Sousa chinensis (Osbeck 1765)

El dofí d'estuari indopacífic o dofí geperut indopacífic (Sousa chinensis) és una espècie de dofí oceànic (família Delphinidae).

Particularitats

Els dofins adults solen ser blancs o grisos, però la població que viu a la costa xinesa té una pell rosa.^[1] Aquest color de pell no és el resultat d'una pigmentació, sinó que es deu als vasos sanguinis utilitzats per la termoregulació, per evitar que l'animal se sobreescalfi durant els esforços intensos. Els adults mesuren 2-3,5 metres i les cries un metre. Els adults pesen una mitjana de 150-230 quilograms.

Vegeu també

• Dofí de riu xinès

Referències

Delfín indočínský (Sousa chinensis) je druh živočicha z řádu kytovci, podřádu ozubení, čeledi delfínovití, rodu delfín (Sousa). Vyskytuje se ve dvou poddruzích: Sousa chinensis chinensis, zvaný též čínský bílý delfín, a Sousa chinensis plumbea, zvaný též honkongský růžový delfín.^[2][3]

Vzhled

Barva delfína indočínského je po narození téměř černá,^[3] v mládí zbarvená do růžova, postupně se mění ve světle šedivou,^[2][3] dospělý jedinec má barvu krémově nebo špinavě bílou až světle šedou či až temně olovnatě šedou nebo má barvu růžovou.^[4] Zbarvení není způsobeno pigmentací, ale sítí krevních žil, sloužících k lepší termoregulaci.^[2]

Dospělý delfín indočínský dosahuje délky 1,6–2,6 m a váží asi 150 kg. Hřbetní ploutev má vysokou a trojúhelníkovou se širokou základnou, hrudní ploutve jsou malé. Horní čelist i dolní čelist má na levé i na pravé straně 32–37 zubů.^[4]

Výskyt

Delfín indočínský žije v oceánu, ale dokáže žít i ve sladkých vodách.^[2]

Výzkumníci z Wildlife Conservation Society, kteří studovali jejich genetiku, došli k závěru, že delfíni indočínští žijí ve skupinách tvořenými samostatnými populacemi, které se vzájemně nekříží.^[5]

Ohrožení

Delfín indočínský je kriticky ohrožený druh. Je ohrožen především znečištěním velkých řek, především v Číně (včetně Hongkongu). V Pearl River žije jen asi 40–80 jedinců.^[2]

Odkazy

Reference

1. ↑ Červený seznam IUCN 2018.1. 5. července 2018. Dostupné online. [cit. 2018-08-10]
2. ↑ ^{a b c d e} http://www.balzarova.cz/cz/clanky.php?i=15
3. ↑ ^{a b c} http://www.czech-press.cz/index.php?option=com_content&view=article&id=692&catid=13&Itemid=4
4. ↑ ^{a b} http://zabaci.cz/fauna-a-flora/130-delfini.html
5. ↑ http://www.rozhlas.cz/leonardo/zpravy/_zprava/morske-proudy-oddeluji-delfiny--870641

Der Chinesische Weiße Delfin (Sousa chinensis, chinesisch 中華白海豚, Pinyin Zhōnghuá bái hǎitún) ist eine Delfinart aus dem zentralen, tropischen Indopazifik.

Systematik

Der Artstatus des Kamerunflussdelfins (Sousa teuszii), dessen Verbreitungsgebiet im Atlantik weit entfernt von dem der anderen Tiere der Gattung Sousa liegt und der sich auch in Anzahl der Wirbel und Zähne unterscheidet, ist weitgehend außer Zweifel. Die Populationen im Indopazifik wurden traditionell als eine einzige Art (Sousa chinensis) betrachtet. Dale Rice,^[1] Rüdiger Wandrey,^[2] sowie Mendez und Mitarbeiter^[3] unterschieden jedoch eine westliche Art, den Bleifarbenen Delfin (Sousa plumbea), der sich farblich unterscheidet, einen deutlichen Rückenbuckel besitzt und dessen Verbreitungsgebiet von Südafrika bis Ostindien reicht. Sousa sahulensis, eine bis 2014 unbeschriebene Art, lebt an der Nordküste Australiens.^[4] 2015 wurde Sousa chinensis taiwanensis beschrieben, eine in der Formosastraße vorkommende Unterart des Chinesischen Weißen Delfins, die sich durch eine Musterung mit kleinen, dunklen Punkten von der Nominatform (S. c. chinensis) unterscheidet.^[5]

Verbreitung

Chinesische Weiße Delfine sind im tropischen Indopazifik beheimatet, ihr Verbreitungsgebiet reicht von der Ostküste des Indischen Subkontinents etwa von den Mündungen von Krishna und Godavari über Südostasien, einschließlich des indonesischen Raums bis zum südlichen China.^[3] Sie bevorzugen Küstenregionen mit einer Wassertiefe von höchstens 20 Meter und kommen selten auf das offene Meer hinaus. Allerdings sind diese Tiere gelegentlich in Flüssen zu finden, wie dem Jangtsekiang, allerdings schwimmen sie nur selten weiter ins Landesinnere und halten sich vorwiegend in den Mündungsbereichen auf.

Beschreibung

Chinesische Weiße Delfine erreichen eine Länge von 2,4 bis 2,8 Meter und ein Gewicht von 170 bis 260 kg. Die Färbung variiert je nach Alter und Population, ist jedoch meist ein hellgrau oder weiß, das bis ins rosafarbene übergehen kann. Der für die Gattung typische Rückenbuckel, auf dem bei anderen Sousa-Arten die dreieckige Finne sitzt, fehlt beim Chinesischen Weißen Delfin.^[6] Der Kopf ist durch eine lange Schnauze und eine leicht eingedrückte Melone gekennzeichnet.

Lebensweise

Der Lebensraum dieser Delfine sind seichte, warme Küstengewässer und Brackwasserregionen. Sie bevorzugen Sandbänke oder mangrovenbestandene Küstenabschnitte, sind aber auch in Riffregionen wie dem Great Barrier Reef zu finden. Sie leben in kleinen Gruppen von drei bis sieben Tieren, können sich aber auch zu größeren Verbänden zusammenschließen. Manchmal vergesellschaften sie sich mit Großen Tümmlern, Glattschweinswalen und anderen Walarten. Chinesische Weiße Delfine gelten als langsame Schwimmer und vorsichtige Tiere, die sich von Booten eher entfernen. Die Nahrung dieser Tiere besteht vorwiegend aus Fischen, daneben nehmen sie auch Krebstiere zu sich.

Bedrohung

Manchmal werden diese Delfine wegen ihres Fleisches gejagt, allerdings nicht in großem und kommerziellem Ausmaß. Größer sind andere Bedrohungen für diese Tiere: die Fischerei, da sie sich immer wieder in Fischernetzen verfangen, der Bootsverkehr, da die Motorengeräusche die Unterwasserortung der Tiere stören oder sie durch Schiffspropeller getötet werden, die Rodung der Mangrovenwälder an den Küsten sowie die Verschmutzung der Meere. Vor allem in dicht besiedelten Regionen wie dem südöstlichen China haben diese Praktiken zu einem Rückgang der Population geführt.

Literatur

• Hadoram Shirihai, Brett Jarrett: Meeressäuger: Alle 129 Arten weltweit. Franckh-Kosmos-Verlags GmbH, 2008, ISBN 3-440-11277-2.
• Rüdiger Wandrey: Die Wale und Robben der Welt. Franckh-Kosmos Verlags GmbH, 1997, ISBN 3-440-07047-6

Einzelnachweise

1. ↑ Dale W. Rice (1998): Marine Mammals of the World. Systematics and Distribution, Society of Marine Mammalogy as Special Publication No. 4
2. ↑ Wandrey (1997), Seite 76.
3. ↑ ^{a b} Martin Mendez, Thomas J. Jefferson, Sergios-Orestis Kolokotronis, Michael Krützen, Guido J. Parra, Tim Collins, Giana Minton, Robert Baldwin, Per Berggren, Anna Särnblad, Omar A. Amir, Vic M. Peddemors, Leszek Karczmarski, Almeida Guissamulo, Brian Smith, Dipani Sutaria, George Amato, Howard C. Rosenbaum. Integrating multiple lines of evidence to better understand the evolutionary divergence of humpback dolphins along their entire distribution range: a new dolphin species in Australian waters? Molecular Ecology, 2013; DOI: 10.1111/mec.12535
4. ↑ Thomas A. Jefferson und Howard C. Rosenbaum: Taxonomic revision of the humpback dolphins (Sousa spp.), and description of a new species from Australia. Marine Mammal Science, Volume 30, Issue 4, pages 1494–1541, Oktober 2014, DOI: 10.1111/mms.12152
5. ↑ John Y Wang, Shih Chu Yang and Samuel K Hung. 2015. Diagnosability and Description of A New Subspecies of Indo-Pacific Humpback Dolphin, Sousa chinensis (Osbeck, 1765), from the Taiwan Strait. Zoological Studies. 54:36. DOI: 10.1186/s40555-015-0115-x
6. ↑ Shirihai & Jarrett (2008), Seite 161.

