| Summary: | Progress Code: completed Statement: This voyage is one of six which are studying the abundance and disribution of Euphausia superba and other zooplankton. This provides a good coverage of the area at varying season times and conditions. Ship-board instrumentation: A Simrad echosounding system was used, comprising of an EK-38 echosounder operating at 38 kHz, and EK-120 echosounder operating at 120 kHz, a QD echointegrator and grey scale chart recorders. The EK-38 was only used intermittently. The echosounder transducers were hull mounted approximately 6m below the surface. The towed transducer system was deployed at a nominal depth of 30m. Data collection: Fourteen transects were made, eleven in an east-west direction, parallel to the mean direction of the prevailing ocean currents and to the continental shelf, and three in a north-south direction. The 120kHz echosounder was run continuously while MV Nella Dan was in the study area. The QD integrator was set to integrate 8 depth layers between 1m and 200m below the transducer. The effective integration range was 7-206m. The echointegrator output, including the mean volume backscatter strength for each of the eight layers, was recorded on paper tape at the end of each 1 nautical mile integration interval. The mean target strength of krill were calculated from the lengths of the individual krill. Post-cruise processing: Acoustic data were processed on a VAX 11/750 computer. Mean density and variance of the mean were estimated using the ratio estimator, a process adopted at the second post-FIBEX acoustic workshop. Biomass was estimated for an area defined by a box drawn around the transects and extended on two sides by half the mean spacing between the transects. Mean krill biomass, variance of the biomass, and 95% confidence limits about the mean were calculated from the estimated mean and variance of the krill surface density. Please see the documentation reference for further details, and theoretical information. Data are logically consistent, as oceanographic ...
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