Desarrollo de la Antártica

EL DESARROLLO DE LA ANTARTlCA yet been elasified in detail, and therefore prompt promotions of systematic geolQ,gical, geophysical and geochemical studies ineluding the mining geology should be emphasized in the near future by t:1- king into consideration the Antarctic potentiality for mineral re– sources. d) Marine Lz:vimg Resouroes i. Euphausia superba (krills) Figures 14 and 15 in lO' illustrate the food chain systems in the pe– lagic zone and the pack-ice zone respectively in the Antarctic Ocean. In botlh cases, Euphausia superba (Antarctic krills) play the most .important role. As shown in Fig. 14, Baleen whales (Fin, Blue, Sei, Humpback and Minke whales) eat mostly krills together much less amounts of fishes and squids, whereas Sperm whales do squids and a little amount of fishes. Since the total biomass of Antarctic whales has muoh decreased owing to the failure in a scientifically sufficient measures for Ilhe conservation of whale stocks (from 43 x 10'6 tons. to 17 x W 6 tons. for Baleen whales, and from 2.6 x 10'6 tons. to 1.2 x 10'6 tons. fM ISperm whal,es), it is believed tJhat a large abundance of Antarctic krills are being kept in the Antarctic Ocean without a useful con– sumption. The surplus of Antarctic krills at present is presumed to be (l.O' ----1.5) x 10 8 tons. at minimum. This estimated value of krill biomass is derived from a difference between the estimatecl consumption of krills by Baleen whales at present and that in the l'95O"s, so that considerably more Ilhan 1.151 x l(J8 tons. could be ex– pected for the potential surplus of iAntarctic krills. Studies on krills during about lO' years and mainly between 20'° E and 7O'aw ihave led to the conelusion that .E. superba matures and breeds two summers after being spawned, namely, age = 2 + years. lt is reported however tJhat krill samples collected in the Scotia Sea demonstrate) a 4 year life cyele. These data seem to suggest a possibility of utilizing the krill resources of several t,ens of million tons per year by fisheries. However, cri tical aspects of the biology and ecology of krill still remain to be clarified. These inelude growth rates, longevity, fecun– dity, hydrographic features of areas of high population densities and causal factors of swarming, spawning areas and depths, distribution and transportation of early larval stages, pairing and repeat spawn– ing, etc. 12 4