The Indo-Pacific humpback dolphin (Sousa chinensis)^[3] is a species of humpback dolphin inhabiting coastal waters of the eastern Indian and western Pacific Oceans.^[4] This species is often referred to as the Chinese white dolphin in mainland China, Macao, Hong Kong, Taiwan and Singapore as a common name. Some biologists regard the Indo-Pacific dolphin as a subspecies of the Indian Ocean humpback dolphin (S. plumbea) which ranges from East Africa to India. However, DNA testing studies have shown that the two are distinct species.^[1] A new species, the Australian humpback dolphin (S. sahulensis), was split off from S. chinensis and recognized as a distinct species in 2014.^[5] Nevertheless, there are still several unresolved issues in differentiation of the Indian Ocean-type and Indo-Pacific-type humpback dolphins.

Taxonomy

Two subspecies of the Indo-Pacific humpback dolphin are currently recognized:^[6]

• S. c. chinensis, or the Chinese humpback dolphin
• S. c. taiwanensis, or the Taiwanese humpback dolphin

Description

Tail with visible grey and pink colours

An adult Indo-Pacific humpback dolphin is grey, white or pink^[7] and may appear as an albino dolphin to some. Populations along the coasts of China^[8] and Thailand ^[9] have been observed with pink skin. The pink colour originates not from a pigment, but from blood vessels which were overdeveloped for thermoregulation. The body length is 2 to 3.5 m (6 ft 7 in to 11 ft 6 in) for adults , 1 m (3 ft 3 in) for infants. An adult weighs 150 to 230 kg (330 to 510 lb). Indo-Pacific humpback dolphins live up to 40 years,^[10] as determined by the analysis of their teeth.

Calves are dark grey or black at birth and measure around 1 m (3.3 ft) in length. Their coloration lightens through a mottled grey as they age.^[7]

Behaviour

Indo-Pacific humpback dolphins live in small groups, generally with fewer than ten individuals. They hunt as a group using echolocation.^[11]

Adult dolphins come to the water surface to breathe for 20 to 30 seconds before diving deep again, for two to eight minutes. Dolphin calves, with smaller lung capacities, surface twice as often as adults, staying underwater for one to three minutes. Adult dolphins rarely stay under water for more than four minutes. They sometimes leap completely out of the water. 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 air and water.

Reproduction

Female dolphins reach sexual maturity at around ten years old, while males mature at around 13 years old. They usually mate from the end of summer to autumn, and calves are born after a gestation period of eleven months. The mother stays with her calf until it can find food for itself, usually when it reaches 3–4 years old.^[10]

Threats

The Indo-Pacific humpback dolphin is threatened by habitat loss, water pollution, coastal development, overfishing and an increase in marine traffic within its range.^[12][13]

In 2015 the Indo-Pacific humpback dolphin was classed as "vulnerable" on the IUCN Red List of Threatened Species.^[13]

Water pollution

In 2013, conservationists in Hong Kong warned that the local population had fallen from 158 individuals in 2003 to just 78 in 2011. Members of Hong Kong Dolphinwatch spotted a group of dolphins helping a mother to support her dead calf above the water in an attempt to revive it. A Dolphinwatch spokeswoman claimed that the calf had died after ingesting toxins from polluted seawater through its mother's milk. The Hong Kong Dolphin Conservation Society warned of a further decline in dolphin numbers in the area.^[12]

Plastic pollution

Indo-Pacific humpback dolphins are at particular risk of exposure to organic pollutants because they inhabit shallow coastal waters, which are often impacted by human activities. Anthropogenic pollutants pose a risk to marine mammals that reside in coastal waters. Discharge of organic pollutants into marine environments has been shown to decrease water quality, resulting in habitat loss and a significant reduction in species richness.^[14] The loss of key pods has caused species fragmentation, also due to habitat loss, which increases species isolation and decreases connectivity, resulting in population decline.

Plastic pollution is widespread across all oceans due to the buoyant and durable properties of plastic, which allow for sorption of toxicants to plastic while traveling through the environment.^[15][16] This has led researchers to the conclusion that synthetic polymers are hazardous to marine life and should be declared as a hazardous waste type. There are many transit paths that allow for plastics and pollutions to enter oceans: freshwater waste can enter oceans by rivers at the delta or estuary, by humans discarding their waste directly into marine waters, or through photo-degradation and other forms of weathering processes that aid in plastic fragmentation and dispersal. Large quantities of fragmented plastics collect in subtropical ocean gyres.^[16] Plastic accumulation is not limited to ocean gyres; closed bays, gulfs and seas surrounded by densely populated coastlines and watersheds are all susceptible.^[17]

Bioaccumulation:Plastic pollutants traveling from lower-trophic levels to higher-trophic levels.

The consumption of plastics causes adverse effects in marine mammals such as disease susceptibility, reproductive and developmental toxicity.^[14] Constant absorption of organic pollutants like plastic can be transferred into the dolphin's tissues and organs through an ingestion pathway that is impacting megafauna, lower trophic levels and predators (not limited to Indo-Pacific).^[18] Organ toxicity can lead to organ failure, loss of offspring and milk toxicity. Even if the dolphin is not consuming plastic directly then it can take in plastic pollutants through biomagnification and bioaccumulation. Bioaccumulation is defined as the uptake of chemicals from the environment through dietary intake, dermal (skin) absorption or respiratory transport in air or water. This is a huge factor in plastic toxicity consumption in this species due to its long lifespan, which makes it susceptible to chronic exposure. Also, these dolphins contain a large quantity of blubber, lipids, which can result in an excess of toxicity storage in their tissues.

Echolocation, also known as sonar

Plastic pollution can also interfere with dolphins' use of echolocation. Echolocation is the main sense that all dolphins use to navigate, as well as to pinpoint prey and predators.^[19] Dolphins and whales use echolocation by bouncing high-pitched clicking sounds off underwater objects, similar to shouting and listening for echoes. The sounds are made by squeezing air through nasal passages near the blowhole. These sound-waves then pass into the forehead, where a big blob of fat called the melon focuses them into a beam.^[20] This process can be interrupted by noise pollution, as well as by obstructions in the water such as masses of oil or plastics.^[21] Large blockages in the water can refract sound-waves, misleading the dolphin to falsely detect prey, kin or a predator in the area. This can become confusing and frustrating which can lead to extreme stress and potential health issues.

Clusters of plastic debris can cause noise pollution which interferes with the dolphins' sense of echolocation. As plastic debris is hurled together by ocean currents, sound is produced underwater. An excess of sound waves underwater can render the dolphins' sense of echolocation useless.

Distributions and watching

Adult Chinese white dolphin swimming off the coast of Lantau Island, Hong Kong

In Hong Kong, boat trips to visit the Indo-Pacific humpback dolphins have been running since the 1990s.^[22] The dolphins mainly live in the waters of Lantau North, Southeast Lantau, the Soko Islands and Peng Chau. A code of conduct regulates dolphin-watching activity in Hong Kong waters.^[23]

There have been some reports of dolphin watching practices that have further endangered the Indo-Pacific humpback dolphins, such as in Sanniang Bay dolphin sanctuary in Qinzhou^[24] and off Xiamen.^[25] However, these generally are small, locally organised one-off tours or private pleasure boats that do not adhere to the Hong Kong Agricultural and Fisheries Department's voluntary code of conduct.

Nánpēng Islands Marine Sanctuary in Nan'ao County is also home to local pods.^[26] The population in Leizhou Bay, Leizhou Peninsula, comprising nearly 1,000 animals and the second largest population in the nation, may also be targeted for future tourism.^[27] Hepu National Sanctuary of Dugongs, and waters around Sanya Bay and other coasts adjacent on Hainan Island are home to some dolphins.^[28] As the environment and local ecosystems recovery, dolphins' presences in nearby waters have been increasing such as vicinity to the nature sanctuary of Weizhou and Xieyang Islands.^[29][30] Gulf of Tonkin waters in Vietnam may have unstudied populations that may appear elsewhere such as along Xuân Thủy National Park and Hòn Dáu Island in Hải Phòng.^[31]

Cantonese slang

The Cantonese language has a slang expression wu gei bak gei (often written as 烏忌白忌, "black taboo white taboo") which means someone or something is a bad omen or a nuisance. The phrase originates from the Cantonese fisher people, because they claim the dolphins eat the fish in their nets. However, in formal Chinese, it should be written as 烏鱀白鱀, with the gei originally in old Chinese, meaning dolphins. The wu refers to the finless porpoises, which are black, and the bak, white, referring to Chinese river dolphins. These two species often interrupt and ruin the fishermen's catch. As years passed, because "dolphin" sounds the same as "bad luck", the meaning of the phrase changed. However, in Cantonese, wu refers to the calves of Chinese white dolphin and bak refers to the adults. Nowadays, dolphins are not called gei anymore, but 海豚 (hai tun), literally meaning "sea pig", with none of the negative connotations for pig found in English.

