The Overfishing of Canadian Atlantic Cod: Prospects for Recovery

The fishing-induced decline of Canadian Atlantic cod in the early 1990s – perhaps the highest numerical loss of a Canadian vertebrate (1.5-2.5 billion reproductive individuals) – is among the greatest of fisheries collapses and is one from which the species has yet to recover. Despite massive reductions in fishing mortality, almost all stocks remain well below their conservation reference points. At least one is facing extirpation because of unsustainably high natural mortality. Depending on the stock, the lack of recovery can be attributed to ongoing fishing mortality (targeted, bycatch), changes to life history (reductions in age and size at maturity, truncations in age and size structure), and altered inter-specific interactions caused primarily by past fishing pressure. Emergent and demographic Allee effects, coupled with altered inter-specific interactions, render questionable the presumption that the recovery of heavily depleted populations can be reliably forecasted by population dynamical behaviour during decline.