlier by diverse marine reptiles of the Mesozoic. Here, we investigate convergence in skull morphology between modern baleen whales and one of the earliest marine reptiles, the basal ichthyosauromorph Hupehsuchus nanchangensis, from the Early Triassic, a time of rapid recovery of life following profound mass extinction. Two new specimens reveal the skull morphology especially in dorsal view. The snout of Hupehsuchus is highly convergent with modern baleen whales, as shown in a morphometric analysis including 130 modern aquatic amniotes. Convergences in the snout include the unfused upper jaw, specialized intermediate space in the divided premaxilla and grooves around the labial margin. Hupehsuchus had enlarged its buccal cavity to enable efficient filter feeding and probably used soft tissues like baleen to expel the water from the oral cavity. Coordinated with the rigid trunk and pachyostotic ribs suggests low speeds of aquatic locomotion, Hupehsuchus probably employed continuous ram filter feeding as in extant bowhead and right whales. The Early Triassic palaeoenvironment of a restrictive lagoon with low productivity drove Hupehsuchus to feed on zooplankton, which facilitated ecosystem recovery in the Nanzhang-Yuan’an Fauna at the beginning of the Mesozoic.

Risk factors for neck pain in college students: a systematic review and meta-analysis

BackgroundDuring the COVID-19 epidemic, the prevalence of neck pain among college students has increased due to the shift from offline to online learning and increasing academic and employment pressures. Therefore, this systematic review aimed to identify the personal, occupational, and psychological factors associated with the development of neck pain to promote the development of preventive strategies and early intervention treatment.MethodsSeven electronic databases were searched from inception to December 2022 for cross-sectional studies, cohort studies, case­­-­control studies, and randomized controlled trials (RCTs) on neck pain. The quality of the selected studies were assessed by American Agency for Healthcare Research and Quality (AHRQ) or the Newcastle-Ottawa Scale (NOS). Pooled odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were calculated to evaluate the effects of the included risk factors on neck pain.ResultsThirty studies were included, including 18,395 participants. And a total of 33 potentially associated risk factors were identified. Ultimately, 11 risk factors were included in the meta-analysis after assessing, and all results were statistically significant (P < 0.05). The factors supported by strong evidence mainly include the improper use of the pillow (OR = 2.20, 95% CI: 1.39 to 3.48), lack of exercise (OR = 1.88, 95% CI: 1.53 to 2.30), improper sitting posture (OR = 1.97, 95% CI: 1.39 to 2.78), history of neck and shoulder trauma (OR = 2.32, 95% CI: 1.79 to 3.01), senior grade (OR = 2.86, 95% CI: 2.07 to 3.95), staying up late (OR = 1.80, 95% CI: 1.35 to 2.41), long-time electronic product usage daily (OR = 1.53, 95% CI: 1.33 to 1.76), long-time to bow head (OR = 2.04, 95% CI: 1.58 to 2.64), and emotional problems (OR = 2.09; 95% CI: 1.66 to 2.63). Risk factors supported by moderate evidence were high stress (OR = 1.61, 95% CI: 1.02 to 2.52) and female gender (OR = 1.69, 95% CI: 1.52 to 1.87).ConclusionThis study obtained 11 main risk factors affecting college students neck pain, including improper use of the pillow, lack of exercise, improper sitting posture, history of neck and shoulder trauma, senior grade, staying up late, long-term electronic product usage daily, long time to bow head, high stress, emotional problems and female gender.

Accommodating False Positives Within Acoustic Spatial Capture–Recapture, with Variable Source Levels, Noisy Bearings and an Inhomogeneous Spatial Density

Passive acoustic monitoring is a promising method for surveying wildlife populations that are easier to detect acoustically than visually. When animal vocalisations can be uniquely identified on an array of sensors, the potential exists to estimate population density through acoustic spatial capture–recapture (ASCR). However, sound classification is imperfect, and in some situations, a high proportion of sounds detected on just a single sensor (‘singletons’) are not from the target species. We present a case study of bowhead whale calls (Baleana mysticetus) collected in the Beaufort Sea in 2010 containing such false positives. We propose a novel extension of ASCR that is robust to false positives by truncating singletons and conditioning on calls being detected by at least two sensors. We allow for individual-level detection heterogeneity through modelling a variable sound source level, model inhomogeneous call spatial density, and include bearings with varying measurement error. We show via simulation that the method produces near-unbiased estimates when correctly specified. Ignoring source-level variation resulted in a strong negative bias, while ignoring inhomogeneous density resulted in severe positive bias. The case study analysis indicated a band of higher call density approximately 30 km from shore; 59.8% of singletons were estimated to have been false positives.

