Abstract: From 2000 to 2013, use of land as a seasonal habitat by polar bears (Ursus maritimus) of the southern Beaufort Sea (SB) subpopulation substantially increased. This onshore use has been linked to reduced spatial and temporal availability of sea ice, as well as to the availability of subsistence-harvested bowhead whale (Balaena mysticetus) bone piles. Here, we evaluated the role of climate conditions on consumption of traditional ice-associated prey relative to onshore bowhead whale bone piles. We determined seasonal and interannual trends in the diets of SB polar bears using fatty acid-based analysis during this period of increasing land use. Diet estimates of 569 SB polar bears from 2004 to 2012 showed high seasonal fluctuations in the proportions of prey consumed. Higher proportions of bowhead whale, as well as ringed seal (Pusa hispida) and beluga whale (Delphinapterus leucas), were estimated to occur in the winter–spring diet, while higher proportions of bearded seal (Erignathus barbatus) were estimated for summer–fall diets. Trends in the annual mean proportions of individual prey items were not found in either period, except for significant declines in the proportion of beluga in spring-sampled bears. Nonetheless, in years following a high winter Arctic oscillation index, proportions of ice-associated ringed seal were lower in the winter–spring diets of adult females and juveniles. Proportions of bowhead increased in the winter–spring diets of adult males with the number of ice-free days over the continental shelf. In one or both seasons, polar bears that were in better condition were estimated to have consumed less ringed seal and/or more bowhead whale than those in worse condition. Therefore, climate variation over this recent period appeared to influence the extent of onshore vs. on-ice food use, which in turn, appeared to be linked to fluctuating condition of SB polar bears.

Abstract: There has been extensive sea ice loss in the Chukchi and Beaufort seas where two beluga whale (Delphinapterus leucas) populations occur between July-November. Our goal was to develop population-specific beluga habitat selection models that quantify relative use of sea ice and bathymetric features related to oceanographic processes, which can provide context to the importance of changing sea ice conditions. We established habitat selection models that incorporated daily sea ice measures (sea ice concentration, proximity to ice edge and dense ice) and bathymetric features (slope, depth, proximity to the continental slope, Barrow Canyon, and shore) to establish quantitative estimates of habitat use for the Eastern Chukchi Sea (‘Chukchi’) and Eastern Beaufort Sea (‘Beaufort’) populations. We applied ‘used v. available’ resource selection functions to locations of 65 whales tagged from 1993–2012, revealing large variations in seasonal habitat selection that were distinct between sex and population groups. Chukchi whales of both sexes were predicted to use areas in close proximity to Barrow Canyon (typically <200 km) as well as the continental slope in summer, although deeper water and denser ice were stronger predictors for males than females. Habitat selection differed more between sexes for Beaufort belugas. Beaufort males selected higher ice concentrations (≥40%) than females (0–40%) in July-August. Proximity to shore (<200 km) strongly predicted summer habitat of Beaufort females, while distance to the ice edge was important for male habitat selection, especially during westward migration in September. Overall, our results indicate that sea ice variables were rarely the primary drivers of beluga summer-fall habitat selection. While diminished sea ice may indirectly affect belugas through changes in the ecosystem, associations with bathymetric features that affect prey availability seemed key to habitat selection during summer and fall. These results provide a benchmark by which to assess future changes in beluga habitat use of the Pacific Arctic.

Abstract: The expansion of hydrocarbon exploration in northwest Greenland has made it increasingly important to understand the occurrence of marine mammals in the region. We describe the seasonal occurrence of marine mammals and the spatial distribution of their calls in Baffin Bay and Melville Bay. Four Autonomous Multichannel Acoustic Recorders (AMARs) were deployed during summer 2012 (late July to early October), five recorders during September 2013, and two recorders from late September 2013 to early September 2014. The call presence of several species was analyzed using automatic call detection and manual verification analysis methods. A novel approach to discern narwhal ( Monodon monoceros ) clicks from beluga ( Delphinapterus leucas ) clicks was implemented during the verification process. Narwhal calls were detected in spring and fall, showing a south-to-north migration pattern in spring and a north-to-south migration pattern in fall. Few beluga whales were detected during fall 2013 and spring 2014. Bearded seal ( Erignathus barbatus ) calls were detected mainly during spring (mating period). A small number of bowhead whale calls ( Balaena mysticetus ) were detected during fall 2013 and spring and summer 2014. For the first time at this latitude in Baffin Bay, long-finned pilot whales ( Globicephala melas ) and sperm whales ( Physeter macrocephalus ) were detected during summer and fall. Our results suggest that the presence of marine mammals in Baffin Bay and Melville Bay is governed mainly by the annual cycle of sea ice formation and decay.

