Abstract

Ecological isolation is an important yet underappreciated factor affecting marine reserve performance. Isolationmay preclude recruit subsidies, thus slowing recovery when base populations are small and causing a mismatch between perfor-mance and stakeholder expectations. Mona Island is a small, oceanic island located within a partial biogeographic barrier - 44 km from the Puerto Rico shelf. We investigated if Mona Island’s no-take zone was successful in increasing mean size and abundance of reef fishes 14 years after designation. The La Parguera Natural Reserve (LPNR) was chosen for evalua-tion of temporal trends at a fished location. Fish assemblage metrics collected in diver surveys were assessed with univari-ate and multivariate PERMANOVA based on multifactorial mixed models. Perceptions of fishing effort and enforcement in both MPAs were collected with fisher interviews. Despite indications of fishing within the no-take area, a reserve effect at Mona Island was evidenced from increasing mean sizes and abundances of some commercial taxa, with mean total abundance 36% greater relative to 2005. These re-sults should be viewed cautiously, however, as our design lacks seasonal replication within 2005 and 2010. The larger pred-atory species remained rare at Mona, preventing meaningful analysis of population trends. At LPNR, most commercial spe-cies (e.g., lane snapper, schoolmaster, mahogany snapper) did not change significantly in biomass or abundance, but some species (yellowtail snapper, hogfish), increased in abundance. This work shows that recovery at Mona is slow and limited to smaller sized species, highlighting both the need for better compliance and the substantial recovery time required by commercially valuable, coral reef fishes in isolated marine reserves.

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