Taiwanese humpback dolphin

The Taiwanese humpback dolphin (S. c. taiwanensis) is a subspecies of the Indo-Pacific humpback dolphin found in the Eastern Taiwan Strait. The Indo-Pacific humpback dolphins were first discovered along the west coast of Taiwan in 2002. Based on a survey done in 2002 and 2003, they are often found in waters <5m deep, and no evidence shows that they appear in water deeper than 15m.^[32] A study in 2008 found that the population of humpback dolphins, which occupies a linear range of about 500 km^2 along the central west coast of Taiwan, is genetically distinct from all populations living in other areas.^[33] And this population is called Eastern Taiwan Strait (ETS) population.

Taiwan is a densely populated island and highly developed area, which has many industrial development projects, especially along the west coast, where the ETS populations of Indo-Pacific humpback dolphins live. Based on data collected between 2002 and 2005, the ETS population of humpback dolphins was less than 100 individuals.^[32] Unfortunately, the newest data released in 2012 shows that only 62 individuals are left. It means during those 7 years, population of humpback dolphins is being destroyed constantly and severely. A preliminary examination revealed that the ETS humpback dolphin population meets the IUCN Red List criteria for "Critically endangered".^[34] Without further protection and regulation, this population will go extinct quickly. The ETS is listed as Endangered species Under the Endangered Species Act by NOAA Fisheries since 2018.^[35]

There are several facts that result in the decreasing number of ETS population of humpback dolphins. First, large-scale modification of the shoreline by industrial development including hydraulic filling for creating industrial or science parks, seawall construction and sand mining cause habitat fragmentation and diminish dolphin's habitats. In addition, exploitation of shoreline also contributes to toxic contamination flows into dolphin's habitats. The chemical pollution from industrial or agricultural and municipal discharge results in impaired health of dolphins, for instance, reproductive disorders, and compromised immune system.^[36]

Second, fishing activities along the west coast of Taiwan are thriving, and cause many impacts on dolphins. Widespread and intensive use of gillnets and vessel strikes are potential threats for dolphins. Over exploitation of fish by fisheries' is another threat for the dolphin population. It has led to disturbance of marine food web or trophic level and reduces marine biodiversity. Therefore, dolphins have not enough prey to live on.

Still another problem is reduced amount of freshwater flows into estuaries from rivers. Since ETS population of humpback dolphins is closely associated with estuaries habitat, the elimination of freshwater discharge from rivers significantly decreases the amount of suitable habitats for dolphins.^[32]

Hydroacoustic disturbance is another critical issue for dolphins. Sources of noise can come from dredging, pile driving, increased vessel traffic, seawall construction, and soil improvement. For all cetaceans, sound is vital for providing information about their environment, communicating with other individuals, and foraging; also, they are very vulnerable and sensitive to the effects of noise. Elevated anthropogenic sound level causes many dysfunctions of their behaviors, and even leads to death.^[32]

In addition to threats from anthropogenic activities, dolphins are potentially at the risk due to the small population size, which may result in inbreeding and decreased genetic and demographic variability. Finally, climate change causes more typhoons to hit the west coast of Taiwan and cause great disturbance to dolphins' habitats.

Conservation

The Indo-Pacific humpback dolphin is listed on Appendix II^[37] of the convention on the Conservation of Migratory Species of Wild Animals (CMS). It is listed on Appendix II^[37] as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements. In the interim of 2003–2013, the number of these dolphins in the bay around Hong Kong has dwindled from a population of 159 to just 61 individuals, a population decline of 60% in the last decade. The population continues to be further threatened by pollution, vessel collision, overfishing, and underwater noise pollution.^[38]

In addition to their natural susceptibility to anthropogenic disturbances, the Chinese white dolphin's late sexual maturity, reduced fecundity, reduced calf survival, and long calving intervals heavily curtails their ability to naturally cope with elevated rates of mortality.^[39]

In recent years, Taiwan launched the largest Indo-Pacific Humpbacked Dolphin sanctuary on the Taiwanese coast, stretching from Miaoli County to Chiayi County.^[40] The Indo-Pacific humpback dolphin is also covered by the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU).

Timeline of main events

• 1637: The Indo-Pacific humpback dolphin was first documented in English by the adventurer Peter Mundy in Hong Kong near the Pearl River. The species are attracted to the Pearl River Estuary because of its brackish waters.
• 1765: Pehr Osbeck gives the first scientific description of the species.^[41]
• Late 1980s: Environmentalists started to pay attention to the Indo-Pacific humpback dolphin population.
• Early 1990: The Hong Kong public started to become aware of the Indo-Pacific humpback dolphin. This was due to the side effects of the construction of the Chek Lap Kok Airport. It was one of the world's largest single reclamation projects: the reclamation of nine square kilometers of the seabed near Northern Lantau, which was one of the major habitats of the dolphins.
• Early 1993: Re-evaluation of the environmental effects of the construction of Chek Lap Kok Airport. This alerted eco-activists such as those from the World Wide Fund for Nature in Hong Kong, in turn bringing media attention on the matter. Soon enough, the Hong Kong Government began getting involved by funding projects to research on the Indo-Pacific humpback dolphins
• Late 1993: The Agriculture, Fisheries and Conservation Department was founded.
• 1996: Dr. Thomas Jefferson began to conduct research on the Indo-Pacific humpback dolphins in hope of discovering more about them.
• 1997: The Indo-Pacific humpback dolphin became the official mascot of the 1997 sovereignty changing ceremonies in Hong Kong.
• 1998: The research results of Dr. Thomas Jefferson was published in "Wildlife Monographs".
• 1998: The Hong Kong Dolphinwatch was organized and began to run dolphin watching tours for the general public to raise the public's awareness of the species.
• 2000: The Agriculture, Fisheries and Conservation Department started to conduct long-term observation of the Indo-Pacific humpback dolphins in Hong Kong.
• 2000: The population of Indo-Pacific humpback dolphins has reached around 80–140 dolphins in the Pearl River waters.
• 2014: Jefferson and Rosenbaum revised the taxonomy of the humpback dolphins (Sousa spp.). They describe a new species, the Australian humpback dolphin and define the accepted common name for this species, the Indo-Pacific Humpback dolphin.^[5]

See also

• Hong Kong Dolphin Conservation Society
• Wildlife of China
• List of endangered and protected species of China
• List of cetaceans

References

El delfín rosado de Hong Kong (Sousa chinensis) es una especie de cetáceo odontoceto de la familia Delphinidae que habita desde el cabo de Buena Esperanza hasta China y el norte de Australia.

Descripción

Al igual que el delfín giboso atlántico (S. teuszii) presenta una joroba de tejido adiposo bajo la aleta dorsal. Mide aproximadamente 2 metros de largo. Su fórmula dentaria es 26-38/26-38. Nace presentando la piel negra, pero con el tiempo va cambiando hasta adquirir la coloración rosada de los adultos.

Es inteligente y muy sociable. Se relacionan fácilmente con los humanos, especialmente con aquellos que se desplazan en embarcaciones pequeñas. Durante el apareamiento nadan con la parte ventral hacia la superficie, cerca de la orilla del río. Su reproducción depende del nivel estacional de las aguas.

Conservación

Esta amenazada por la contaminación, las redes de pesca y las presas hidroeléctricas. Debido a la vulnerabilidad de la especie se han tomado medidas para su protección en todos los países que habita. Algunas muertes de delfines rosados ocurren por envenenamiento por mercurio del ambiente, debido que en las minas de oro, el mercurio se utiliza para separar el oro de roca circundante.

Referencias y bibliografía

Referencias

Bibliografía

Sousa chinensis Sousa generoko animalia da. Artiodaktiloen barruko Delphinidae familian sailkatuta dago.

