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 upon them. In fact, it is shown that fish species in the family Clupeidae including the skipjack shad comprise up to 45% of the diet of these avian species. The spawning season for skipjack shad is from early March to late April in the southern extent of its range. In the upper Mississippi river drainage spawning time is from early May to early July. Females produce about 100,000 to 300,000 eggs per year, presumably after 2 to 3 years of growth with an average size being Spawning is thought to occur in the depths of main channel over coarse sand-gravel