Long-term stability in modelled zooplankton influx could uphold major fish spawning grounds on the Norwegian continental shelf

Early life stages of fish spawned on the Norwegian continental shelf have long been suggested to depend on eggs and nauplii from the crustacean zooplankton Calanus finmarchicus, for survival. Calanus overwinters in the deep basins of the Norwegian Sea, and gravid females must be advected onto the shelf prior to spawning if eggs and nauplii larvae are to serve as food for fish larvae. In this study, cross-shelf advection of calanus is simulated over 52 years (1960-2011), using a numerical ocean model coupled with an individual-based model. The results suggest that cross-shelf transport of calanus is surprisingly stable across years, and that transport is particularly concentrated immediately upstream of the two major spawning areas for the Northeast Arctic cod and the Norwegian spring spawning herring, namely Lofoten and Møre, respectively. Two large topographical features, the Træna trough and the Norwegian trench, appear to be funnelling calanus onto the shelf in these two areas. This could suggest that the fish spawning grounds outside Møre and Lofoten are, in part, maintained due to stable inter-annual food supply in spring.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author