(15)In a number of Member States, inland navigation is an infrequent activity, serving only local or seasonal interests in waterways with no connections to other Member States. While the principle of the recognition of professional certificates under this Directive should also be respected in those Member States, the administrative burden should be proportional. Implementing tools such as databases and registers would create a significant administrative burden without presenting a real benefit, as the flow of information between Member States can also be achieved through other means of cooperation. It is therefore justified to allow the Member States concerned to transpose only the minimum provisions needed for the recognition of professional certificates issued in accordance with this Directive.