Sousa+Chinensis

How many species? The taxonomy of humpback dolphins genus //Sousa// has been unresolved for a long time as there appears to be several species. Recent work have shown strong evidence from skeletal morphology, external morphology, molecular genetics and biogeography for 4 species of Sousa .   Generally, there are two types of humpback dolphins recognised according to region, the Atlantic humpback dolphin endemic to the west coast of Africa, and the Indo-Pacific humpback dolphin of the coastal Indian Ocean and western Pacific Ocean. The Atlantic humpback dolphin have been known to consist of one species, //Sousa teuszii//, while the highly variable Indo-Pacific Humpback Dolphins is being debated. Originally, the Indian humpback and Pacific humpback was considered to be of one species called the Indo-Pacific humpback dolphin, //Sousa chinensis.// In 2014, the Autralian humpback dolphin, //Sousa sahulensis// was confirmed to be of a different species from the rest of the Indo-Pacific humpback dolphins [1] .   The remaining Indo-Pacific humpback dolphins are still being debated but many biologists now strongly believe that they consist of two species, the Indian humpback, //Sousa plumbea// along the Indian Ocean coast, and the Indo-Pacific humpback, //Sousa chinensis// that is found in eastern India to central China and throughout Southeast Asia* [2]. .
 * //Sousa chinensis// (Osbeck, 1765) ** **Indo-Pacific Humpback Dolphin** **Chinese White Dolphi**n

 *In this webpage, the dolphin names used will be based on this categorisation. Readers should take note that general information from other websites and papers before August 2014 groups //Sousa sahulensis, Sousa plumbea// and //Sousa chinensis// as one highly variable and widespread species: //Sousa chinensis// (Indo-Pacific humpback dolphin).

 What do they look like? 

// **Diagnostic** ** traits **// ** //of// //Sousa chinensis// ** > Maximum weight: 280kg  //** Distinct differences in appearance **//  [1][3]
 * Dorsal fin
 * Hump on midback
 * Medium sized
 * Robust body
 * Long and slender beak
 * Broad flippers (rounded at the tip)
 * Broad flukes
 * Maximum length: 2.8m

> <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 8pt; line-height: 1.5;"> Illustrations obtained with permission from Dr. Thomas Jefferson <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 8pt; line-height: 1.5;">
 * 1) Color pattern
 * 2) Form of dorsal fin
 * 3) Presence of hump

<span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 12pt; line-height: 1.5;"> The humpback dolphins around Singapore are part of the //S. chinensis// species and they are pink.

<span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 12pt; line-height: 1.5;"> When born, they are dark grey in colour and look very like a bottlenose dolphin but as they mature their colour changes and the hump on the back becomes more prominent. The dorsal fin triangular and positioned in the centre of the back. They grow to about 2.5-2.8m long and can weigh up to 260kg.

<span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 12pt; line-height: 1.5;"> <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 12pt;"> There appears to be no sexual dimorphism in body length and shape for this species but it is speculated for the other species that the males might be larger than the females <span style="font-family: Arial,sans-serif; font-size: 9.75px;">[1].

<span style="background-color: #ffffff; color: #0f0bed; font-family: 'Arial Black',Gadget,sans-serif; font-size: 25pt; line-height: 1.5;">Their behaviour? <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 12pt; line-height: 1.5;"> The behavior of //Sousa chinensis// is not well-studied but there are a few studies done on certain aspects of the humpback dolphin's behavior.

