حوت حقيقي جنوبي

Die Suidelike noorkapper (Eubalaena australis) is 'n walvis wat aan die hele Suid-Afrikaanse kus voorkom. Die walvis word uitgeken aan die wit, vratagtige groeisels op die kop. Die soogdier het groot spaanvormige borsvinne maar geen rugvin nie.

Hulle kom in die oop see voor; in die suidelike halfrond se somer kom hulle by Antartika voor, terwyl hulle van Julie na die Suid-Afrikaanse kus beweeg om te paar. Dan is die walvisse, wat selfs in kleiner baaie kom baljaar, gewilde trekpleisters vir besoekers aan Hermanus, Kaap Agulhas, Witsand, Stilbaai, Gouritsmond, Vleesbaai, Mosselbaai, Knysna en die tuinroete, Algoabaai en selfs tot by Mosambiek.

Die walvis se Engelse naam is die Southern Right Whale bedoelende dat dit die 'regte' walvis was om dood te maak destyds deur die walvisjagters. Die walvis mag egter nie meer gejag word nie.

Fotogalery

• 'n Suidelike noorkapper in Argentinië.

• Stertvin van 'n noorkapper.

• 'n Noorkapper spring bo die water uit.

• 'n Noorkapper swem na 'n boot vol toeriste op 'n besigtigingstoer.

• Bronsbeeld van 'n noorkapper in Tasmanië.

Sien ook

Wikispecies het meer inligting oor: Eubalaena australis

• Lys van Suider-Afrikaanse soogdiere
• Lys van Suider-Afrikaanse soogdiere volgens wetenskaplike name
• Suider-Afrikaanse soogdiere en hul ordes

Nota: Walvisse is soogdiere en nie visse nie.

Bron

• Gids tot die Kusgebiede van Suid-Afrika. Jacana Media. 2007. ISBN 978-1-77009-215-0

Verwysings

Hierdie artikel is ’n saadjie. Voel vry om Wikipedia te help deur dit uit te brei.

Cənub balinası (Cənub hamar balinası) (lat. Eubalaena australis) - Əsl balinalar (Balaenidae). O digər iki növ olan Eubalaena — Yapon balinası və Şimal hamar balina ilə eyni olması fikiri dolaşırdı.

Görünüşü

Ölçülərinin insana olan nisbəti

Balinalar açıq-qəhvəyi və göyütül-qara rəngdə olurlar. Ağ ləkələrə rast gəlinir. Bəzən ağ erkək balalar doğulur (albinos sayılmır). Cənub balinaları 18 metr uzunluğa, 80 ton çəkiyə malik olur. Bir qayda olaraq dişilər erkəklərə nisbətən iri olur. Bütün cənub hamar balinalarında olduğu kimi Cənub balinaları iri kəlləyə mlikdirlər (ümumi uzunluğun ⅓ təşkil edir).

Yayılması

Cənub balinaları əsasən subarktik və mülayim enliklərdə (Cənub okeanı), bir qayda olaraq 30° və 50°cənub enliklərində yaşayır. Ona əsasən Cənubi Amerika, Afrikanın cənubu, Avstraliya və Yeni Zelandiya və kiçik suantarktik adaların sahillərində üzür. Cütləşmə dövrü isti sulara üz tutur. Yayda isə daha cənub sulara qida dalınca üz tuturlar.

Çoxalması

Ana balina uzun sürən hamiləlikdən sonra qış və ya yazda bala doğulur. Onun uzunluğu 5-6 metr, çəkisi 1000 - 1500 kq təşkil edir. Dişilər əsasən dəniz buxtalarında balalayır. Körpə tez böyüyür (günə 3 sm). Balina balasını 6 ay südlə bəsləyir. Cənub balinaları canlılar arasında ən böyük cinsiyyət üzvünə malikdir. Cinsiyyət üzvünün çəkisi ümumi çəkisinin 2% bərabərdir (bir tona yaxın).

Təhlükə

Uzun zaman Şimalatlantik balinaları kimi Cənub balinalarıda kütləvi şəkildə ovlanılırdı. Onların hər şeyə maraq göstərməsi, onları ovçular üçün asan şikara çevirirdi. 1937-ci ildən tətbiq edilən qadağa sayəsində onların sayı bərpa olur. Hal-hazırada dünyada 7000 baş Cənub balinası vardır.

Cənub balinaların görünmə yeri

Cənub balinasının skleti

Cənub balinalaın ən çox rast gəlinən ərazisi Valdes yarımadası yaxınlığıdır. Onları katerdən iyun-dekabr ayları ərzində daha yaxşı müşahidə edilir. İyun-noyabr aylarında isə Qərbi Avstraliyada Olbani şəhəri sahilində görünürlər.

Ədəbiyyat

• R. R. Reeves, B. S. Stewart, P. J. Clapham, J. A. Powell: See Mammals of the World - a complete Guide to Whales, Dolphins, Seals, Sea Lions and Sea Cows. A&C Black, 2002, ISBN 0-7136-6334-0
• M. Würtz, N. Repetto: Underwater world: Dolphins and Whales. White Star Guides, 2003, ISBN 88-8095-943-3

Eubalaena australis és una balena, una de les tres espècies de balenes franques del gènere Eubalaena. Aproximadament 12.000 E. australis viuen als mars de la part meridional de l'hemisferi sud.

Com altres espècies de balenes tenen unes callositats en el seu cos característiques causades per crustacis ectoparàsits del gènere Cyamidae

Referències

Tento článek není dostatečně ozdrojován a může tedy obsahovat informace, které je třeba ověřit.
Jste-li s popisovaným předmětem seznámeni, pomozte doložit uvedená tvrzení doplněním referencí na věrohodné zdroje.

Velryba jižní (Eubalaena australis) je kytovec dorůstající 15 metrů a vážící okolo 50 tun.^[2] Nemá hřbetní ploutev. Po smrti vydrží jeho tělo určitou dobu nad hladinou. Jeho hlava je porostlá parazitujícími korýši podle kterých jsou vědci schopni rozlišit jednotlivé jedince.

Reference

1. ↑ Červený seznam IUCN 2018.1. 5. července 2018. Dostupné online. [cit. 2018-08-10]
2. ↑ Branch, G.M., Branch, M.L, Griffiths, C.L. and Beckley, L.E. 2010. Two Oceans: a guide to the marine life of southern Africa ISBN 978-1-77007-772-0

Externí odkazy

• Obrázky, zvuky či videa k tématu velryba jižní ve Wikimedia Commons

Den sydlige rethval (Eubalaena australis) er en art i rethvalsfamilien under bardehvalerne. Dyret lever især ved kysterne omkring Argentina, Sydafrika og Australien. Den bliver op til 18 m lang og vejer 80 t. Bestanden er ca. 3-5.000 individer.

Verbreitungsgebiet

Der Südkaper (Eubalaena australis) ist eine Walart aus der Familie der Glattwale (Balaenidae). Er ähnelt den beiden anderen Arten der Gattung Eubalaena, dem Atlantischen und Pazifischen Nordkaper und wurde früher sogar mit diesen als eine Art gezählt. Eine andere Bezeichnung im Deutschen ist Südlicher Glattwal.

