Four Japanese krill fishing vessels operated in Area 48 during the 1999/2000 split year. In Subarea 48.1, the operation started in December and lasted until June. In Subarea 48.2, operation took place in December, March, and May to June. In subarea 48.3, operation took place only in June. Trawling positions, CPUEs and body length of Antarctic krill during the period is described. The krill length frequency distribution was further compared with those obtained by the CCAMLR international observer undertaken at the same time, and they resulted in good agreements. The discussion was extended to the possibility of intra-annual variability of two krill stocks (Antarctic Peninsula and Weddell Sea stocks).