<span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 12pt; line-height: 1.5;"> //** Movement **// <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 12pt; line-height: 1.5;"> //Sousa chinensis// moves slowly and surfaces at a regular interval. The long beak of the humpback dolphins are often exposed when they surfaces and they strongly arch their back and raise their tail flukes while diving. <span style="color: #191818; font-family: Arial,Helvetica,sans-serif; font-size: 16px;">This is a unique diving posture whereby the dolphin first lift its beak out of the water and arch its back, then pausing before dipping below the surface and flipping its tail to dive [9] <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 13pt; line-height: 1.5;">. Humpback dolphins also have a characteristic rolling manner of surfacing described by Karczmarski et al (1997), often with their beak hitting the water before the melon reaches the surface of the water. The rest of the body remains submerged when the blowhole is open.

media type="youtube" key="QkVQdwDhx0E" width="616" height="346" align="center" Indo-pacific humpback dolphins surfacing and diving near a boat in Hong kong. Credit: Patty Tse/Carefordolphins.net

<span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 12pt; line-height: 1.5;">**// Occurrence //** <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 13pt; line-height: 1.5;"> <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 12pt; line-height: 1.5;"> Humpback dolphins are shy animals and so they are not often sighted near boats. They occur in tropical coastal waters, preferring areas less than 25 metres deep [9] <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 13pt; line-height: 1.5;">, so they are usually found in areas including open coasts and bays, coastal lagoons, rocky and coral reefs, mangrove swamps and estuarine areas. It is rare to find them more than a few kilometres from shore [2]. <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 13pt; line-height: 1.5;"> <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 16px; line-height: 24px;"> They travel in small sizes of school, usually in three to eight animals, and have been sighted to be in singles or pairs [9] <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 16px; line-height: 24px;">. Parsons (2004) noticed that the occurrence of the dolphins was affected by the tide cycle, with sighting frequency increasing during the ebb tide [12] <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 13pt; line-height: 1.5;">.

<span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 12pt; line-height: 1.5;"> **// Social behavior //** <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 13pt; line-height: 1.5;"> <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 13pt; line-height: 1.5;"> Saayman & Tayler (1973) described some social behaviors exhibited by humpback dolphins in Plettenberg Bay, including leaping, airborne cartwheels, chasing,rubbing against and mouthing each other, and striking each other with their flukes.These social behaviors were often observed when groups and individuals first came together. In Hong Kong, there seems to be a seasonal variation in the occurrence of social interactions between the humpback dolphins, with frequency of social behavior increasing between August and November (Parsons, 1998b). This increase in social behavior also was noted by Jefferson (2000) [12].

<span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 13pt; line-height: 1.5;"> <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 13pt; line-height: 1.5;"> Another study done by Karczmarski, Thornton & Cockroft (1997) observed courtship initiation with some vigorous movement of two individuals side by side with consistent, helical interchanging of positions. The dolphins exposed half of their body above the water and displayed prolonged body contact. Aerial displays such as quasi-leaps, side leaps and vertical leaps were also observed. Such behvaior was repeated before the dolphins apparently initiated true mating [11].

<span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 12pt; line-height: 1.5;"> **//<span style="font-family: Arial,Helvetica,sans-serif; font-size: 18pt;">Vocalisation //** <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 13pt; line-height: 1.5;"> <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 13pt; line-height: 1.5;"> Very little is known about the acoustic repertoire of the Indo-Pacific humpback dolphin. As of now, i <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 17.3333px; line-height: 26px;">t is unknown whether the different species of humpback dolphins produce different sounds. <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 13pt; line-height: 1.5;">Delphinid sounds generally consists of clicks,often used for echolocation, burst-pulses that is generally used for communication, and whistles which are believed to be be used for communication. <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 13pt; line-height: 1.5;"> A study done by Parijs and Corkeron (2001) off eastern Australia, supported by a study done by Sims et al [13], <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 13pt; line-height: 1.5;">documented five types of vocalisation produced by humpback dolphins:

