Abstract: A software model estimating zones of impact on marine mammals around man-made noise [C. Erbe and D. M. Farmer, J. Acoust. Soc. Am. 108, 1327–1331 (2000)] is applied to the case of icebreakers affecting beluga whales in the Beaufort Sea. Two types of noise emitted by the Canadian Coast Guard icebreaker Henry Larsen are analyzed: bubbler system noise and propeller cavitation noise. Effects on beluga whales are modeled both in a deep-water environment and a near-shore environment. The model estimates that the Henry Larsen is audible to beluga whales over ranges of 35–78 km, depending on location. The zone of behavioral disturbance is only slightly smaller. Masking of beluga communication signals is predicted within 14–71-km range. Temporary hearing damage can occur if a beluga stays within 1–4 km of the Henry Larsen for at least 20 min. Bubbler noise impacts over the short ranges quoted; propeller cavitation noise accounts for all the long-range effects. Serious problems can arise in heavily industrialized a...

Abstract: Depletion of sturgeon stocks world-wide has increased interest in aquaculture-based restoration programmes. The Caspian Sea Sturgeon Ranching Programme (SRP) of the former Soviet Union represents a unique opportunity to evaluate expense, benefits and potential ecological and genetic effects of such restoration programmes. The SRP was initiated in the 1950s to compensate for lost spawning habitat in the Volga River and elsewhere. After its completion in 1962, the Volgograd Dam reduced spawning grounds in the Volga River system, the principal spawning tributary of the Caspian Sea, by ∼80%. For two of the three commercial sturgeon species (Russian sturgeon, Acipenser guldenstadti, and stellate sturgeon, A. stellatus), yields improved after the imposition of the 1962 moratorium on sturgeon harvests in the Caspian Sea. Volga River fisheries were managed for spawning escapement. Although imprecisely known, the contribution of the millions of stocked Russian and stellate juveniles during 1962–91 was most likely important to sustaining fisheries, although less so (contributing to <30% of the adult stock) than natural recruitment. Apparently, reduced spawning grounds, supplemented with artificial spawning reefs were sufficient to support reproduction and large fishery yields of Russian and stellate sturgeons. For beluga sturgeon, Huso huso, harvests in the Volga River were nearly all dependent upon hatchery stocking. Beluga sturgeon spawning grounds were mostly eliminated with the construction of the Volgograd Dam. Without the hatchery programme, beluga sturgeon in the Volga River and Caspian Sea would in all likelihood have been extirpated. Currently, sturgeons are severely depleted in the Volga River and Caspian Sea due to poaching and lack of co-operation between countries exploiting the species. Aquaculture-based restoration in Russia is now viewed a chief means of rebuilding stocks of Caspian Sea sturgeons.

Abstract: A review of available information describing habitat associations for belugas, Delphinapterus leucas, in Cook Inlet was undertaken to complement pouplation assessment surveys from 1993-2000. Available data for physical, biological, and anthropogenic factors in Cook Inlet are summarized followed by a provisional description of seasonal habitat associations. To summarize habitat preferences, the beluga summer distribution pattern was used to partition Cook Inlet into three regions. In general, belugas congregate in shallow, relatively warm, low-salinity water near major river outflows in upper Cook Inlet during summer (defined as their primary habitat), where prey availability is comparatively high and predator occurrence relatively low. In winter, belugas are seen in the central inlet, but sightings are fewer in number, and whales more dispersed compared to summer. Belugas are associated with a range of ice conditions in winter, from ice-free to 60% ice-covered water. Natural catastrophic events, such as fires, earthquakes, and volcanic eruptions, have had no reported effect on beluga habitat, although such events likely affect water quality and, potentially, prey availability. Similarly, although sewage effluent and discharges from industrial and military activities along Cook Inlet negatively affect activities along Cook Inlet negatively affect water quality, analyses of organochlorines and heavy metal burdens indicate that Cook Inlet belugas are not assimilating contaminant loads greater than any other Alaska beluga stocks. Offshore oil and gas activities and vessel traffic are highin the central inlet compared with other Alaska waters, although belugas in Cook Inlet seem habituated to these anthropogenic factors. Anthropogenic factors that have the highest potential negative impacts on belugas include subsistence hunts (not discussed in this report), noise from transportation and offshore oil and gas extraction (ship transits and aircraft overflights), and water quality degradation (from urban runoff and sewage treatment facilities). Although significant impacts from anthropogenic factors other than hunting are not yet apparent, assessment of potential impacts from human activities, especially those that may effect prey availability, are needed.

