June 2 1915, Lesbos–The British had effectively cut off Germany from all trade except with her allies and the neutrals which bordered her. The blockade had proven contentious for its blocking of all cargoes (regardless of its military uses or lack thereof) and the position of the blockading fleets–in the English Channel and between Britain and Norway, rather than off the German coast itself. These violations of commonly accepted blockade practices were largely accepted by the neutral powers (William Jennings Bryan’s protests notwithstanding), who reserved their protests for limits on shipping between neutrals (i.e. between the United States and the Netherlands). Furthermore, the blockade was generally overshadowed in the American press by the deadly nature of the German reaction, the U-boat war.
On June 2, Britain declared a blockade on Turkey as well. Unlike the blockade on Germany, this was more limited in scope and conformed itself to pre-war notions of a blockade. Largely, this was a function of geography and the disposition of the Allied navies. Turkey’s entire coastline, stretching from Bulgaria to Egypt, could not be effectively blockaded (and searching all ships at Suez or Gibraltar would be neither worthwhile nor politically feasible); the blockade was limited to the stretch of Asia Minor from the Dardanelles to Samos. The bulk of the fleet supporting the Gallipoli landings was there anyway, harboring in the Greek islands just off the coast of Asia Minor; this was exceptionally true after the loss of the Triumph and Majestic the previous week.
Sources include: Randal Gray, Chronicle of the First World War.