Physical effects on recruitment of Faroe Plateau cod

The cod stock on the Faroe Plateau has traditionally been considered as relatively stable, with fairly constant recruitment levels. In the late 1980s this situation changed dramatically when recruitment levels dropped by one or two orders of magnitude below what appears to have been due to processes operating during the first three months of the life history. Combining the available biological information on this stock with results from investigations on zooplankton and hydrography, it is argued that survival during these first months is critically dependent upon the advection of spawning products from spawning grounds to the shallow parts of the self, and upon the production and advection of Calanus finmarchicus from the Faroe Bank Channel to the shelf. Evidence is presented that during the period of recruitment collapse spring winds were abnormally strong from the southwest, increasing the probability of the transport of cod eggs and larvae copepods off the shelf and possibly also affecting primary production and hence production of copepod nauplii. In addition, the Faroe Plateau seems to have been less dominated by Atlantic waters with weaker copepod import and less stable advection paths as conceivable consequences.