Abstract: Killer Whales ( Orcinus orca ) were observed on 4 August 2012 attacking Belugas ( Delphinapterus leucas ) at high tide near the mouth of the Seal River (59°9'19"N, 94°45'28"W) in southwest Hudson Bay, near the location where six Belugas had been fitted with satellite transmitters three weeks earlier. The distribution of Belugas was analyzed before, during, and after the attack. In the presence of Killer Whales, the six Belugas altered their behaviour by reducing their combined range size from 285 km2 four days before the attack to 172 km2 on the day of the attack. Their range more than tripled, to 655 km2, in the days immediately following the attack before returning to the pre-attack size. Following the attack, the tagged Belugas expanded their range northward, going from a mean pre-attack distance of 9.4 km from the attack site to a maximum of 23.5 km. Visual observations of Belugas clumping together and moving toward shore corroborated satellite data. This evasive behaviour by Belugas was different from that reported for Narwhals (Monodon monoceros) suggesting that the two monodontid species may have evolved different survival strategies related to the risk of Killer Whale predation. With predicted changes to Arctic sea ice, the summering habitat of Belugas will be available to their main predator for longer periods. A better understanding of Beluga behaviour and risk of predation is required for Beluga conservation and stock management.

Abstract: Live, dead stranded, and harvested belugas (Delphinapterus leucas) in Alaska and the western Canadian Arctic were screened for viruses utilizing a primary beluga cell line. Samples consisted of swa...

Abstract: The research on imitation in the animal kingdom has more than a century-long history. A specific kind of imitation, auditory–vocal imitation, is well known in birds, especially among songbirds and parrots, but data for mammals are limited to elephants, marine mammals, and humans. Cetaceans are reported to imitate various signals, including species–specific calls, artificial sounds, and even vocalizations from other species if they share the same habitat. Here we describe the changes in the vocal repertoire of a beluga whale that was housed with a group of bottlenose dolphins. Two months after the beluga’s introduction into a new facility, we found that it began to imitate whistles of the dolphins, whereas one type of its own calls seemed to disappear. The case reported here may be considered as an interesting phenomenon of vocal accommodation to new social companions and cross-species socialization in cetaceans.

Abstract: This study was funded by the Greenland Bureau of Minerals and Petroleum, the Danish Cooperation of the Environment in the Arctic (DANCEA, Danish Ministry of the Environment) and the Greenland Institute of Natural Resources.

Abstract: Beluga whales (Delphinapterus leucas) are facing profound changes in their habitat, with impacts expected at the individual and population level. Detecting and monitoring exposure and response to environmental stressors is necessary for beluga conservation and management of human activities. Cortisol has proven as a useful tool to assess stress on wildlife. Cortisol was measured in three blubber layers and plasma in subsistence-hunted beluga whales from the summers of 2007 to 2010 using an HPLC/MS/MS. We assessed the effect of biological and biochemical factors. Cortisol ranged from undetectable to 17.8 ng/g in blubber and 2.5 to 61.2 ng/mL in plasma. Concentrations were highest in the inner blubber layer likely reflecting circulating levels. All tissues were significantly higher in 2008 for reasons that remain unclear. Cortisol levels were on par with resting levels in captive belugas. Best fit models for cortisol revealed age to be an important determinant along with length and blubber thickness. Lack o...

