The introduction of a new marine activity in marine spatial planning often imposes spatial restrictions on existing marine users. This chapter describes the potential effects of offshore energy developments on established widespread marine users, using the commercial wild-capture fishing sector as an example. The potential for fishing effort displacement is a concern amongst stakeholders and has a range of direct and indirect, positive and negative, economic, social, and environmental effects on individual fishers, the fishing industry, fishery-dependent coastal communities, and wider society. We present methods for assessment of possible impacts, as well as management recommendations for prevention and mitigation.