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 shad was impounded, and currently skipjack shad are most abundant in the upper Mississippi River below the mouth of the Ohio River. In recent years, human modifications to the middle Missouri River have made conditions more favorable for skipjack shad and their distribution has expanded upstream to the Nebraska-South Dakota border. Skipjack shad were historically found in the northern upper Mississippi River and the St. Croix River; however, there have only been four records of skipjack shad in Wisconsin waters since the 1950s. Because this fish is a migratory species, dams have diminished its distribution. It cannot continue to migrate northward