Dynamics of coastal cod populations: intra- and intercohort density dependence and stochastic processes

• Published in: Proceedings of the Royal Society of London. Series B: Biological Sciences
• Main Authors: Stenseth, N. C., rnstad, O. N. Bj, Falck, W., Fromentin, J.-M., ter, J. Gj s, Gray, J. S.
• Format: Text
• Language: English
• Published: 1999
• Subjects: Article; atlantic cod; Gadus morhua
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1690186; https://doi.org/10.1098/rspb.1999.0827

Skagerrak populations of Atlantic cod (Gadus morhua L.) have been surveyed at several fixed stations since 1919. These coastal populations consist of local stocks with a low age of maturity and a short life span. We investigated 60 time-series of 0-group juveniles (i.e. young of the year) sampled annually from 1945 to 1994. An age-structured model was developed which incorporates asymmetrical interactions between the juvenile cohorts (0-group and 1-group; i.e. one-year-old juveniles) and stochastic reproduction. The model was expressed in delay coordinates in order to estimate model parameters directly from the time-series and thereby test the model predictions. The autocovariance structure of the time-series was consistent with the delay coordinates model superimposed upon a long-term trend. The model illustrates how both regulatory (density-dependent) and disruptive (stochastic) forces are crucial in shaping the dynamics of the coastal cod populations. The age-structured life cycle acts to resonance the stochasticity inherent in the recruitment process.