Size selective mortality in Norwegian spring spawning herring juveniles?

Abstract

The growth-mortality hypothesis, where survival during the larval stage is positively related to size, is tested for Norwegian spring spawning herring (Clupea harengus L.). The daily increment width in the otoliths is compared between larvae sampled in May-June along the Norwegian shelf and the surviving population of 0-group juveniles sampled in fjords and inlets along the coast and in the Barents Sea in autumn (August-December). In order to select juveniles from the same cohort as the larvae sampled on the Norwegian shelf (May-June), a numerical model was used to simulate the drift of larvae from the shelf areas to the nursery areas where 0-group juveniles had been sampled. Samples from years with low high recruitment and from different areas are compared. The results are discussed in relation to variations in environmental conditions