Abstract: For Canadian Arctic indigenous populations, marine mammal (MM) traditional foods (TFs) represent sources of both important nutrients and hazardous environmental contaminants. Food preparation is known to impact the nutrient and environmental contaminant content of processed items, yet the impacts of preparation on indigenous Arctic MM TFs remain poorly characterized. In order to determine how the various processes involved in preparing beluga blubber TFs affect their levels of nutrients and environmental contaminants, we collected blubber samples from 2 male beluga whales, aged 24 and 37 years, captured during the 2014 summer hunting season in Tuktoyaktuk, Northwest Territories, and processed them according to local TF preparation methods. We measured the levels of select nutrients [selenium (Se), polyunsaturated fatty acids (PUFAs)] and contaminants [organochlorine pesticides, perfluoroalkyl and polyfluoroalkyl substances (PFASs), polybrominated diphenyl ethers, polychlorinated biphenyls, polycyclic aromatic hydrocarbons (PAHs), mercury (Hg)] in raw and prepared (boiled, roasted, aged) beluga blubber TFs. The impacts of beluga blubber TF preparation methods on nutrient and environmental contaminant levels were inconsistent, as the majority of processes either did not appear to influence concentrations or affected the two belugas differently. However, roasting and ageing beluga blubber consistently impacted certain compounds: roasting blubber increased concentrations of hydrophilic substances (Se and certain PFASs) through solvent depletion and deposited PAHs from cookfire smoke. The solid–liquid phase separation involved in ageing blubber depleted hydrophilic elements (Se, Hg) and some ionogenic PFASs from the lipid-rich liquid oil phase, while PUFA levels appeared to increase, and hydrophobic persistent organic pollutants were retained. Ageing blubber adjacent to in-use smokehouses also resulted in considerable PAH deposition to processed samples. Our findings demonstrated that contaminant concentration differences were greater between the two sets of whale samples, based on age differences, than they were within each set of whale samples, due to variable preparation methods. When considering means to minimize human contaminant exposure while maximizing nutrient intake, consumption of aged liquid from younger male whales would be preferred, based on possible PUFA enhancement and selective depletion of hydrophilic environmental contaminants in this food item.

Abstract: Juvenile beluga sturgeon, Huso huso (initial weight 50 ± 0.2 g), were fed with two lipid levels (120 g kg−1 lipid as low-energy diet, LE; 240 g kg−1 lipid as high-energy diet, HE) at different feeding times for 8 weeks, and the effects on growth, hematology, muscle composition, and apparent digestibility coefficients of dry matter, lipid, and protein were examined. Feeding times were as follows: (1) at 09:00 and 16:00 (under light regime), (2) at 21:00 and 04:00 (under dark regime), and (3) at 13:00 and 20:00 (under light–dark regime). Dietary lipid levels did not affect the hematological indices or apparent digestibility coefficients of dietary nutrients (P > 0.05); however, they affected the growth and muscle composition (P 0.05). Accordingly, juvenile beluga sturgeon can be fed at different times of the day without suffering growth loss, because probably, they have a low dependency on vision to detect food.

Abstract: The influence of three different initial stocking densities (low stocking density [LSD] = 1.5 kg/m2; medium stocking density [MSD] = 3 kg/m2; and high stocking density [HSD] = 6 kg/m2) in flow-through systems was evaluated on growth and welfare in beluga, Huso huso, and ship sturgeon, Acipenser nudiventris, juveniles for 2 mo. Fish were kept in 18 concrete square tanks (2.0 × 1.0 × 1.2 m3) at 22.3 ± 0.4 C and under a natural photoperiod. In both species, the growth performance in terms of final body weight, weight gain, specific growth rate, and feed intake significantly decreased with increasing stocking density (P < 0.05). In both species, the percent of neutrophils increased after 60 d of trial (P < 0.05). Moreover, hematocrit and white blood cell counts increased after 60 d of trial in ship sturgeon (P < 0.05). Plasma immunoglobulin significantly decreased with increasing stocking density in both species. Plasma insulin-like growth factor I decreased with increasing stocking density in beluga; however, it was not affected in ship sturgeon. Overall, these results showed that the LSD group in both species demonstrated more homogeneous and higher growth rate than the MSD and HSD groups.

