Life history strategies, population regulation, and implications for fisheries management

TLDR

Life‑history theories model trait evolution as adaptations to environmental variation, and a triangular model of three primary strategies predicts population resilience, production potential, and density‑dependent regulation more comprehensively than single‑trait or fast‑slow schemes. The study applies this triangular life‑history model to guide sustainable harvest, conservation, stocking, and ecological index transferability, providing qualitative management guidance when detailed data are lacking. Periodic and opportunistic species show high recruitment variability and poor conformity to density‑dependent recruitment models, whereas equilibrium species conform better but have lower demographic resilience.

Abstract

Life history theories attempt to explain the evolution of organism traits as adaptations to environmental variation. A model involving three primary life history strategies (endpoints on a triangular surface) describes general patterns of variation more comprehensively than schemes that examine single traits or merely contrast fast versus slow life histories. It provides a general means to predict a priori the types of populations with high or low demographic resilience, production potential, and conformity to density-dependent regulation. Periodic (long-lived, high fecundity, high recruitment variation) and opportunistic (small, short-lived, high reproductive effort, high demographic resilience) strategies should conform poorly to models that assume density-dependent recruitment. Periodic-type species reveal greatest recruitment variation and compensatory reserve, but with poor conformity to stock–recruitment models. Equilibrium-type populations (low fecundity, large egg size, parental care) should conform better to assumptions of density-dependent recruitment, but have lower demographic resilience. The model's predictions are explored relative to sustainable harvest, endangered species conservation, supplemental stocking, and transferability of ecological indices. When detailed information is lacking, species ordination according to the triangular model provides qualitative guidance for management and development of more detailed predictive models.