THE OASIS OF MALPELO
Farther inshore than the Costa Rica Dome or the Galapagos, Malpelo sits in relatively warm, nutrient-poor seas between these two vast productive zones. Even tinier than Cocos, at less than a mile long and a third of a mile wide, Malpelo is a magnet to silky and hammerhead sharks. Only the island breaks the surface, but its submarine ridge is extensive. At a little more than 300 miles offshore, Malpelo is close enough to the coast to benefit from upwellings that run along the ridge with the Panama Current, enriching the seas for the first few months of the year, which bring the greatest numbers of hammerheads. The seasonal offshore Panama Current, and its position between the two great systems, allows Malpelo to act as a steppingstone, an oasis between the great northern and southern ecosystems. A handful of hammerheads tagged at Malpelo early in the year have been seen just a few days later off the Galapagos, more than 600 miles away, and several migrated from Malpelo to Cocos. Later in the year, the number of resident hammerheads at Malpelo drops, leaving the Dome and Galapagos systems more isolated.