The crew of ships or vessels flying the national flag must have Portuguese nationality or a European Union or EEA country or a Portuguese-speaking country. With the exception of crew members who perform the functions of captain or master of ships or vessels, ships or vessels flying the national flag may be manned by seafarers from non-EU/EEA or Portuguese-speaking countries, up to a limit of 40% of the respective crew on board, except in duly justified exceptional cases. For fishing vessels, the limit is 50% of their crew on board or three crew members, whichever is more favourable, and a different limit may be set in fisheries agreements concluded with third States.