>> >> >> >> >> >> media type="youtube" key="lC1XGhaEjtc" width="560" height="315" align="center" [|Australian Humpback dolphin swimming near a diver, producing a sound. (Video credits: Jasmine Tan & Clarissa Tan)]
 * 1) Broad band clicks (also known as "click trains")
 * High in frequency (8 kHz to >22 kHz)
 * Occurred as a series of clicks
 * Frequent during foraging and sometimes in social behavior
 * 1) Barks
 * Variable frequency (0.6kHz to >22 kHz)
 * Burst pulse sound
 * Frequent during foraging and social behavior
 * 1) Quak
 * Variable frequency (slightly lower and shorter duration than Barks')
 * Broad band, burst pulse sound with harmonic structure
 * Predominant in social behavior and sometimes foraging
 * 1) Grunts
 * Low frequency (0.9 kHz to 1.4 kHz), short duration
 * Occurred as a series of clicks
 * Only recorded in social behavior
 * 1) Whistle (Type 1 & 2)
 * Middle frequency (6.7 kHz to 10.5 kHz)
 * Narrow band, frequency modulated sound
 * Type 1 and 2 predominant, during milling and traveling

<span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 12pt; line-height: 1.5;">**//<span style="font-family: Arial,Helvetica,sans-serif; font-size: 18pt;">Reproduction //** <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 13pt; line-height: 1.5;"> <span style="background-color: #ffffff; color: #222222; font-family: Arial,Helvetica,sans-serif; font-size: 13pt; line-height: 1.5;"> Little is known about the reproduction of humpback dolphins as well. Generally, gestation period is approximately 10-12 months and there appears to be a calving peak from spring to summer. Calves are about 100cm long and 14kg at birth [6]. <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 12pt; line-height: 1.5;"><span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt;">Scant data indicate that sexual maturity in females may occur at about 9-10 years of age, with males maturing late r.

<span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 12pt; line-height: 1.5;"> **//<span style="font-family: Arial,Helvetica,sans-serif; font-size: 18pt;">What do they eat? //** <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 12pt; line-height: 1.5;"> <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 13pt; line-height: 1.5;"> <span style="background-color: #ffffff; color: #222222; font-family: Arial,Helvetica,sans-serif; font-size: 13pt; line-height: 1.5;"> The humpback dolphins appear to be opportunistic feeders, consuming a wide variety fishes. Sometimes they feed on cephalopods, while crustaceans are rare in their diet <span class="reference" style="color: #222222; font-family: Arial,sans-serif; font-size: 9.75px; vertical-align: baseline;">[2] [9] <span style="color: #222222; font-family: Arial,Helvetica,sans-serif; font-size: 13pt;">. Feeding primarily occurs near shore, estuaries and reefs [10]. <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">.

<span style="background-color: #ffffff; color: #0d16ed; font-family: 'Arial Black',Gadget,sans-serif; font-size: 25pt; line-height: 1.5;">Where are they found?

<span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 12pt; line-height: 1.5;"> <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 12pt; line-height: 1.5;"> //Sousa chinensis// is distributed in waters from central China, south throughout the waters of Southeast Asia as far southeast at least as Borneo, and as far west as the Orissa coast of India. Its distribution overlaps with that of //Sousa plumbea//. Range states include the People’s Republic of China (including the SARs of Hong Kong and Macau), Taiwan (Republic of China), Vietnam, Cambodia, Thailand, Myanmar, Bangladesh, India, Indonesia, Malaysia, Singapore, and Brunei Darussalam. <span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt;">Indo-pacific humpbackdolphins typically has a near shore distribution throughout its range [2] [1][9]



<span style="background-color: #ffffff; color: #1a08eb; font-family: 'Arial Black',Gadget,sans-serif; font-size: 25pt; line-height: 1.5;">Conservation <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 13pt; line-height: 1.5;"> <span style="background-color: #ffffff; color: #222222; font-family: Arial; font-size: 12pt; line-height: 1.5;"> Under IUCN//,// the humpback dolphins in the Pacific Ocean and Indian Ocean as a whole is classified under “Near Threatened” and is listed in Appendix I of CITES. These classifications are based on the combination of the humpback dolphins in the Indian Ocean, Pacific Ocean and Australia, consisting of more than 10,000 individuals. Despite the huge total number, these dolphins are under substantial threat <span class="reference" style="color: #222222; font-family: Arial,sans-serif; font-size: 9.75px; vertical-align: baseline;">[2] <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">. <span style="color: #222222; font-family: Arial,sans-serif; font-size: 16px; line-height: 1.5;">The situation is especially critical for the population of //Sousa chinensis// in Hong kong and Taiwan. For the eastern Taiwan trait subpopulation, they are classified under critically endangered under IUCN. <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 12pt; line-height: 1.5;"> An alarming decline of the population in Hong kong was reported from 158 <span style="background-color: #fefefe; color: #262626; font-family: CNN,'Helvetica Neue',Helvetica,Arial,Utkal,sans-serif; font-size: 18px;"> dolphins in 2003 to just 61 <span style="background-color: #fefefe; color: #262626; font-family: CNN,'Helvetica Neue',Helvetica,Arial,Utkal,sans-serif; font-size: 18px;"> dolphins in 2012.

