Allee effect considerations to support the spatial management of a sedentary marine species: the queen conch (

Abstract

Context Density-dependent marine sedentary species exhibit heterogeneous distribution in response to biological needs and exploitation. Sustainable management requires consideration of factors influencing this distribution, including Allee effects and source–sink dynamics. Aim This study investigates the implications of the Allee effect and source–sink dynamics in the management of a sedentary species, queen conch (Aliger gigas) on the Pedro Bank Jamaica. Method We used spatial analysis of spatio-temporal survey data obtained over an 11-year period to determine spatial distribution and preferences. A depensation model along with knowledge of the connectivity of the population was used to model the Allee effect and define source and sink areas. Key results We found that mate-finding Allee effects and exploitation are major drivers of source–sink dynamics in this population. Sources (the effective spawning stock) consisted of less than 30% of total adult population and were being driven to a low-density stable state because of intensification of the Allee effect from high exploitation. Conclusions Management must explicitly consider Allee effects and source–sink dynamics to avoid overestimations of stock productivity and spatial mismatches of biological and management units. Stocks should be managed well above determined critical-density thresholds because stocks are unlikely to recover once they fall below them.