OCCURRENCE AND COASTAL MORTALITY OF CETACEANS ON THE ARCTIC COAST OF CHUKOTKA PENINSULA IN THE WATERS OF CAPE VANKAREM IN 2017–2021

Six species of cetaceans have been found to occur in the Chukchi Sea adjacent to the Pacific walrus rookery at Cape Vankarem: the Grey whale, the Bowhead whale, the Humpback whale, the Killer whale, the Beluga whale, and the Fin whale. The Humpback whale is noted to have become abundant in the Chukchi Sea in the summer in recent years. The coastal mortality of cetaceans in a 100-km section in the western part of the distribution range of both Gray and Bowhead whales has been established to average 1.66 and 0.3 whales per year, respectively. Mostly young animals of 1–2 years of age appear to die, the main cause of death of which being predation by killer whales. The most common whales in that area in the summer-autumn period are humpback whales, which at the same time form significant concentrations in the coastal waters during the accumulation of the main food items. Both bowhead and gray whales are much less frequent, also being rather irregular to be found, while despite the relative scarcity of encounters these species account for the lion’s share of all dead cetaceans.

Observations of bowhead whales in west Greenland during summer

Observations of bowhead whales in west Greenland during summer

Auditory Health of Bowhead Whales (Balaena mysticetus) of the Bering-Chukchi-Beaufort Stock Based on Inner Ear Neuron Counts

Auditory Health of Bowhead Whales (Balaena mysticetus) of the Bering-Chukchi-Beaufort Stock Based on Inner Ear Neuron Counts

Prolonged baleen hormone cycles suggest atypical reproductive endocrinology of female bowhead whales.

Serial measurements of hormone concentrations along baleen plates allow for reconstructions of mysticete whale reproductive histories. We assessed gestation and calving interval in bowhead whales (Balaena mysticetus) by measuring progesterone, oestradiol, corticosterone and nitrogen stable isotope ratios (δ15N) along baleen of 10 females from the eastern Canada-west Greenland population. Three immature females (body size < 14.32 m) had uniformly low progesterone concentrations across their baleen, while seven mature females (body size ≥ 14.35 m) had repeated, sustained elevations of progesterone indicative of pregnancies. The mean duration of progesterone elevations (23.6 ± 1.50 months) was considerably longer than the approximately 14 month gestation previously estimated for this species. We consider several possible explanations for this observation, including delayed implantation or sequential ovulations prior to gestation, strategies that would allow females to maximize their fitness in variable Arctic conditions, as well as suggest modified criteria defining gestation as a shorter component of the entire progesterone peak. Calving intervals varied within and among individuals (mean = 3.7 years; range = range 2.8-5.7 years), providing population-specific reproductive estimates for growth models used in bowhead whale management and conservation.

Mapping vessel traffic patterns in the ice-covered waters of the Pacific Arctic

Recent climate change has caused declines in ice coverage which have lengthened the open water season in the Arctic and increased access to resources and shipping routes. These changes have resulted in more vessel activity in seasonally ice-covered regions. While traffic is increasing in the ice-free season, the amount of vessel activity in the marginal ice zone (ice concentration 15–80%) or in pack ice (>80% concentration) remains unclear. Understanding patterns of vessel activities in ice is important given increased safety challenges and environmental impacts. Here, we couple high-resolution ship tracking information with sea ice thickness and concentration data to quantify vessel activity in ice-covered areas of the Pacific Arctic (northern Bering, Chukchi, and western Beaufort Seas). This region is a geo-strategically critical area that contains globally important commercial fisheries and serves as a corridor for Arctic access for wildlife and vessels. We find that vessel traffic in the marginal ice zone is widely distributed across the study area while vessel traffic in pack ice is concentrated along known shipping routes and in areas of natural resource development. Of the statistically significant relationships between vessel traffic and both sea ice concentration and thickness, over 99% are negative, indicating that increasing sea ice is associated with decreasing vessel traffic on a monthly time scale. Furthermore, there is substantial vessel traffic in areas of high concentration for bowhead whales (Balaena mysticetus), and traffic in these areas increased four-fold during the study period. Fishing vessels dominate vessel traffic at low ice concentrations, but vessels categorized as Other, likely icebreakers, are the most common vessel type in pack ice. These findings indicate that vessel traffic in areas of ice coverage is influenced by distant policy and resource development decisions which should be taken into consideration when trying to predict future vessel-ice interactions in a changing climate.

