Situated 3 miles off of Maui’s southwestern shore, Molokini shoal is a hotspot of marine biodiversity. After years of being used for military target practice during World War II, the area was established as a Marine Life Conservation District (MLCD) in 1977, which prohibited fishing and limited other recreational activities within and around the island’s crescent-shaped crater. Since its designation as an MLCD, Molokini has become popular among commercial snorkel and dive tour operators and local residents alike (for details visit here). The resulting high levels of human activity have raised concerns that noise and other disturbances may be negatively impacting important fish stocks, including sharks, jacks and large herbivores. To better understand the effects of vessel traffic on these fish resources, OSI has partnered with the State of Hawaii’s Department of Land and Natural Resources, Division of Aquatic Resources, and the University of Hawaii to use Ecological Acoustic Recorders to monitor ambient noise levels contributed by vessels operating inside Molokini crater. The results of OSI’s noise analyses will be integrated with a parallel project led by University of Hawaii researchers to document the movement patterns of apex predators and large herbivores within the Molokini MLCD using acoustic tracking tags. The objective of this combined effort is to establish whether current levels of human use are affecting fish movements within the MLCD.