Using AIS Data to Document Changes in Large Vessel Traffic along the Coast of California and Understand Implications for Marine Conservation

Automatic identification system (AIS) data provide a rich resource for the characterization of vessel traffic patterns in both space and time that can be used by researchers and policy analysts in numerous fields. These data can be challenging to process and analyze due to the enormous, and growing, volumes and inherent qualities. We explore methods to process and analyze these data. The resulting analysis demonstrates that such a resource can provide key insights into the dynamic nature of vessel traffic. For large vessels (greater than, or equal to, 80 meters in length), we summarize changes in traffic density and volume along the coast of California for a recent period of available data (June 2008 - December 2015). The analysis further disaggregates the presentation of results by vessel type. Changes in vessel speed are also observed during this period and explored. Observations related to spatiotemporal changes are discussed in the context of potential economic and environmental regulatory drivers in the region, as well as in terms of coincidence with important marine conservation areas and cetacean habitat. We also discuss the potential utility of the data with respect to marine conservation research applications.