Estimation of krill (Euphausia superba) mortality and production rate in the Antarctic peninsula region

A net sampling survey for krill was carried out by RV ‘Meteor’ along the Antarctic Peninsula from 26 December 1989 to 14 January 1990. Results were compared with data of an identical survey with RV ‘Polarstern’ in 1987/88. Seasonal variation between summer and winter abundance/biomass data exceeded a factor of 35 times, while interannual variability between available surveys reached only a factor of 1.6 times. Krill mortality was calculated by linearized catch curve analysis and resulted a rate of Z=0.88 (1989/90) and Z=0.96 (1987/88). Production was estimated and resulted a P/B ratio of 0.88 to 0.94 for different years. The exchange rate of water masses and krill biomass within one summer season was roughly estimated as 2 times from which follows a maximum total effective biomass (including production) of 4.3 and 5.0*106 tonnes passing through the survey area during the respective summer.