3 resultados para Ronne Antarctic Research Expedition, 1946-1948

em DigitalCommons@University of Nebraska - Lincoln


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Eighteen years after initiating scientific whaling in Antarctic waters, Japan presented a new and more ambitious program to the International Whaling Commission (IWC); the proposal was made in early June during the IWC’s annual meeting in Ulsan, Korea. Japan now wishes to more than double its annual catch of Antarctic minke whales (from about 440 to 935), and to expand lethal sampling to include an additional yearly take of 50 humpback and 50 fin whales. Unlike catches for commercial whaling, scientific catches are unregulated. Since 1987, Japan has taken some 6,800 minke whales from Antarctic waters, despite ongoing criticism of the relevance and direction of Japan’s research. The IWC was set up to regulate commercial whaling and to conserve whale populations, under the authority of the 1946 International Convention for the Regulation of Whaling. Following a well-documented failure of management that led to the collapse of most global whale populations, the IWC set a zero quota for commercial whaling (the moratorium). This was made effective from 1986. Norway, the former Soviet Union and Japan initially objected to the moratorium, but Japan withdrew its objection and ceased commercial whaling in 1988.

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Although Lewis and Clark literature has proliferated in the last decade, few works have added scholarly discourse to this field of study. The highly focused Venereal Disease and the Lewis and Clark Expedition, however, will likely stand out on the Lewis and Clark bookshelf as an important contribution.

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Antarctic fur seals (Arctocephalus gazella) in the South Shetland Islands are recovering from 19th-century exploitation more slowly than the main population at South Georgia. To document demographic changes associated with the recovery in the South Shetlands, we monitored fur seal abundance and reproduction in the vicinity of Elephant Island during austral summers from 1986/1987 through 1994/1995. Total births, mean and variance of birth dates, and average daily mortality rates were estimated from daily live pup counts at North Cove (NC) and North Annex (NA) colonies on Seal Island. Sightings of leopard seals (Hydrurga leptonyx) and incidents of leopard seal predation on fur seal pups were recorded opportunistically during daily fur seal research at both sites. High mortality of fur seal pups, attributed to predation by leopard seals frequently observed at NC, caused pup numbers to decline rapidly between January and March (i.e., prior to weaning) each year and probably caused a long-term decline in the size of that colony. The NA colony, where leopard seals were never observed, increased in size during the study. Pup mortality from causes other than leopard seal predation appeared to be similar at the two sites. The number of pups counted at four locations in the Elephant Island vicinity increased slowly, at an annual rate of 3.8%, compared to rates as high as 11% at other locations in the South Shetland Islands. Several lines of circumstantial evidence are consistent with the hypothesis that leopard seal predators limit the growth of the fur seal population in the Elephant Island area and perhaps in the broader population in the South Shetland Islands. The sustained growth of this fur seal population over many decades rules out certain predator–prey models, allowing inference about the interaction between leopard seals and fur seals even though it is less thoroughly studied than predator–prey systems of terrestrial vertebrates of the northern hemisphere. Top-down forces should be included in hypotheses for future research on the factors shaping the recovery of the fur seal population in the South Shetland Islands.