An estimation of walrus (Odobenus rosmarus) predation on bivalves in the Young Sound area (NE Greenland)

The total consumption of bivalve prey by walruses (Odobenus rosmarus) in the important inshore summer feeding area Young Sound (about 74° N) in Northeast Greenland was estimated. To determine relative area use, the movement and activity of three adult male walruses carrying satellite transmitters were studied during the open-water season in 1999 and 2001. Because one of the animals was tracked during both years the study covered a total of four “walrus seasons”. Overall, the animals spent c. 30% of their time in the water inshore in Young Sound between Sandøen and Zackenberg. The remaining time was spent along the coast north and south of Young Sound and offshore in the Greenland Sea. The total amount of bivalve food consumed in Young Sound by the walruses during a total of 1620 “walrus feeding days” was calculated from information on the total number of walruses using the area (n=60), occupancy in the study area, and estimates obtained from satellite telemetry on the number of daily feeding dives (118-181/24 h at sea). Depending on the applied estimator of number of feeding dives, the estimated consumption by walruses of shell-free (SF) bivalve wet weight (WW) during the open-water period ranged between 111 and 171 tons. Based on estimates of mean total body mass (TBM: 1000 kg) of walruses using the area and daily per capita gross food intake (6% of TBM), the corresponding estimate of consumption by walruses is c. 97 tons SF WW. It is suggested that the two lowest estimates of total consumption are the most plausible

Prolonged chemical restraint of walrus (Odobenus rosmarus) with etorphine supplemented with medetomidine

Physiological studies involving the use of isotopic water required chemical restraint of free- ranging walruses (Odobenus rosmarus) for several hours. In August 2000, six male walrus (total body mass: 1050–1550 kg) were immobilized in East Greenland by remote delivery of 8.0–9.8 mg of etorphine and subsequently restrained for up to 6.75 h by administration of medetomidine. The effects of etorphine were reversed with 10–24 mg diprenorphine. After termination of the etorphine-induced apnoea, lasting an average of 15.8 min (SD = 9.7, range = 9.5–35.2 min, n = 6), the animals were initially given 10–20 mg medetomidine intramuscularly. The initial dose was further augmented by 5 mg at intervals of 5 min. In two cases, when medetomidine was administered through a catheter inserted in the extradural vein, the animal became instantly apnoeic and regained respiratory function only after intravenous injection of the prescribed dose of the antagonist atipamezole and of the respiratory stimulant doxapram. After an average of 3.5 hours of immobilisation, rectal temperature began to increase and it is conceivable that this is the factor that will ultimately limit the duration of immobilisation. The animals became conscious and fully mobile shortly after an intravenous injection of a dose of atipamezole approximately twice the mass of the total dose of medetomidine given during the procedure followed by 400 mg of doxapram. It is concluded that medetomidine appears to be a suitable drug for chemical restraint of walruses for time-consuming procedures following initial immobilisation by etorphine. With animals of total body mass around 1,000–1,500 kg, the drug should be given intramuscularly in 10–20 mg increments (total mass 10–60 mg) until the breathing rate falls to approximately 1 min-1. At this level, breathing is maintained and animals do not respond to touch or injection

Total mercury in hair of polar bears (Ursus maritimus) from Greenland and Svalbard

Concentrations (ppm = ug/g dry weight) of total mercury (Hg) were determined in hair of polar bears (Ursus maritimus) from northwestern Greenland (N = 22; period of sampling: 1978-1989), eastern Greenland (N = 44: 1984-1989) and Svalbard (N = 31; 1980). For subadults (2-6 years of life), adults (7-10 years). and old bears (>10 years), concentrations of total Hg in hair were not found to be dependent on age or sex. A decreasing trend in Hg concentrations was found from west to east. The mean concentrations of total Hg in hair (cubs of the year and yearlings excluded) were: northwestern Greenland, x = 8.38 ppm (min.-max.: 4.71-14.19 ppm. N = 21); eastern Greenland: x = 4.58 ppm (min.-max.: 2.50-8.83 ppm. N = 41); and Svalbard, x = 1.98 ppm (min.-max.: 1.02-4.55 ppm, N = 29). Concentrations found in northwestern Greenland were similar to those reported by others from the hair of polar bears sampled within management zone F of the eastern Canadian High Arctic. Concentrations of total Hg in polar bear hair from eastern Greenland were similar to concentrations found by others in contemporary (1988) material collected during spring in western Svalbard. However, the mean concentration of total Hg in the 1980 Svalbard material, which was collected during July-September, was significantly lower than concentrations found in samples taken during late winter and spring in eastern Greenland and at Svalbard, respectively. Presumably the relatively low concentrations found in the 1980 Svalbard sample arc attributable to the period of moult and hence a larger proportion of newly grown hair in the individual samples. In a subsample consisting of internal tissues from 19 polar bears from eastern Greenland (1984-1987), concentrations of total Hg in hair correlated positively with concentrations of total Hg (wet weight) in muscle (N = 6), liver (N = 19) and kidney (N = 19) tissue. For liver and kidney tissue these relationships were statistically significant

Overview of the special issue "Studies of white whales (Delphinapterus leucas) and narwhals (Monodon monoceros) in Greenland and adjacent waters".

