Zooplankton in relation to herring in the Norwegian Sea, June 1959

Abstract

1. During a cruise with RV "Johan Hjort" from 2. to 28. June 1959 zooplankton was collected at 121 stations in the Norwegian Sea. 2. The zooplankton was most abundant in the border area between Atlantic waters and Norwegian coastal waters, and scanty in the cold water of the East-Icelandic current. 3. Calanus finmarchicus was the dominating copepod, except at a few stations off Iceland. Pseudocalanus elongatus, Themisto abyssorum and larval stages of euphausids were common all over the area investigated. In the Atlantic waters Oithona similis, Oncaea borealis, Aglantha digitale and Oikopleura vanhöffeni were common, while Collozoum inerme also occurred in mixed waters. Larvae of Sebastes marinus and Gadus esmarki were found at Storegga off the west coast of Norway. 4. Both in Norwegian coastal waters, Atlantic waters, mixed waters and in the Irminger current the copepodite stages IV and V of Calanus finmarchicus dominated. In the East-Icelandic current and also off Møre a high percentage of adults occurred. 5. The relation between herring, phytoplankton and zooplankton is discussed.