Erreferentziak

• 'Sousa chinensis'ri buruzko informazioa Mammals of The World datubasean

Ikus, gainera

• Delphinidae

Intiankyttyrädelfiini^[2] (Sousa chinensis) on ryhädelfiineihin kuuluva delfiinilaji, joka elää Kaakkois-Aasiassa. Nisäkäsnimistötoimikunnan ehdotus lajin uudeksi suomenkieliseksi nimeksi on kyttyrädelfiini.^[2] Intiankyttyrädelfiinin uhanalaisuusluokitus on vaarantunut.^[1] Intiankyttyrädelfiini on joskus väritykseltään vaaleanpunainen.^[3] Sillä on yksi sukulaislaji, afrikankyttyrädelfiini (Sousa teuszii).

Lajin koko ihmiseen verrattuna.

Lähteet

Aiheesta muualla

• Laji.fi: Kyttyrädelfiini (Sousa chinensis)
• ITIS: Sousa chinensis (englanniksi)
• University of Michigan, Animal Diversity Web (ADW): Sousa chinensis, Indo-Pacific humpbacked dolphin (englanniksi)
• Food and Agriculture Organization of the United Nations (FAO): Sousa chinensis (englanniksi)
• Kuvia lajista www.hkdcs.org -sivustolla (englanniksi)

Sousa chinensis

Le dauphin à bosse du Pacifique ou sotalie de Chine (Sousa chinenses) est une espèce de mammifères de l'ordre des cétacés.

Habitat et répartition

Ce dauphin se trouve dans l'océan pacifique, en Asie du Sud-Est de l'Est du Sri Lanka à la Chine et à l'Indonésie.

Il vit le long des côtes, dans les eaux peu profondes des baies, près des mangroves et il remonte dans les estuaires^[1].

Description

Le dauphin à bosse du Pacifique mesure de 1,80 m à 3 m de long et pèse jusqu'à 280 kg.

Jeune, il est gris uniforme et ressemble à un jeune grand dauphin. Son dos est arqué. Il a de 60 à 76 dents à chaque mâchoire. Avec l'âge, il devient rose-blanc, moucheté de noir sur le dos^[2].

• Dauphin à bosse du Pacifique ou Sotalie de Chine adulte

• Jeune, encore gris, dans un marine land à Singapour

• Tête de spécimen âgé devenant rose moucheté de noir

• Détail de la queue aux couleurs grises et roses

Il communique par sifflements. Son écholocalisation est efficace jusqu'à 25 m de profondeur.

Il est grégaire et assez sédentaire. Il vit en petit groupe familiale.

Parfois, mais rarement, il chasse en groupe pouvant atteindre jusqu'à une quarantaine d'individus. Il mange des sardines, des chinchards et des mulets. Il se nourrit aussi de céphalopodes, d'échinodermes dont des oursins...

Il atteint la maturité sexuel vers l'âge de 10 ans. La gestation dure de 10 à 12 mois. Le nouveau-né mesure près d'un mètre pour une masse d'une quinzaine de kilogrammes ; il est allaité plus de 6 mois et sevré à 2 ans. Les mises bas peuvent avoir donc lieu tous les 3 ans.

Menaces

Les filets de pêche constituent un danger mortel ; de plus, il est victime d'empoisonnement aux métaux lourds et aux produits chimiques.

Voir aussi

• Sousa chinensis chinensis, dauphin blanc de Chine, une sous-espèce.

Références taxinomiques

• (en) Référence Mammal Species of the World (3^e éd., 2005) : Sousa chinensis
• (fr) Référence CITES : taxon Sousa chinensis (sur le site du ministère français de l'Écologie) (consulté le 19 mai 2015)
• (fr+en) Référence ITIS : Sousa chinensis (Osbeck, 1765)
• (en) Référence Animal Diversity Web : Sousa chinensis

Notes et références

1. ↑ Alain Diringer (préf. Marc Taquet), Mammifères marins et reptiles marins de l'océan Indien et du Pacifique, Éditions Orphie, 2020, 272 p. (ISBN 979-10-298-0254-6), p. Les dauphins à bosse de l'Indo-Pacifique page 101
2. ↑ Alain Diringer (préf. Marc Taquet), Mammifères marins et reptiles marins de l'océan Indien et du Pacifique, Éditions Orphie, 2020, 272 p. (ISBN 979-10-298-0254-6), Dauphin à bosse du Pacifique pages 102 et 103

La susa indopacifica (Sousa chinensis (Osbeck, 1765); 中華白海豚^T, Zhōnghuá bái hǎitún^P), nota anche come delfino bianco cinese, è una specie di delfino diffusa nelle acque tropicali dell'Indo-Pacifico centrale.^[2]

Tassonomia

Lo stato di specie a sé della susa atlantica (Sousa teuszii), il cui areale nell'Atlantico è molto lontano da quello degli altri membri del genere Sousa, dai quali differisce anche per il numero di vertebre e denti, è in gran parte fuori di dubbio. Le popolazioni indopacifiche venivano tradizionalmente considerate come un'unica specie (Sousa chinensis), ma Dale Rice,^[3] Rüdiger Wandrey^[4] e Mendez et al.^[5] hanno in seguito distinto una specie occidentale, la susa indiana (Sousa plumbea), che differisce per la colorazione e la presenza di una gobba dorsale distinta, diffusa dal Sudafrica all'India orientale, e successivamente, nel 2014, è stata descritta Sousa sahulensis, che vive lungo la costa settentrionale dell'Australia.^[6] Nel 2015 è stata descritta Sousa chinensis taiwanensis, una sottospecie della susa indopacifica presente nello stretto di Formosa, che differisce dalla forma nominale (S. c. chinensis) per il motivo a piccoli punti scuri.^[7]

Descrizione

Le suse indopacifiche sono caratterizzate da un corpo robusto e di medie dimensioni: raggiungono una lunghezza di 2-2,6 metri e un peso che va da 230 a 250 kg. La colorazione è generalmente grigia ma può variare notevolmente con l'età e l'area geografica. La maggior parte degli adulti provenienti dalla Cina meridionale è di colore bianco puro, mentre altri conservano una parte della loro pigmentazione grigio scuro e sviluppano macchie scure o punteggiature. La gobba caratteristica delle specie S. teuszii e S. plumbea è assente nelle suse indopacifiche e le loro pinne dorsali tendono a essere più grandi e di forma più marcatamente triangolare.^[8]

Distribuzione e habitat

Come indica il nome, la susa indopacifica è originaria dell'Indo-Pacifico tropicale: il suo areale si estende dalla costa orientale del subcontinente indiano, a partire dalle foci dei fiumi Krishna e Godavari, attraverso il Sud-est asiatico, regione indonesiana compresa, fino alla Cina meridionale.^[5] Preferisce le regioni costiere con una profondità dell'acqua non superiore a 20 metri e si spinge raramente in mare aperto. Tuttavia, le suse si trovano occasionalmente in fiumi come lo Yangtze, sebbene nuotino raramente nell'entroterra e tendano a rimanere negli estuari.

Biologia

Questi delfini vivono in acque costiere calde e poco profonde, ma anche nell'acqua salmastra. Preferiscono i banchi di sabbia o le coste fiancheggiate da mangrovie, ma si possono trovare anche nei pressi delle barriere coralline. Vivono in piccoli gruppi da tre a sette esemplari, ma possono anche formare gruppi più grandi. A volte socializzano con tursiopi, neofocene e altre specie di cetacei. Le suse indopacifiche sono note per essere nuotatori lenti e cauti che tendono a stare alla larga dalle imbarcazioni.

Questi delfini sono considerati opportunisti e si alimentano in modo generalista, mangiando una varietà di pesci di scogliera costiera e di estuario. Alcuni catturano anche cefalopodi e crostacei. Questa specie si nutre in associazione con i pescherecci a strascico di Hong Kong.^[9]

L'accoppiamento e il parto sembrano avvenire tutto l'anno. Il periodo di gestazione dura 10-12 mesi, l'allattamento può durare più di 2 anni, la maturità sessuale è raggiunta a 9-10 anni per le femmine e 12-13 anni per i maschi, ed è stato ipotizzato un intervallo di 3 anni tra i singoli parti. Gli individui possono vivere almeno 30 anni.^[9]

Conservazione

Nel mondo sono rimasti solamente 6000 esemplari di susa indopacifica^[10] e le varie popolazioni constano di poche decine o poche centinaia di esemplari; tuttavia, almeno 1200 animali vivono nell'estuario del Fiume delle Perle, nella Cina meridionale.^[9] A volte questi delfini vengono cacciati per la loro carne, ma non su scala ampia e commerciale. Sono altre le principali minacce che gravano sulla specie: la pesca, in quanto continuano a rimanere impigliati nelle reti, il traffico navale, perché il rumore dei motori disturba il loro sistema di ecolocalizzazione e le eliche delle navi possono ucciderli, il disboscamento delle foreste di mangrovie sulle coste e l'inquinamento dei mari. Soprattutto nelle regioni densamente popolate, come la Cina sud-orientale, queste pratiche hanno portato a un notevole calo demografico.

