Pelagic fish Atlantic Ocean, the Gulf of Mexico and the Mediterranean Sea. The term highly migratory species (HMS) is a legal term which has its origins in Article 64 of the United Nations Convention on the Law of the Sea (UNCLOS). The highly migratory species include: tuna and tuna-like species (albacore, Atlantic bluefin, bigeye tuna, skipjack, yellowfin, blackfin, little tunny, Pacific bluefin, southern bluefin and bullet), pomfret, marlin, sailfish, swordfish, saury and oceangoing sharks, dolphins and other cetaceans. Essentially, highly migratory species coincide with the larger of the "large pelagic fish", discussed in the previous section, if cetaceans are added and some
Skipjack-class submarine from the s that preceded the "Skipjack"s. Unlike the "Skate"s, this new design was maximized for underwater speed by fully streamlining the hull like a blimp. This required a single screw aft of the rudders and stern planes. Adoption of a single screw was a matter of considerable debate and analysis within the Navy, as two shafts offered redundancy and improved maneuverability. The so-called "body-of-revolution hull" reduced her surface sea-keeping, but was essential for underwater performance. Also like "Albacore", the "Skipjack"s used HY-80 high-strength steel, with a yield strength of , although this was not initially used to increase the