Science News –
Marine fisheries are typically managed by individual nations. But the fish in those stocks often originate elsewhere, according to a computer simulation of how eggs and larvae from hundreds of fish species ride ocean currents around the world.
That finding means that many nations with economies that rely on fishing must depend on other countries to maintain important spawning grounds. The results of the simulation highlight the importance of international cooperation in sustaining the fisheries that provide millions of people with food and livelihoods, researchers report in the June 21 Science.
Oceanographer Nandini Ramesh of the University of California, Berkeley and colleagues simulated ocean currents transporting the eggs and larvae of more than 700 species of commercially harvested fish among 249 national fishing grounds. More than 90 percent of the world’s fish are caught within these marine territories, which extend a few hundred kilometers off the shores of coastal nations. The simulation accounted for when and where different species lay eggs, as well as the speeds and directions of ocean currents throughout the year.
A vast network of larval flows connects fisheries across the globe, the researchers found. In 114 national territories, at least 1,000 tons of catch per year originates from elsewhere. Many countries, from Indonesia to Norway to Mexico, harvest hundreds of thousands of tons of fish born outside their jurisdictions.