Using GIS and spatial analysis for fisheries management in the American Samoa EEZ

Riolo, Francesca

GIS and Spatial analysis techniques are being used to analyze and display the entity, distribution and success of longline fishery in the American Samoa Exclusive Economic Zone (EEZ). There was a clear lack of understanding the spatial distribution of fishing activities prior to this study. The study is based on the data collected as part of the federal longline logbook system implemented by National Marine Fisheries Service since 1996 containing detailed data on each fishing set and the resulting catch for all registered vessels. Since January 2000, logbook data collecting, data entry and processing have been carried out by the Department of Marine and Wildlife Resources in American Samoa. Fishing pressure maps are developed based on spatial density of deployed longlines weighted by number of hooks. Total catch and catch for key species (Albacore, Skipjack, Yellowfin Tuna and others) are also being analyzed and mapped using spatial density techniques. Catch per Unit of Effort (CPU) maps are produced as ratio between the above outputs. Areas with high fishing pressure as well as changes in pressure and catches among years, seasons and other time frames are being spatially and temporally identified and can be presented as animations. A Visual Basic/ARCObjects application was developed to automate analysis from the retrieval of the longline fisheries database data to the output production as well as to provide a user-friendly analysis interface. This study clearly shows how GIS and Spatial Analysis can be used to support fisheries management providing both data analysis capability and a clear mean to visualize and present results.