Note

Dolphin Bongkok Bernie (bahasa Inggeris: Indo-Pacific Hump-backed Dolphin) merupakan salah satu daripada haiwan yang terdapat di Malaysia. Nama saintifiknya Sousa chinensis. Dolphin Bongkok Bernie merupakan haiwan yang dilindungi dan memerlukan lesen pemburuan.

Malaysia merupakan salah satu daripada 12 negara yang telah diiktiraf sebagai kepelbagaian raya (mega diversity) dari segi bilangan dan kepelbagaian flora dan fauna dengan 15,000 spesies pokok berbunga yang diketahui, 286 spesies mamalia, lebih daripada 1,500 vertebrat darat, lebih daripada 150,000 spesies invertebrat, lebih daripada 1,000 spesies rama-rama dan 12,000 spesies kupu-kupu dan lebih daripada 4,000 spesies ikan laut.

Ciri-ciri

Dolphin Bongkok Bernie adalah haiwan berdarah panas, melahirkan anak, menjaga anak sehingga mampu berdikari, dan mempunyai bulu di badan.

Jantung Dolphin Bongkok Bernie terdiri daripada empat kamar seperti manusia. Kamar atas dikenali sebagai atrium, sementara kamar bawah dikenali sebagai ventrikel.

De Chinese witte dolfijn of Chinese sousa (Sousa chinensis) is een soort dolfijn.

Kenmerken

De Chinese witte dolfijn is een stevige, torpedovormige dolfijn. Hij heeft een lichtgrijze tot witte rug, die lichter is op de flanken en de buik. Veel exemplaren zijn geheel wit of rozewit van kleur. Volwassen dieren kunnen gele, roze, grijze of bruine vlekjes krijgen. De rugvin is klein en driehoekig en geplaatst in het midden van de rug, sikkelvormig bij jonge dieren, meer afgerond bij volwassen dieren. De flippers zijn afgerond. De bek is lang en slank en bevat zo'n 120 tanden. Op het voorhoofd zit een lichte meloen. Bij dieren die ten westen van Sumatra leven is er een vetbult achter de rugvin aanwezig, die bij de dieren die ten oosten en zuiden van Sumatra leven ontbreekt. Bij de laatste dieren is echter de rugvin wel een stuk hoger. Mannetjes worden tot 320 cm lang, vrouwtjes 200 tot 240 cm. Het lichaamsgewicht is ongeveer 85 kg.

Leefwijze

De Chinese witte dolfijn leeft van scholenvissen als harders en haringachtigen, aangevuld met schaaldieren en weekdieren. Tijdens de jacht maakt hij gebruik van echolocatie. Hij leeft in kleine hechte groepjes van maximaal twintig dieren. Vaak wordt hij met andere dolfijnen waargenomen, voornamelijk tuimelaars, maar ook langsnuitdolfijnen en Indische bruinvissen. Soms jaagt hij ook samen met deze soorten. Bij het zwemmen steekt hij eerst de snuit of de hele kop boven het water. Hierna komt hij gedeeltelijk boven het water uit, om vervolgens weer te verdwijnen. Een pasgeboren jong is ongeveer 110 cm lang.

Bescherming

De Chinese witte dolfijn is een belangrijke toeristische attractie in Hongkong, waar excursies te volgen zijn naar de "roze dolfijnen". De habitat van deze dieren werd echter in het midden van de jaren negentig bedreigd door de aanleg van een vliegveld.

Verspreiding

Deze soort komt voor in de Indische en Westelijke Stille Oceaan. Hij is nauw verwant aan de Kameroendolfijn (Sousa teuszii), die leeft aan de Atlantische kust van West-Afrika. Mogelijk behoort de populatie in de Westelijke Indische Oceaan tot een aparte soort, Sousa plumbea. Het eiland Sumatra is aangewezen als de grens tussen S. chinensis en S. plumbea. Ook de Australische vorm zou tot een andere soort kunnen behoren.

De Chinese witte dolfijn leeft in de gematigde en tropische wateren van de Indische Oceaan en de Westelijke Stille Oceaan en in de Rode Zee en de Zuid-Chinese Zee. Hij komt voor in ondiepe kustwateren van zuidelijk en oostelijk Afrika, via Arabië en India tot de Pacifische kust van China, Indonesië, de Filipijnen en Noord-Australië. De soort verdraagt brakwater prima en laat zich regelmatig zien rond estuaria en andere riviermondingen en in mangrovemoerassen. Soms zwemt hij een rivier op als de Jangtsekiang.

Garbogrzbiet chiński^[4], delfin garbaty^[5], sotalia chińska^[6] (Sousa chinensis) – gatunek ssaka z rodziny delfinowatych (Delphinidae) żyjącego w wodach Oceanu Inyjskiego i Spokojnego^[3][2]. Jest gatunkiem zagrożonym z powodu zanieczyszczeń wód.

Podgatunki

Wyróżniono dwa podgatunki S. chinensis^[4][3]:

• S. chinensis chinensis – garbogrzbiet chiński
• S. chinensis plumbea – garbogrzbiet indyjski

Pożywienie

Delfin garbaty żywi się rybami i mięczakami.

Ubarwienie

Dorosłe osobniki mają kolor biało-różowy z powodu dobrze unaczynionej skóry, młode są szare lub czarne.

Przypisy

O golfinho-corcunda-indopacífico (Sousa chinensis) é uma espécie de cetáceo da família Delphinidae encontrada no oceano Índico e sudoeste do Pacífico, principalmente em águas costeiras.

Nomenclatura e taxonomia

A espécie foi descrita por Pehr Osbeck em 1765 como Delphinus chinensis.^[2] Foi recombinada para Steno chinensis por John Edward Gray em 1871^[3] e para Sotalia sinensis por William Henry Flower em 1883.^[4]

A população do Índico, Sousa plumbea, é considerada como uma espécie distintas por alguns autores,^[5] entretanto, as diferenças morfológicas entre as populações geográficas são consideradas plesiomórficas.^[6] De maneira conservativa Sousa plumbea é mantida como sinônimo de Sousa chinensis até que uma revisão taxonômica ampla seja feita.^[7]

Referências

Delfinul alb chinezesc (Sousa chinensis), cunoscut și sub denumirea de delfinul alb-cu-cocoașă,^{[necesită citare]} sau colocvial, delfinul roz^{[necesită citare]} este o specie de delfini.

Caractere morfologice

Delfinii albi chinezești au o culoare unică. Aproape negri la naștere, delfinii maturi ajung gri-deschis, iar în cele din urmă se schimbă până ajung la culoarea lor roz-pal. Cresc până la 3 m și pot trăi până la 40 de ani.

Răspândire

Delfinii albi chinezești trăiesc de-a lungul țărmurilor, de multe ori la gurile râurilor sau în apropierea pădurilor de mangrove. Ei fac parte din una din cele 80 de specii, cetacee care se găsesc în număr mic și ajung în apele din Australia, Africa de Sud și de-a lungul costei chineze, până la râul Yangtze.

Populație

Cercetătorii marini din Hong Kong estimează că numărul delfinilor albi chinezești care trăiesc în delta Râului Perlei, ale cărei ape sălcii oferă un mediu ideal pentru aceștia , este de aproximativ 1000 , iar între 100 și 200 trăiesc în apele Hong Kongului, mai mult în apele din nordul Insulei Lantau.

Referințe

Bibliografie

• Național Geographic Traveler: Hong Kong, pag. 207–208
• Enciclopedii-Dicționare, Editura Flamingo GD

Deltadelfin eller puckeldelfin (Sousa chinensis) är en delfinart som lever längs med de asiatiska kusterna i Sydostasien, från Sydafrika till Australien.

En vuxen deltadelfin kan väga 150^[2] till 280 kilogram och bli ungefär 180 – 300 centimeter lång. En nyfödd kalv är cirka en meter när den föds.^[3] Den maximala längden för honor är 240 cm och för hannar 320 cm.^[2]

Deltadelfinen är unik, för att en vuxen delfin är rosa. Den rosa färgen är inte ett pigment, utan det är istället blodkärl som finns alldeles under huden. Blodkärlen gör att delfinen inte blir överhettad om den blir utsatt för stark sol. De ändrar färg ju äldre de blir.

• En nyfödd kalv är helt svart.
• En äldre kalv har blivit grå.
• En ”tonåring” är grårosa med fläckar.
• Ett vuxet djur är vitrosa.

Den äldsta deltadelfin man känner till lever i Hongkong och är ungefär 33 år gammal, men de kan bli ungefär 40 år. Forskare har upptäckt att man kan avgöra en delfins ålder genom att undersöka en skiva av deras tänder.

