In 2006, researchers from Univeristy of North Carolina Willmington collaborated with Grouper Moon Project researchers from REEF and Cayman Island Department of Environment to conduct mobile hydroacoustic surveys on the Little Cayman spawning aggregation site. Hydroacoustics, which is similar to a fish finder device found on a recreational fishing boat, but with better resolution and technology, has emerged as a valuable tool in fishery population assessments. The goal of the study was to determine the utility of this emerging technology to assist in the estimation of density, spatial extent, and total abundance of a Nassau grouper. This report summarizes the field effort and findings.