Verbreitung

Südkaper leben zirkumpolar in den subpolaren und gemäßigten Meeren der Südhalbkugel, ungefähr zwischen dem 30. und 50. südlichen Breitengrad. Regelmäßige Beobachtungen gibt es von den Küsten des südlichen Südamerika, Südafrikas, Australiens, Neuseelands und kleineren Inseln der Subantarktis. Im Winter ziehen sie zur Fortpflanzung in wärmere Meeresregionen, im Sommer wandern sie zur Nahrungssuche in den Süden.

Beschreibung

Kopf eines Südkapers mit typischen hellen Hautwucherungen

Fluke eines Südkapers beim sogenannten Segeln

Die Kolorierung dieser Walart ist hellbraun bis blauschwarz, wobei weiße Flecken vorkommen können, gelegentlich kommen weiße männliche Kälber vor, bei denen es sich nicht um Albinos handelt. Im Kopfbereich, vor allem am Unterkiefer, um das Blasloch und über dem Auge haben sie Hautwucherungen, die bei jedem Tier individuell gestaltet sind und zur Unterscheidung einzelner Individuen dienen können. Sie erreichen eine Länge von bis zu 18 m und ein Gewicht von bis zu 80 t, wobei Weibchen etwas größer als Männchen werden. Wie alle Glattwale sind sie durch den großen Kopf (der rund ein Drittel der Körperlänge ausmacht) und durch das Fehlen der Finne gekennzeichnet.

Lebensweise

Südkaper halten sich eher in der Nähe von Inseln oder großen Landmassen auf. Trotz ihrer Größe gelten sie als aktive Tiere. Wie alle Bartenwale sieben sie die Nahrung mit den Barten und ernähren sich hauptsächlich von Ruderfußkrebsen und Leuchtkrebsen.

Fortpflanzung

Nach rund einjähriger Tragzeit bringt das Weibchen im Winter oder Frühling (Juni bis November) ein rund fünf bis sechs Meter langes, 1000 bis 1500 kg schweres Kalb zur Welt. Zum Schutz vor Räubern zieht sich das Weibchen zur Geburt in Meeresbuchten zurück. Das Kalb wächst sehr schnell, bis zu drei Zentimeter pro Tag, und wird rund vier bis sechs Monate lang gesäugt. In der Tierwelt hat der männliche Südkaper die größten Hoden, sie machen mit je 500 kg 2 % des Körpergewichts aus. Bei einem Samenerguss werden bis zu 20 Liter Sperma freigesetzt.

Bedrohung

Wie die Nordkaper wurden die Südkaper intensiv bejagt, ihre Geselligkeit und ihre Neugier machten sie zu einer leichten Beute für Walfänger. Seitdem die Art 1935 geschützt wurde, beginnen sich die Bestände wieder zu erholen, in etwas größerem Ausmaß als bei ihren nördlichen Verwandten. Die Gesamtpopulation der Art ist im Steigen begriffen und wird auf etwa 7000 Exemplare geschätzt.

Vor der argentinischen Halbinsel Valdés haben Dominikanermöwen in den letzten 30 Jahren begonnen, sich auch von den Südkapern zu ernähren. Sie landen auf den Walen und picken Parasiten, lose Stückchen Haut, aber auch gesunde Fleischstücke von bzw. aus den Walen. Die Möwen sind für die Wale, die in der Region ihren Nachwuchs großziehen, zu einer Plage geworden. Die Wale tauchen viel häufiger als gewöhnlich, um sich vor den Möwen in Sicherheit zu bringen, und benötigen dadurch viel Energie; gerade die Walmütter würden für die Aufzucht ihrer Kälber viel Ruhe benötigen. Zudem konzentrieren sich die Möwen auf die Walmütter und ihre Kälber, die viel häufiger an die Wasseroberfläche kommen müssen als die anderen Wale.^[1][2][3]

Beobachtungsmöglichkeit

Südkaper vor Valdés

Fluke eines Südkapers beim Abtauchen

Gute Walbeobachtungsmöglichkeiten bestehen vor der Halbinsel Valdés in Argentinien sowie an der brasilianischen Südküste z. B. in Laguna/Santa Catarina. Zwischen Juni und Dezember kann man die Wale vom Ufer und besser noch vom Boot aus sichten. Die Wale mit ihren Kälbern kommen in großer Zahl auf wenige Meter an das Boot heran, auch die Beobachtung von springenden Walen (siehe Bild) ist keine Seltenheit.

Auch die Walker-Bucht mit den Orten Hermanus und vor allem De Kelders in Südafrika eignet sich hervorragend für die Beobachtung dieser Wale in der Zeit von Juni bis November. Die Wale kommen mit ihren Jungen auf wenige Meter an das Ufer heran, deshalb ist eine Beobachtung vom Boot nicht notwendig. Die Bucht ist von der UNESCO mit als bester Walbeobachtungsort bestätigt worden. In West-Australien, am Strand der Stadt Albany, kann man diese Wale spielen und springen sehen. Mütter mit Kälbern und junge Wale halten sich gern in den Buchten auf.

Literatur

• M. Carwardine: Wale und Delfine. Delius Klasing, 2008, ISBN 978-3768824736 (hochwertiger Führer)
• Ralf Kiefner: Wale und Delfine weltweit. Jahr Top Special Verlag, 2002 (Führer der Zeitschrift tauchen, sehr detailliert)
• J. Niethammer, F. Krapp (Hrsg.): Handbuch der Säugetiere Europas. Band 6: Meeressäuger, Tel 1A: Wale und Delphine 1. AULA-Verlag, Wiesbaden 1994 (sehr detailliertes Fachbuch)
• R. R. Reeves, B. S. Stewart, P. J. Clapham, J. A. Powell: Sea Mammals of the World. A Complete Guide to Whales, Dolphins, Seals, Sea Lions and Sea Cows. Black, London 2002, ISBN 0-7136-6334-0 (Führer mit zahlreichen Bildern).
• M. Würtz, N. Repetto: Underwater world: Dolphins and Whales. White Star Guides, 2003, ISBN 88-8095-943-3 (Bestimmungsbuch)

Einzelnachweise

1. ↑ V.J. Rowntree, P. MacGuiness, K. Marshall, R. Payne, J. Seger, M. Sironi: "Increased harassment of Right Whales (Eubalaena australis) by Kelp Gulls (Larus dominicanus) at Península Valdés, Argentina". Marine Mammal Science. 1998. 14(1): 99–115, doi:10.1111/j.1748-7692.1998.tb00693.x.
2. ↑ sueddeutsche.de, 26. Juni 2009: Vögel auf Walfang (Memento des Originals vom 29. Juni 2009 im Internet Archive) Info: Der Archivlink wurde automatisch eingesetzt und noch nicht geprüft. Bitte prüfe Original- und Archivlink gemäß Anleitung und entferne dann diesen Hinweis.@1@2Vorlage:Webachiv/IABot/www.sueddeutsche.de
3. ↑ BBC News, 24. Juni 2009: Gulls' vicious attacks on whales (Fotoserie)

Lâm Chiàⁿ Hái-ang, sio̍k-tī Balaenidae kho ê ū keng-chhiu ê hái-ang.