Abstract: The acoustic ecology of Arctic marine mammals is driven by anthropogenic, biotic, and abiotic factors each of which may influence the behavioral ecology of each species. The acoustic environment of bowhead (Balaena mysticetus) and beluga (Delphinapterus leucas) whales in three core-use regions of the Pacific Arctic was examined during the months in which both species occur in these regions. The Anadyr Strait region in winter was dominated by the signals of bowhead whales, walrus and bearded seals. In Bering Strait in late fall and winter, wind noise predominated in November but once the region was ice-covered, bowhead and walrus were the main sources of noise. Barrow Canyon in late summer and fall was the only region in which anthropogenic sources overlapped with both whale species. Overall, ambient noise levels were low in the Pacific Arctic when compared to other ocean basins in which anthropogenic noise dominates low frequencies. However, climate change-driven increases in open water are leading to ris...

Abstract: There is a need for a better understanding of how sturgeon, especially hatchery reared juveniles, respond to salinity challenges. Therefore, here we examined the effects of different field-based salinities (Freshwater [FW] (0.5), 3, 6, 9 and 12 ppt) on osmoregulatory characteristics and growth performance of juvenile beluga sturgeon, Huso huso , (22.1±1.1 g body weight) over a 60-day period. Survival rate was relatively high in all treatments although there was a sign of adverse effects of salinity on the survival as fish at 12 ppt salinity. Growth performance was better in fish reared at 3 ppt, followed by 6, 9 and 12 ppt. Overall, an increase in plasma sodium, potassium, calcium, magnesium and glucose levels was found in association with the increase of salinity, while the FW control group maintained basal levels. Haematocrit levels were also affected by the salinity and the observed levels in FW, 3 and 6 ppt salinities were lower than other salinity concentrations. The results indicated that the beluga sturgeon juveniles are able to survive and acclimate to moderate salinities. Here, we also discussed the importance of evaluating and comparing specific mechanisms of acclimation in populations across brackish waters of the southern Caspian Sea as such investigations may aid and improve aquaculture strategies.

Abstract: The qualitative composition of the Caspian Sea sturgeon has been studied on the basis of multiyear factual material. The relationship between the length, weight and age, marked a slowdown of growth the sturgeon. At present, the size of the population of Russian sturgeon and other major sturgeon species as beluga and stellate sturgeon have fallen sharply in the last 10-15 years (2000-2016), almost the recruitment absent, both, from the natural and of aquaculture. The findings suggest that the anthropogenic factor, over the past 40 years, has a negative impact on the biological productivity of fishery water bodies (Caspian Sea and adjacent rivers) and have an impact on fishes, their biological and physiological state. Evaluation of morphophysiological transformations in sturgeons based on the use of a variety of morphophysiological and biochemical parameters gives us grounds to speak about a certain deterioration of the physiological conditions of these fishes over time, in the sea and river periods of their life.

Abstract: Based on the literature, non-published and survey data, information on the occurrence of anadromous sturgeons after the regulation of the Don River downstream and upstream of the Tsimlyansk Dam is given. There were two peaks of mature adults approaching the dam, namely, in the 1950s and 1980s. The first mass peak was associated with the wild population existed then; the second one was a result of mass artificial breeding. At the first stage, the sturgeon (Acipenser gueldenstaedtii Brandt et Ratzeburg, 1833) and beluga (Huso huso (Linnaeus, 1758)) prevailed below the dam; at the second one, just the sturgeon did. Since 1955, only 21 individuals of anadromous sturgeons were transported through the dam by a fish ladder. During 1952-1961, 1,145 individuals were transported into the reservoir, including 218 belugas. Separate beluga individuals were transported later on as well. There is evidence of the presence of young beluga individuals from natural spawning in the reservoir before the 1970s. The latest known adult sturgeon and stellate sturgeon (Acipenser stellatus Pallas, 1771) in the reservoir were noted in the 1980-90s. Separate beluga individuals have been met until now. The youngest of the noted individuals belong roughly to the generations of the early 1990s. It is concluded on the existence of an extremely low-abundant landlocked form of the Azov beluga in the reservoir.