An exploratory assessment of the Bering-Chukchi-Beaufort Seas stock of bowhead whales using a stochastic population dynamics model

The stochastic population dynamics model used by Aboriginal Whaling Management Procedure developers is revised to correct weaknesses related to uncertainty parameterisation and replacement yield estimation. Two variants of this model, along with the standard deterministic version, are used to assess the Bering-Chukchi-Beaufort Seas stock of bowhead whales. The variants differ with respect to the magnitude and complexity of the stochastic variation they introduce into natural mortality and birth/calf survival processes. An allowable catch statistic, E (Q0), is defined for appropriate use with stochastic model assessments. Using the same assessment methods, likelihood and priors as IWC (1999a), 5th percentiles of E (Q0) were found to be 117, 106 and 91 for the deterministic, simpler stochastic and extreme stochastic models, respectively. Bayes factor results show that there is no evidence suggesting that either stochastic model should be favoured over any simpler alternative, and the deterministic model yielded the best fit overall. The E (Q0) estimates confirm and strengthen past IWC Scientific Committee inference that under current bowhead subsistence hunting levels the stock should continue to increase towards stabilisation above its maximum sustainable yield level.

Observations and Detailed Descriptions of Sociosexual Behavior in Wild Indo-Pacific Bottlenose Dolphins (Tursiops aduncus)

Sociosexual behavior is not directly related to reproduction. It is observed between mature and immature individuals of both sexes and interactions can be between mixed- or same-sex individuals. This behavior may have important social functions. We observed and recorded the sociosexual behavior of wild Indo-Pacific bottlenose dolphins (Tursiops aduncus), underwater off Mikura Island, Japan, with regards to erection and mounting. This behavior was observed mainly between mothers and sons and in groups of subadult males (age 1–13 years). In subadult males, mounting behavior toward one passive individual from two or more individuals playing an active role, occurred in most cases. This behavior involving three or more participants has rarely been observed in other animal species, except for bowhead whales (Balaena mysticetus), common bottlenose dolphins (T. truncatus), and beluga whales (Delphinapterus leucas). Sociosexual behavior in the Mikura Island dolphins may not be agonistic because individuals in the passive role did not try to escape from the individuals playing the active role. Further studies on sociosexual behavior T. aduncus could reveal the social functions of this behavior, such as younger animals practicing mating behaviors required as adults and developing their relationships for when they are adults.

Research on Railway Dispatcher Fatigue Detection Method Based on Deep Learning with Multi-Feature Fusion

Traffic command and scheduling are the core monitoring aspects of railway transportation. Detecting the fatigued state of dispatchers is, therefore, of great significance to ensure the safety of railway operations. In this paper, we present a multi-feature fatigue detection method based on key points of the human face and body posture. Considering unfavorable factors such as facial occlusion and angle changes that have limited single-feature fatigue state detection methods, we developed our model based on the fusion of body postures and facial features for better accuracy. Using facial key points and eye features, we calculate the percentage of eye closure that accounts for more than 80% of the time duration, as well as blinking and yawning frequency, and we analyze fatigue behaviors, such as yawning, a bowed head (that could indicate sleep state), and lying down on a table, using a behavior recognition algorithm. We fuse five facial features and behavioral postures to comprehensively determine the fatigue state of dispatchers. The results show that on the 300 W dataset, as well as a hand-crafted dataset, the inference time of the improved facial key point detection algorithm based on the retina–face model was 100 ms and that the normalized average error (NME) was 3.58. On our own dataset, the classification accuracy based the an Bi-LSTM-SVM adaptive enhancement algorithm model reached 97%. Video data of volunteers who carried out scheduling operations in the simulation laboratory were used for our experiments, and our multi-feature fusion fatigue detection algorithm showed an accuracy rate of 96.30% and a recall rate of 96.30% in fatigue classification, both of which were higher than those of existing single-feature detection methods. Our multi-feature fatigue detection method offers a potential solution for fatigue level classification in vital areas of the industry, such as in railway transportation.

A note on the possibility of identifying Leydig and Sertoli cells by immunohistochemistry in bowhead whales (Balaena mysticetus)

Leydig cells have been found to be either unidentifiable or at apparent low numbers during routine histologic examination of bowhead whale testes. Therefore, formalin-fixed, paraffin-embedded testicular tissues from 14 bowhead whales were retrospectively examined to determine if immunohistochemical staining could aid in identification of Sertoli and Leydig cells. Multiple intratesticular samples were examined when available. Sertoli and Leydig cells were differentiated using inhibin and calretinin stains. Significant whale length and seasonal differences were not found; however, a trend toward increased staining intensity was noted for autumn harvested whales.