Chham-khó chu-liāu

Cetacean Specialist Group (1996). Eubalaena australis. 2006 nî IUCN Siū Ui-hia̍p Bu̍t-chéng Âng Miâ-toaⁿ. IUCN 2006. 2006/06/25 chih-chiap.

The southern right whale (Eubalaena australis) is a baleen whale, one of three species classified as right whales belonging to the genus Eubalaena. Southern right whales inhabit oceans south of the Equator, between the latitudes of 20° and 60° south.^[5] In 2009 the global population was estimated to be approximately 13,600.^[6]

Taxonomy

Right whales were first classified in the genus Balaena in 1758 by Carl Linnaeus, who at the time considered all right whales (including the bowhead) to be a single species. In the 19th and 20th centuries the family Balaenidae was the subject of great taxonometric debate. Authorities have repeatedly recategorised the three populations of right whale plus the bowhead whale, as one, two, three or four species, either in a single genus or in two separate genera. In the early whaling days, they were all thought to be a single species, Balaena mysticetus.^[7]

The southern right whale was initially described as Balaena australis by Desmoulins in 1822. Eventually, it was recognised that bowheads and right whales were different, and John Edward Gray proposed the genus Eubalaena for the right whale in 1864. Later, morphological factors such as differences in the skull shape of northern and southern right whales indicated at least two species of right whale—one in the Northern Hemisphere, the other in the Southern Ocean.^[7] As recently as 1998, Rice, in his comprehensive and otherwise authoritative classification, Marine mammals of the world: systematics and distribution, listed just two species: Balaena glacialis (all of the right whales) and Balaena mysticetus (the bowheads).^[8]

In 2000, Rosenbaum et al. disagreed, based on data from their genetic study of DNA samples from each of the whale populations. Genetic evidence now shows that the northern and southern populations of right whale have not interbred for between 3 million and 12 million years, confirming the southern right whale as a distinct species. The northern Pacific and Atlantic populations are also distinct, with the North Pacific right whale being more closely related to the southern right whale than to the North Atlantic right whale.^[9] Genetic differences between E. japonica (North Pacific) and E. australis (South Pacific) are much smaller than other baleen whales represent among different ocean basins.^[10]

It is believed that the right whale populations first split because of the joining of North and South America. The rising temperatures at the equator then created a second split, into the northern and southern groups, preventing them from interbreeding.^[11]

In 2002, the Scientific Committee of the International Whaling Commission (IWC) accepted Rosenbaum's findings, and recommended that the Eubalaena nomenclature be retained for this genus.^[12]

The cladogram is a tool for visualising and comparing the evolutionary relationships between taxa. The point where a node branches off is analogous to an evolutionary branching – the diagram can be read left-to-right, much like a timeline. The following cladogram of the family Balaenidae serves to illustrate the current scientific consensus as to the relationships between the southern right whale and the other members of its family.

Other junior synonyms for E. australis have included B. antarctica (Lesson, 1828), B. antipodarum (Gray, 1843), Hunterus temminckii (Gray, 1864), and E. glacialis australis (Tomilin, 1962) (see side panel for more synonyms).^[1][4]

Description

Two distinctive colouration patterns

Like other right whales, the southern right whale is readily distinguished from others by the callosities on its head, a broad back without a dorsal fin, and a long arching mouth that begins above the eye. Its skin is very dark grey or black, occasionally with some white patches on the belly. The right whale's callosities appear white due to large colonies of cyamids (whale lice). It is almost indistinguishable from the closely related North Atlantic and the North Pacific right whales, displaying only minor skull differences. It may have fewer callosities on its head than North Atlantic and more on its lower lips than the two northern species.^[7][13] The biological functions of callosities are unclear, although protection against predators has been put forward as the primal role.

An adult female is 15 m (49 ft)^[14] and can weigh up to 47 tonnes (46 long tons; 52 short tons),^[14] with the larger records of 17.5–18 m (57–59 ft)^[15][16] in length and 80 tonnes (79 long tons; 88 short tons)^[17] or up to 90 tonnes (89 long tons; 99 short tons) in weight,^[18] making them slightly smaller than other right whales in the Northern Hemisphere.^[19] The testicles of right whales are likely to be the largest of any animal, each weighing around 500 kg (1,100 lb). This suggests that sperm competition is important in the mating process.^[20]

The proportion and numbers of molten-coloured individuals are notable in this species compared with the other species in the Northern Hemisphere. Some whales remain white even after growing up.^[21]

Life span is not clear although whales seem to reach over 100 years old.^[22]

Behaviour

Surfacing behaviour

"Sailing"

Like other right whales, they are rather active on the water surface and curious towards human vessels. Southern rights appear to be more active and tend to interact with humans more than the other two northern species. One behaviour unique to the southern right whale, known as tail sailing, is that of using their elevated flukes to catch the wind, remaining in the same position for a considerable amount of time. It appears to be a form of play and is most commonly seen off the coast of Argentina and South Africa.^[13] Some other species such as humpback whales are also known to display. Right whales are often seen interacting with other cetaceans, especially humpback whales^[23] and dolphins. There have been records of southern rights and humpbacks thought to be involved in mating activities off Mozambique,^[24] and along Bahia, Brazil.^[25]

On several occasions, calving mothers have been recorded to nurse non-offspring calves along with their own calves.^[26] Additionally, a female was seen to accompany a lone humpback whale calf although the actual relationship of this pair is unclear.^[27]

Reproduction

Southern right whales display strong maternal fidelity to their calving grounds.^[28][29] Calving females are known to return to calving grounds at 3-year intervals.^[30] The most commonly observed calving interval is 3 years, but intervals can range from 2 to 21 years.^[31][32] Calving takes place between June and November^[33] in calving grounds between 20 and 30° S.^[34]

In Australia, southern right whales have shown a preference for calving grounds along coastlines with high wave energy, such as the Head of the Bight. Here, the sound of breaking waves may mask the sound of the whales' presence, and so protect infants and calving cows from predators such as killer whales. Deep waters alongside shallower calving grounds may serve as training grounds for calves to build up their stamina ahead of migration.^[35]

Females give birth to their first calf when they are between eight and ten years old.^[36] A single calf is born after a gestation period of one year, about 1 short ton (0.91 t) in weight and 4–6 m (13–20 ft) in length.^[37] The calf usually remains with its mother during the first year of its life, during which time it will double in length.^[5]

This species has been recognized to nurse unrelated orphans on occasions.^[38]

Feeding

Like right whales in other oceans, southern right whales feed almost exclusively on zooplankton, particularly krill.^[5] They feed just beneath the water's surface, holding their mouths partly open and skimming water continuously while swimming. They strain the water out through their long baleen plates to capture their prey. A southern right whale's baleen can measure up to 2.8 m (9 ft 2 in) long, and is made up of 220-260 baleen plates.^[33]

Population and distribution

The global population of southern right whales was estimated at 13,611 in 2009.^[6] An estimate published by National Geographic in October 2008 put the southern whale population at 10,000. An estimate of 7,000 followed a March 1998 IWC workshop. Researchers used data about adult female populations from three surveys (one in each of Argentina, South Africa and Australia, collected during the 1990s) and extrapolated to include unsurveyed areas, number of males and calves using available male:female and adult:calf ratios to give an estimated 1999 figure of 7,500 animals.^[39] Recovery of the overall population size of the species is predicted to be at less than 50% of its pre-whaling state by 2100 due to heavier impacts of whaling and slower recovery rates.^[40] Since hunting ceased, the population is estimated to have grown by 7% a year.