Abstract: —Beluga, Delphinapterus leu­cas, distribution in the Gulf of Alaska and adjacent inside waters was examined through a review of surveys conducted as far back as 1936. Although beluga sight­ings have occurred on almost every marine mammal surve y in northern Cook Inlet (o ver 20 surveys reported here), beluga sightings have been rare outside the inlet in the Gulf of Alaska. More than 150,000 km of ded­icated survey effort in the Gulf of Alaska resulted in sightings of over 23,000 indi­vidual cetaceans, of which only 4 beluga sightings (5 individuals) occurred. In addi­tion, nearly 100,000 individual cetaceans were reported in the Platforms of Opportu­nity database; yet, of these , only 5 sightings (39 individuals) wer e belugas. Furthermor e, approximately 19 beluga sightings (>260 individuals), possibly including r esightings, have been reported without information on effort or other cetacean sightings. Of the 28 sightings of belugas outside of Cook Inlet, 9 were near Kodiak Island, 10 were in or near Prince William Sound, 8 were in Yaku­tat Bay, and 1 anomalous sighting was well south of the Gulf. These sightings support archaeolo gical and commer cial harvest e vi­dence indicating the only persistent group of belugas in the Gulf of Alaska occurs in Cook Inlet.

Abstract: This article examines the masking by anthropogenic noise of beluga whale calls. Results from human masking experiments and a software backpropagation neural network are compared to the performance of a trained beluga whale. The goal was to find an accurate, reliable, and fast model to replace lengthy and expensive animal experiments. A beluga call was masked by three types of noise, an icebreaker's bubbler system and propeller noise, and ambient arctic ice-cracking noise. Both the human experiment and the neural network successfully modeled the beluga data in the sense that they classified the noises in the same order from strongest to weakest masking as the whale and with similar call-detection thresholds. The neural network slightly outperformed the humans. Both models were then used to predict the masking of a fourth type of noise, Gaussian white noise. Their prediction ability was judged by returning to the aquarium to measure masked-hearing thresholds of a beluga in white noise. Both models and the whale identified bubbler noise as the strongest masker, followed by ramming, then white noise. Natural ice-cracking noise masked the least. However, the humans and the neural network slightly overpredicted the amount of masking for white noise. This is neglecting individual variation in belugas, because only one animal could be trained. Comparing the human model to the neural network model, the latter has the advantage of objectivity, reproducibility of results, and efficiency, particularly if the interference of a large number of signals and noise is to be examined.

Abstract: A longitudinal serologic survey was conducted for morbillivirus antibodies in Atlantic walruses (Odobenus rosmarus rosmarus), narwhal (Monodon monoceros), and beluga (Delphinapterus leucas) from the Northwest Territories, Nunavut and the St. Lawrence estuary (Canada). Sixty-five of 131 (50%) walruses sampled between 1984 and 1993 had detectable morbillivirus neutralizing antibodies. Positive walrus were identified from four of five Arctic sampling sites, to as far back as 1984. Prevalence of morbillivirus neutralizing antibodies in walruses from Foxe Basin ranged from a high of 76% (n = 21) in 1993 to a low of 22% (n = 28) in 1984. Limitations in sample acquisition may have produced underestimates for the 1984 data. There are no reports of clinical morbillivirus infection in walruses. Our results are consistent with the hypothesis that a morbillivirus similar or identical to phocine distemper virus (PDV) has circulated among walrus populations of the eastern Canadian Arctic, at least since the early 1980s...

Abstract: T issues from Cook Inlet beluga whales, Delphinapterus leucas, that were collected as part of the Alaska Marine Mammal Tissue Archival Project were ana­ lyzed for polychlorinated biphenyls (PCB's), chlorinated pesticides, and heavy metals and other elements. Concentrations of total PCB's (∑ PCB's), total DDT (∑ DDT), chlor­ dane compounds, hexachlorobenzene (HCB), dieldrin, mirex, toxaphene, and hexachlor­ ocyclohexane (HCH) measured in Cook Inlet beluga blubber were compared with those reported for belugas from two Arctic Alaska locations (Point Hope and Point Lay), Greenland, Arctic Canada, and the highly contaminated stock from the St. Law­ rence estuary in eastern Canada. The Arctic and Cook Inlet belugas had much lower concentrations (∑PCB's and ∑DDT wer e an order of magnitude lower) than those

