Freshwater ecosystems are vulnerable to the introduction and establishment of invasive species often leading to a substantial alteration of the community structure and function of local ecosystems. Early detection monitoring is one of the most effective methods to control invasive species, because intensive management actions can be undertaken to eliminate the population before it spreads further. The Australian red-claw crayfish Cherax quadricarinatus is one of the most prolific freshwater invaders in the Caribbean. A native of Australia and Papua New Guinea, these crayfish are a popular species in aquaculture and the pet trade, making them easily accessible and commonly transported across their native range boundaries. In Puerto Rico, there are two recorded events of C. quadricarinatus making its way from aquaculture facilities into the local watersheds: a flood following hurricane Georges in 1998, and a flood in a different region of the island in the early 2000s. All previous surveys and recorded sightings of these invaders came from physical sampling in reservoirs and most of them reported low abundances, potentially underestimating their current invasion range. Streams in Puerto Rico are dominated by amphidromous native freshwater shrimps that potentially occupy a similar niche to C. quadricarinatus. However, large dams without spillway discharge completely extirpate all native shrimp assemblages from stream reaches above the dam. Therefore, these shrimp-inhibited habitats may be invasion hotspots for C. quadricarinatus and other aquatic invaders. In this study we present preliminary results from a 2023 survey of C. quadricarinatus in Puerto Rico to describe the invasion extent across habitats accessible and inhibited to shrimp using eDNA. We hypothesize that eDNA will be more sensitive to detecting populations at low abundances, and shrimp-free habitats are more vulnerable to C. quadricarinatus invasion. This informs an island wide early detection monitoring plan to manage the species.