The southern right whale spends summer in the far Southern Ocean feeding, probably close to Antarctica. If the opportunity arises, feeding can occur even in temperate waters such as along Buenos Aires.^[41][42] It migrates north in winter for breeding and can be seen by the coasts of Argentina, Australia, Brazil, Chile, Namibia, Mozambique, Peru, Tristan de Cunha, Uruguay, Madagascar, New Zealand and South Africa; whales have also been known to winter in sub-Antarctic regions.^[43][44] It appears that the South American, South African and Australasian groups intermix very little if at all, because maternal fidelity to feeding and calving habitats is very strong. The mother also passes these choices to her calves.^[45]

Right whales do not normally cross the warm equatorial waters to connect with the other species and (inter)breed: their thick layers of insulating blubber make it difficult for them to dissipate their internal body heat in tropical waters. Based on historical records and unconfirmed sightings in modern periods, E. australis transits may sometimes occur through equatorial waters.^[46]

Whaling records for the hemisphere include a whaling ground in the central northern Indian Ocean^[47] and recent sightings among near-equatorial regions. If the sighting off Kiribati was truly of E. australis, this species may have crossed the Equator on irregular occasions and their original distributions might have been much broader and more northerly distributed than is currently believed.^[46][48] A stranding of a 21.3 m (71 feet) right whale at Gajana, northwestern India in November 1944 was reported, but the true identity of this animal is unclear.^[49][50]

Aside from impacts on whales and environments caused by mankind, their distributions and residences could be largely affected by presences of natural predators or enemies,^[43] and similar trends are also probable for other subspecies.^[51]

Many locations throughout the Southern Hemisphere were named after current or former presences of southern rights, including Walvis Bay, Punta Ballena, Right Whale Bay, Otago Harbour, Whangarei Harbour, Foveaux Strait,^[52] South Taranaki Bight, Moutohora Island and Wineglass Bay.

Africa

Breaching in the De Hoop Nature Reserve

South Africa

Hermanus in South Africa has become known as a centre for whale watching. During the Southern Hemisphere winter months (June – October) the southern right whales migrate to the coastal waters of South Africa, with more than 100 whales known to visit the Hermanus area. Whilst in the area, the whales can be seen with their young as they come to Walker Bay to calve and mate. Many behaviours such as breaching, sailing, lobtailing, or spyhopping can be witnessed. In False Bay whales can be seen from the shore from July to October while both Plettenberg Bay and Algoa Bay are also home to the southern right whales from July to December. They can be viewed from land as well as by boat with licensed operators conducting ocean safaris throughout the year.

Mother and calf in Hermanus

Recent increases in numbers of whales visiting the north-eastern part of South Africa, the so-called Dolphin Coast such as around Ballito^[53] and off Umdloti Beach,^[54] indicates the whales' normal ranges are expanding and that re-colonising historical habitats will likely continue as more whales migrate further north.

Western Africa

In Namibia, the majority of confirmed whales are restricted to the south of Luderitz, on the southwestern coast. Only a handful of animals venture further north to historical breeding grounds such as at Walvis Bay, but their numbers are slowly increasing. Until illegal hunting ceased, whales were rare along Namibian shores, with no sighting recorded north of Orange River until 1971.^[55] Calving activities were first confirmed as recently as the 1980s.^[56]

Historical records suggest that this whale's regular range could have once reached further northwards up the coasts of Cape Fria (northern Namibia)^[57] and Angola as far as Baia dos Tigres (Tiger Bay).^[58][57]

Whaling is known to have been carried out off the coast of Gabon,^[46] for example at Cape Lopez, and there have been a few confirmed and unconfirmed sightings including one by Jim Darling, a renowned whale researcher.^[59][60][61]

Eastern Africa

Rare appearance along Madagascar at Île Sainte-Marie

Southern right whales have been spotted in very small numbers off Mozambique^[62] and Madagascar.^[63] Whales were historically seen in large numbers at various locations such as off the coast of Durban, in Delagoa/Maputo Bay,^[64] Inhaca Island, Ponta do Ouro, and around the Bazaruto Archipelago.^[24] The first sighting off Mozambique since the end of whaling was in 1997.^[65] In recent years, more whales seem to migrate further north to calve, such as at Île Sainte-Marie,^{[66][67][68][69]} Antongil Bay,^[60] Fort Dauphin^[70] Toliara,^[71] Anakao, Andavadoaka, and Antsiranana Bay,^[72][73][74] at Madagascar's northern tip. Infrequent sightings have been confirmed off the island of Mayotte.^[75] Whales were historically taken off the coast of Tanzania, and may still be present occasionally around Zanzibar.^[76]

Mid–South Atlantic

Due to illegal whaling by the USSR, the recovery of many stocks including the population off Tristan da Cunha^[77] and adjacent areas such as Gough Island has been severely hindered, resulting in relatively few numbers of visiting animals.

Based on catch records and recent observations, right whales may be seen as far north as the islands of Saint Helena and Ascension Island.^[48][78]

South America

Brazil

Cow – calf pair at Abrolhos

In Brazil, more than 300 individuals have been cataloged through photo identification (using head callosities) by the Brazilian Right Whale Project, maintained jointly by Petrobras (the Brazilian state-owned oil company), and the conservation group, the International Wildlife Coalition. The State of Santa Catarina hosts a concentration of breeding and calving right whales from June to November, and females from this population also calve off Argentinian Patagonia and Uruguay. In recent years, possibly due to changing habitat environments by human activities and conflicts with local fisheries, the number of whales visiting the coasts is decreasing.^[79] Sighting in locations other than Santa Catarina and Rio Grande do Sul^[80] remain sporadic, such as along Cidreira,^[81] Rio de Janeiro coasts like Sepetiba Bay (pt),^[82] Cabo Frio,^[83][84] Macaé,^[85] Prado, Bahia,^[86][87] Castelhanos Bay in Ilha Bela,^[88][89][90] São Paulo coasts^[91] such as within Ilha Anchieta State Park,^[92] Honey Island,^[93][94][95] and bays and estuaries of Paranaguá and Superagui National Park,^[96] Paraná,^[97][98][99] and even entering into the lagoon of Lagoa dos Patos.^[100][101] Recent studies^[102] also show a decrease in the number of sightings along the southeastern Brazilian coast, which includes the highly urbanized States of São Paulo and Rio de Janeiro.

