Edible crab (Cancer pagurus—also known as brown crab) support one of the most important fisheries in Europe and receive research attention. However, its stock structure is poorly understood throughout its range, including off of the coast of Scotland and in the Orkney assessment unit of Northeast Scotland.

Attaining a clear understanding of edible crab stock structure is complicated by the species' life history, which entails distinct dispersal characteristics during larval and adult life stages. It is difficult to distinguish between migrations undertaken for reproductive purposes and those that are indicative of a shared stock (McKeown et al. 2017) (Öndes et al. 2019). A recent tagging study has aimed to distinguish between those two possibilities with respect to the Orkney population—the study found that Orkney male crabs mostly remain in the Orkney (inshore) area, and some females do likewise, while another group of females undertakes long migrations that traverse several stock assessment boundaries including delving into deeper waters of the adjacent Sule assessment unit (Coleman and Rodrigues 2017). More research, including tagging and genetics, is needed to draw conclusions about stock structure.