scholarly journals Whales as Indicators of Historical and Current Changes in the Marine Ecosystem of the Indo-Pacific Sector of the Antarctic

2020 ◽  
Author(s):  
Yoshihiro Fujise ◽  
Luis A. Pastene
Keyword(s):  
Marine Ecosystem ◽  
Recruitment Rate ◽  
Minke Whale ◽  
Past Century ◽  
Baleen Whale ◽  
The Past ◽  
Antarctic Minke Whale ◽  
Minke Whales ◽  
Nutritional Conditions ◽  
The Antarctic

We review the scientific information on whales that could be indicative of historical and current changes in the ecosystem in the Indo-Pacific sector of the Antarctic. The increased krill availability in the middle of the past century as a result of the heavy harvesting of the larger baleen whale species could have been translated into better nutritional conditions for the Antarctic minke whale, resulting in a decreasing trend in the age at sexual maturity and an increasing trend in recruitment rate and hence total population size between approximately 1940 and 1970. This nutritional condition has deteriorated more recently, as revealed by a decrease in energy storage and stomach content weight since the 1980’s; these changes coincide with appreciable increases in the abundances of humpback and fin whales, which were heavily harvested in the first half of the past century. The historical demographic changes observed in the Antarctic minke whale are consistent with the pattern to be expected under the krill surplus hypothesis, with minke whales now again competing with other (recovering) baleen whale species for krill. However, these minke whales could also be using alternative feeding areas (e.g. polynias within the pack-ice) in response to the increase in abundance and geographical expansion of these other large whale species. This could provide an alternative explanation for indications from sighting surveys and population models of a decrease and then re-stabilisation of minke whale abundance in open water areas since the 1970s.

A note on minke whales (Cetacea: Balaenopteridae) in Uruguay: strandings review

2020 ◽  
Vol 21 (1) ◽  
pp. 135-140
Author(s):  
Eduardo Juri ◽  
Meica Valdivia ◽  
Paulo Cesar Simoes-Lopes ◽  
Alfredo Le Bas
Keyword(s):  
Atlantic Ocean ◽  
Minke Whale ◽  
Balaenoptera Acutorostrata ◽  
Southwest Atlantic ◽  
Antarctic Minke Whale ◽  
Minke Whales ◽  
Important Region ◽  
The Common ◽  
The Antarctic ◽  
Common Minke Whale

The minke whale is the smallest of the living rorquals and is widely distributed in the tropical, temperate and polar waters of both hemispheres. In the western Southwest Atlantic Ocean there are two currently recognised species, the dwarf form of the common minke whale, Balaenoptera acutorostrata unnamed subsp. and the Antarctic minke whale B. bonaerensis. All stranding records and collected specimens of minke whale on the coast of Uruguay were reviewed and analysed. Between 1962 and 2018, 33 records were gathered in a non-systematic way, 22 specimens of B. acutorostrata and 11 of B. bonaerensis. It was found that most animals were discovered alive or recently dead and assigned as neonates/young calves. This supports the hypothesis that Uruguayan coasts are part of an important region for reproduction and breeding for the species.

scholarly journals Comparison of progesterone concentrations in blubber and plasma among female Antarctic minke whales of known reproductive status

2019 ◽  
Vol 85 (6) ◽  
pp. 971-977
Author(s):  
Satoko Inoue ◽  
Genta Yasunaga ◽  
Luis A. Pastene
Keyword(s):  
General Pattern ◽  
Austral Summer ◽  
Minke Whale ◽  
Reproductive Status ◽  
Antarctic Ocean ◽  
Progesterone Concentration ◽  
Antarctic Minke Whale ◽  
Minke Whales ◽  
Overlap Ratio ◽  
The Antarctic

Abstract The utility of progesterone concentration in blubber as a means of determining reproductive status in the Antarctic minke whale Balaenoptera bonaerensis was assessed through a comparative analysis of progesterone concentration in blubber and plasma among 230 female whales of known reproductive status (immature, resting, ovulating or pregnant). Whales were sampled during the austral summer in the Antarctic Ocean. The general pattern of progesterone concentration by reproductive category was well correlated between blubber and plasma samples, validating in principle the use of progesterone concentrations in blubber to determine the reproductive status of females. However, some differences were found for resting and ovulating females, which require further consideration. For blubber, overlap of progesterone concentrations was observed between reproductive categories with the exception of immature/ovulating and immature/pregnant. This result suggests that the method of using progesterone concentration in blubber cannot distinguish between pregnant and non-pregnant mature females. However, it can be used to distinguish between immature and mature females. Although a low overlap ratio in concentration was found between immature and resting females, the method is still useful for determining sexual maturity, because resting females of the Antarctic minke whale are seldom found in the Antarctic Ocean.