Further north, small numbers of whales migrate every year to winter or calve in Bahia,^[25] in particular at the Abrolhos Archipelago. Here, certain individuals are recorded returning at intervals of 3 or 4 years.^[103] Whaling records including those prior to Maury and Townsend indicate that right whales were once more frequent visitors further north, for example at Salvador, Bahia.^[46][48]

Argentina

Submerges off Valdes Peninsula

During the 2012 annual meeting of the International Whaling Commission's Scientific Committee, data was presented regarding the continued phenomenon of southern right whale strandings and high rate of mortality at Península Valdés, Argentina. Between 2003 and 2011, a total of 482 dead right whales were recorded at Península Valdés. There were at least 55 whale deaths in 2010, and 61 in 2011. As in previous years, the vast majority of strandings were calves of the season.^[104] There have been increasing sightings in various other locations in recent years, such as on Golfo San Jorge,^[105] Tierra del Fuego,^[106][107] Puerto Deseado,^[108][109] Mar del Plata,^[110][111] Miramar, Buenos Aires,^[112][113] and Bahía Blanca.^[114]

Uruguay

In Uruguay, coastal areas such as Punta del Este host congregating sites for whales in breeding seasons, but these are not likely to be calving grounds.^[115] In 2013 the Uruguayan parliament approved the creation of a whale sanctuary off Latin America^[116] to aid the recovery of the population. The creation of this protected area had been prevented for nearly a decade by pro-whaling nations such as Japan.

Chile and Peru

For the critically endangered Chile/Peru population, the Cetacean Conservation Center (CCC) has been working on a separate programme for right whales. This population, containing no more than 50 individuals, is under threat from an increase in shipping lanes and the fishing industries.^[117] 124 sightings in total were recorded during the period 1964–2008.^[118] Aside from vagrants' records, Peru's coastlines possibly host one of the northernmost confirmed range of the species along with Gabon,^[46] Senegal, Tanzania, Brazilian coasts, Madagascar, Indian Ocean, western Australia, Kermadec Islands, and tropical waters including South Pacific Islands.^[46] The Alfaguara project targeting cetaceans in Chiloe^[119][120] may possibly target this species as well in the future since calving activities have been confirmed in Chiloé Archipelago.^[121] Foraging grounds of this population is currently undetected, but possibly Chiloé and down south of Caleta Zorra to southern fiords such as from Penas Gulf to Beagle Channel although numbers of confirmations are small in the Beagle Channel.^[122] Hopes are arising for the establishment of a new tourism industry on the eastern side of the Strait of Magellan,^[123] especially near Cape Virgenes^[124] and Punta Dungeness, as the number of sightings increases.^{[125][126][127]} It is unknown whether these increases are due to re-colonisation by whales from the Patagonian population.

Occurrences of brindle individuals have been confirmed from this population as well.^[128][129]

Oceania

Historically, populations of southern right whales in Oceanian regions were robust.^[48] Early settlers of Wellington, New Zealand, and the River Derwent in Tasmania complained that sounds of cavorting whales kept them awake at night.^[130] In July 1804, clergyman Robert Knopwood claimed that in crossing the River Derwent, "we passed so many whales that it was dangerous for the boat to go up the river unless you kept very near the shore".^[131] By the 1890s southern right whales had been brought to the brink of extinction, with over 25,000 whales killed in Australia and New Zealand.^[132]

Studies of population structure and mating systems have shown that the southwest Australian and New Zealand populations are genetically differentiated.^[133] The results of satellite tracking suggest that there are at least some interactions between populations in Australia and New Zealand,^[134][135] but the extent of this is unknown. The two groups may share migratory corridors and calving grounds.^[133] The return of southern right whales to the Derwent River and other parts of Australia in recent decades is a sign that they are slowly recovering from their earlier exploitation to near extinction.^[132]

Australia

In Lipson Cove, Spencer Gulf

Southern right whales in Australian waters show higher rate of recoveries, as they have increased from 2,100 whales in 2008^[136] to 3,500 in 2010.^[30] Two genetically distinct groups inhabit Australian waters: the southwestern population of 2,900 whales - in 2012 currently holding the majority of the overall Australian population - and the critically endangered southeastern group, counting only dozens to 300 individuals.

South Australia

Right whales can be found in many parts of southern Australia, where the largest population is found at the Head of the Bight in South Australia, a sparsely populated area south of the middle of the Nullarbor Plain. Over 100^[137] individuals are seen there annually from June to October. Visitors can view the whales from cliff-top boardwalks and lookouts, with whales swimming almost directly below, or by taking a scenic flight over the marine park. A more accessible South Australian location for viewing whales is Encounter Bay where the whales can be seen just off the beaches of the Fleurieu Peninsula, centred around the surfing town of Middleton. The whales have established a newer nursery-ground near Eyre Peninsula, especially at Fowlers Bay. Numbers are much smaller at these locations compared to those in the Bight, with an average of a couple of whales per day, but as of 2009 there were regular sightings of more than ten whales at a time off Basham Beach, near Middleton.^[138] The South Australian Whale Centre at Victor Harbor has information on the history of whaling and whale-watching in the area, and maintains an on-line database of whale sightings.^[139] In June 2021 a female gave birth off Christies Beach, a southern suburb of Adelaide, and remained in the shallows off the beach for some time, attracting large crowds.^[140]

Victoria and Tasmania

Whale numbers are scarcer in Victoria, where the only established breeding ground which whales use each year, in very small numbers, is at Warrnambool. However, as the whales do seem to be increasing in number generally, but not showing any dramatic increases at Warrnambool, they may be extending their wintering habitats into other areas of Victoria, where the numbers of sightings are slowly increasing. These areas include around Melbourne, such as in Port Phillip Bay, along Waratah Bay, at Ocean Grove, Warrnambool, on Mornington Peninsula, in Apollo Bay, and on Gippsland coasts and at Wilsons Promontory.^[141]

Whale numbers in Tasmania are relatively small, however sightings have increased in recent years. Some whales migrate through Tasmanian waters while some others remain throughout wintering seasons.^[142]

Other states and territories

In Waychinicup National Park

Waters off the coasts of Western Australia, New South Wales, and Queensland coasts have all historically been inhabited by whales. Their historical range was much wider than it is today, and reached around the southern coast of the continent, extending up to Australian Abrolhos Island,^[143] Exmouth and Shark Bay on the west coast, and on the east coast as far north as Hervey Bay, Moreton Bay^[144] and Great Barrier Reef.^[145] Today, the east-coast population remains endangered and very small (in the low-tens),^[146] contributing to small numbers and limited re-colonization, but increases have been confirmed in many areas such as Port Jackson, Port Stephens, Twofold Bay, Jervis Bay, Broulee,^[147] Moruya River,^[148][149] Narooma,^[150] and Byron Bay.^[151] 12 foraging areas have been officially announced by the Australian government.^[152]

In sub-Antarctic regions, numbers of whales visiting long-used habitats differ drastically by location. The population is recovering well at the New Zealand Subantarctic Islands, while whale numbers are less successful at Macquarie Island.^[153]

It is not known whether Australian populations will re-colonise historical oceanic habitats such as Norfolk Island and Lord Howe Island with Lord Howe Seamount Chain (historically known as the "Middle Ground" for whalers^[154][155]) in the future.

