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Information and statistics including trade statistics on catches of narwhals, Monodon monoceros, in Greenland since 1862 are reviewed. Detailed statistics split by hunting grounds are missing for most of the years until 1993. For the northernmost area, Avanersuaq, only sporadic reporting exists. Based on statistics from the recent three decades, a time series is constructed for West Greenland with catches split into hunting grounds and corrected for underreporting assessed from purchases of whale skin called 'mattak,' for periods without catch records and from rates of struck-but-lost whales ('low,' 'medium,' and 'high option'). This reveals a time series of somewhat realistic catch levels from 1862 through 2017. Since 1993 catches have declined in West Greenland, especially in Uummannaq and Disko Bay where the decline is significant. In East Greenland, there has been an increase in catches from Ittoqqortoormiit and a decrease in catches from Tasiilaq from 1993 to 2017., Introduction For the development of management advice on sustainable harvest levels of narwhals, Monodon monoceros, it is important that a complete history of removals by humans be reconstructed. Catch statistics [...]

Hunted animals are often managed as static management units, or stocks, specific to hunting regions. However, movement of animals between regions poses a particular challenge for management to ensure that the hunt of individual stocks is sustainable. The incorporation of genetic information in stock assessments can improve management decisions, but the resolution of genetics may not differentiate stocks, making the use of movement data necessary. The Joint Working Group of the North Atlantic Marine Mammal Commission (NAMMCO) and the Canada-Greenland Joint Commission on Conservation and Management of Narwhal and Beluga (JCNB) has developed a model that allocates catches in different hunting regions and seasons to different stocks based on movement data, local knowledge, and expert opinion. The model uses information on stock size, catches in different hunting areas/seasons, and a matrix which estimates the proportion of animals in each stock that are available to hunters in different regions and seasons. This matrix can be informed by quantitative data on stock structure (e.g., genetics, telemetry) or qualitative information (local knowledge, expert opinion, etc.). Uncertainty in the availability of animals and individual stock sizes is incorporated in a stochastic version. The model is presented using a case study of narwhals, which are managed as stocks based on their summer distribution in Canada and Greenland., Introduction Marine mammal populations or stocks often have large spatial distributions and follow seasonal migration patterns that expose them to taking by hunters or other risks at different times and [...]

The monodontids--narwhals, Monodon monoceros, and belugas, Delphinapterus leucas--are found in much of the Arctic and in some subarctic areas. They are hunted by indigenous subsistence users. In the past, some populations were substantially reduced by commercial hunting and culling; more recently, some populations have declined due to uncontrolled subsistence hunting and environmental degradation. Monodontids are impacted increasingly by human activities in the Arctic including ship and boat traffic, industrial development, icebreaking, seismic surveys, competition with fisheries, and alteration of habitat due to climate change. Since comprehensive reviews in the 1990's, substantial new information has become available on both species and on changes to their habitat as a result of human activities and climate change. Thus NAMMCO and partners undertook an updated review in 2017. The review recognized 21 extant beluga stocks, 1 extirpated beluga stock, and 12 stocks of narwhals. The available information on each stock regarding population size, depletion level, current and past removals, and trends in abundance was reviewed to determine status. Concern was expressed where the lack of information prevented reliable assessment, removals were thought to be unsustainable, or the population was deemed at risk of declining even without direct removals by hunting. Beluga stocks of greatest concern are the small stocks in Ungava Bay (possibly extirpated), Cook Inlet (ca 300), St. Lawrence Estuary (ca 900), and Cumberland Sound (ca 1,100), and the stocks with uncertainty in Eastern Hudson Bay and the Barents-Kara-Laptev Seas. Narwhal stocks of greatest concern are those in Melville Bay and East Greenland., Introduction The family Monodontidae is comprised of the narwhal, Monodon monoceros, and the beluga or white whale, Delphinapterus leucas (Rice, 1998). These two species are found in much of the [...]

