Green crab (Carcinus maenas) density from intertidal surveys in the Gulf of Maine during 1973, 2003, 2017-2018 and 2021

The impact of invasive predators during the early stages of invasion is often variable in space and time. Such variation is expected to initially favor plasticity in prey defenses but fixed defenses as invaders become established. This dataset contains green crab density (Carcinus maenas) data for multiple sites throughout the Gulf of Maine that were collected in 1973, 2003, 2017-2018 and 2021. These data were used to examine historical changes in the latitudinal distribution of green crabs and their potential role in shaping spatiotemporal changes in snail (Littorina obtusata) shell thickness and thickness plasticity.