Predicting recruitment of 0-group gadoids in the Barents Sea - critical interaction between models and observations

Abstract

The most important gadoid fish stocks of the Barents Sea spawn along the coast of Norway. The eggs, larvae and juveniles are transported northwards with the oceanic coastal currents from the spawning grounds towards their nursery and feeding areas in the Barents Sea. In this work, we present a conceptual model of the vertical dynamics of 0-group during the transport and settlement phase. Field observations of the vertical distribution and behaviour of 0-group fish recorded by a stationary acoustic system are compared to the conceptual model to validate critical assumptions. They also serve as an example of some critical observations needed to improve hydrodynamic modelling of the transport. We used two different vertical distribution algorithms for particles representing juvenile fish in a Lagrangian particletracking model. One is based on the behaviour described in the conceptual model and the other assumes random vertical distribution at a fixed depth range throughout the whole period. The distribution predicted from the vertical behaviour algorithms fits best to observations from surveys. Based on this experience we propose an observation program for collecting the needed observations to obtain a more realistic recruitment prediction model.