Spatial Analysis of the Invasive Striped Eel Catfish in the Saipan Lagoon

The striped eel catfish, Plotosus lineatus, was first documented in the Commonwealth of the Northern Marianas (CNMI) in Saipan Lagoon in 2005 in the CNMI Division of Fish and Wildlife Sportfish Restoration Research Program Annual Report. The striped eel catfish has been identified as an invasive threat in other regions, and information pertaining to its abundance and distribution in the CNMI was unknown prior to this study. This study began by identifying and interviewing key informants comprised of fishermen, divers, fisheries managers, and watermen regarding their knowledge of the striped eel catfish, its arrival in Saipan, behavior, ecological effects, and geographic distribution. A participatory heat map was generated based on these interviews and used to identify regions to investigate through survey methods including shoreline walks, directional free swims, and hot spot surveys targeting artificial structures. Surveys were conducted using a semi-stratified design across seventeen one-mile segments at four different time intervals to maximize lagoon coverage and potential observation of catfish. Waypoints and GPS tracks were mapped in ArcGIS to analyze the distribution and relative population sizes. Behavioral observations were included to better understand the species and predict fish movement and habitats. As a baseline, this study sets the stage for more complex studies to be conducted regarding distribution and general abundance of the striped eel catfish in the Saipan Lagoon.