This overview introduces the collection of papers on the Distribution and abundance; Exploitation and status; Habitat use and behaviour; and Life history, stock identity and toxicology of white whales (Delphinapterus leucas) and narwhals (Monodon monoceros) in Greenland and adjacent waters. It includes brief summaries of the 19 included papers and calls attention to ongoing and future studies on the same or related subjects

Do Wild Polar Bears (Ursus maritimus) Use Tools When Hunting Walruses (Odobenus rosmarus)?

Since the late 1700s, reports of polar bears (Ursus maritimus) using tools (i.e., pieces of ice or stones) to kill walruses (Odobenus rosmarus) have been passed on verbally to explorers and naturalists by their Inuit guides, based on local traditional ecological knowledge (TEK) as well as accounts of direct observations or interpretations of tracks in the snow made by the Inuit hunters who reported them. To assess the possibility that polar bears may occasionally use tools to hunt walruses in the wild, we summarize 1) observations described to early explorers and naturalists by Inuit hunters about polar bears using tools, 2) more recent documentation in the literature from Inuit hunters and scientists, and 3) recent observations of a polar bear in a zoo spontaneously using tools to access a novel food source. These observations and previously published experiments on brown bears (Ursus arctos) confirm that, in captivity, polar and brown bears are both capable of conceptualizing the use of a tool to obtain a food source that would otherwise not be accessible. Based on the information from all our sources, this may occasionally also have been the case in the wild. We suggest that possible tool use by polar bears in the wild is infrequent and mainly limited to hunting walruses because of their large size, difficulty to kill, and their possession of potentially lethal weapons for both their own defense and the direct attack of a predator. Depuis la fin des années 1700, des signalements d’ours polaires (Ursus maritimus) se servant d’outils (comme des morceaux de glace ou des pierres) pour tuer des morses (Odobenus rosmarus) ont été communiqués verbalement par des guides inuits à divers explorateurs et naturalistes. Les guides en question se fondaient sur les connaissances écologiques traditionnelles (CET) locales de même que sur les interprétations de traces dans la neige ou les récits d’observations directes des chasseurs inuits ayant fait les signalements. Pour évaluer la possibilité que les ours polaires puissent parfois se servir d’outils pour chasser les morses en milieu sauvage, nous résumons : 1) les observations décrites aux premiers explorateurs et naturalistes par les chasseurs inuits au sujet de l’utilisation d’outils par les ours polaires; 2) la documentation récente attribuable aux chasseurs inuits et aux scientifiques; et 3) les récentes observations de l’ours polaire d’un zoo se servant d’outils spontanément pour avoir accès à une nouvelle source de nourriture. Ces observations, alliées à des expériences publiées au sujet d’ours bruns (Ursus arctos), permettent de confirmer qu’en captivité, tant les ours bruns que les ours polaires sont capables de conceptualiser l’utilisation d’un outil pour se procurer de la nourriture qui ne serait autrement pas accessible. D’après les renseignements prélevés auprès de toutes nos sources, cela aurait aussi pu être occasionnellement le cas en milieu sauvage. Nous suggérons que l’utilisation possible d’outils par les ours polaires en milieu sauvage n’est pas fréquente et qu’elle est surtout limitée à la chasse au morse en raison de la grande taille de cette espèce, de la difficulté à l’abattre et des armes potentiellement mortelles qu’elle possède, tant pour se défendre que pour attaquer un prédateur directement.&nbsp

Habitat Use of Ringed Seals (Phoca hispida) in the North Water Area (North Baffin Bay)