Abstract: Beluga whales are an Arctic and subarctic cetacean, with an overall “near threatened” conservation status, yet some populations are considered endangered. Apart from threats such as whaling, predation, contamination, and pathogens, underwater noise is of increasing concern. In the early 1990s, Fisheries & Oceans Canada started to fund research on underwater noise emitted by icebreakers and its bioacoustic impacts. In collaboration with the Vancouver Aquarium, beluga whales were trained for masked hearing experiments. Apart from measuring pure-tone audiograms in quiet conditions, animals were trained to listen for beluga vocalizations in different types of noise, including artificially created white noise, naturally occurring thermal ice-cracking noise, and an icebreaker’s propeller cavitation and bubbler system noise. Based on this data, software models for masking in beluga whales were developed. More than 20 years later, this dataset remains the only one on masking in cetaceans using both complex signal...

Abstract: Data on distribution of digestive enzymes along the intestinal tract of mature specimens of the beluga Huso huso and Russian sturgeon Acipenser gueldenstaedtii are presented. The absence of a distinct proximo-distal gradient of the enzyme activity can be explained by short length of the intestine of sturgeons. Considerable differences are found in the distribution pattern of enzymes along the intestinal tract of beluga and Russian sturgeon. The effect of the method of calculation of the enzyme activity on the data on the proximo- distal gradient is considered.

Abstract: The spectral parameters of heart rate variability are a measure of activation of the sympathetic and parasympathetic branches of the mammalian autonomic nervous system. In this study, spectral analysis was used for the first time to evaluate the impact of acoustic noise (one of the major anthropogenic factors) on a cetacean. We analyzed cardiac intervals in a captive beluga (a member of the Odontoceti whales) in response to a 10-min band-pass acoustic noise at an intensity of 150–165 dB and frequency of 19–38 kHz. The beluga’s response to acoustic noise, when examined shortly after the animal’s capture, was characterized by a sharp tachycardia (the first phase) followed by a decrease in the heart rate (the second phase). Based on spectral analysis, the frequency range of heart rate oscillations in the beluga decreased during the period of tachycardia while shifting to a lower frequency range (below 0.01 Hz) as compared with the control conditions. Accordingly, the spectral power of low-frequency components was reduced. During the second phase, the range of heart rate variability oscillations expanded and fully recovered only after the noise had been turned off. After one year in captivity, no significant changes in the heart rate parameters (both in time and frequency domain) were recorded in response to a similar noise exposure. Therefore, the changes in the heart rate spectral components in the studied beluga exposed to acoustic noise were comparable to those recorded in terrestrial mammals and in humans in stressful and emotionally negative situations. The spectral characteristics of heart rate oscillations can be used as a quantitative measure of beluga whales’ response to acoustic noise as a stress factor.

Abstract: To understand beluga whale (Delphinapterus leucas) estuarine use in the Nelson River estuary, southwest Hudson Bay, we recorded and examined beluga movements and habitat associations for the July through August period in 2002–2005. We compared locations of belugas fitted with satellite transmitters (“tags”) (2002–2005) and aerial-surveyed (2003 and 2005) belugas for years of differing freshwater flow from the Nelson River which is influenced by hydroelectric activity. Using the beluga telemetry location data, we estimated an early August behavioral shift in beluga distribution patterns from local estuarine use to a progressively more migratory behavior away from the estuary. The timing of this shift in behavior was also apparent in results of beluga aerial surveys from the 1940s–1960s, despite environmental changes including later freeze-up and warming ocean temperatures. Overall, during the higher than average discharge (“wet”) year of 2005, the three tagged belugas ranged farther from the Nelson River but not farther from the nearest shore along southwestern Hudson Bay, compared to the 10 tagged belugas tracked during the “dry” years of 2002–2004 with below average discharges. Aerial survey data for 2003 and 2005 display a similar dry vs. wet year shift in spatial patterns, with no significant change in overall density of belugas within the study area. In the Nelson estuary, proximity to the fresh-salt water mixing area may be more important than the shallow waters of the upper estuary. Killer whales (Orcinus orca) were observed in the Churchill area (200 km northwest) during each year of study, 2002–05, and belugas may benefit from the proximity to shallow estuary waters that provide protection from the larger-bodied predator. Study results contribute to an understanding of the influence of environmental variation on how and why belugas use estuaries although considerable uncertainties exist and additional research is required.

