排序方式: 共有25条查询结果,搜索用时 16 毫秒
1.
Morphometric data are given for 41 adult male Atlantic walruses ( Odobenus rosmarus rosmarus) immobilized at Svalbard. Total body weight ranged from 960 to 1450 kg. Standard body length ranged from 258 to 380 cm, while curvilinear tusk length ranged from 17 to 65 cm. Immobilized animals were selected for their large size. The sample is therefore biased towards larger animals. Based on regression equations developed for walruses caught in Greenland, the weights of Svalbard walruses were estimated from standard body length and axillary girth. Estimated weights ranged from 632 to 1883 kg. The present data suggest that Atlantic walruses at Svalbard can attain the same body size as Pacific ( O. r. divergens ) and Laptev walruses (O. r. laptevi). 相似文献
2.
Three juvenile narwhals captured during August 1998 in the northeast of Svalbard, Norway, were equipped with satellite-relayed
data loggers (SRDLs) that transmitted diving and swim-speed data, in addition to location, for up to 46 days. A total of 1,354
complete dive cycles were recorded. Most of the diving was shallow and of short duration. Maximum recorded dive depth was
546 m, maximum recorded dive duration was 24.8 min, and maximum recorded swim-speed was 4.7 ms−1. Ascent speed, vertical ascent speed, descent speed and vertical descent speed were all significantly higher during deep
dives (>200 m) than for shallow dives (<200 m). In addition both ascent and descent angles were much steeper for deep dives
than during shallow dives. Most of the shallow diving seemed to be associated with travelling, with the animal shifting between
various locations, while the deep diving (often to the bottom) for extended periods in some specific areas might have been
associated with foraging. Even though the sample size in this study is small, the data are the first information available
for movements and diving behaviour of narwhals near Svalbard. 相似文献
3.
The aim of this study was to describe growth, determine age at sexual maturity and investigate the condition of bearded seals
(Erignathus barbatus) collected in the fjords of Spitsbergen, Svalbard, Norway. Morphometric data, teeth and sex organs were collected from 110
animals. Age was determined by reading the cementum layers in hard longitudinal sections of canine teeth. Sexual maturity
in males was determined according to the size of the testes and bacula. Females were defined as being sexually mature according
to findings of mature follicles or corpora lutea/albicantia. Von Bertalanffy growth curves were applied to both standard length and body mass, and asymptotic values for males and females
were 231.1 ± 11.4 cm and 269.9 ± 26.2 kg, and 233.1 ± 7.5 cm and 275.3 ± 47.8 kg, respectively. Maximum recorded lengths and
masses were 254 cm and 313 kg in males and 242 cm and 358 kg in females. All males older than 6 years were found to have been
sexually mature. Females were found to attain sexual maturity at about 90% of the asymptotic length, corresponding to an age
of 5 years. In males a significant decrease in condition was observed from June to August, with a subsequent increase in September.
In adult females, condition decreased from May to June and increased again from June to September. The conditional changes
seen are likely to be due to the extra energetic cost and reduced food intake associated with reproduction, lactation and
molt.
Accepted: 28 July 1998 相似文献
4.
Wynen LP Goldsworthy SD Guinet C Bester MN Boyd IL Gjertz I Hofmeyr GJ White RW Slade R 《Molecular ecology》2000,9(3):299-314
Commercial sealing in the 18th and 19th centuries had a major impact on the Antarctic and subantarctic fur seal populations (Arctocephalus gazella and A. tropicalis) in the Southern Ocean. The intensive and unrestricted nature of the industry ensured substantial reductions in population sizes and resulted in both species becoming locally extinct at some sites. However, both species are continuing to recover, through the recolonization of islands across their former range and increasing population size. This study investigated the extent and pattern of genetic variation in each species to examine the hypothesis that higher levels of historic sealing in A. gazella have resulted in a greater loss of genetic variability and population structure compared with A. tropicalis. A 316-bp section of the mitochondrial control region was sequenced and revealed nucleotide diversities of 3.2% and 4.8% for A. gazella and A. tropicalis, respectively. There was no geographical distribution of lineages observed within either species, although the respective PhiST values of 0.074 and 0.19 were significantly greater than zero. These data indicate low levels of population structure in A. gazella and relatively high levels in A. tropicalis. Additional samples screened with restriction endonucleases were incorporated, and the distribution of restriction fragment length polymorphism (RFLP) and sequence haplotypes were examined to identify the main source populations of newly recolonized islands. For A. tropicalis, the data suggest that Macquarie Island and Iles Crozet were probably recolonized by females from Marion Island, and to a lesser extent Ile Amsterdam. Although there was less population structure within A. gazella, there were two geographical regions identified: a western region containing the populations of South Georgia and Bouvetoya, which were the probable sources for populations at Marion, the South Shetland and Heard Islands; and an eastern region containing the panmictic populations of Iles Kerguelen and Macquarie Island. The latter region may be a result of a pronounced founder effect, or represent a remnant population that survived sealing at Iles Kerguelen. 相似文献
5.
