Disentangling the effects of ocean transport, temperature and food concentration on the distribution of fish larvae

No abstracts are to be cited without prior reference to the author.

The causes of the large interannual fluctuations in the recruitment to many marine fishes remain incompletely understood. Two complementary approaches to studying these causes are coupled physical-biological modelling of the behaviour and drift of the early life stages of the fish, and statistical modelling of the observed spatial and temporal variation in their abundances in relation to environmental factors. By combining these approaches, the effect of variable drift can be accounted for in the statistical modelling, allowing for increased statistical power to detect effects of covariates such as temperature and zooplankton abundance. We here show the results of such combined modelling approaches for studying the spatiotemporal distribution of larval Northeast Arctic cod, Gadus morhua. A coupled physical-biological model is used to simulate the transport and development of cod eggs and larvae from spring to summer. The predictions from this model are used as input in a statistical analysis of the summer data, to investigate effects of covariates thought to be linked to survival. The results shed new light on the roles of temperature and zooplankton in the early life stages of cod.