scholarly journals Decline in body condition in the Antarctic minke whale (Balaenoptera bonaerensis) in the Southern Ocean during the 1990s

Polar Biology ◽  
2021 ◽  
Vol 44 (2) ◽  
pp. 259-273
Author(s):  
Céline Cunen ◽  
Lars Walløe ◽  
Kenji Konishi ◽  
Nils Lid Hjort
Keyword(s):  
Model Selection ◽  
Body Condition ◽  
Model Building ◽  
Research Question ◽  
Information Criterion ◽  
The Body ◽  
Antarctic Minke Whale ◽  
Minke Whales ◽  
Balaenoptera Bonaerensis ◽  
The Antarctic

AbstractChanges in the body condition of Antarctic minke whales (Balaenoptera bonaerensis) have been investigated in a number of studies, but remain contested. Here we provide a new analysis of body condition measurements, with particularly careful attention to the statistical model building and to model selection issues. We analyse body condition data for a large number (4704) of minke whales caught between 1987 and 2005. The data consist of five different variables related to body condition (fat weight, blubber thickness and girth) and a number of temporal, spatial and biological covariates. The body condition variables are analysed using linear mixed-effects models, for which we provide sound biological motivation. Further, we conduct model selection with the focused information criterion (FIC), reflecting the fact that we have a clearly specified research question, which leads us to a clear focus parameter of particular interest. We find that there has been a substantial decline in body condition over the study period (the net declines are estimated to 10% for fat weight, 7% for blubber thickness and 3% for the girth). Interestingly, there seems to be some differences in body condition trends between males and females and in different regions of the Antarctic. The decline in body condition could indicate major changes in the Antarctic ecosystem, in particular, increased competition from some larger krill-eating whale species.

Cryosphere

2004 ◽  
Author(s):  
Kenneth M. Hinkel ◽  
Andrew W. Ellis
Keyword(s):  
Sea Ice ◽  
Snow Cover ◽  
Global Climate ◽  
Ice Sheets ◽  
Past Century ◽  
High Latitudes ◽  
Ice Shelves ◽  
The Past ◽  
Third Assessment Report ◽  
The Antarctic

The cryosphere refers to the Earth’s frozen realm. As such, it includes the 10 percent of the terrestrial surface covered by ice sheets and glaciers, an additional 14 percent characterized by permafrost and/or periglacial processes, and those regions affected by ephemeral and permanent snow cover and sea ice. Although glaciers and permafrost are confined to high latitudes or altitudes, areas seasonally affected by snow cover and sea ice occupy a large portion of Earth’s surface area and have strong spatiotemporal characteristics. Considerable scientific attention has focused on the cryosphere in the past decade. Results from 2 ×CO2 General Circulation Models (GCMs) consistently predict enhanced warming at high latitudes, especially over land (Fitzharris 1996). Since a large volume of ground and surface ice is currently within several degrees of its melting temperature, the cryospheric system is particularly vulnerable to the effects of regional warming. The Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) states that there is strong evidence of Arctic air temperature warming over land by as much as 5 °C during the past century (Anisimov et al. 2001). Further, sea-ice extent and thickness has recently decreased, permafrost has generally warmed, spring snow extent over Eurasia has been reduced, and there has been a general warming trend in the Antarctic (e.g. Serreze et al. 2000). Most climate models project a sustained warming and increase in precipitation in these regions over the twenty-first century. Projected impacts include melting of ice sheets and glaciers with consequent increase in sea level, possible collapse of the Antarctic ice shelves, substantial loss of Arctic Ocean sea ice, and thawing of permafrost terrain. Such rapid responses would likely have a substantial impact on marine and terrestrial biota, with attendant disruption of indigenous human communities and infrastructure. Further, such changes can trigger positive feedback effects that influence global climate. For example, melting of organic-rich permafrost and widespread decomposition of peatlands might enhance CO2 and CH4 efflux to the atmosphere. Cryospheric researchers are therefore involved in monitoring and documenting changes in an effort to separate the natural variability from that induced or enhanced by human activity.

scholarly journals Structure and Steroidogenesis of the Placenta in the Antarctic Minke Whale (Balaenoptera bonaerensis)

