ISSN:
1432-2056
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary Continuous acoustic observations with a 30 kHz and a 150 kHz echo-sounder were made from November 1988 to January 1989 on one repeatedly sampled transect, running along 49°W from the open waters of the Scotia Sea into the Weddell Sea pack-ice. Swarm signals occurring on the echorecords were mainly found in the upper 100 m of the watercolumn, in size varying vertically from 1 to 70 m, and horizontally from less than 5 to over 3,000 m. Catches with a RMT 1+8 indicated that the observed swarm signals were most probably caused by krill, Euphausia superba. From late November to early January the swarms migrated northwards away from the ice-edge and towards greater depths, while simultaneously growing in size. The average number of swarms observed per 10 nautical miles along the transects remained fairly constant throughout the cruise, but the average swarmsize and total aggregation size increased during the period studied. The echo-data give evidence of the spring-summer migration of major parts of the krill stock from under the ice-cover towards open waters.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00238268
