the Eastern Mediterranean. Piraeus is also the commercial hub of Greek shipping. Piraeus bi-annually acts as the focus for a major shipping convention, known as Posidonia, which attracts maritime industry professionals from all over the world. Piraeus is currently Greece's third-busiest port in terms of tons of goods transported, behind Aghioi Theodoroi and Thessaloniki. The central port serves ferry routes to almost every island in the eastern portion of Greece, the island of Crete, the Cyclades, the Dodecanese, and much of the northern and the eastern Aegean Sea, while the western part of the port is used for cargo services. As of 2007, the Port of Thessaloniki was the second-largest container port in Greece after the port of Piraeus, making it one of the busiest ports in Greece. In 2007, the Port of Thessaloniki handled 14,373,245 tonnes of cargo and 222,824 TEU's. Paloukia, on the island of Salamis, is a major passenger port. Fishing Fish are Greece's second-largest agricultural export, and Greece has Europe's largest fishing fleet. Fish captured include sardines, mackerel, grouper, grey mullets, sea bass, and seabream. There is a considerable difference between fish catches between the pelagic and demersal zones; with respect to pelagic fisheries, the catches from the northern, central and southern Aegean area groupings are dominated, respectively, by anchovy, horse mackerels, and boops. For demersal fisheries, the catches from the northern and southern Aegean area groupings are dominated by grey mullets and pickerel (Spicara smaris) respectively. The industry has been impacted by the Great Recession. Overfishing and habitat destruction is also a concern, threatening grouper, and seabream populations, resulting in perhaps a 50% decline of fish catch. To address these concerns, Greek fishermen have been offered a compensation by the government. Although some species are defined as protected or threatened under EU legislation, several illegal species such as the molluscs Pinna nobilis, Charonia tritonis and Lithophaga lithophaga, can be bought in restaurants and fish markets around Greece. Tourism The Aegean islands within the Aegean Sea are significant tourist destinations. Tourism to the Aegean islands contributes a significant portion of tourism in Greece, especially since the second half of the 20th century. A total of five UNESCO World Heritage sites are located the Aegean Islands; these include the Monastery of Saint John the Theologian and the Cave of the Apocalypse on Patmos, the Pythagoreion and Heraion of Samos in Samos, the Nea Moni of Chios, the