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. [ABSTRACT FROM AUTHOR]

Stable carbon (δ13C) and nitrogen (δ15N) isotopic compositions of bone and dentine collagen extracted from museum specimens have been widely used to study the paleoecology of past populations. Due to possible systematic differences in stable isotope values between bone and dentine, dentine values need to be transformed into bone-collagen equivalent using a correction factor to allow comparisons between the two collagen sources. Here, we provide correction factors to transform dentine δ13C and δ15N values into bone-collagen equivalent for two toothed whales: narwhal and beluga. We sampled bone and dentine from the skulls of 11 narwhals and 26 belugas. In narwhals, dentine was sampled from tusk and embedded tooth; in belugas, dentine was sampled from tooth. δ13C and δ15N were measured, and intra-individual bone and dentine isotopic compositions were used to calculate correction factors for each species. We detected differences in δ13C and δ15N. In both narwhals and belugas, we found lower average δ13C and δ15N in bone compared with dentine. The correction factors provided by the study enable the combined analysis of stable isotope data from bone and dentine in these species. [ABSTRACT FROM AUTHOR]

Limited polar geographical range, narrowly defined migratory routes, and deep‐diving behaviours make narwhals exceptionally vulnerable to anthropogenic disturbances including oceanic noise. Although behavioural studies indicate marked responses of cetaceans to disturbance, the link between fear reactions and possible injury from noise exposure is limited for most species.To address this, we deployed custom‐made heart rate‐accelerometer‐depth recorders on 13 adult narwhals in Scoresby Sound, East Greenland across a five‐year period (2014–2018). Physiological responses of the cetaceans were monitored in the absence (n = 13 animals) or presence (n = 2 animals across 3 acoustic events) of experimentally directed, seismic airgun pulses and associated vessels (full volume source level = 241 dB re 1 μPa‐m).We found that anthropogenic noise resulted in marked cardiovascular, respiratory and locomotor reactions by two narwhals exposed to seismic pulses across three acoustic events. The general behavioural response to seismic and vessel noise included an 80% reduction in the duration of gliding during dive descents by seismic‐exposed narwhals compared to controls, and the prolongation of high intensity activity (ODBA > 0.20 g) with elevated stroke frequencies exceeding 40 strokes per minute. Noise exposure also resulted in intense (<10 bpm) bradycardia that was decoupled from stroking frequency. This decoupling instigated increased variability in heart rate, with the heart switching rapidly between bradycardia and exercise tachycardia during noise exposure. The maximum respiratory frequency following seismic exposure, 12 breaths/min, was 1.5 times control levels.Overall, the effect of seismic/ship noise exposure on Arctic narwhals was a 2.0–2.2‐fold increase in the energetic cost of diving, which paradoxically occurred during suppression of the cardiac exercise response. This unusual relationship between diving heart rate and exercise intensity represents a new metric for characterizing the level of fear reactions of wild marine mammals exposed to different environmental stressors. Together, the multi‐level reactions to anthropogenic noise by this deep‐diving cetacean demonstrated how a cascade of effects along the entire oxygen pathway could challenge physiological homeostasis especially if disturbance is prolonged. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Eyes from 75 narwhals (Monodon monoceros) were collected in West Greenland in 1993 and 2004 for the purpose of age estimation. Age estimates were based on the racemization of L-aspartic acid to D-aspartic acid in the nucleus of the eye lens. The ratio of D- and L-enantiomers was measured using high-performance liquid chromatography. The aspartic acid racemization rate ([k.sub.Asp]) was estimated to be 0.001045/year [+ or -] 0.000069 SE by regression of D/L ratios on age estimated by length from 15 young narwhals ([less than or equal to] 298 cm) and by earplug laminations from 13 fin whales (Balaenoptera physalus). The D/L ratio at age 0 ([(D/L).sub.0]) was estimated to be 0.0288 by regression of D/L ratios against the estimated age of the 15 young narwhals. The intercept of the regression slope, providing twice the [(D/L).sub.0] value, was 0.05759 [+ or -] 0.00147 SE. The maximum estimated age was a 115-year-old ([+ or -] 10 SE) female. Asymptotic body length was estimated to be 396 cm for females and 457 cm for males, and asymptotic body mass was estimated to be 904 kg for females and 1,645 kg for males. Using the von Bertalanffy growth model, age at sexual maturity was estimated to be 6-7 years for females and 9 years for males. Key words: age estimation, aspartic acid racemization, Monodon monoceros, narwhal

