TY - JOUR N2 - On the basis of acoustically registered cross-sections of krill aggregations, regular, irregular and layer forms were distinguished. Regular forms are most frequently observed during spring and in the day time, while irregular forms are most frequent during summer and night hours. The density histograms made for two hour intervals clearly show the day-night difference, but the seasonal (spring, summer) difference is less pronounced. Mean density of swarm is lowest during the night and reaches a maximum in early morning hours. The mean volume backscattering strength values (Sv) for spring and summer are nearly identical. We suggest that regular forms correspond to foraging swarms and irregular forms to feeding swarms as described by Hamner (1984). L1 - http://www.journals.pan.pl/Content/111282/PDF/1988_2-3_357-366.pdf L2 - http://www.journals.pan.pl/Content/111282 PY - 1988 IS - No 2-3 EP - 366 KW - Antarctica KW - krill KW - BIOMASS III A1 - Godlewska, MaƂgorzata A1 - Klusek, Zygmunt PB - Polish Academy of Sciences PB - Committee on Polar Research VL - vol. 9 DA - 1988 T1 - The density structure of krill aggregations and their diurnal and seasonal changes (BIOMASS III, October- November 1986 and January 1987) SP - 357 UR - http://www.journals.pan.pl/dlibra/publication/edition/111282 T2 - Polish Polar Research ER -