++++ Fisheries - Conservation of fishery resources - National measures of a local nature authorized by Community rules - Prohibition on nationals' carrying a particular type of net on fishing vessels while they are sailing in waters adjacent to part of the national territory - Prohibition of discrimination on grounds of nationality inapplicable - Discrimination between producers or consumers - None - Interference with the fundamental right to the free exercise of a professional activity - None ( EEC Treaty, Arts 7 and 40(3 ), second subparagraph; Council Regulation No 171/83, Art . 19(2 ) )