Modelling the variability of the drift of blue whiting larvae and its possible importance for recruitment

Abstract

The first 8 months of the drift of blue whiting larvae has been simulated and studied for the 20 year period 1976-1994, using the 3-dimensional numerical model system NORWECOM (the NORWegian ECOlogical Model system). The model particles assumed to represent larvae are released identically in space and time each year according to best "average" knowledge. Large variations in the drift pattems are seen from year to year, but generally much larger amounts of larvae than expected seems to drift southward from the Porcupine Bank area west of Ireland to the Bay of Biscay. Many of these larvae drift into deep water where chances of survival are assumed to be small. Typically larvae hatched on the northem side of the Porcupine Bank drift northwards through the Faeroe-Shetland Channel, and most of these larvae are located on the shelf. Several distribution parameters are selected and compared with ICES time-series of recruitment.