A framework for evaluating Strike Limit Algorithms for populations reduced to small numbers

A generic framework is outlined within which operating models for populations reduced to low numbers but still subject to exploitation (‘type 3 fisheries’) can be developed. This framework is founded on an individual-based operating model that includes temporally correlated environmental variation in births and survival as well as the possibility of occasional catastrophic reductions in survival. Methods are developed to specify the value of the parameter that determines the productivity of the resource from that for MSYR, to enable simulation trials based on this framework to be parameterised in terms of MSYR. Three potential candidate Strike Limit Algorithms are evaluated using 14 ‘generic’ simulation trials that capture a range of factors pertinent to type 3 fishery situations. The ‘Maximum-likelihood-like’ SLA developed for use in the management of the Bering-Chukchi-Beaufort Seas stock of bowhead whales performs adequately for many of these 14 trials, but not all. In contrast, a variant of the ‘PBR approach’ is shown to perform adequately in terms of achieving conservation objectives for all of the trials. The information needed to specify trials for actual type 3 fishery situations is outlined.

Sexual maturation in male bowhead whales (Balaena mysticetus) of the Bering-Chukchi-Beaufort Seas stock

Since the mid-1970s, study has focused on reproductive biology of female bowhead whales, while little has been described for males. This study evaluates testicular morphology (mass and length) and histology in relation to body length to determine the onset of male sexual maturity. Mean testis mass and mean testis length were highly correlated. Body length and mean testis mass were significantly correlated and an inflection of increased testicular mass occurred at approximately 12.5-13.0m suggesting the onset of puberty, and also indicated by histologic findings. Biological variability and the fact that few male animals have been examined within this critical length cohort do not allow determination of the onset of maturity with higher precision. Too few mature males have been landed in spring to make statistical comparisons of testes mass with autumn-landed animals within specific size cohorts. Two large (15.7m and 17.7m) males landed in spring had relatively small inactive testes and were diagnosed as pseudohermaphrodites; body length and mean testis length and seminiferous tubule diameter (STD) were not correlated with the other ‘normal’ whales. The smallest male confirmed as mature based on the presence of spermatocytes was 12.7m. The largest testes measured (combined mass 203kg) were from a whale landed in autumn. Mean STD for individual whales ranged from 33.3-170.9m and increased with mean testis weight and whale length. The STD is similar within a testis regardless of region evaluated, with minor variability. Some variation was noted for transverse sections within a cross section for some whales but no pattern was evident.

Bowhead whales' cancer secret

Their cells are very good at repairing DNA, which may explain the mammals' lasting health

Categorisation of the length of bowhead whales from British Arctic whaling records

British whalers were the first and last from Europe to hunt bowhead whales (Balaena mysticetus) commercially from the Arctic whaling grounds of the Greenland Sea (East Greenland-Svalbard-Barents stock) and Davis Strait (East Canada-West Greenland stock). Thus, British Arctic whaling records are unique, as they include both the beginning and the final story of the near extirpation of the species from these waters. By consolidating, cross-checking, and updating the work of numerous colleagues over the years, a database of over 11,000 individual records of British whaling voyages to these grounds between 1725 and 1913 has been established. Using conversion algorithms, it has been possible to derive statistically robust information on the length of the bowheads caught from the amount of oil they yielded. Translating oil yield to whale length is an important step as oil yield is one of the most common parameters documented within historical whaling records. Analysis suggests the length of whales caught at these two whaling grounds, Greenland Sea and Davis Strait, were different. A higher proportion within the East Greenland-Svalbard-Barents stock, taken from the Greenland Sea grounds, measured less than 12.5m (classed as juveniles), whilst the East Canada-West Greenland stock, taken from Davis Strait grounds, were skewed towards larger whales, 13 to 14 m long (classed as sexually mature). Furthermore, there was clear evidence that a shift in the distribution of whale length occurred when the whalers extended their hunting grounds to encompass additional regions within the Greenland Sea and Davis Strait in 1814 and 1817 respectively. Prior to expansion, we find that that the vast majority (85%) of the East Canada-West Greenland stock were of the length that are classified as sexually mature (&amp;gt;13.0 m), whereas only 39% of East Greenland-Svalbard-Barents stock taken were of this size. After the enlargement of the whaling grounds, the length distribution shifted with a reduction to 50% of the East Canada-West Greenland stock and an increase to 44% of the East Greenland-Svalbard-Barents stock being categorised as sexually mature. These results show the important information that may be derived from historical whaling records. Since the commercial hunt of the bowheads ceased in the European Arctic there have been substantial changes in both the oceanographic and sea ice regime in the region, thus understanding the past through whaling records can help to understand the implications of future climate-induced changes in bowhead whale populations and their habitat.

