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

Authored by Frode B Vikebo, Anders Frugard Opdal

Date Published: 2016

DOI: 10.1139/cjfas-2014-0524

Sponsors: No sponsors listed

Platforms: No platforms listed

Model Documentation: Other Narrative

Model Code URLs: Model code not found

Abstract

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 finmarchicus 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 C. finmarchicus 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 C. finmarchicus is surprisingly stable across years and that transport is particularly concentrated immediately upstream of the two major spawning areas for the Northeast Arctic cod (Gadus morhua) and the Norwegian spring-spawning herring (Clupea harengus), namely Lofoten and More, respectively. Two large topographical features, the Traena Trough and the Norwegian Trench, appear to be funnelling C. finmarchicus onto the shelf in these two areas. This could suggest that the fish spawning grounds outside More and Lofoten are, in part, maintained owing to stable interannual food supply in spring.
Tags
Variability Population-dynamics Northeast arctic cod Calanus-finmarchicus Barents sea Future climate Seasonal vertical migration Overwintering calanus Atlantic oscillation Nordic seas