Potential effects of human activities on billfishes (Istiophoridae and Xiphiidae) in the western Atlantic Ocean

Billfishes (Istiophoridae [sailfish, marlins, and spearfish] and Xiphiidae [swordfish]) spawn in offshore waters, usually far from land, and, except for sailfish (Istiophorus platypterus), are found inshore only when deep water or currents are near shore. Offshore waters are likely to be less affected by human activity than coastal waters, where anthropogenic effects are rather well-documented. However, human activities in oceanic waters can potentially affect the spawning behavior, location, and success of adult reproductive activity of billfishes as well as the survival, development, feeding, growth, and mortality of larvae, juveniles, and subadults. These activities include: (1) mining; (2) OTEC (Ocean Thermal Energy Conversion); (3) oil drilling; (4) radionuclides; (5) sewage wastes; (6) desalinization wastes; (7) agricultural pollution; (8) pesticides and heavy metals; (9) fishing; (10) harvesting of sargasso weed; (11) ozone depletion; (12) ; and (13) coastal development. The various physical, chemical, and biological effects of these human activities are discussed, and recommendations offered for field and laboratory investigations on early life stages.