166 CURRENT CONSERVATION ISSUES AFFECTING DOLPHINS IN THE TROPICS Jennifer Lewis, Mahmud Rahman, Sol Milne, and Ashik Jahan Galib INTRODUCTION There are approximately 35 species of dolphins. Of these, 23 species range either entirely or par- tially in the tropics and subtropics, a region that includes high freshwater and marine biodiversity, making it a very important area for focused con- servation efforts. Problematic is the fact that this region includes primarily developing nations. Because these nations are struggling to feed their people, environmental planning and management is of an understandable secondary concern, and resources to preserve the species and habitats in this area do not exist. For this reason, for much of this region, most of the dolphin species are listed as data deficient according to the International Union for Conservation of Nature (IUCN) Red List of Threatened Species (http://www.iucnredlist.org/ ). Many of the dolphins that are currently listed as endangered, threatened, or vulnerable also inhabit the tropics, for example, Irrawaddy dol- phin, Orcaella brevirostris, Asiatic river dolphin, Platanista gangetica, humpback dolphin, Sousa spp., Amazon river dolphin, Inia geoffrensis, Franciscana, Pontoporia blainvillei , and Tucuxis, Sotalia spp. (fig. 11.1). It is for these reasons that discussing trop- ical dolphins is important. Conservation issues affecting tropical dolphins using information currently available will be high- lighted in this chapter. The topics covered include threats from permanent removal of individuals (through bycatch, hunting, poaching, and capture for display), habitat destruction, disturbance, and contaminants. The limitations of chapter length prevent extensive coverage of each subtopic, but allow us to bring some perspective about the prob- lems that do exist and to discuss some potential so- lutions. We see this chapter as the start of a broad discussion and a place to learn more about the prob- lems these species are facing. Tropical dolphin con- versation must start with sharing information and educating others about the issues that affect them in light of what we know today. PERMANENT REMOVAL OF INDIVIDUALS Fisheries Bycatch The term “bycatch” refers to all unintended organ- isms caught by fisheries (i.e., not the targeted fishery 11 Aguirre040316ONATUS.indb 166 6/9/2016 5:34:22 PM