| Summary: | Progress Code: completed Statement: This cruise provides data from the fourth of six cruises, which provides a good coverage of the area over varying seasons and conditions. Data collection: A rectangular midwater trawl net (RMT8+1) was used for the collection of larval and post larval krill Euphausia superba. 66 stations were completed. At each station, a shallow oblique haul, from 0 to 200 m, was made. At every third station a deep haul, from 0 to 1000 m, was made. Horizontal tows were also made when krill swarms were located at a particular depth, using a Simrad EK 120 echo sounder. Onboard-ship processing: Large and fragile specimens were removed from the main catch, and all specimens were preserved in Steedman's solution. Krill catches from swarms were weighed using a clock-faced spring balance, and at least 200 species from each catch were preserved in Steedman's solution. Post-ship processing: The RMT8 krill samples were sorted into juvenile, male and female specimens, and body length and weight were measured, using a slide caliper and Mettler top-pan balance. The males and females were classified into maturation stages according to the Makarov and Denys (1981) system. The non krill specimens in the RMT8 catches were identified according to phylum, class, sub-class or order level, and weighed. Euphausiids were identified to the following species: Euphausia crystallorophias, Euphausia frigida, Euphausia triacantha, and Thysanoessa macrura. The RMT1 samples contained a large amount of phytoplankton, which made the measurement of wet weight of the whole sample difficult. Settling volume was measured instead, by standing the samples in a 2 litre measuring cylinder for 2 weeks. Krill larvae and other Euphausiid species larvae were extracted, staged and counted under a dissecting microscope. Larvae from Euphausia superba and Euphausia crystallorophias were raised from eggs in the laboratory and used as a reference. Consistency can be established through comparison of different net methods. Oceanography and ...
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