This is one of the most biologically diverse regions of the world's oceans, including an important migration route for critically endangered Pacific leatherback turtles. The western and central Pacific contains the world's largest tuna fishery, with fleets from Asia, Europe and elsewhere exploiting these seas. Over half of the tuna consumed worldwide is taken from this area, especially from the waters of the Pacific Island nations. The impact of these tuna fisheries is the greatest current threat to this region, with concerns over the survival of some tuna species like bigeye and yellowfin. The associated bycatch from tuna fishing also endangers threatened species of sea birds, sharks and turtles.