Category: China

Pantropical Spotted Dolphin

Pantropical spotted dolphin

The pantropical spotted dolphin is a species of dolphin found in all the world’s temperate and tropical oceans.

The rise of so called, “Dolphin friendly” tuna capture (in the1980s), is thought to have saved millions of this species, in the eastern pacific. This  species was first described by John Gray in 1846. Gray’s initial analysis included the Atlantic spotted dolphin in this species. They are now regarded as separate. Both the genus and specific names come from Latin words meaning thin or thinning.

Two subspecies of the pantropical spotted dolphin are recognized, (Another unnamed subspecies, which inhabits inland Hawaiian waters, was recognized in Rice (1998)’s overview of marine mammal taxonomy, its unclear why this has not been fully recognized)

          S. a. attenuata or offshore pantropical spotted dolphin, found worldwide in tropical waters

          S. a. graffmani or coastal pantropical spotted dolphin, found in coastal waters in the eastern tropical Pacific. 

The pantropical spotted dolphin regularly making large, splashy leaps from the sea. It is a common Whale surfacing behaviour and will often clear the water for a second or more. Bow-riding and other play with boats is common. In the eastern Pacific, they often swim with yellow fin tuna (causing the problem with dolphin deaths caused by tuna fishing, though they do not eat them).  In fact, the two species have similar diets of small epipelagic fish. In other areas, the species may also feed on squid and crustaceans.

Indo-Pacific Humpback Dolphin

Indo-Pacific Humpback dolphin

The Indo-Pacific humpback dolphin (Sousa chinensis) is a species of humpback dolphin found in the coastal waters of the eastern Indian and western Pacific Oceans.In much of Asia it is referred to as the  Chinese white dolphin  Some biologists regard the Indo-Pacific dolphin as a subspecies of the Indian Ocean humpback dolphin  which ranges from East Africa to India, though DNA testing studies have shown that the two are distinct species. A new species, the Australian humpback dolphin, was split off from this species and recognized as a distinct species in 2014.  There are still need of clarification of the Indian Ocean-type and Indo-Pacific-type humpback dolphins and telling them apart.

Two subspecies of the Indo-Pacific humpback dolphin are currently recognized:

  • S. c. chinensis, or the Chinese humpback dolphin – fewer than 100 of this group remain
  • S. c. taiwanensis, or the Taiwanese humpback dolphin – fewer than 100 of this group remain
Given how close to extinction they both are, we can only hope that these two subspecies are capable of remerging.
 
Indo-Pacific humpback dolphins live in small groups, generally with fewer than ten individuals. They hunt as a group using echolocation. Adult dolphins come to the water surface to breathe for 20 to 30 seconds before diving deep again, for two to eight minutes (though it is rare that they stay under for more than 4). Dolphin calves, with smaller lung capacities, surface twice as often as adults, staying underwater for one to three minutes. They sometimes leap completely out of the water, though they may also rise up vertically from the water, exposing the dorsal half of their bodies. A pair of protruding eyes allows them to see clearly in both above and beneath the water surface.

 

Females reach sexual maturity at 10, while males do at 13. Gestation is 11 months, and rearing takes 3-4 years. The Indo-Pacific humpback dolphin is threatened by habitat loss, water pollution, coastal development, overfishing and an increase in marine traffic within its range. In 2015 the Indo-Pacific humpback dolphin was classed as “vulnerable” on the IUCN Red List of Threatened Species. In 2013 the number of dolphins around Hong Kong halved – it is thought because of pollution.

There is a dolphin-watching industry, that has been going around 30 years, in this area.

It is listed on CITES Appendix ii.

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