Spinner Dolphins occur both on the high seas and in inshore waters associated with islands or banks. In the ETP, they are present in very large numbers many hundreds of kilometers from the nearest land, and they favour a specific habitat type, which oceanographers call "tropical surface water" that is typified by a shallow mixed layer, a sharp thermocline, and relatively small annual variation in surface temperature (Perrin and Gilpatrick 1994). They are often found there in close association with Pantropical Spotted Dolphins (Stenella attenuata), Yellowfin Tuna (Thunnus albacares) and birds of several species. School size varies greatly, from just a few to a thousand or more dolphins, and is often larger in pelagic than inshore waters (Perrin 2018). Numerous islands or island groups host small groups of Spinner Dolphins that predictably use shallow, near-shore areas for resting during the day. These include the Hawaiian Islands (Tyne et al. 2015a), Maldives (Ballance and Pitman 2001), and many islands in the South Pacific including Fiji, Tahiti, and Moorea (Oremus et al. 2007).

The dwarf form of the Spinner Dolphin in Southeast Asian waters inhabits shallow coral reef habitat (Perrin and Gilpatrick 1994, Perrin et al. 1999). In the north-central and western Gulf of Mexico, Stenella longirostris is found over intermediate bottom depths (Davis et al. 1998).

Most Spinner Dolphins feed predominantly at night, on small (<20 cm) mid-water fishes of many different families (including myctophids), squids, and sergestid shrimps (Perrin et al. 1973, Dolar et al. 2003). Dwarf Spinner Dolphins are exceptional, however; they feed (presumably during daylight hours) on small, reef-associated organisms (benthic reef fishes and invertebrates) (Perrin et al. 1999).

Spinner Dolphins occur throughout tropical and subtropical waters in both hemispheres from approximately 40°N to 40°S. They inhabit the Pacific, Atlantic, and Indian Oceans, including the Persian Gulf and the Red Sea, however they do not occur in the Mediterranean Sea.

Stenella longirostris longirostris is the most common and widely distributed subspecies. It occurs mainly around oceanic islands and near coastlines in the tropical Atlantic and Indian Oceans and in the central and western Pacific (Rice 1998). Distribution in many parts of East and West Africa as well as in South America is poorly known.

Stenella longirostris orientalis inhabits pelagic waters of the eastern tropical Pacific (ETP) east of about 145°W, from 24°N off Baja California (Mexico) to 10°S off Peru, but exclusive of the range of S. l. centroamericana (Perrin 1990).

Stenella longirostris centroamericana is found in coastal waters over the continental shelf of the ETP, from the Gulf of Tehuantepec in southern Mexico, southeastward to Costa Rica (Perrin 1990).

Stenella longirostris roseiventris is distributed in shallow waters of inner Southeast Asia, including the Gulf of Thailand, the Timor and Arafura Seas off northern Australia, and other similar areas off Indonesia and Malaysia. It is replaced in deeper waters by the larger pelagic subspecies S. l. longirostris (Perrin et al. 1999).

The Spinner Dolphin is listed in Appendix II of the Convention on International Trade in Endangered Species.

The taking of Spinner Dolphins and other cetaceans affected by the ETP tuna purse-seine fishery is managed both nationally by the coastal countries and internationally by the IATTC. The IATTC has imposed annual stock mortality limits on each purse seine fleet and promulgated regulations regarding the safe release of dolphins (Gosliner 1999, Bayliff 2001).

In several locations where Spinner Dolphins are the target of dolphin tourism, including Samadai Reef in Egypt and the Hawaiian Islands, local authorities have implemented management measures to control the number of visitors and boats, and thus to limit the impacts on dolphins (Notarbartolo et al. 2009, Tyne et al. 2015b).

The species is composed of several subspecies and numerous regional populations, each of which could be assessed separately for the IUCN Red List. The eastern spinner dolphin (Stenella longirostris orientalis) is currently listed as Vulnerable (http://www.iucnredlist.org/details/133712/0). The available estimates of abundance and removals suggest that some of the other populations may also fall into a Threatened category.