The role of skin biopsy in the detection of exposure to endocrine disrupting chemicals in Mediterranean cetaceans

Use of skin biopsy is proposed as a sensitive non-lethal technique for the hazard assessment of Mediterranean cetaceans exposed to endocrine disrupting chemicals (EDCs). EDCs are a structurally diverse group of compounds that may adversely affect the health of humans and wildlife or their progeny, by interaction with the endocrine system. In the Mediterranean environment top predators accumulate high concentrations of polyhalogenated aromatic hydrocarbons (PHAHs) and toxic metals, incurring high toxicological hazard. In this paper, the hypothesis that Mediterranean cetaceans are potentially at risk due to PHAH-EDCs is investigated using skin biopsy samples. Benzo-a-pyrene monoxigenase (BPMO) activity in skin biopsies was used as a potential indicator of exposure to different organochlorines (OCs) known to have endocrine disrupting properties. The main objective of this paper was to use this non-destructive ecotoxicological tool to define the potential hazard to Mediterranean odontocete and mysicete species, comparing the present data with values detected in other cetaceans from heavily polluted areas, affected by pseudohermaphroditism and other reproductive dysfunction. Subcutaneous tissue consisting of skin and blubber was obtained from striped dolphins (Stenella coeruleoalba), bottlenose dolphins (Tursiops truncatus), common dolphins (Delphinus delphis) and fin whales (Balaenoptera physalus) in the Mediterranean basin. Sampling was performed in the western Ligurian Sea, between Corsica and the French-Italian coast, and in the Ionian Sea. High concentrations of DDT metabolites and PCB congeners (known as Endocrine Disruptors) were detected in the different species. Significant differences in BPMO induction and OC levels were found between odontocetes and mysticetes. Differences in organochlorine bioaccumulation and consequently potential risk due to endocrine disruptors were primarily related to different positions in the marine food web. A statistical correlation was found between BPMO activity and organochlorine (op’DDT, a potent estrogen and antiandrogen and pp’DDE, a potent antiandrogen) levels in skin biopsy specimens of the endangered Mediterranean population of common dolphin. Several conclusions on the potential risk to Mediterranean cetaceans can be drawn from comparison of the levels of OC-EDs detected in Mediterranean odontocetes with those in white whales (Delphinapterus leucas) of the St Lawrence estuary and bowhead whales (Balaena mysticetus) affected by pseudohermaphroditism and other reproductive dysfunction. Finally, these results suggest that BPMO induction may be an early sign of exposure to EDCs such as OCs and a warning of the possibility of transgenerational effects through exposure of future generations via the placenta and milk.

DNA methylation-based biomarkers for ageing long-lived cetaceans.

Epigenetic approaches for estimating the age of living organisms are revolutionizing studies of long-lived species. Molecular biomarkers that allow age estimates from small tissue biopsies promise to enhance studies of long-lived whales, addressing a fundamental and challenging parameter in wildlife management. DNA methylation (DNAm) can affect gene expression, and strong correlations between DNAm patterns and age have been documented in humans and nonhuman vertebrates and used to construct "epigenetic clocks". We present several epigenetic clocks for skin samples from two of the longest-lived cetaceans, killer whales and bowhead whales. Applying the mammalian methylation array to genomic DNA from skin samples we validate four different clocks with median errors of 2.3-3.7 years. These epigenetic clocks demonstrate the validity of using cytosine methylation data to estimate the age of long-lived cetaceans and have broad applications supporting the conservation and management of long-lived cetaceans using genomic DNA from remote tissue biopsies.

Empirical estimation of safe aboriginal whaling limits for bowhead whales

This paper provides a complete description of a Strike Limit Algorithm (SLA) considered by the International Whaling Commission (IWC) for the management of hunting of the Bering-Chukchi-Beaufort Seas stock of bowhead whales by native Alaskans to meet their cultural and subsistence needs. The algorithm applies a statistical estimation and optimisation strategy to extract the best features of selected SLAs to form a Bayes rule estimator. It focuses on safely satisfying moderate subsistence need, while favouring stock protection by setting strike limits below what would be required to fully satisfy need in the final portion of this century if need were more than doubled.