Proportional recruitment indices of Antarctic krill from Japanese fisheries data in Subareas 48.1, 48.2 and 48.3 during 1980 through 1997

Proportional recruitments (R1 and R2) were calculated for Subareas 48.1, 48.2 and 48.3 from logbook data of Japanese commercial krill fisheries during 1980 to 1997. Inter-annual patterns of R1 and R2 in Subarea 48.1 generally showed similar trends to Siegel et al. (1 998)'s values around the Elephant Island. However, the values especially R1 in this study were extremely smaller than Siegel et al. (1 998)'s values. This may be due to the net selectivity and/or incomplete coverage of the distribution of small krill by commercial fisheries. Inter-annual pattern of R1 and R2 in Subarea 48.2 showed somewhat similar pattern to Subarea 48.1. However, because of inconsistency of the operation periods and occasional small sample size, interpretation of it's pattern in this Subarea should be dealt very carefully. In Subarea 48.3, R1 values showed the evidence of recruitments in two year classes, which coincided with the year classes of strong proportional recruitments in Subarea 48.1. However, the complexity of length composition in this Subarea was also pointed out.