In order to identify whether or not there was a marked change in two kinds of CPUEs, body length and greenness of krill during the fishing season, these parameters were examined for each 10-day period of the Japanese krill fishery in the northern waters of Livingston Island in the 1987/88 season. It appears that Japanese trawlers have not fished krill concentrations to the extent that a decrease in krill biomass in this area can be detected from these data. The percentages of “Egui” as an indicator of greenness of krill were too variable among trawlers to be an objective indicator at present.