Abstract: Asymmetrical intraguild predation (AIGP), which combines both predation and competition between predator species, is pervasive in nature with relative strengths varying by prey availability. But with species redistributions associated with climate change, the response by endemic predators within an AIGP context to changing biotic–abiotic conditions over time (i.e. seasonal and decadal) has yet to be quantified. Furthermore, little is known on AIGP dynamics in ecosystems undergoing rapid directional change such as the Arctic. Here, we investigate the flexibility of AIGP among two predators in the same trophic guild: beluga ( Delphinapterus leucas ) and Greenland halibut ( Reinhardtius hippoglossoides ), by season and over 30 years in Cumberland Sound—a system where forage fish capelin ( Mallotus villosus ) have recently become more available. Using stable isotopes, we illustrate different predator responses to temporal shifts in forage fish availability. On a seasonal cycle, beluga consumed less Greenland halibut and increased consumption of forage fish during summer, contrasting a constant consumption rate of forage fish by Greenland halibut year-round leading to decreased AIGP pressure between predators. Over a decadal scale (1982–2012), annual consumption of forage fish by beluga increased with a concomitant decline in the consumption of Greenland halibut, thereby indicating decreased AIGP pressure between predators in concordance with increased forage fish availability. The long-term changes of AIGP pressure between endemic predators illustrated here highlights climate-driven environmental alterations to interspecific intraguild interactions in the Arctic.

Abstract: Asymmetrical intraguild predation (AIGP), which combines both predation and competition between predator species, is pervasive in nature with relative strengths varying by prey availability. But with species redistributions associated with climate change, the response by endemic predators within an AIGP context to changing biotic–abiotic conditions over time (i.e. seasonal and decadal) has yet to be quantified. Furthermore, little is known on AIGP dynamics in ecosystems undergoing rapid directional change such as the Arctic. Here, we investigate the flexibility of AIGP among two predators in the same trophic guild: beluga (Delphinapterus leucas) and Greenland halibut (Reinhardtius hippoglossoides), by season and over 30-years in Cumberland Sound—a system where forage fish capelin (Mallotus villosus) have recently become more available. Using stable isotopes, we illustrate different predator responses to temporal shifts in forage fish availability. On a seasonal cycle, beluga consumed less Greenland halibut and increased consumption of forage fish during summer, contrasting a constant consumption rate of forage fish by Greenland halibut year-round leading to decreased AIGP pressure between predators. Over a decadal scale (1982–2012), annual consumption of forage fish by beluga increased with a concomitant decline in the consumption of Greenland halibut, thereby indicating decreased AIGP pressure between predators in concordance with increased forage fish availability. The long-term changes of AIGP pressure between endemic predators illustrated here highlights climate-driven environmental alterations to interspecific intraguild interactions in the Arctic.

Abstract: The study was performed to examine the efficacy of ginger (Zingiber officinale) extract on growth performance, biochemical and hemato-immunological parameters in juvenile beluga (Huso huso). Fish were divided into 4 groups before fed diet for 8 weeks with 0.5%, 1% and 1.5% ginger extract and with unsupplemented commercial diet as the control. Results showed that there was a significant different in weight gain in fish fed ginger extract diet compared to the control (P<0.05). There were no significant differences in condition factor, feed conversion ratios, specific growth rate and survival between juveniles fed control and ginger extract supplementation (P>0.05). Correspondence R Akrami, Department of Fisheries, Azadshahr Branch, Islamic Azad University, Azadshahr, Iran (email: akrami.aqua@gmail.com ) In addition, there were no significant differences of RBC, WBC counts, Hct, monocyte, lymphocyte, neutrophil, eosinophil, glucose, TPP, triglyceride, lipid and globulin levels between the treatment groups (P>0.05). Furthermore, alternative complement activity (ACH50), serum total immunoglobulin (Ig) and lysozyme activity were significantly increased in 1.5% ginger fed fish (P<0.05); however, it did not change the SOD activity, significantly (P>0.05). Therefore, the results suggest that by using 1.5% this extract there will be an improvement in hemato-biochemical parameters and immune function of juvenile beluga.