New Zealand

The current population of right whales in New Zealand waters is difficult to establish. However, studies by the Department of Conservation and sightings reported by locals have helped to build up a better picture.^[156] The pre-exploitation size of the New Zealand group is estimated at between 28,800 and 47,100 whales. 35,000 – 41,000 catches were made between 1827 and 1980. The number of whales surviving commercial and illegal whaling operations is estimated to have decreased to just 110 whales (around 30 of which were females) in 1915.^[133][157] As a result of such a steep decline in numbers, the population of southern right whales in this region has experienced a population bottleneck and suffers from low genetic diversity.^[158]

In Port Ross, Auckland Islands

The population at the sub-Antarctic Auckland Islands is showing a remarkable recovery but continues to have some of the lowest genetic diversities in the world.^[158] In the Campbell Islands, recovery is slower.^[44] Here, the population is estimated to have dropped to as low as 20 individuals post WWII.^[134] There had been no confirmed sightings or strandings of right whales for 36 years until 1963 when four separate sightings including a cow-calf pair were made over a wide area. Remnants of sub-Antarctic populations were reported in the 1980s and re-discovered in the 1990s.^[134]

Today, the majority of right whales congregate at the Auckland and Campbell Islands, where they form exceptionally dense and limited congregations including mating adults and calving females. In the waters around Port Ross^[159] up to 200 whales may winter at the same time.^[160] It is notable that whales of all age groups^[161] are present in this small area annually, not only using them as feeding and summering^[162] grounds but also for wintering, breeding, and calving during harsh, cold periods. Low genetic diversity as a result of population decline has caused changes in skin coloration amongst this group.^[158] Scientists used to believe there was a very small remnant population of southern right whales inhabiting New Zealand's main islands (North and South Island), estimated to contain 11 reproductive females.^[163] In winter, whales migrate north to New Zealand waters and large concentrations occasionally visit the southern coasts of South Island. Bay areas along Foveaux Strait from Fiordland region to northern Otago are important breeding habitats for right whales, especially Preservation,^[164] Chalky Inlets,^[165] Te Waewae Bay,^[166] and Otago Peninsula.^[167][168] Calving activities are observed all around New Zealand, but with more regularity around North Island shores from the Taranaki coast in the west to Hawke's Bay, Bay of Plenty in the east, and areas in Hauraki Gulf such as Firth of Thames or Bay of Islands in the north.

There are various parts of the nation where large numbers of whales were seen historically, but sightings are less common nowadays. These areas include the Marlborough Region, especially from Clifford Bay and Cloudy Bay to Port Underwood,^[169] Golden Bay, Awaroa Bay, and coastlines on West Coast and Hokianga Harbour in Northland. Other than a handful of confirmed observations, very little information is available for modern migrations to historical oceanic habitats of Kermadec Islands^[170][171] and Chatham Islands.^[172] The northernmost sighting recorded historically was at 27°S.^[173]

A 2009 study revealed that the right whale populations from New Zealand's main islands and the sub-Antarctic islands interbreed, though it is still unknown whether the two stock originally came from a single population.^[174] Feeding areas in pelagic waters are unclear while congregations have been confirmed along the southern edge of the Chatham Rise.^[175]

Some Australian ranges are located close to the ranges of New Zealand groups (Norfolk Island, Macquarie Island). It is unclear whether whales historically or currently from these Australian ranges once originated in New Zealand groups.

Other

Fluking off South Georgia near a gentoo penguin

In oceanic islands and offshore waters other than the above-mentioned areas, very little about the presence and recovery status of southern right whales is known. Right whales' historical ranges were much greater than today; during the whaling era of the 19th century whales were known to occur in lower latitude areas such as around the Pacific Islands, off the Gilbert Islands (nowadays Kiribati),^[176] and also to frequent lower latitudes of the central Indian Ocean.

It is unclear whether right whales have been historically or currently distributed among parts of hemisphere lacking great land masses and reached far more pelagic islands such as Alejandro Selkirk and Robinson Crusoe Islands, Hanga Roa, Pitcairn, Galapagos Islands, and the Easter Island.

Populations among sub-Antarctic islands in the Scotia Sea^[80] such as South Georgia and the South Sandwich Islands and Falkland Islands were severely damaged and show slower recoveries today. Antarctic distributions are difficult to establish due to low levels of sightings around oceanic islands in these areas, including Elephant Island.^[a]

Indian Ocean

Historically, there were known to be populations which summered in the Crozet Islands and the Kerguelen Islands, and migrated to La Roche Godon and Île Saint-Paul, Île Amsterdam, and the Central Indian Ocean. They may be distinct from the population of whales seen on Mozambique coasts.^[177] Repopulation of whales among these areas of the Indian Ocean is likely to be happening at even lower rates than in other areas. Sightings have been fewer in modern periods among Crozet,^[178][179] Réunion,^{[180][64][181][182]} Mauritius, Marion Islands,^[43] Île Amsterdam, and Kerguelen.^[183]

Killings of these whales have been recorded on central Indian Ocean near the equator, especially around the area between Diego Garcia, Egmont Islands, and the Great Chagos Bank in the west, and the Cocos (Keeling) Islands in the east. The range of whales in the Indian Ocean is comparable to the range of some other populations around South America, Africa, and the South Pacific islands including Kiribati, the northernmost reach of all the populations known today.^[47]

Whaling

Sculpture of southern right whale at Cockle Creek on Recherche Bay, Tasmania, where bay whaling was performed extensively during the 1840s and 1850s

By 1750 the North Atlantic right whale was as good as extinct for commercial purposes, and the American whalers moved into the South Atlantic before the end of the 18th century. The most southerly Brazilian whaling station was established in 1796, in Imbituba. Over the next hundred years, American whaling spread into the Southern and Pacific Oceans, where the American fleet was joined by fleets from several European nations.

