Fig. 7. Conceptual model of hypothesized effects of fishing on a stock-recruitment relationship under conditions where age structure and age diversity are maintained (solid line) and where these attributes are truncated and eroded (dotted line) from heavy exploitation. Resilience and sustainability of a stock are hypothesized to be at risk when age structure and diversity are diminished. The solid circles (●) indicate points of stable equilibria on the stock-recruitment relationship; there is no equilibrium for the case of heavy fishing with low age diversity and truncated age structure.