Abstract: We conducted gamma spectrometric analyses on more than 200 arctic marine mammal tissue samples. These samples were primarily provided by subsistence hunters from northern Alaska, with a smaller number of samples from the Resolute region in Canada. The majority of samples (>90%) had detectable levels of the anthropogenic radionuclide 137 Cs, with a mean level observed in all samples of 0.67 Bq kg -1 dry weight ± 0.81 (SD). Converted to wet weight, the mean was 0.21 Bq kg -1 ± 0.19 SD. The median activity observed was 0.45 Bq kg -1 dry weight (0.18 Bq kg -1 wet weight) with a range from detection limits to 6.7 Bq kg -1 dry weight (1.1 Bq kg -1 wet weight). These findings confirm expectations that current anthropogenic gamma emitter burdens in marine mammals used in the North American Arctic as subsistence food resources are well below activities that would normally merit public health concern (~1000 Bq kg -1 wet weight). Some differences among species and tissues were observed. Beluga tissues had slightly higher mean burdens of 137 Cs overall, and epidermis and muscle tissues in bowhead and beluga whales typically had higher burdens than other tissues analyzed. Low levels of the neutron activation product 108m Ag (half-life 418 yr.), probably bioaccumulated from bomb fallout sources, were observed in 16 of 17 beluga livers analyzed, but were not found in any other tissues of beluga or in any other species sampled. A subset of 39 samples of various tissues was analyzed for the alpha and beta emitters 239,240 Pu and 90 Sr. Plutonium levels were near the threshold of detectability (~0.1 Bq kg -1 dry weight) in 6 of the 39 samples; all other samples had no detectable plutonium. A detectable level of 90 Sr (10.3 ± 1.0 Bq kg -1 dry weight) was observed in only one of the 39 samples analyzed, a bowhead epidermis sample. Although the accumulation of 108m Ag has not been previously reported in any marine mammal livers, all of our analytical measurements indicate that only very low levels of anthropogenic radioactivity are associated with marine mammals harvested and consumed in the North American Arctic.

Abstract: Four sturgeon species have been reported to exist in Greek waters: the Atlantic sturgeon, the great sturgeon, the stellate sturgeon and the Adriatic sturgeon. The Atlantic sturgeon Acipenser sturio L., 1758 has an almost regular presence in the Evros River (Aegean Sea), and is rather rare in the Pinios and Acheloos Rivers. The great sturgeon or beluga Huso huso L., 1758 is suspected to be an occasional visitor in Greek waters, or it is a case of undocumented information. The presence of the stellate sturgeon Acipenser stellatus Pallas, 1771 has been recently verified by a specimen caught close to the Thracian shore. The Adriatic sturgeon Acipenser naccarii Bonaparte, 1836 is supposed to have its southern distribution limits in the waters around the island of Corfu, although this information has never been confirmed. The distribution of these species is obviously related to salinity, probably prohibiting the extension of other sturgeon species to the Mediterranean, except for A. sturio. The discontinuous distribution of H. huso and A. stellatus may be a result of sea-level changes, while salinity played some role in the last period of glaciation. In the marine area of the Evros River A. sturio has been economically significant until 1975, supporting a small black caviar industry. Since then, the species has become rare mainly because of overfishing, and the reduction and pollution of the Evros River, in the upstream of which some important sturgeon spawning sites have been located.

Abstract: Of the five populations of beluga, Delphinapterus leucas, in Alaska, the most isolated is the one in Cook Inlet (Hazard, 1988; Hill and DeMaster, 1998) (Fig. 1). The geographic and genetic segregation of this stock (O’Corry-Crowe et al., 1997), combined with the beluga’s tendency toward site fidelity in summer, makes this population especially vulnerable to impacts from large or persistent harvests.

Abstract: In an effort to gain knowledge on immune functions in beluga whales, Delphinapterus leucas , we have used two physical methods for the purification of T lymphocytes of spleen cells. Isolation by sheep red blood cells (SRBC) rosetting and by adherence on nylon wool columns were tested. SRBC-rosetting gave unreliable results in obtaining purified T cells. Therefore, the purification of T cells was done using nylon wool columns. Less than 3% of the IgM + B cells remained in effluent populations. In the later population, 45% gave positive staining with mouse anti-human CD4 allowing us to verify functionality of the cells. The study of calcium mobilization and tyrosine kinase activation, mediated by CD4 cross-linking permitted verification of the functionality of cells. We also showed that upon activation with mitogens, beluga T cells upregulate the density of MHC class II molecules on their surfaces. CD4 cross-linking with a specific antibody inhibited the proliferation response. Overall, the activation of beluga whales lymphocytes did not differ markedly from what is known in other species. This study can help in the groundwork for functional investigation of the beluga whale’s immune system.

Abstract: Carbonic anhydrase (CA) expression was examined in the red cells of two mammals that have adapted to low oxygen stress: the llama, which has adapted to high altitudes, and the beluga (or white) whale, which routinely dives for extended periods. Immunodiffusion analyses of their Hb-free hemolysates and partial amino acid sequencing of their HPLC-separated nonheme proteins indicate that the low-activity CA I isozyme is the major nonheme protein in erythrocytes of both the beluga whale and the llama. The high-activity CA II isozyme was not detected in the whale red cells but was present at low levels in erythrocytes of the llama. These results suggest that the absence or decrease in the expression of the high-activity CA II isozyme may be advantageous under hypoxic conditions.

