The mid-Pacific is a vast desert of life. The reason is that almost all forms of life sink when they die, taking the nutrients in their bodies with them. There is no mechanism in the open ocean to get those nutrients back up into the light because there is nothing to return their nutrients to the surface—nothing to bring them back into the light where plants can grow. That is because there is little to no upwelling in the open ocean.
Life can only be truly abundant where deep ocean currents strike a continental slope or an island slope and upwell, bringing their nutrients up with them. Water that upwells to the surface typically carries nutrients such as iron to the surface and they are generally a lot colder. The result is that many coasts where upwelling is common and strong, host good fishing grounds.
The best of all such grounds are the waters that Sea Shepherd is about to make the subject of its protection—the Eastern Tropical Pacific: the Galapagos corridor between the coasts of Central and South America all the way from Clipperton Island to Easter Island.
It is now clear that the productivity of this area is greater than the productivity of any other waters of the global ocean. Even though it represents less than a thousandth of the surface of the total ocean, the Eastern Tropical Pacific produces about 10% of the world fish catch.