Abstract

Management of highly exploited marine resources necessitates a rigorous definition of geographic boundaries that separate stocks because different stocks (populations or subpopulations) may possess local adaptations that lead to differences in important life-history parameters such as growth, fecundity, and disease resistance. Failure to recognize locally-adapted stocks potentially can result in extirpation and irretrievable loss of genetic resources. Identifying separate stocks, based on genetic data, is problematic for marine species with high dispersal capability, particularly when selectively neutral genetic markers are employed. The issue is that homogeneity in such markers may not necessarily reflect homogeneity in genes affecting life-history and/or fitness traits. Moreover, historical events, e.g., population expansion or decline, often leads to violations of equilibrium assumptions inherit in traditional population genetics models. When ‘traditional’ FST-based approaches are combined with spatial and demographic analyses, important aspects of cryptic population structure may be revealed. A review of stock-structure assessment in exploited species of snappers (Lutjanidae) in the Gulf of Mexico and Caribbean Sea demonstrates that even for species with similar life histories, patterns of population structure vary and require robust analytical methodologies to detect fine-scale differences.

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