Arten vistas främst i kustens närhet och iakttas sällan i regioner med mer än 20 meter vattendjup. Den hittas även i floder som Yangtze, men stannar vanligen i närheten av mynningen.

Deltadelfiner är sociala djur som lever i små flockar med tre eller fyra delfiner. Ibland syns arten tillsammans med öresvin, asiatisk tumlare eller andra valarter. Honorna blir könsmogna när de är ungefär 10 år och hanarna blir könsmogna lite senare vid 13 år. Efter att varit dräktig i 11 månader föder honan vanligen en kalv. En vuxen hona föder en kalv vart tredje år.

Eftersom deltadelfiner inte gärna flyttar sig ifrån sitt revir blir städernas föroreningar ett stort hot mot dem. Sjötrafik, överfiske och gifter är andra hot. Man har undersökt döda deltadelfiner och konstaterat att de har stora mängder med olika tungmetaller, polyklorerade bifenyler och DDT. Eftersom de är i toppen av näringskedjan är de hårt utsatta. Deltadelfin jagas ibland för köttets skull men jakten har ingen kommersiell status. Hotet utgörs av fiskenät där delfinen fastnar och drunknar, oljud från fartygsmotorer, fartygspropeller som sårar delfinen samt omvandling av mangrove till odlingsmark och avloppsvatten som hamnar i havet.

Referenser

Noter

1. ^ Sousa chinensis på IUCN:s rödlista, auktor: Reeves, R.R. et. al. (2008), besökt 7 januari 2009.
2. ^ [a b] Shanan Atkins (20 augusti 2002). ”Indo-Pacific humpback dolphin”. ARKive. Arkiverad från originalet den 4 november 2016. https://web.archive.org/web/20161104021807/http://www.arkive.org/indo-pacific-humpback-dolphin/sousa-chinensis/. Läst 1 november 2016.
3. ^ Stephanie Napier (27 april 2011). ”Sousa chinensis” (på engelska). Animal Diversity Web. University of Michigan. http://animaldiversity.org/accounts/Sousa_chinensis/. Läst 1 november 2016.

Webbkällor

Fritt översatt från engelska Wikipedia.

• 1 Поширення
• 2 Фізичні характеристики
• 3 Поведінка
• 4 Життєвий цикл
• 5 Посилання

Cá heo lưng bướu Thái Bình Dương, cá heo lưng gù hay còn gọi là cá heo trắng Trung Quốc (danh pháp khoa học: Sousa chinensis chinensis, tên Trung Quốc: 中华白海豚; bính âm: Zhonghua bái hǎitún) là một loài động vật có vú thuộc chi cá heo lưng bướu, họ Cá heo đại dương. Một con cá heo trưởng thành có màu trắng hoặc hồng^[2] (màu hồng của chúng được cho là do các mạch máu tạo nên sắc tố)

Phân bố

Khu vực phân bố của chúng bao gồm các vùng biển thuộc khu vực Đông Nam Á, Nam Trung Quốc đến Úc và quanh đảo Papua. Có hai phân loài của loài này là Sousa chinensis chinensis và Sousa chinensis plumbea. Trong khi loài Sousa chinensis chinensis phân bố từ Trung Quốc tới khu vực các đảo của Indonesia còn phân loài của chúng có nguồn gốc từ bờ biển Nam Phi đã di chuyển tới khu vực phía Nam Indonesia và quanh đại lục Úc. Hai phân loài này khác nhau về màu sắc và kích thước của vây lưng. Các phân loài được tìm thấy ở Đông Nam Á có màu trắng hồng và một vây lưng lớn hơn, nhưng lại không có cái bướu như phân loài ở Úc.

Đặc điểm

Chiều dài cơ thể của cá heo trắng Trung Quốc có chiều dài từ 2 đến 3,5 mét (6 ft 7 đến 11 ft 6 in) đối với con trưởng thành và hơn 1 mét (3 ft 3 in) đối với những con non. Một con trưởng thành có trọng lượng trung bình khoảng 150 đến 230 kg (330 510 lb). Cá heo trắng Trung Quốc có thể sống đến 40 năm.

Khi mới sinh ra, một con cá heo Trung Quốc có màu đen, sau đó chuyển dần sang màu xám rồi hồng nhạt có thêm những đốm nhỏ. Đến khi trưởng thành, chúng có màu hồng hoặc màu trắng.

Cá heo trắng Trung Quốc ngoi lên mặt nước để thở 20 - 30 giây đối với những con trưởng thành và cần thời gian gấp đôi đối với những con nhỏ do phổi của chúng chưa phát triển hết. Cá heo trưởng thành có thể ở dưới nước khoảng 2-8 phút, nhưng một con non chỉ có thể ở dưới nước trong 1-3 phút. Chúng di chuyển theo chiều thẳng đứng lên mặt nước. Do có một cặp mắt lồi nên chúng có thể quan sát một cách rõ ràng ở cả hai môi trường nước và không khí.

Sinh sản

Cá heo trắng Trung Quốc là những sinh vật hòa đồng, sống theo nhóm nhỏ khoảng 3 hoặc bốn con. Con cái trưởng thành khi đạt 10 năm tuổi, trong khi những con đực trưởng thành khi được 13 năm tuổi. Thời gian giao phối là vào cuối hè tới mùa thu. Cá heo con ra đời sau khoảng 11 tháng và được cha mẹ chúng chăm sóc cho đến khi chúng tự kiếm được thức ăn. Cá heo trắng Trung Quốc sinh sản 3 năm một lần, thường đẻ duy nhất một con.

Bảo tồn

Do việc khai thác thủy sản, cùng với việc ô nhiễm trong quá trình khai thác cùng với việc quan sát xem cá heo khiến cá heo trắng nằm trong danh sách các loài gần bị đe dọa của IUCN. Vì vậy, một số nơi như ở Hồng Kông khi tổ chức các chuyến du lịch du thuyền quan sát cá heo thực hiện các nguyên tắc ứng xử khi xem cá heo như quan sát từ một khoảng cách, không ném các thức ăn và các chất độc hại xuống cho cá heo, Tàu thuyền di chuyển với tốc độ chậm (không quá 10 hải lý một giờ), song song với việc di chuyển của cá heo^[3].

Cá heo trắng Trung Quốc được liệt kê trong Phụ lục II^[4] của Công ước về bảo tồn các loài động vật hoang dã di cư (CMS) Chúng cũng được bảo tồn theo biên bản ghi nhớ về Bảo tồn động vật biển có vú và môi trường sống của chúng tại các đảo thuộc Thái Bình Dương.

Tham khảo

Liên kết ngoài

• The Agriculture, Fishies and Conservation Department
• Hong Kong Dolphinwatch
• Hong Kong Dolphin Conservation Society
• Convention on Migratory Species page on the Indo-Pacific humpback dolphin
• Official webpage of the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region

本文介绍的是哺乳類動物。

• 關於太平洋颱風季的熱帶氣旋，請見「颱風白海豚」。
• 關於淡水鯨類白鱀豚科動物，請見「白鱀豚」。

中華白海豚（學名：Sousa chinensis），又稱太平洋駝背豚、印度太平洋駝背豚^[2]，臺灣俗稱為媽祖魚^[3][4][5]，屬鯨目海豚科，身長由一米到三米不等。主要生活在熱帶及溫帶沿岸水域，例如澳洲中部及北部、華南、印尼等西太平洋水域，也有在河流出現及鹹淡水及沼澤一帶，例如長江、閩江、九龍江、珠江口、漢江和珠江等，分布極之廣泛。西方文獻有關中華白海豚的最早紀錄是在1637年由探險家彼得文地（Peter Mundy）在珠江口發現的紀錄，而中國的最早紀錄是在唐朝。名為白海豚，剛出生的中華白海豚是呈白色，年輕的會呈灰色，至於成年的則會呈粉紅色。

中華白海豚是香港的吉祥物之一。2007年11月15日世界自然基金會香港分會公佈「我最喜愛海洋10寶」公眾網上投票結果，此網上投票為期4個月選出最受歡迎十種本地海洋生物。中華白海豚得3679票榮獲「我最喜愛海洋10寶」第一位^[6][7][8]。

名称及亞種

“中华白海豚”又稱為“太平洋駝背豚”，清朝初期，廣東珠江口一帶稱牠為盧亭，也有漁民稱之為白忌和海豬，其他俗名尚有粉紅海豚、白鯃等。

2015年王愈超（John Wang）等人在《Zoological Studies》發表研究，认为中華白海豚可以分為“中華白海豚”（Sousa chinensis chinensis）與“臺灣白海豚”（Sousa chinensis taiwanensis）兩個亞種，兩者的斑點圖樣幾乎完全不同，兩者在地理區隔與動物行為上也不同。^[9][10][11]

