Larval dispersal and mother populations of Pandalus borealis investigated by a Lagrangian particle-tracking model

Sammendrag

Larval dispersal and spatial distribution of reproducing females of Pandalus borealis in the Barents Sea were investigated. The approach was based on particle tracking using flow fields and a biological model incorporating ontogenetic migration and temperature dependent development of the zoea stages. By the use of individual-based particle-tracking models it is possible to assess the life history of individuals, as opposed to an Eulerian model. The years simulated in this study were 1996–1998. New data on larval hatching, development and behaviour from laboratory experiments and field studies are presented. Annual shrimp surveys conducted by the Norwegian Institute of Fisheries and Aquaculture provided abundance estimates of spawning and one year old shrimp. The biological model simulated the larval development of shrimp from hatching to zoea V, and their vertical migratory behaviour. The results indicated large inter-annual variability with respect to dispersion. This is most likely explained by the position of the Polar Front and the inflow of Atlantic water into the Barents Sea. The spatial distribution of modelled settled larvae was in good agreement with the abundance of 1 year old juveniles obtained from trawl surveys. The distance travelled by a shrimp larvae varied between 0 and 330 km and the annual mean distance varied between 74 and 122 km. Female shrimp in the entire Barents Sea contributed to recruitment to the stock, which is considered to be one population. Therefore, the female component of the shrimp stock has to be the target of management throughout the Barents Sea.