ABSTRACT
This chapter treats only high seas fisheries of demersal/ deep-sea fishes. The deep ocean is a vast, complex and diverse space that still remains poorly known. The high seas, is essentially an area of 'deep sea' since more than 90" of this area is deeper than 200 m. The high seas hold among others several types of ecosystems like fracture zones or oceanic ridges, abyssal plans, hydrothermal vents or seamounts. Taking into account the surface areas of those topographic features where deep-sea fishing potentially occurs in each of the main oceans regions, the Pacific Ocean comprises about 61" of the available area of seamounts, ridges and canyons. In the Northeast Atlantic, trawl fisheries for deep-water fishes developed along the western Atlantic continental margins and the Reykjanes Ridge and subsequently the continental margins of Europe. Global changes in the oceans include warming temperatures, increased stratification and more acidic waters, decrease of sea ice, increase of sea level, deoxygenation and decreased productivity.
