New publication: Reproductive strategy of a migratory fish stock: implications of spatial variations in natural mortality

Øystein Langangen*, Geir Ottersen*, Lorenzo Ciannelli, Frode B. Vikebø, and Leif Christian Stige* in Canadian Journal of Fisheries and Aquatic Sciences

Abstract

We investigate how the reproductive strategy in a migratory marine fish may be influenced by spatial variations in mortality in early life stages. In particular, we examine how spawning time and location affect offspring survival and growth. A drift model for early life stages (eggs to age 1) of the Barents Sea cod (Gadus morhua) is combined with empirical estimates of spatial variation inmortality at two different life stages.We examine seasonal and interannual differences in survival and growth in offspring originating from two spawning grounds, with the central site requiring higher migration distance, and hence cost, than the northern site. When accounting for spatially explicit mortality fields, central and northern spawned offspring have about equal survival, as do early and late spawned offspring. Furthermore, central spawned offspring grow faster and are likely to reach a larger size compared with northern spawned offspring. Our results indicate that the fitness benefit of southward migration in the Barents Sea cod is not mainly due to higher early survival of offspring, but rather due to effects of offspring acquiring a larger size.


First published: 12 May 2016
DOI: 10.1139/cjfas-2015-0321
Publication webpage.

*Centre for Ecological and Evolutionary Synthesis (CEES). See the publication for full author information.

Tags: Canadian Journal of Fisheries and Aquatic Sciences;
Published Aug. 8, 2016 2:24 PM - Last modified Aug. 9, 2016 9:48 AM