生活習慣

很多的海豚或是鯨魚都住在深水處；但中華白海豚則喜歡住在淺水地如澳門沿海一帶。但根據Saayman&Taylor的研究指出中華白海豚會在不同的地方活動。

一般生活地方多是淺水處，牠們的休息或是遊玩都會集結在近沙灘的海域，在捕獵的時候，牠們會在淺水及多岩石的水域一帶出現。

出現的時間

一般來說中華白海豚的生活是要配合潮水和日照的時間，牠們會在潮漲的時候出外捕食；例如到淺水或多岩石處，便可以在黎明或黃昏時看白海豚，因為那段時間牠們是最活躍的。

分布地區

其近親印度太平洋駝背豚又稱灰白海豚（Sousa plumbea已知的分佈地區自西向東包括開普省福爾斯灣（18°30'E），北沿非洲東部，包括馬達加斯加海岸，印度洋海岸線以至南非，紅海北至蘇伊士灣，阿拉伯海，和波斯灣，往東沿亞洲南部海岸到孟加拉灣西部。它從海洋可以上溯恒河250公里，或經過人工的蘇伊士運河進入地中海。

中華白海豚只分布於太平洋的部分沿岸水域，中華白海豚從孟加拉灣東部到中國南部，包括臺灣海岸，從東京灣到江蘇，進入珠江下游，九龍江和閩江，沿長江可到達武漢，泰國灣，馬六甲海峽，婆羅洲西北海岸(從砂拉越的士馬丹到沙巴的山打根)。^[12]

臺灣

在臺灣海峽西部，苗栗後龍溪/龍鳳漁港、臺灣、彰化、雲林、嘉義、臺南曾文溪/將軍漁港等臺灣中西部離岸三至五公里的水域有一群數量不到一百隻的白海豚，濁水溪口等處的泥灘地海域是其迴游覓食的棲地。一隻白海豚為了覓食，活動範圍可以長達一百多公里。白海豚被臺灣漁民稱為「媽祖魚」，因為牠們一年四季住在中部沿海，但只要一到農曆3月媽祖生日、東北季風減弱後，能見度就大幅提升，好像來為媽祖祝壽。也有傳說是曾經有漁船遇難，在白海豚引領下安全回航。^[3][4][13]這些活動於東臺灣海峽的白海豚因背鰭斑點比身體多等特徵之明顯區分而被鑑定為一有別於中國大陸沿海白海豚之獨立族群，王愈超博士所帶領的福爾摩莎鯨保育研究小組利用體色色斑證明了東臺灣海峽的白海豚是長期生活在臺灣西岸水深30公尺之內的小型鯨類。^[14]生態學會專案秘書甘宸宜表示臺灣的白海豚與其他地區族群沒有交集，可能較像一個亞種。^[15]

香港

中華白海豚主要出沒於屯門及大嶼山對出的一帶水域，包括沙洲、龍鼓洲、望后石、大角咀、大小磨刀、赤鱲角東北面及大嶼山西面的大澳、雞翼角及分流等水域。

威脅

中華白海豚面對填海和水質污染和大量捕捉造成生存範圍的縮窄問題，繁忙的海上交通亦造成船隻撞擊。此外，中華白海豚亦可能遭漁民誤捕，但除馬達加斯加外，基本上並沒有以中華白海豚為目標的獵殺活動。中華白海豚很少用作人工飼養，全球只有中國大陸廣西的南寧動物園、泰國和新加坡的水族館飼養中華白海豚，例如新加坡海底世界便飼養了從泰國暹羅灣捕捉的中華白海豚。2005年海洋公園曾承認考慮增購中華白海豚，引起國際保育組織的關注。

目前人類所知有關中華白海豚的資料不多，珠江口和南非的中華白海豚是少數曾進行較詳盡的研究及調查的種群。中華白海豚亦列入《瀕危野生動植物種國際貿易公約》附錄一，完全禁止有關的國際貿易。

臺灣

自2002年才由福爾摩沙鯨保育研究小組與香港鯨豚研究計劃在台灣西岸進行的海上調查正式紀錄，在此以前，台灣只有零星的白海豚擱淺記錄。台灣西岸海域的族群在2008年被列入「極度危險」^[16]，已被聯合國鯨豚專家列為野生動物紅皮書最高保育等級的極危等級（CR，Critically Endangered），僅次於「絕種」。2010年台灣的白海豚數量估計只剩不到一百隻，在中華民國政府興建八輕計畫之下，處境堪憂^{[3][17][18][15]}。學術團隊指雲林六輕附近海域水質酸化、船隻噪音等問題，都會危及白海豚生存。^[13]中央研究院生物多樣性研究中心、台灣蠻野心足生態協會和台灣媽祖魚保育聯盟舉辦研討會邀請國際鯨豚保育學者發表相關研究，會議結論為台灣白海豚面臨棲地消失、水下噪音、淡水流量減少、污染及漁業誤捕等五大威脅。學者呼籲政府將白海豚棲息地劃定為海洋保育區，制訂強制禁止在白海豚棲地內使用三層網、刺網和拖網等漁業規範，讓白海豚和漁業真正永續生存。^[19]

香港

中華白海豚受香港法例第170章《野生動物保護條例》及第187章《動植物（瀕危動植物）條例》保護，沙洲及龍鼓洲海岸公園亦是為保護中華白海豚而設。漁農自然護理署自1995年開始長期研究香港水域內的中華白海豚。1995年9月至1998年3月期間，漁護署在大嶼山北面錄得88至145條白海豚，而近年該署數據顯示從香港水域內中華白海豚從2011年的80多條減至2017年只餘47條，為14年以來最低數字^[20]。世界自然基金會香港分會認為北大嶼山水域近年不斷進行發展工程，如機場三跑道計劃和港珠澳大橋香港口岸都需要在白海豚棲息處進行大規模填海，加上海上交通日益繁忙，這些因素都嚴重威脅中華白海豚的生存空間^[21]。該會批評政府「先發展後保育」政策無幫助，例如港珠澳大橋香港口岸完工後白海豚數目沒有如預期般回復舊態，認為唯有設立和擴大海岸公園範圍，才能保護碩果僅存的中華白海豚^[22]。

俗語

廣東有俗話稱為“烏忌白忌”，意味是一個壞預兆。此稱呼起源于廣東漁民，因為他們声称中華白海豚等海豚吃他們漁網中的魚獲。然而，一般漢語多寫作為“烏鱀白鱀”，鱀在古時的漢語中解作海豚，烏指黑色的江豚，白則指白色的白鱀豚。這兩個種類曾經經常被指破壞的魚獲。而在廣東， 烏指中華白海豚的幼海豚; 白則指成年中華白海豚，出現此不同意思可能是因白鱀豚不存在於香港和廣東。現今漢語中，海豚已不称為鱀，而海豚逐字地解意为海豬，因豚在中文解作豬。

重大事件

• 1637年：中華白海豚在香港近珠江河口首先被冒險家彼得文地（Peter Mundy）發現，這是西方文獻最早有關中華白海豚的紀錄。
• 1980年代末：環保人士開始關注中華白海豚群。
• 1990年初：香港公眾開始關注中華白海豚。這歸因於香港國際機場的興建計劃。這是其中一個世界上最大的單一填海項目——在北大嶼山附近的九平方公里海床進行填海，而當地是其中一個中華白海豚的主要棲所。
• 1993年初：有關香港國際機場興建計劃的環境影響再進行批估。這使香港的環保人士，如世界自然基金會在中華白海豚的保育上引起傳媒的注意，而香港政府隨即開始資助中華白海豚的研究項目。
• 1996年：斐生博士（Thomas Jefferson）開始開展對中華白海豚的研究。
• 1997年：中華白海豚成為香港主權移交的吉祥物。
• 1998年：斐生博士的研究結果出版在「Wildlife Monographs」。同年，香港一些機構開始組織出海觀豚活動。
• 2000年：香港漁農自然護理署開始對香港的中華白海豚進行長期觀察。記錄中珠江河口約有80-140隻中華白海豚。
• 2002年：臺灣發現中華白海豚的確實記錄。這個種群主要分佈在苗栗、彰化及臺中沿岸，現被世界保育聯盟（IUCN）列作極危的種群。
• 2003年：廣西欽州市的三娘灣湧現大量中華白海豚，欽州市因此被稱為「中華白海豚之鄉」，北京大學於次年在欽州成立了欽州灣中華白海豚研究基地。
• 2009年9月25日：大約上午7時，臺灣苗栗縣通霄鎮新埔漁港的沙灘漁民發現有一隻白海豚擱淺，身長260公分，屬成年豚^[23]。
• 2010年：在臺灣，政府擬於彰化縣海岸興建國光石化開發案，預計在濁水溪口海域填海造陸超過四千公頃，亦將台灣白海豚洄游路徑攔腰截斷，馬英九政府在知道這個問題後曾堅持興建，吳敦義也認為臺灣白海豚會自己轉彎，使保育團體發起全民認股購地的環境信託活動，搶救瀕臨絕種、只剩不到一百隻的臺灣白海豚^[4]。2011年4月22日總統馬英九親自宣布不支持國光石化案在彰化縣繼續進行^[24][25]。
• 2017年，中國廣東珠海有人販賣疑似中華白海豚，目前珠海市公安部門與海洋農業和水務局已經介入此事，3名涉事村民被傳喚，殘存骸骨亦送往中山大學展開鑑定。^[26]另據涉事村民表示，該海豚為3月29日上午9時許在南水鎮附近海域發現，發現時已經死亡。^[27]

