biomass of scyphozoan jellyfish, and its spatial association with 0-group fish in the barents seascyphozoan水母,生物量及其空间联系0组鱼在巴伦支海.pdfVIP

Biomass of Scyphozoan Jellyfish, and Its Spatial Association with 0-Group Fish in the Barents Sea 1 2 2 1 Elena Eriksen *, Dmitry Prozorkevich , Aleksandr Trofimov , Daniel Howell 1 Institute of Marine Research, Bergen, Norway, 2 Polar Research Institute of Marine Fisheries and Oceanography, Murmansk, Russia Abstract An 0-group fish survey is conducted annually in the Barents Sea in order to estimate fish population abundance. Data on jellyfish by-catch have been recorded since 1980, although this dataset has never been analysed. In recent years, however, the ecological importance of jellyfish medusae has become widely recognized. In this paper the biomass of jellyfish (medusae) in 0–60 m depths is calculated for the period 1980–2010. During this period the climate changed from cold to warm, and changes in zooplankton and fish distribution and abundance were observed. This paper discusses the less well known ecosystem component; jellyfish medusae within the Phylum Cnidaria, and their spatial and temporal variation. The long term average was ca. 9 6108 kg, with some years showing biomasses in excess of 5 6109 kg. The biomasses were low during 1980s, increased during 1990s, and were highest in early 2000s with a subsequent decline. The bulk of the jellyfish were observed in the central parts of the Barents Sea, which is a core area for most 0-group fishes. Jellyfish were associated with haddock in the western area, with haddock and herring in the central and coastal area, and with capelin in the northern area of the Barents Sea. The jellyfish were present in the temperature interval 1uC,T,10uC, with peak densities at ca. 5.5uC, and the greatest proportion of the jellyfish occurring between 4.0–7.0