Glossary: H

highly migratory species	INDEX
Marine species (fish and mammals) which migrate large distances during their life-cycle. Most types of tuna are good examples of highly migratory species. Generally accepted scientific views of which species are highly migratory do not always accord with the legal version: the LOS Convention does not define highly migratory species but refers instead to a list of species in Annex I (mainly tuna, but also cetaceans and some other species) which are considered as highly migratory. However, it is widely recognized that not all highly migratory species are included in Annex I and it is also questioned whether all the species in Annex I are, in fact, highly migratory.

high seas	INDEX
High seas comprises all parts of the sea that are not included in the EEZ, in the territorial sea or in the internal waters of a State, or in the archipelagic waters of an archipelagic State. The notion of the high seas developed when the claims to sovereignty over vast expanses of sea advanced by various maritime powers at the end of the 15th Century to the 17th Century conceded to general acceptance of the notion of mare liberum or freedom of the high seas advanced by, amongst others, the Dutch jurist Hugo Grotius in the 18th Century. Within this area, all States enjoyed certain freedoms, such as the freedom of navigation and the freedom of fishing. These rules were largely codified in the Geneva Convention on the High Seas and, later, in the LOS Convention. Article 87(1) of the LOS Convention provides: The high seas are open to all States, whether coastal or land-locked. Freedom of the high seas is exercised under the conditions laid down by this Convention and by other rules of international law. It comprises, inter alia, both for coastal and land-locked States: (a) freedom of navigation; (b) freedom of over flight; (c) freedom to lay submarine cables and pipelines, subject to Part VI; (d) freedom to construct artificial islands and other installations permitted under international law, subject to Part VI; (e) freedom of fishing, subject to the conditions laid down in section 2; (f) freedom of scientific research, subject to Parts VI and XIII. These freedoms must be exercised with "due regard" for the interests of other States and, as regards fishing, exercised subject to other requirements, namely the treaty obligations of the fishing State; the rights and duties as well as the interests of coastal States provided for, inter alia, in Article 63(2) and Articles 64 to 67; and the general principles and rules of conservation contained in Articles 117-120 of the Convention (Art. 116). The flag State is, in general, given exclusive jurisdiction over its vessels on the high seas. Thus, vessels exercising these freedoms are generally free from interference from vessels from third States, although according to general international law, third States are entitled to exercise the right to visit on the high seas regarding ships engaged in piracy or in the slave trade and the Geneva Convention on the High Seas and the LOS Convention have added three further situations: where a vessel is engaged in unauthorized broadcasting; where the ship is without nationality; or where the vessel, though flying a foreign flag or refusing to show its flag, is, in reality, of the same nationality as the vessel seeking to visit. Article 110 of the LOS Convention also envisages rights of interference being conferred by treaty, as occurs in the United Nations Fish Stocks Agreement.