On the rational utilization of the Icelandic cod stock

The Icelandic cod stock is analysed with respect to the probable effects of different harvesting strategies on yield, spawning stock biomass, and economic benefits. Simulations are used to investigate the probability of stock recovery and collapse. Potential yield and economic benefits/costs are also investigated, using stochastic and deterministic models. In stochastic simulations, attention is paid to the apparent stock recruitment relationship, the highly variable weight-at-age and maturity-at-age in Icelandic water along with the inevitable inaccuracies in current and future assessments. Regardless of method, substantial reduction in catches from recent (1993) levels is seen to be necessary in order to rebuild the stock. In the deterministic model, profit maximization mandates closure of the fishery until stock is rehabilitated. Using the stochastic model, it is predicted that recent catch level lead to eventual extinction of the stock with high probability. A management procedure is formulated and its application to the model is shown to lead to stabilization of the stock around an economically and biologically acceptable level.