The Southern Ocean Research Partnership (SORP) is an international collaborative initiative to develop novel research techniques and conduct non-lethal research on whales in the Southern Ocean. One of SORP’s original five research projects is the Blue and Fin Whale Acoustic Trends Project which aims to implement a long term acoustic research program examining trends in Southern Ocean blue and fin whale population growth, distribution, and seasonal presence using passive acoustic monitoring techniques. Passive acoustic monitoring is a robust means of monitoring whales in remote and difficult to study areas such as the Antarctic over long time periods. Analysis of a wide range of available passive acoustic data has demonstrated spatial and temporal patterns in the occurrence of blue and fin whales in the Southern Ocean. However, the lack of overlap in years and locations monitored, and differences among instrumentation and analysis methods used, underlines the need for coordinated effort. To best exploit passive acoustic methods for monitoring purposes in the future, the SORP Acoustic Trends steering group proposes the placement and maintenance of a pan-Antarctic monitoring system with consistent spatial and temporal coverage in each of the six IWC management areas. Further, blueprints for instrument choice, hardware configurations and analysis methods are being prepared to suggest how data might be best collected and analyzed in a uniform manner to best address the specific research questions for each study species. Through a consistent multi-disciplinary approach with international collaborators, the Blue and Fin Whale Acoustic Trends Project aims to use passive acoustic recordings to measure long term distribution, seasonal occurrence, and population growth trends of fin and Antarctic blue whales in the Southern Ocean.