Spinner dolphin  (Stenella longirostris)

Spinner dolphins in the eastern tropical Pacific have been killed incidentally since the early 1960s by tuna purse seine fisheries. They were caught in such large numbers that the population of S. l. orientalis was reduced to less than one third of its original size (5). Following raised awareness of the number of dolphins killed in tuna purse seine fisheries, measures were implemented to reduce dolphin by-catch. Today spinner dolphins continue to be killed in this way, although in greatly reduced numbers (6). However, continued chase, capture and release of large numbers in the fishery may be preventing the population from recovering (11).

In Sri Lanka and the Philippines, large numbers of spinner dolphins have also been captured in gillnets and killed by harpoons for the past 20 years (6), and local harpoon fisheries exist in several more locations throughout the world. Incidentally captured dolphins are consumed by local people, or used as shark bait, and this has led to the development of markets and fisheries directed at dolphins (5) (8). The takes in these fisheries may be unsustainable (5).

The eastern tropical Pacific and Southeast Asian populations of the spinner dolphin are listed on Appendix II of the Convention on Migratory Species (CMS). This means that the spinner dolphin is a migratory species that needs, or would significantly benefit from international co-operation, and the convention encourages the range states to conclude global or regional agreements (4). The spinner dolphin is also listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), meaning that international trade in this species should be carefully regulated (3). The value of dolphins as a tourist attraction offers countries and communities an incentive to protect these beautiful animals. Fernando de Noronha National Marine Park; (an archipelago off equatorial Brazil) was established in 1988, to provide nominal protection to spinner dolphins and support dolphin watching tourism (12), and it has been reported that in Zanzibar, the value of spinner dolphins for tourism far exceeded that of using them as bait for sharks (8). It is hoped that with meaningful laws, the will and resources to enforce them, continued attention by non-governmental organizations and efforts to make the public aware of the intrinsic value of their endemic dolphins (13), this charismatic species will continue spinning in our oceans forever.