In conjunction with the International North Water Polynya Study in Smith Sound (northern Baffin Bay) in 1997-99, we examined the area use and diving activity of 23 ringed seals (Phoca hispida) that had been equipped with satellite transmitters on the Greenland side of the North Water (NOW) area. The study covered the period 12 August 1996-30 June 1999. Contact with the seals was maintained for an average of 108 days (range: 8-332 days). Four seals emigrated from the NOW area. During all seasons, the seals that remained in the area spent about 90% of the time in coastal (< 100 m deep) waters in the eastern parts of the NOW area. The total area visited by the seals during the open-water season ranged between 10 300 km² (1996) and 18 500 km² (1998), corresponding to about 15% to 25% of the entire NOW area. In winter, the total area visited by the seals varied between 2500 km² (1996-97) and 7000 km² (1998-99), and in spring, between 800 km² (1999) and 2100 km² (1997). Individual movement was significantly greater during the open-water season than during winter and spring. Maximum dive depths recorded were over 500 m (maximum for the instrument) outside and 376 m inside the NOW, for a 96 kg male seal. Non-adult seals spent about 99% of the time in waters less than 100 m deep, and more than 92% of the time in the upper 50 m. In contrast, adults tended to spend more time at greater depths. The study indicated that (1) the ringed seals took advantage of the generally lighter ice conditions in the eastern NOW, and (2) that non-adults likely exploited ice-associated amphipods and young polar cod (Boreogadus saida), and adults, mainly older polar cod and cephalopods taken at greater depths.Conjointement avec l'étude internationale sur la polynie de l'Eau du Nord dans le détroit de Smith (partie nord de la baie de Baffin) menée de 1997 à 1999, on a examiné l'utilisation de cette zone et l'activité de plongée de 23 phoques annelés (Phoca hispida) munis d'émetteurs-satellite du côté groenlandais de la région de l'Eau du Nord («NOW»). L'étude a couvert la période allant du 12 août 1996 au 30 juin 1999. Le contact avec les phoques a été maintenu pendant une moyenne de 108 jours (étendue: 8-332 jours). Quatre phoques ont émigré de la zone NOW. Durant toutes les saisons, les phoques qui restaient dans la zone passaient environ 90% du temps dans des eaux côtières (profondeur < 100 m) dans les secteurs orientaux de NOW. La superficie totale visitée par les phoques durant la saison d'eau libre allait de 10 300 km² (1996) à 18 500 km² (1998), correspondant à environ 15 à 25% de toute la zone NOW. En hiver, l'étendue totale fréquentée par les phoques allait de 2500 km² (1996-1997) à 7000 km² (1998-1999), et au printemps, de 800 km² (1999) à 2100 km² (1997). Les déplacements individuels étaient de beaucoup plus grands durant la saison d'eau libre qu'au cours de l'hiver et du printemps. Les profondeurs maximales de plongée enregistrées dépassaient 500 m (limite de l'instrument) à l'extérieur de la zone NOW et 376 m à l'intérieur, pour un phoque mâle de 96 kg. Les phoques non adultes passaient environ 99% du temps dans des eaux à une profondeur ne dépassant pas 100 m, et plus de 92% du temps dans les 50 m supérieurs. En revanche, les adultes avaient tendance à passer plus de temps à de plus grandes profondeurs. L'étude révèle 1) que les phoques annelés tiraient parti du fait qu'il y avait moins de glace dans la partie orientale de NOW, et 2) que, selon toute vraisemblance, les non-adultes exploitaient amphipodes et jeune morue polaire (Boreogadus saida) associés à la glace, les adultes se nourrissant surtout de morue polaire plus âgée et de céphalopodes prélevés à de plus grandes profondeurs

The Atlantic walrus (Odobenus rosmarus rosmarus) in West Greenland

In the early part of the 20th century Atlantic walruses (Odobenus rosmarus rosmarus) occurred abundantly between approximately 66°N and 70°45'N in Central West Greenland from September until mid June. Between September and December several hundred walruses hauled out on small islands and promontories between the entrance to Nassuttooq (Nordre Strømfjord, approx. 67°30'N) and approximately 67°45'N, south of the settlement of Attu. From 1911, the hunt for walruses at terrestrial haul out sites was intensified, and by the late 1930s the walruses had abandoned the terrestrial haul outs in this area. Between 1911 and the early 1940s, the catches of walruses in western Greenland (excluding the Avanersuaq/Thule area) increased rapidly, reaching a maximum of more than 600 animals reported for 1938 and 1940. Mainly reproductive females were caught and the proportion of unretrieved kills was high. Between the early 1940s and the mid 1960s catches decreased rapidly, apparently reflecting a decrease in the stock of walruses wintering off Central West Greenland. Between 1965 and 1987, the recorded annual catch in western Greenland south of 76°N averaged 56 walruses (SD = 19.7; range 19- 101 animals). It is estimated that during this period the total number of walruses removed by hunting was about 100 per year. Comparisons of the results of systematic aerial surveys conducted in early spring of 1981, 1982, 1984, 1990 and 1991 over the walrus wintering grounds at Central West Greenland revealed no trend in abundance. The line transect methods used in the 1990 and 1991 surveys gave higher and more robust estimates of abundance than the strip censuses used in the previous surveys, and resulted in estimates of abundance of about 500 walruses (not corrected for submerged animals). The stock structure of the total walrus population in the Baffin Bay and Davis Strait regions is obscure. However, this study has shown that the numbers of walruses in Central West Greenland are much lower than historical levels, and that walruses in this area are vulnerable

Line-transect estimation of abundance of narwhal (Monodon monoceros) in Scoresby Sund and adjacent waters

An aerial line transect survey of narwhal (Monodon monoceros) abundance in Scoresby Sund and adjacent fjords in East Greenland was conducted in September 1983 and 1984. An effort of 1747 and 1973 linear kilometers resulted in 66 and 19 primary sightings of narwhal pods in 1983 and 1984. respectively. The mean pod size increased slightly but not significantly from 1.99 to 2.56 between the two years. The resulting estimates of abundance of narwhals (not corrected for submerged animals) were 300 (95% Cl 165- 533) and 102 (95~ Cl 36-276) in 1983 and 1984, respectively. These two estimates are not significantly different. The difference between the two estimates is most likely due to annual variation, perhaps in combination with the formation of new ice in 1984, which could have forced the narwhals out of the study area