参考文献

外部連結

• 台灣媽祖魚保育聯盟
• 漁護署海洋護理
• 香港海豚保育學會 (網絡檔案)
• 中華白海豚之旅2004^{[永久失效連結]}
• 台灣白海豚粉絲團

参见

• 白鱀豚
• 江豚

シナウスイロイルカ（支那薄色海豚、学名：Sousa chinensis）はクジラ目ハクジラ亜目マイルカ科ウスイロイルカ属に分類されるイルカである。

ウスイロイルカと合わせて一つの種 Sousa chinensis として、シナウスイロイルカをその亜種 Sousa chinensis chinensis とする場合もある。

分布[編集]

シナウスイロイルカ (Sousa chinensis) の生息域

生息域は、東シナ海、インドネシア、ニューギニア島からオーストラリア北部にかけての浅い海域である。

Riceは、スマトラ島を境界とし、スマトラ島およびそれより東に棲息するものをシナウスイロイルカ (Sousa chinensis) 、スマトラ島より西側に棲息するものをウスイロイルカ (Sousa plumbea) と分類した^[2]が、交雑は不可避であろうと考えられている。そのため、シナウスイロイルカ (Sousa chinensis) とウスイロイルカ (Sousa plumbea) を合わせて一つの種と考える分類法もある。

形態[編集]

シナウスイロイルカ (Sousa chinensis) はウスイロイルカ (Sousa plumbea) に似ている。生息域によりその形態は異なり、また成長とともに変化する。ウスイロイルカ (Sousa plumbea) に比べると背びれが大きく、背中の隆起が小さい。口吻は細長い。

成体の体長は2mから2.8m、体重は150kgから200kgである。生まれた直後の体長は1m程度である。

生まれた直後の体色は全身が黒あるいは濃い灰色であるが、成長するに従って名前の通り薄い色に変化し、成体では全身ピンクあるいはピンクと白色あるいは明るい灰色の斑模様になる。

寿命は約40年である。香港において、およそ33歳であることがわかっているシナウスイロイルカが生息していた。死亡した個体については、歯の断面図の観察によって、およその年齢を調べることが可能であることがわかっている。

行動[編集]

シナウスイロイルカの成体は、通常は20秒から30秒に一度の割合で呼吸を行う。深く潜水する場合には、2分から8分程度の潜水を行うが、平均的には4分以上の潜水を行うことは稀である。未成熟の個体の場合には、呼吸の速度は成体の倍ほどであり、潜水も3分程度が限界である。

集団で行動する社交的なイルカであり、通常は3、4頭ほどの小さな群を成して行動する。雌は約10歳、雄は約13歳で性的に成熟する。 通常、夏の終わりから秋にかけて交尾を行い、妊娠期間は約11ヶ月である。子育ては仔イルカが自分で餌を捕ることが可能になるまで続けられる。成熟した雌は約3年に一度のペースで出産する。

人間との関り[編集]

ドルフィンウォッチ[編集]

香港では本種を「中華白海豚」と呼び、マスコットとして使う例があるほか、野生のシナウスイロイルカを船から観察するドルフィンウォッチングが商業的に行われている。主な海域はランタオ島北部や南東部、索罟群島沖、坪洲沖などである。ドルフィンウォッチングにより、香港の一般の人々がシナウスイロイルカへの関心を持つ機会を増やしたり、利益の一部をFriends of the Earth (HK) へ寄付する業者も存在するため、香港の沿岸環境保護に繋がるという意見がある。一方、ドルフィンウォッチングは、シナウスイロイルカに過剰なストレスを与え、持続的な生存を脅かすものであるという批判もある。

環境汚染、埋め立てなど[編集]

香港近海はシナウスイロイルカにとっては危険な生息域になってきている。主な原因は、密漁、埋め立ての増加、海上交通の発達などである。

シナウスイロイルカはほぼ一定の海域を生息域とし、その生息域から離れることはほとんどないため、工業排水、農業排水、生活排水による香港近海の汚染の影響が深刻になってきている。珠江デルタでは、毎日19万m³の汚水が全く処理されることなく、そのまま海へ排出されている。未処理の汚水や化学物質は海全体の環境を悪化させ、シナウスイロイルカの生息環境も悪化させている。 シナウスイロイルカの死骸からは水銀などの重金属、PCBやDDTなどの塩化有機物、トリブチルスズ (TBT)、合成保存料などが検出されており、食物連鎖の中にこれらの有害な物質が既に組み込まれていることが明らかになっている。

香港国際空港の建設によって、シナウスイロイルカの生息海域が9.5km²減少した。同空港には第三滑走路の建設計画があり、更に影響を与えることが危惧されている。他にも、北大嶼山公路（英語版）、屯門と青山火力発電所（英語版）を繋ぐ香港内河碼頭（River Trade Terminal）、香港ディズニーランドといった開発に伴う大規模な埋め立てが実施あるいは予定されており、シナウスイロイルカの生息域に壊滅的な打撃を与える恐れがある。さらに索罟群島においてはLNGターミナルの建設の動きもあり、潜在的な脅威となっている。

ランタオ島北部の海域における魚の乱獲や多数の船舶の航行もシナウスイロイルカへの脅威となり得る。香港政府による商業的な漁業に対する規制はほとんどないため、魚の乱獲は混獲によるシナウスイロイルカの被害を増大させる可能性がある。1日あたり平均70艘の船舶が香港海峡を通過する。多数の船舶が発生するエンジンの雑音は、シナウスイロイルカが行う反響定位の妨げとなって悪影響を与える恐れもある。

絶滅危惧種としての位置づけ[編集]

• NEAR THREATENED (IUCN Red List Ver. 3.1 (2001))^[1]
  
• 中国国家一級重点保護野生動物

年表[編集]

1637年

冒険家ピーター・マンディー (Peter Mundy) により、香港では最初のシナウスイロイルカが珠江の近くで発見された。河口付近の水には塩分が含まれており、シナウスイロイルカの生息域となっている。

1980年代後半

環境保護主義者がシナウスイロイルカの生息数に注目し始めた。

1990年の初め

香港の一般市民がシナウスイロイルカに注目し始めた。これは香港国際空港の建設によるものである。空港建設のため、ランタオ島北部の9.5km²の海域が埋め立てられた。これは単一の埋め立て工事としては世界有数の規模であった。

1993年の初め

香港国際空港建設の環境への影響の再調査が実施された。香港の世界自然保護基金などの自然保護団体の活動が発端であるが、香港のマスメディアがこの問題に注目するきっかけにもなった。これからまもなく香港政府がシナウスイロイルカの調査に取りかかることとなる。

1993年の終わり

香港農業水産管理局（漁農自然護理署、Agriculture, Fisheries and Conservation Department）設立。

1996年

トーマス・ジェファーソン (Thomas Jefferson) によるシナウスイロイルカの調査が始まる。

1997年

シナウスイロイルカが香港の中華人民共和国への返還式典の公式マスコットになる。

1998年

トーマス・ジェファーソンによる研究成果が "Wildlife Monographs" で発表される。

香港ドルフィンウォッチ (Hong Kong Dolphinwatch) が設立される。一般市民にドルフィンウォッチを経験させ、シナウスイロイルカへの興味を持ってもらうことを目的とする団体である。

2000年

香港農業水産管理局によるシナウスイロイルカの長期間の観察が始まる。

珠江における生息数が80～140頭程度にまで減少。

脚注[編集]

関連項目[編集]

• ヨウスコウカワイルカ - 長江（揚子江）に固有で、ほぼ絶滅状態であると考えられているカワイルカ。シナウスイロイルカとは全く別の種である。

外部リンク[編集]

• Sousa chinensis CMS (Conservation on Migratory Species)

인도태평양혹등고래(Sousa chinensis)는 참돌고래과 혹등돌고래속에 속하는 돌고래의 일종이다.^[2]

각주