{"id":17964,"date":"2019-09-19T03:39:00","date_gmt":"2019-09-19T03:39:00","guid":{"rendered":"https:\/\/www.lifeandnews.com\/articles\/?p=17964"},"modified":"2019-09-21T02:18:42","modified_gmt":"2019-09-21T02:18:42","slug":"fish-larvae-float-across-national-borders-binding-the-worlds-oceans-in-a-single-network","status":"publish","type":"post","link":"https:\/\/www.lifeandnews.com\/articles\/fish-larvae-float-across-national-borders-binding-the-worlds-oceans-in-a-single-network\/","title":{"rendered":"Fish larvae float across national borders, binding the world’s oceans in a single network"},"content":{"rendered":"

Nandini Ramesh<\/a>, University of California, Berkeley<\/a><\/em>; James Rising<\/a>, London School of Economics and Political Science<\/a><\/em>, and Kimberly Oremus<\/a>, University of Delaware<\/a><\/em><\/p>\n

Fish populations are declining<\/a> around the world, and many countries are trying to conserve them by regulating their fishing industries. However, controlling fishing locally may not do enough to strengthen fish populations. Often one nation\u2019s fish stocks depend on the spawning grounds of a neighboring country, where fish release eggs and sperm into the water and larvae hatch from fertilized eggs.<\/p>\n

We do research on oceans<\/a>, climate<\/a> and fisheries<\/a>. In a recent study, we showed that global fisheries are even more tightly connected<\/a> than previously understood. The world\u2019s coastal marine fisheries form a single network, thanks to the drift of larvae along ocean currents.<\/p>\n

This suggests that country-by-country fishery management may be fundamentally insufficient. If a fish species that provides food to one country should decline, the amount of fish spawn, or eggs and larvae, riding the ocean currents from there to other countries would also decline dramatically, resulting in further loss of fish elsewhere.<\/p>\n

Many countries live with this risk, although they may not realize it. To manage fisheries effectively, nations must understand where the fish in their territories originate.<\/p>\n

Ocean currents affect the speed at which fish eggs and larvae drift and vary through the year. This map shows surface current speeds for January: yellow = fastest, dark blue = slowest. Each country\u2019s territory is highlighted with red dots during the month of maximum spawning activity in that country. In each territory, a different number of species spawn in each month of the year. The red dots appear in the month during which the largest number of species spawn in that territory.<\/span><\/figcaption><\/figure>\n

Crossing national borders<\/h2>\n

Fish don\u2019t recognize political boundaries, and regularly travel internationally. Scientists have tracked adult fish movements<\/a> using electronic tags, and have shown that a few species migrate over long distances<\/a>.<\/p>\n

Countries and territories have negotiated agreements to ensure sustainable sharing of migratory fish. One such agreement joins several nations in the Western and Central Pacific Fisheries Commission to ensure that the territories fish cross share them sustainably<\/a>.<\/p>\n

But fish eggs and larvae are much harder to follow. Many species lay eggs in large numbers that float near the ocean surface. When they hatch, larvae measure a few millimeters long and continue to drift as plankton until they grow large enough to swim. During these stages of the life cycle, ocean currents sweep fish spawn across international boundaries.<\/p>\n