The elongated, spiraled tusk of male narwhals (Monodon monoceros) grows continuously throughout the life of the whale and is most likely a secondary sexual trait used in male-male hierarchical competition and possibly in female mate choice. Sex determination in narwhals is typically based on the presence (male) or absence (female) of an erupted tusk, but anomalies such as females with tusks, tuskless males or double-tusked whales occur, although infrequently. In this study, we collected reproductive data and recorded the presence or absence of a tusk in narwhals from the Inuit hunt in Greenland (1993 and 2010-19) with the purpose of estimating the frequency of tusk anomalies. We found that of the 173 whales, 2.9% displayed tusk anomalies. Tusked females constituted 1.5% of sampled females, tuskless males 2.8% of sampled males and double-tusked males 0.9% of sampled males. Biological information on a tusked female, a tuskless male and a double-tusked male was collected and is presented here. The tusked female was sexually mature, and 18 ovarian scars (indicating pregnancies) documented a long reproductive lifespan. The complete female tusk was estimated to be between 146 and 151 cm in length. The tuskless male was sexually maturing, as indicated by body dimensions, and the double-tusked male was sexually immature, with the two tusks measuring <90 cm in length. Although narwhals exhibit extremely low levels of genetic diversity, tusk anomalies persist in the populations, perhaps facilitated by the reproductive ability of whales with tusk anomalies. [ABSTRACT FROM AUTHOR]

The narwhal (Monodon monoceros) is a high‐Arctic species inhabiting areas that are experiencing increases in sea temperatures, which together with reduction in sea ice are expected to modify the niches of several Arctic marine apex predators. The Scoresby Sound fjord complex in East Greenland is the summer residence for an isolated population of narwhals. The movements of 12 whales instrumented with Fastloc‐GPS transmitters were studied during summer in Scoresby Sound and at their offshore winter ground in 2017–2019. An additional four narwhals provided detailed hydrographic profiles on both summer and winter grounds. Data on diving of the whales were obtained from 20 satellite‐linked time‐depth recorders and 16 Acousonde™ recorders that also provided information on the temperature and depth of buzzes. In summer, the foraging whales targeted depths between 300 and 850 m where the preferred areas visited by the whales had temperatures ranging between 0.6 and 1.5°C (mean = 1.1°C, SD = 0.22). The highest probability of buzzing activity during summer was at a temperature of 0.7°C and at depths > 300 m. The whales targeted similar depths at their offshore winter ground where the temperature was slightly higher (range: 0.7–1.7°C, mean = 1.3°C, SD = 0.29). Both the probability of buzzing events and the spatial distribution of the whales in both seasons demonstrated a preferential selection of cold water. This was particularly pronounced in winter where cold coastal water was selected and warm Atlantic water farther offshore was avoided. It is unknown if the small temperature niche of whales while feeding is because prey is concentrated at these temperature gradients and is easier to capture at low temperatures, or because there are limitations in the thermoregulation of the whales. In any case, the small niche requirements together with their strong site fidelity emphasize the sensitivity of narwhals to changes in the thermal characteristics of their habitats. [ABSTRACT FROM AUTHOR]

Eyeballs from 121 fin whales ( Balaenoptera physalus) and 83 harbor porpoises ( Phocoena phocoena) were used for age estimation using the aspartic acid racemization (AAR) technique. The racemization rate ( kAsp) for fin whales was established from 15 fetuses (age 0) and 15 adult whales where age was estimated by reading growth layer groups (GLGs) in the earplugs. The ( kAsp) for harbor porpoises was derived from 15 porpoises (two calves and 13 > 1 yr old) age-estimated by counting GLGs in the teeth and two calves classified to age based on length. The ( kAsp) values were estimated by regression of GLGs against D/L ratios. For the fin whales an ( kAsp) of 1.15 × 10−3/yr (SE ± 0.00005) and a D/L ratio at birth [(D/L)0] of 0.028 (SE ± 0.0012) were estimated, which is in agreement with rates for other mysticeti. For the harbor porpoises a ( kAsp) of 3.10 × 10−3/yr (SE ± 0.0004) and a (D/L)0 value of 0.023 (SE ± 0.0018) were estimated, which is considerably higher than found for other cetaceans. Correlation between chosen age estimates from AAR and GLG counts indicated that AAR might be an alternative method for estimating age in marine mammals. [ABSTRACT FROM AUTHOR]

