Complex sentence: European Commissioner for Fisheries & Maritime Affairs is a member of the European Commission responsible for policies such as the Common Fisheries Policy, which is largely a competence of the European Union rather than the members.
Split into simpler sentences: European Commissioner for Fisheries & Maritime Affairs is a member of the European Commission. The portfolio is responsible for policies such as the Common Fisheries Policy, which is largely a competence of the European Union rather than the members.