Abstract: Acquisition of sounds emitted by marine mammals (porpoise and beluga) living in the Black Sea was made using active echosounder (BioSonics Model 102) with down‐looking 120‐ and 200‐kHz transducers. The sounds of the mammals displayed different structures not similar to each other. The individual amplitude of the porpoise sound was significantly discriminated and varied between −55 and −62 dB at 200 kHz. The echoes were characterized with decreasing amplitude from the deep water to the surface. It looked like vertical lineations. The sound scattering was fluctuated in a range of 10–20 dB. Sound emitted by beluga displayed a structure like rakes of a comb. The echo was captured first very weak at 120 kHz and then strong at 200 kHz. The volume scattering changed within a range of 60 and −70 dB at 200 kHz. While the whale was close to the transducer, it emitted the sound every 300 s. It sometimes gave sound in different patterns from some reason. As we got away from the whale, while on the way, we detected the sound at 10 s. Each lineation of the comb‐rake structure appeared in a certain time delay and the strength decreased toward the surface.

Abstract: This paper reports relationships between bulk Hg concentrations in the tooth cementum and soft tissues of free-living beluga (Delphinapterus leucas). Total Hg levels were determined in slivers of cementum using a solid-sample Hg analyzer, a recent advance in Hg analysis that avoids acid predigestion. Tooth Hg concentrations ranged up to about 350 ng/g dry weight and were significantly correlated with Hg levels in kidneys, liver, muscle, and muktuk (skin) and with the age of the animals. The Hg/Se ratio in liver, the organ with the highest Hg concentrations, may have been an important determinant of tooth Hg. At hepatic Hg/Se molar ratios {ge}0.6, tooth Hg increased steeply, suggesting that Hg in teeth may reflect physiologically available Hg that was not bound in the liver and that was circulating in the bloodstream. This Hg/Se ratio was exceeded in most beluga aged {ge}20 years. The results indicate that teeth can be used as biomonitors to reconstruct temporal and geographic trends in the soft tissue Hg concentrations of beluga, provided that the age structures of the different populations are known.

Abstract: Kowledge is limited regarding methylsulfone (MeSO2)-polychlorinated biphenyl (PCB), and especially MeSO2–2,2-bis(chlorophenyl)-1,1-dichloroethylene (DDE), metabolites in cetacean species. We hypothesized that the ability of beluga whale (Delphinapterus leucas) to biotransform PCB and DDE compounds, and to form and degrade their MeSO2 PCB and -DDE metabolites, is related to the capacity for xenobiotic metabolism. Adipose biopsies were collected from male and female beluga whale from distinct populations in the St. Lawrence River estuary (STL) and western Hudson Bay (WHB), Canada, which are contrasted by the exposure to different levels of cytochrome P450 enzyme-inducing, chlorinated hydrocarbon contaminants. The PCBs, DDTs, DDEs, 28 MeSO2 metabolites of 14 meta-para chlorine-unsubstituted PCBs, and four MeSO2 metabolites of 4,4′- and 2,4′-DDE were determined. The mean concentrations of total (Σ-) MeSO2-PCB in male STL beluga (230 ng/g), and ratios of Σ-MeSO2-PCB to Σ-PCB (0.05) and Σ-precursor-PCB (0.17) were approximately twofold higher, whereas the Σ-precursor-PCB to Σ-PCB ratio was approximately twofold lower, than in male WHB beluga. Both populations had a low formation capacity for MeSO2-PCBs with ≥six chlorines (<4% of Σ-MeSO2-PCBs). The congener patterns were dominated by trichloro- and tetrachloro-MeSO2-PCBs, and tetrachloro- and pentachloro-MeSO2-PCBs in WHB and STL animals, respectively. In addition to 2- and 3-MeSO2-4,4′-DDE, two unknown MeSO2-2,4′-DDEs were detected. The mean 3-MeSO2-4,4′-DDE concentration in STL beluga (1.2 ng/g) was much greater than in WHB (<0.01 ng/g) animals. The concentrations of 4,4′-DDE, and not 3-MeSO2-4,4′-DDE, increased with age in male STL animals. We demonstrated that sulfone formation and clearance is related to metabolic capacity, and thus PCB, DDE, and MeSO2-PCB and -DDE toxicokinetics differ for STL and WHB beluga. In the past, the capacity of odontocetes for PCB and DDE biotransformation leading to persistent sulfone metabolites has been underestimated. More information is needed for other cetacean species and marine mammals. The results of this study indicate that MeSO2-PCBs and -DDEs need to be included in the toxicologic risk assessment of PCB and DDT exposure in odontocetes, and perhaps for cetaceans in general.