A case study on the distribution of cod larvae and availability of prey organisms in relation to physical processes in Lofoten. In: The propagation of cod Gadus morhua L.: an international symposium, Arendal, 14 - 17 June 1983

Abstract

The distribution of cod larvae and copepod nauplii off the Lofoten islands was studied in the years 1979-82. The highest concentrations of cod larvae and copepod nauplii were found in the Austnesfjord, Hølla-Henningsvær and the Vesterålsfjord area. The feeding condition of cod larvae was studied in relation to prey abundance, and a direct proportionality was seen between gut content and prey abundance in the larvae at the end of the first feeding period. Vertical migration of cod larvae was observed at a diurnal station in the Vesterålsfjord under calm weather conditions. The feeding condition of the cod larvae were bad under the prevalent prey density (<10 prey org. per 1) at this station. At a diurnal station in the Austnesfjord, the onset of turbulent mixing lowered the prey and cod larval densities and created a homogeneous vertical distribution of cod larvae and prey animals. This was reflected in the gut content analysis when the percentage of cod larvae with gut contents, and the number of prey organisms per larval gut and the percentage of newly taken prey organisms fell to a critical level.