Throughout the world, freshwater ecosystems are considered to be among the most vulnerable systems. In the isolated Pacific islands there are a relatively small number of native freshwater species, which are mainly endemic to these locations (found nowhere else in the world). These species are characterized by an amphidromous lifecycle; reproducing in the stream, with larvae drifting to the ocean and eventually returning to a stream as juveniles and spending the remainder of their lifecycle there. Throughout the region, native flora and fauna face significant threats from species introductions and habitat destruction. The National Parks in the Pacific Island Network (PACN) protect some of the last relatively pristine stream systems. Monitoring based on this protocol: Pacific Islands Stream Monitoring: Fish, Shrimp, Snails and Habitat Characterization, will provide park managers with some of the information necessary to understand status and trends in biotic integrity within park stream systems.