Highly migratory species

Shortfin mako shark make long seasonal migrations. They appear to follow temperature gradients, and have been recorded travelling more than 4,500 km in one year.

Epipelagic fish generally move long distances between feeding and spawning areas, or as a response to changes in the ocean. Large ocean predators, such as salmon and tuna, can migrate thousands of kilometres, crossing oceans.

In a 2001 study, the movements of Atlantic bluefin tuna from an area off North Carolina were studied with the help of special popup tags. When attached to a tuna, these tags monitored the movements of the tuna for about a year, then freed themselves, and floated to the surface where they transmitted their information to a satellite. The study found that the tuna had four different migration patterns. One group confined itself to the western Atlantic for a year. Another group also stayed mainly in the western Atlantic, but migrated to the Gulf of Mexico for spawning. A third group moved across the Atlantic ocean and back again. The fourth group crossed to the eastern Atlantic and then moved into the Mediterranean Sea for spawning. The study indicates that, while there is some differentiation by spawning areas, there is essentially only one population of Atlantic bluefin tuna, intermixing groups that between them use all of the north 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 ocean going 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 commercially unimportant fish, such as the sunfish, are excluded. These are high trophic level species which undertake migrations of significant but variable distances across oceans for feeding, often on forage fish, or reproduction, and also have wide geographic distributions. Thus, these species are found both inside the 200-nautical-mile (370 km) exclusive economic zones and in the high seas outside these zones. They are pelagic species, which means they mostly live in the open ocean and do not live near the sea floor, although they may spend part of their life cycle in nearshore waters.

migratory species – мигрирующие виды

shortfin mako shark – чернорылая акула

epipelagic fish – эпипелагическая рыба

spawning areas – нерестовая акватория

albacore – альбакор

atlantic bluefin – атлантический голубой тунец

bigeye tuna – большеглазый тунец

skipjack – парусная шлюпка

yellowfin – желтопер

blackfin – малый морской дракон

little tunny – малый тунец

Pacific bluefin – тихоокуанский голубой тунец

bullet – грузило

pomfret – морской лещ

marlin – марлин

sailfish – парусниковые

swordfish – рыба-меч

saury – сайра

capelin – мойва

upwelling – подъем глубинных вод на поверхность

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