Ages of marine mammals have traditionally been estimated by counting dentinal growth layers in teeth. However, this method is difficult to use on narwhals (Monodon monoceros) because of their special tooth structures. Alternative methods are therefore needed. The aspartic acid racemization (AAR) technique has been used in age estimation studies of cetaceans, including narwhals. The purpose of this study was to estimate a species-specific racemization rate for narwhals by regressing aspartic acid D/L ratios in eye lens nuclei against growth layer groups in tusks (n = 9). Two racemization rates were estimated: one by linear regression (r² = 0.98) based on the assumption that age was known without error, and one based on a bootstrap study, taking into account the uncertainty in the age estimation (r² between 0.88 and 0.98). The two estimated 2kAsp values were identical up to two significant figures. The 2kAsp value from the bootstrap study was found to be 0.00229±0.000089 SE, which corresponds to a racemization rate of 0.00114-yr±0.000044 SE. The intercept of 0.0580±0.00185 SE corresponds to twice the (D/L)0 value, which is then 0.0290±0.00093 SE. We propose that this species-specific racemization rate and (D/L)0 value be used in future AAR age estimation studies of narwhals, but also recommend the collection of tusks and eyes of narwhals for further improving the (D/L)0 and 2kAsp estimates obtained in this study. [ABSTRACT FROM AUTHOR]

The article focuses on a study that analyzes the sensitivity of narwhals or Monodon monoceros to human-made noise and the negative impact of noise stressors on these Niche-conservative species. It found that deep diving is avoided by narwhals with simultaneous reduction of foraging, increasing shallow diving activity and reducing forage activity as a reaction to either the noise of ship alone or ship sound with simultaneous seismic airgun pulse.

The ability of animals to respond to changes in their environment is critical to their persistence. In the Arctic, climate change and mercury exposure are two of the most important environmental threats for top predators. 1–3 Rapid warming is causing precipitous sea-ice loss, with consequences on the distribution, composition, and dietary ecology of species 4–7 and, thus, exposure to food-borne mercury. 8 Current understanding of global change and pollution impacts on Arctic wildlife relies on single-time-point individual data representing a snapshot in time. These data often lack comprehensive temporal resolution and overlook the cumulative lifelong nature of stressors as well as individual variation. To overcome these challenges, we explore the unique capacity of narwhal tusks to characterize chronological lifetime biogeochemical profiles, allowing for investigations of climate-induced dietary changes and contaminant trends. Using temporal patterns of stable isotopes (δ13C and δ15N) and mercury concentrations in annually deposited dentine growth layer groups in 10 tusks from Northwest Greenland (1962–2010), we show surprising plasticity in narwhal feeding ecology likely resulting from climate-induced changes in sea-ice cover, biological communities, and narwhal migration. Dietary changes consequently impacted mercury exposure primarily through trophic magnification effects. Mercury increased log-linearly over the study period, albeit with an unexpected rise in recent years, likely caused by increased emissions and/or greater bioavailability in a warmer, ice-free Arctic. Our findings are consistent with an emerging pattern in the Arctic of reduced sea-ice leading to changes in the migration, habitat use, food web, and contaminant exposure in Arctic top predators. • Male narwhal tusks provide a lifetime record of stable isotopes and mercury • Narwhals show temporal (1962–2010) diet plasticity at individual and group levels • Changes in diet and mercury exposure correlate with loss of sea ice • Rise in mercury levels since the year 2000 surpasses historical accumulation rate The male narwhal tusk chronologically records ecological information throughout an animal's lifespan. Dietz et al. reconstruct lifetime profiles for stable isotopes (carbon and nitrogen) and mercury to reveal that diet and pollution exposure have shifted over the past decade, likely in response to climate change. [ABSTRACT FROM AUTHOR]