Humpback Dolphins: A Brief Introduction to the Genus Sousa

摘要: The delphinid genus Sousa has recently undergone a major revision, and currently contains four species, the Atlantic humpback (Sousa teuszii), Indian Ocean plumbea), Indo-Pacific chinensis), Australian sahulensis) dolphins. Recent molecular evidence suggests that dolphins in Bay of Bengal may comprise fifth species. These moderate-sized dolphin species are found shallow (< 30 m), coastal waters eastern Atlantic, Indian, western Pacific oceans. Abundance trends have only been studied few areas, mostly Africa, China, northern Australia. No global, empirically derived abundance estimates exist for any but none appear to number more than about 20,000 individuals. Humpback feed on small fishes, sometimes shrimps; occur most part groups (mostly 12 or less); limited nearshore movements; parts their range exhibit fission/fusion type social organization. Major threats affect all entanglement fishing gear, habitat degradation/destruction from various forms development. Impacts vessel traffic (including behavioural disturbance displacement, as well mortality morbidity collisions with vessels) be significant areas. Several other apparently particular some (e.g. high levels organochlorine contaminants affecting Hong Kong). Direct hunting occurs areas primarily scale. Conservation actions so far limited, populations receiving little study almost no management attention. Much work is needed population status, threats, how can reduced eliminated. Extinction risks preliminarily re-assessed using IUCN Red List criteria current volume. results suggest threatened at level (suggested status ranges Vulnerable S. chinensis sahulensis Critically Endangered teuszii).