<span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 12pt; line-height: 1.5;"> **// Major threats //** > The dolphins live in close proximity to the shore, so they often get caught in fish nets. This results in drowning of the dolphins as they are unable to reach the water surface to breathe. Entanglements of humpback dolphins in gill nets have been recorded in coastal waters of the Indian Ocean [10]. Thousands of trammel and gill nets operate in the coastal waters of western Taiwan and this clearly represents one of the most serious threats to this subpopulation. Shark nets in Australia meant for the protection of swimmers have also killed a substantial number of dolphins. > > One of the main driving force due to land reclamation creating disturbance and destroying the dolphins’ habitat. > Since the mid-90s, more than 1,400 hectares of sea area have been reclaimed in Hong Kong’s western waters. This is within the relatively small area inhabited by the dolphins. The construction of the Hongkong-Zhuhai-Macau bridge in recent years runs straight through the dolphins' habitat and the Hongkong government continue to have future coastal development plans. [17]. In addition to a direct loss of the dolphin’s habitats, reclamation has affected fishery resources, which subsequently leads to a decrease in food supply for the dolphins [22]. In China, there are continuing proposals for large-scale industrial development projects involving land reclamation such as offshore wind farms, steel factory of the Formosa Plastic Group, Chinese Petroleum Company’s petrochemical factory within the animals’ restricted habitat [16]. These threats are likely to continue in future with increasing impact as habitat degradation and loss increases with growing human population requirements. > > Living in congested waters with busy marine traffic, it is not surprising to find the dolphins being hit and injured by ferries and propellers. Many cities also provide dolphin watching tour, further increasing the boat traffic in the dolphins' habitat. There have been an increasing sighting of scars and marks on the dolphins living in Hong kong waters. More recently, a mother dolphin was seen carrying her dead calf who have been cut by a boat propeller [19]. Apart from physical injuries, boat traffic can also affect the acoustic behavior and communication with one another. media type="youtube" key="2Rqkrb3lP8U" width="560" height="315" align="center" [|Documentary: The Perilous Recovery of The Taiwanese White Dolphin. Permission granted by Vancouver Aquarium.]
 * Bycatch
 * Habitat destruction
 * Vessel collision
 * Pollution  Hong Kong discharges over 2 billion litres of sewage into the waters daily. Parsons (1997) estimated that a humpback dolphin’s minimum daily intake of sewage bacteria through ingestion of contaminated seawater could be up to 70,500 faecal coliforms. In comparison, a one-off ingestion rate of 200-300 coliforms is considered unacceptable for humans [22].   Industrial, agricultural and residential discharge poses a risk to the dolphins via the consumption of marine prey species. Spills of oil and other toxic substances by commercial ships could be catastrophic for a population so small and limited in its distribution especially the Eastern Taiwan Strait subpopulation [16].