The southern right whale had been coming to Australian and New Zealand waters in large numbers before the 19th century, but was extensively hunted from 1800 to 1850. Hunting gradually declined with the whale population and then all but ended in coastal waters in Australasia.^[184] The beginning of the 20th century brought industrial whaling, and the catch grew rapidly. By 1937, according to whalers' records, 38,000 were harpooned in the South Atlantic, 39,000 in the South Pacific, and 1,300 in the Indian Ocean. Given the incompleteness of these records, the total take was somewhat higher.^[185]

As it became clear that the population was nearly depleted, the harpooning of right whales was banned in 1937. The ban was largely successful, although some illegal whaling continued for several decades. Madeira took its last two right whales in 1968. Illegal whaling continued off the coast of Brazil for years, and the Imbituba station processed right whales until 1973. The USSR admitted to taking illegally over 3,300 during the 1950s and 1960s,^[186] although it only reported taking 4.^[187]

Illegal operations continued even in the 1970s, such as the case in Brazil until 1973.^[15] It was also revealed that Japan was supporting these destructive hunts by neglecting and disregarding its monitoring obligations. There were agreements between Japan and the Soviet Union to keep their illegal mass whaling activities in foreign/international protected waters secret.^[188]

Right whales began to be seen again in Australian and New Zealand waters from the early 1960s.^[184] It is possible that if the Soviet hunts had never happened, the New Zealand population would be three or four times larger than its current size.^[189]

Conservation

The southern right whale, listed as "endangered" by CITES, is protected by all countries with known breeding populations (Argentina, Australia, Brazil, Chile, New Zealand, South Africa and Uruguay). In Brazil, a federal Environmental Protection Area encompassing some 1,560 km² (600 sq mi) and 130 km (81 mi) of coastline in Santa Catarina State was established in 2000 to protect the species' main breeding grounds in Brazil and promote regulated whale watching.^[190] The southern right whale is listed on Appendix I^[191] of the Convention on the Conservation of Migratory Species of Wild Animals (CMS) as this species has been categorized as being in danger of extinction throughout all or a significant proportion of their range. This species is also covered by the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU).^[192] In 2017, the IUCN Red List of Threatened Species listed the species' status as Least Concern with a population trend listed as "unknown".^[193]

In Australia, Southern right wales are listed for protection variously under state and federal legislation, as reflected in the table below:

A two-year, £740,000 project, led by the British Antarctic Survey began in 2016, to discover why almost 500 young have been washed up on the Valdes Peninsula over the last ten years. The project is funded by the UK's Department for Environment, Food and Rural Affairs (Defra) and the EU. Possible reasons are a lack of krill in the whale feeding grounds at South Georgia and the South Sandwich Islands, exposure to toxic algae and attacks by kelp gulls (Larus dominicanus).^[199]

A white calf attacked by a gull off Península Valdés

Gull attacks

One possibly significant contributor to the calf mortality rate has alarmed scientists – since at least 1996, kelp gulls off the coast of Patagonia have been observed attacking and feeding on live right whales.^[200] The kelp gull uses its powerful beak to peck down several centimetres into the skin and blubber, often leaving the whales with large open sores – some of which have been observed to be half a metre in diameter. This predatory behaviour, primarily targeted towards mother/calf pairs, has been continually documented in Argentinian waters, and continues today. Observers note that the whales are spending up to a third of their time and energy performing evasive manoeuvres – therefore, mothers spend less time nursing, and the calves are thinner and weaker as a result. Researchers speculate that many years ago, waste from fish processing plants allowed the gull populations to soar. Their resulting overpopulation, combined with reduced waste output, caused the gulls to seek out this alternative food source.^[201] Scientists fear that the gulls' learned behaviour could proliferate, and the IWC Scientific Committee has urged Brazil to consider taking immediate action if and when similar gull behaviour is observed in their waters. Such action may include the removal of attacking gulls, following Argentina's lead in attempting to reverse the trend.^[104]

Threats

Southern right whales are threatened by entanglement in commercial fishing gear and ship strikes.^[5] Entanglement in fishing gear can cut through a whale's skin, causing infection, amputation and death. Underwater noise from human activities such as drilling and dredging can interfere with whales' communication, and deter them from their usual habitats and breeding grounds.^[202]

Whale watching

Africa

Whale breaching off George, Western Cape with a tanker behind

The southern right whale has made Hermanus, South Africa, one of the world centres for whale watching. During the winter months (June to October), southern right whales come so close to the shoreline that visitors can watch them from the shore as well as from strategically placed hotels. The town employs a "whale crier" (cf. town crier) to walk through the town announcing where whales have been seen.^[203] Hermanus also has two boat–based whale watching operators. Southern right whales can also be watched at False Bay from the shore or from the boats of operators in Simon's Town. Plettenberg Bay along the Garden Route of South Africa is also known for whale watching including both land and boat based watching, not only for southern rights (July to December) but throughout the year.^[204] Southern right whales can also be seen off the coast of Port Elizabeth with marine eco tours running from the Port Elizabeth harbour, as some southern right whales make Algoa Bay their home for the winter months.^[205]

Although southern right whales have been seen in neighboring countries including Namibia, Mozambique, and Madagascar, they are not the targeted species for whale watching tours in these countries.

South America

Southern right whale approaches close to whale watchers near Península Valdés in Patagonia

In Brazil, Imbituba in Santa Catarina has been recognised as the National Right Whale Capital and holds annual Right Whale Week celebrations in September, when mothers and calves are more often seen. The old whaling station there is now a museum that documents the history of right whales in Brazil. In Argentina, Península Valdés in Patagonia hosts (in winter) the largest breeding population, with more than 2,000 catalogued by the Whale Conservation Institute and Ocean Alliance.^[206] As in the south of Argentina, the whales come within 200 m (660 ft) of the main beach in the city of Puerto Madryn and form a part of the large ecotourism industry. Uruguay's Parliament on 4 September 2013, has become the first country in the world to make all of its territorial waters a haven for whales and dolphins. Every year, dozens of whales are sighted, especially in the departments of Maldonado and Rocha during winter.^[207] Swimming activities for commercial objectives had been banned in the area in 1985,^[208] but were legalised in Gulf of San Matías, the only place in the world where humans are formally allowed to swim with the species.^[209] Land-based watching and occasional kayaking with whales activities are seen at other locations not renowned for whale-watching as much as Puerto Madryn and with less restrictions on approaching whales, such as at Puerto Deseado,^{[210][211][212]} Mar del Plata,^[213][214] and Miramar in Buenos Aires.^{[215][216][217][218]}

Though their numbers are dangerously small, land-based sightings of whales are on the increase in recent years off Chile and Peru, with some hope of creating new tourism industries,^[219] especially in the Strait of Magellan, most notably around Cape Virgenes.^[126]

Oceania

Whales cavort next to surfers on Manly Beach.

In Australia's winter and spring, southern right whales can be seen migrating along the Great Australian Bight in South Australia. Viewing locations include the Bunda Cliffs and Twin Rocks, the Head of the Bight (where a visitor centre and cliff-top viewing boardwalks exist) and at Fowler's Bay where accommodation and charter boat tours are offered.^[13] Another popular South Australian locality for Southern right whale watching is Encounter Bay, where the South Australian Whale Centre supports local whale-watchers and tourists. In Warrnambool, Victoria, a right whale nursery is also a popular tourist attraction. The whales' migratory range is extending as the species continues to recover and re-colonize other areas of the continent, including the coastal waters of New South Wales and Tasmania. In Tasmania, the first birth since the 19th century was recorded in 2010 in the River Derwent.

