Meter-scale movements of the invasive European green crab Carcinus maenas measured with acoustic telemetry in a Gulf of Maine estuary

The European green crab Carcinus maenas is a notorious invasive species that can negatively impact coastal ecosystems and is a growing concern for management worldwide. However, knowledge of the basic movement ecology of individual C . maenas , including habitat use and potential differences between sexes and ovigerous status, is limited. We tracked the meter-scale movements of 43 animals using acoustic telemetry via a VEMCO Positioning System (VPS) within the Webhannet River estuary (Maine, USA) from May to December 2021. From the 163307 animal positions used in our analyses, we measured daily position within the estuary along with movement rates, and estimated home range sizes and standardized space use metrics. Individual crabs showed highly variable areas of standardized space use and a core use area that was <4% of the total potential habitat covered by the VPS at high tide, suggesting that the impacts of individuals are localized. Tagged animals remained mostly in the central estuary, and ovigerous females displayed evidence of seaward movements as estimated egg hatch date approached. Overall, these findings quantify the movements of C . maenas and demonstrate that their behaviors can vary with reproductive status and environmental covariates at diel to seasonal scales. Our results may help inform potential future management practices, such as the targeted removal of ovigerous females approaching egg hatch date.