For plannig international big game fishing adventures, wouldn't it be useful to know where the big fish are to be found as they move from place to place during their long-distance annual migration? I'd want to be where they are when I know they are most likely to be there.
Adult blue marlin, white marlin and swordfish generally follow the edges of the major surface currents (shown below for the North Atlantic) in a predictable pattern each year. There they are feeding on prey concentrated along these edges. The yearly pattern they follow starts with spawning during the spring (May to early June in the North Atlantic and November to early December in the South Atlantic). Like salmon, they return to the place where they themselves began life. (Over thousands of years, eggs and larvae survived better here than if spawned elsewhere.) In the case of the North Atlantic, these species' spawning occurs in the deepwater gaps between the major islands of the Caribbean and two large areas well east of Trinidad. For the South Atlantic, it is the Royal Charlotte Bank off the coast of Brazil just a bit north of Rio. After spawning, they follow the edges of the surface currents quickly toward colder water nearer the poles where prey is in much greater abundance. In doing so they pass by celebrated game fishing destinations (such as South Florida, Bimini, Cape Hatteras and Bermuda), but remain there relatively briefly. In contrast, from early summer through fall, adult blue marlin and swordfish can be found for extended periods at the northern extent of the Gulf Stream as it flows across the North Atlantic between the area made famous by the movie "The Perfect Storm" and the Azores and beyond as temperatures fall following the Canary Current past Madeira, the Canary and Cape Verde Islands off northwest Africa. White marlin concentrate during the summer and fall along the edge of the continetal shelf between Cape Hatteras and (formerly) the tip of Georges Bank (off Cape Cod). (Their range has shrunk as the population has been decimated by commercial fishing using longlines - see www.BigMarineFish.com/marlin.html) Juvenile marlin, swordfish and sailfish stay closer to their spawning areas until they mature enough to undertake the long-range migrations of the adults.