<span style="background-color: #fefefe; color: #1e0bed; font-family: 'Arial Black'; font-size: 25pt; line-height: 1.5;">Taxonomy

<span style="background-color: #fefefe; color: #262626; font-family: CNN,'Helvetica Neue',Helvetica,Arial,Utkal,sans-serif; font-size: 18px; line-height: 1.5;"> //** Scientific Name **// > Delphinus chinensis, Osbeck 1765 (Basionym) > Delphinus sinensis, Desmarest 1822 (Synonym) > Sotalia plumbeus, Flower 1883 (Synonym) Sotalia sinensis, Flower 1883 (Synonym) > Steno (Sousa) lentiginosus, Gray 1866 (Synonym) > Steno chinensis, Gray 1871 (Synonym) > Sotalia chinensis, True 1889 (Synonym) > Steno lentiginosus, Blanford 1891 (Synonym) > Sotalia borneensis, Lydekker 1901 (Synonym) > Sousa lengtiginosa, Iredale &Troughton 1934 (Synonym) > Stenopontistes zambezicus, Miranda Ribiero 1936 (Synonym) > Sousa borneensis, Fraser & purves 1960 (Synonym) > Sousa queenslandensis, Gaskin 1972 (Synonym) > Sousa huangi, Wang 1999 (Synonym) > <span style="background-color: #fefefe; color: #262626; font-family: CNN,'Helvetica Neue',Helvetica,Arial,Utkal,sans-serif; font-size: 18px; line-height: 1.5;">**<span style="background-color: #fefefe; color: #262626; font-family: CNN,'Helvetica Neue',Helvetica,Arial,Utkal,sans-serif; font-size: 18px; line-height: 1.5;"> // Classification // ** [25] [2] <span style="background-color: #fefefe; color: #262626; font-family: CNN,'Helvetica Neue',Helvetica,Arial,Utkal,sans-serif; font-size: 18px; line-height: 1.5;">
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt;">**Scientific:** //Sousa chinensis// (Osbeck, 1765)
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt;">**Vernacular**: Indo-Pacific Humpback Dolphin, Chinese white Dolphin, Pink dolphin
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt;">**Synonym**:

<span style="background-color: #fefefe; color: #262626; font-family: Arial; font-size: 11pt; line-height: 1.5;">

<span style="background-color: #fefefe; color: #262626; font-family: Arial; font-size: 8pt; line-height: 1.5;"> Maximum likelihood (ML) reconstruction of relationships among Sousa spp. based on mtDNA control region haplotypes (287-bp) from five regions: China <span style="background-color: #fefefe; color: #262626; font-family: Arial; font-size: 8pt; line-height: 1.5;"> (Xiamen, Hong Kong and other regions), South Africa (Natal), Australia (Queensland and other regions), India, and West Africa (Mauritania). ML bootstrap scores <span style="background-color: #fefefe; color: #262626; font-family: Arial; font-size: 8pt; line-height: 1.5;"> are shown above internal nodes and Bayesian posterior probability scores are shown below. ML and Bayesian methods converged on the same tree. Terminal <span style="background-color: #fefefe; color: #262626; font-family: Arial; font-size: 8pt; line-height: 1.5;"> nodes are labeled with haplotype codes as in Table 2. Sequences from Delphinus delphis and Tursiops aduncus were used as outgroups. <span style="background-color: #fefefe; color: #262626; font-family: Arial; font-size: 8pt; line-height: 1.5;"> Reproduced from Stewart, Clapham & Powell, 2002. The first binomial, //Delphinus chinensis//, was given to the Indo-Pacific humpback dolphin when it was first observed in the Canton (Pearl) River, China and described by Pehr Osbeck (Swedish explorer) in 1757. The species name, //chinensis//, refers to the original location of the animals observed by Osbeck [20 ].
 * // Type information //**

No type specimen was collected [20]. This description was one year before Linnaeus' taxonomic system was published in 1758, thus by the Law of Priority, Osbeck's (1765) German translation must be used for taxonomic purposes as the original description. Flower (1870) provided a type and a detailed description of the skeleton of //Sousa chinensis//, thereby solving the problem of the lack of a holotype specimen. However, the holotype specimen was later destroyed in World War II. A neotype from Hong Kong was later proposed (Porter 1998), but the specimen was <span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt;"> a subadult.

German translation of the original swedish description of //Sousa chinensis// by Osbeck. Photo permission pending.