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CS 1: Cod and herring in the Barents/Norwegian Sea

Foto and Copyright©: Rüdiger Schöne, BFAFi, Hamburg (Germany)

Overview

This case study will focus on the Northeast Arctic cod (Gadus morhua) and Norwegian Spring Spawning herring (Clupea harengus). There is interaction between these two species, however, also capelin (Mallotus villosus) will be considered as it interacts with both species. In fact all three stocks are subject to commercially important fishing. The main objective is to understand the mechanisms supporting or counteracting the recovery of cod and herring stocks in the Barents Sea/Norwegian Sea. In addition, the importance of capelin in the recovery process will be evaluated.

More specifically the objectives are:

  • Knowledge on maturation, fecundity, and migration generated within UNCOVER will be used to improve the models for single-species population dynamics, while analyses of stomach content data within UNCOVER will be used to improve the modeling of species interactions.
  • To explore the relative importance of different processes - single-species population dynamics, species interactions, environmental impact - on recovery paths for cod and herring. This will be done for various exploitation levels and environmental factors, using enhanced versions of existing multispecies models.

Hypotheses

The following hypotheses will be investigated for the cod-capelin-herring system in the Barents Sea:

  1. Population dynamics, e.g. stock level, reproductive potential, recruitment success, early life-stage dynamics, of the key species vary according to fishery strategy and environmental conditions.
  2. Modelling the impact of environmental factors and predation/cannibalism on fish stocks dynamics can lead to better evaluation of fishery recovery strategies
  3. Using the approach outlined in this document it is possible to compare the likelihood of success, and associated uncertainty, of various recovery strategies under different environmental conditions.

Read more: Description of work