2013 ◽  
Vol 59 (2) ◽  
pp. 159-167 ◽  
Author(s):  
Motoki SASAKI ◽  
Yoko AMANO ◽  
Daisuke HAYAKAWA ◽  
Toshio TSUBOTA ◽  
Hajime ISHIKAWA ◽  
...  
Keyword(s):  
Minke Whale ◽  
Antarctic Minke Whale ◽  
Balaenoptera Bonaerensis ◽  
The Antarctic

Reproductive aspects of female crabeater seals (Lobodon carcinophagus) along the Antarctic Peninsula

1981 ◽  
Vol 59 (1) ◽  
pp. 92-102 ◽  
Author(s):  
John L. Bengtson ◽  
Donald B. Siniff
Keyword(s):  
Antarctic Peninsula ◽  
Reproductive Performance ◽  
Sexual Maturity ◽  
Marine Ecosystem ◽  
Geographical Differences ◽  
The Past ◽  
Antarctic Marine ◽  
Crabeater Seals ◽  
Lobodon Carcinophagus ◽  
The Antarctic

Examination of a sample of 94 female crabeater seals collected in November, 1977, indicated that, for the past 7 years, the average age at sexual maturity was 3.8 years. Reproductive performance as evidenced by uterine scars and ovarian corpora is discussed. No females inseminated at age 4 or less successfully carried a fetus full term. Timing of ovulation was affected by both age and social category. Younger seals ovulate later in the season than older seals. No females ovulated prior to weaning their pups. Ovulation in experienced females occurred sometimes while still in a mated pair, but mostly at or after dissolution of the pair bond. Comparison of recent age of sexual maturity with earlier reports shows an increase in this age since 1967. This trend may reflect geographical differences or changes in the Antarctic marine ecosystem following a slowdown in Antarctic whaling.

Chemical Properties of Epidermal Lipids, Especially Sphingolipids, of the Antarctic Minke Whale

Lipids ◽  
2008 ◽  
Vol 43 (2) ◽  
pp. 151-159 ◽  
Author(s):  
Keita Yunoki ◽  
Hajime Ishikawa ◽  
Yutaka Fukui ◽  
Masao Ohnishi
Keyword(s):  
Chemical Properties ◽  
Minke Whale ◽  
Epidermal Lipids ◽  
Antarctic Minke Whale ◽  
The Antarctic

Decline in energy storage in the Antarctic minke whale (Balaenoptera bonaerensis) in the Southern Ocean

Polar Biology ◽  
2008 ◽  
Vol 31 (12) ◽  
pp. 1509-1520 ◽  
Author(s):  
Kenji Konishi ◽  
Tsutomu Tamura ◽  
Ryoko Zenitani ◽  
Takeharu Bando ◽  
Hidehiro Kato ◽  
...  
Keyword(s):  
Energy Storage ◽  
Southern Ocean ◽  
Minke Whale ◽  
Antarctic Minke Whale ◽  
Balaenoptera Bonaerensis ◽  
The Antarctic

scholarly journals Frozen verses: Antarctic minke whales ( Balaenoptera bonaerensis ) call predominantly during austral winter

2020 ◽  
Vol 7 (10) ◽  
pp. 192112
Author(s):  
Diego Filun ◽  
Karolin Thomisch ◽  
Olaf Boebel ◽  
Thomas Brey ◽  
Ana Širović ◽  
...  
Keyword(s):  
Minke Whale ◽  
Weddell Sea ◽  
Austral Winter ◽  
Atlantic Sector ◽  
Antarctic Minke Whale ◽  
Minke Whales ◽  
Ice Concentration ◽  
Vocal Activity ◽  
Passive Acoustic ◽  
Occurrence Patterns

The recent identification of the bio-duck call as Antarctic minke whale (AMW) vocalization allows the use of passive acoustic monitoring to retrospectively investigate year-round spatial-temporal patterns in minke whale occurrence in ice-covered areas. Here, we present an analysis of AMW occurrence patterns based on a 9-year passive acoustic dataset (2008–2016) from 21 locations throughout the Atlantic sector of the Southern Ocean (Weddell Sea). AMWs were detected acoustically at all mooring locations from May to December, with the highest presence between August and November (bio-duck calls present at more than 80% of days). At the southernmost recording locations, the bio-duck call was present up to 10 months of the year. Substantial inter-annual variation in the seasonality of vocal activity correlated to variation in local ice concentration. Our analysis indicates that part of the AMW population stays in the Weddell Sea during austral winter. The period with the highest acoustic presence in the Weddell Sea (September–October) coincides with the timing of the breeding season of AMW in lower latitudes. The bio-duck call could therefore play a role in mating, although other behavioural functions of the call cannot be excluded to date.

Sign in / Sign up

Export Citation Format

Share Document