Seven post-moulting adult ringed seals (Phoca hispida) were equipped with Satellite Linked Dive Recorders in Svalbard in July 1996 to determine if ringed seals conduct long-distance
post-moulting feeding excursions, and to obtain details of their diving behaviour. The mean duration of tags was 206 days
(range 103–325). Two seals swam 400 km north to the drifting pack ice (82°N). The rest undertook more local movements. Forty-eight
percent of all dives were shallower than 20 m and 90% were shallower than 100 m. Ninety-five percent of all dive durations
were shorter than 10 min, and 99.5% were shorter than 15 min. This study has shown that adult ringed seals undertake varying
patterns of post-moulting excursions.
Accepted: 1 April 2000 相似文献
6.
7.
Walruses were on the verge of extinction in Svalbard prior to becoming totally protected in 1952. The present study attempts to determine the number of walruses in Svalbard in summer based on aerial, ground and boat surveys. In 1993, 741 walruses were observed, almost all of which were males. This population, which is shared with the neighbouring Russian archipelago Franz Joseph Land, is believed to consist of an equal number of females. We therefore conclude that the shared population consists of a minimum of about 1450 walruses older than 2 years and an unknown number of calves. 相似文献
8.
C. Lydersen K. M. Kovacs M. O. Hammill I. Gjertz 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1996,166(7):405-411
In this study we measure energy intake via milk in nursing bearded seal (Erignathus barbatus) pups and determine how this energy is allocated into metabolism and storage of new tissues. This was accomplished using
longitudinal mass gain records and the doubly labelled water technique on nursing pups in combination with cross-sectional
data on changes in milk composition from bearded seal mothers. The pups (n=3) were all less than a week old at the start of the experiments. Pups gained 3.3±0.4 kg·day-1 of which 50% was fat, 14% protein and 36% water. Average daily water influx for the pups was 69.5±9.0 ml · kg-1· day-1. Average CO2 production during the study period was 0.99±0.10 ml·g-1·h-1, which corresponds to a field metabolic rate of 642±67 kJ·kg-1· day-1, or 6.0±0.5 times the predicted basal metabolic rate according to Kleiber (1975). The pups drank an average of 7.6±0.5 kg
of milk daily. This corresponds to a daily energy intake of 154±8 MJ, 47±14% of which was stored as new body tissue. Despite
this high energy intake bearded seal pups do not get as fat as do other nursing phocids. This is in part due to their larger
body size but also due to their very active aquatic lifestyle and the lower and more consistent fat content of the milk compared
to other phocid species. Bearded seal mothers forage during lactation and may also be involved in teaching their pups to feed
independently. All these data suggest that the lactation strategy of bearded seals differs from the phocid norm. 相似文献
9.
10.
THE NARWHAL, MONODON MONOCEROS, IN THE NORWEGIAN HIGH ARCTIC 总被引:1,自引:0,他引:1
Narwhals ( Monodon monoceros ) are known to frequent the waters of the Norwegian arctic archipelago of Svalbard. An attempt is made to summarize narwhal observations from the Svalbard area, and from this to deduce their distribution. Observations have been gathered from the literature, sealing vessel log books and official statistics. Interviews have also been conducted with residents of Svalbard. I con&de that narwhals are most frequently observed in the area off the north-west corner of Spitsbergen. 相似文献