Empirical support of predicted larval connectivity patterns demand conservation action for queen conch (Aliger gigas) in The Bahamas

Abstract

The conservation and spatial management of marine species with limited adult mobility, such as queen conch, is dictated by larval connectivity. Effectively placed reserves provide larval spillover to harvested areas while replenishing their own population. In past studies proximate to the Exuma Cays Land and Sea Park (ECLSP), surveys and probabilistic larval transport modeling demonstrated a spillover effect from the ECLSP to surrounding fished areas, while suggesting that incoming larval sources are lacking. Previous work was expanded in both upstream and downstream directions, enabling the statistical examination of (1) how queen conch abundance was linked to predicted larval transport from breeding populations in the ECLSP and (2) how age and size changed throughout the island chain as divided by management and connectivity. Biophysical modeling predictions of larval transport from breeding within the ECLSP were significantly associated with the relative abundance of juvenile conch observed across a nearly 200-km span. Further, the abundance and shell lip thickness (relative age) of adults and the size of juveniles were significantly larger in ECLSP than unprotected areas. This empirical support for an effective, well-enforced marine reserve and for using biophysical larval transport modeling as a spatial planning tool should be strongly considered in conch conservation and management.