Spatial variability in length frequency distribution and growth of shrimp (Pandalus borealis Krøyer 1838) in the Barents Sea

Sammendrag

Shrimp (Pandalus borealis) length frequencies from Barents Sea shrimp surveys were analysed to evaluate their usefulness in determining stock structure and optimising station groupings for assessment purposes. Four groups of stations were identified using cluster analysis on the Spearman coefficients correlating individual station length frequency distributions. The first group consisted mainly of small and some medium sized shrimp, the second mainly of medium and some small sized shrimp, the third mainly of medium and some large shrimp, and the fourth of stations having the largest shrimp. The spatial distribution of the groups was generally depth dependent, however in one year the group comprising the largest shrimp occurred in all depths, possibly due to migration or dispersion by currents. Modal analysis identified fifteen subareas with similar growth characteristics. The results are useful in optimising survey sampling design and improving input data for stock assessment models.