Similarly, southern right whales may provide chances for the public to observe whales from shore on New Zealand's coasts with greater regularity than in the past, especially in southern Fiordland, Southland through to the Otago coast,^[220] and on the North Island coast, especially in Northland and other locations such as the Bay of Plenty and the South Taranaki Bight. Births of calves could have always been occurring on the main islands' coasts, but were confirmed with two cow-calf pairs in 2012.^[221][222]

Subantarctic

In the Subantarctic Islands and in the vicinity of Antarctica,^[223] where few regulations exist or are enforced, whales can be observed on expedition tours with increasing probability. The Auckland Islands are a specially designated sanctuary for right whales, where whale-watching tourism is prohibited without authorisation.^[224]

See also

• List of cetaceans
• List of marine mammal species

References

Notes

Citations

La Aŭstrala baleno (Eubalaena australis) estas lamenbaleno, unu el tri specioj klasitaj kiel veraj balenoj kiuj apartenas al la genro Eubalaena.

Proksimume 10,000 aŭstralaj balenoj estas disvastigitaj tra la suda parto de la Suda Hemisfero.

Taksonomio

La veraj balenoj estis unuafoje klasitaj en la genro Balaena en 1758 fare de Carl Linnaeus, kiuj tiam estis konsiderataj ĉiuj veraj balenoj (inklude la Gronlandan balenon) nome unusola specio. Laŭlonge de la 1800-aj kaj 1900-aj jaroj fakte la familio de Balenedoj estis celo de granda taksonomia debato. Aŭtoritato ripete rekategoriigis la tri populaciojn de veraj balenoj plus la Gronlandan balenon, kiel unu, du, tri aŭ kvar specioj, ĉu en unusola genro aŭ en du apartaj genroj. En la komenco de la epoko de balenkaptado, ili estis ĉiuj konsiderataj unusola specio, Balaena mysticetus.^[1]

La Aŭstrala baleno estis dekomence priskribita kiel Balaena australis fare de Desmoulins en 1822. Finfine, estis agnoskita ke la Gronlanda baleno kaj la veraj balenoj estis fakte diferencaj, kaj John Edward Gray proponis la genron Eubalaena por la veraj balenoj en 1864. Poste, morfologiaj faktoroj kiaj diferencoj en la kraniformo de nordaj kaj sudaj veraj balenoj indikis, ke almenaŭ du specioj de veraj balenoj — unu en la Norda Hemisfero, la alia en la Suda Oceano.^[2] Tiom ĵuse kiom en 1998, Rice, en sia kompleta kaj krome aŭtoritata klasigo, Marine mammals of the world: systematics and distribution, listigis ĝuste du speciojn: Balaena glacialis (ĉiuj veraj balenoj) kaj Balaena mysticetus (Gronlanda baleno).^[3]

En 2000, Rosenbaum et al. malkonsentis, baze sur informo el la genetika studo de montraĵoj de DNA el ĉiu el la balenaj populacioj. Genetika pruvaro nune klare montris, ke la nordaj kaj la sudaj populacioj de veraj balenoj ne interreproduktiĝis dum inter 3 milionoj kaj 12 milionoj da jaroj, konfirmante la sudan veran balenon kiel aparta specio. Ankaŭ la nordaj Pacifikaj kaj Atlantikaj populacioj estas diferencaj, el kiuj la Nordpacifika vera baleno estas pli proksime rilata al la suda vera baleno ol al la Nordatlantika vera baleno.^[4] Genetikaj diferencoj inter E. japonica (nordpacifika) kaj E. australis (sudpacifika) estas multe pli malgrandaj ol aliaj lamenbalenoj reprezentaj en diferencaj oceanbasenoj.^[5]

Oni supozas, ke la populacioj de veraj balenoj unuafoje disiĝis pro la kuniĝo de Norda kaj Suda Amerikoj. La plialtiĝantaj temperaturoj en la Ekvatoro poste kreis duan disigon, en norda kaj suda grupoj, kio malebligis ekde tiam la interreproduktadon.^[6]

En 2002, la Scienca Komitato de la Internacia Balenĉasa Komisio (IWC) akceptis la trovojn de Rosenbaum, kaj rekomendis, ke la nomenklaturo Eubalaena restu por tiu genro.^[7]

Priskribo

Jen du distingaj kolormodeloj.

Kiel ĉe aliaj veraj balenoj, la Aŭstrala baleno estas klare distingeblaj el aliaj pro la kalaĵoj en sia kapo, granda dorso sen dorsa naĝilo, kaj longa arkeca buŝo kiu ekas super la okulo. Ĝia haŭto estas tre malhelgriza aŭ nigra, foje kun kelkaj blankaj makuloj en la ventro. La kaloj de la veraj balenoj aspektas blanke pro la grandaj kolonioj de ciamidoj (balenlaŭsoj). Ĝi estas preskaŭ nedistingebla el la tre proksime rilataj Nordatlantika kaj la Pacifika balenoj, kiuj havas nur minorajn kranidiferencojn. Povas esti pli malmultaj calaĵoj en iliaj kapoj ol en la Nordatlantikaj kaj pli en iliaj malsupraj lipoj ol en la du nordaj specioj.^[8][9] Biologiaj funkcioj de calaĵoj estas neklaraj kvankam oni konsideris la ĉefan rolon por protekto kontraŭ predantoj, kaj fakte la balena malpliiĝo povas ankaŭ tuŝi la diversecon kaj kvanton de ciripedoj.^[10]

Plenkreska ino estas 15 m^[11] kaj povas pezi ĝis 47 tunojn,^[11] el kio la plej grandaj registroj estis de 17.5-18 m^[12][13] laŭ longo kaj 80 tunoj^[14] aŭ eĉ ĝis 90 t en pezo,^[15] kio faras ilin iomete pli malgrandaj ol la veraj balenoj de la Norda Hemisfero.^[16] La testikloj de la veraj balenoj estas verŝajne la plej grandaj el ajna animalo, el kiuj ĉiu pezas ĉirkaŭ 500 kg. Tio sugestas, ke la spermokonkurenco ludas gravan rolon en la pariĝado.^[17]

La veraj balenoj normale ne trapasas la varmajn ekvatorajn akvojn kio permesus konekti kun la aliaj specioj kaj (inter)reproduktiĝu: iliaj dikaj tavoloj de izoliga graso malfacilas ke ilis forigu sian internan korpovarmon en tropikaj akvoj. Tamen, baze sur historiaj registroj kaj nekonfirmitaj vidaĵoj en modernaj periodoj, povas okazi transiroj de E. australis tra ekvatoraj akvoj.^[18] Krome, estis registrita surstrandiĝo de "21.3 m longa vera baleno en Gaĝana, nordokcidenta Barato en Novembro, 1944", tamen, kies vera identeco estas neklara.^[19][20]

Notoj

1. ↑ Müller, J. (1954). "Observations of the orbital region of the skull of the Mystacoceti" (PDF). Zoologische Mededelingen. 32: 239–90.
2. ↑ Müller, J. (1954)."Observations of the orbital region of the skull of the Mystacoceti" (PDF). Zoologische Mededelingen. 32: 239–90.
3. ↑ Rice, Dale W. (1998). Marine mammals of the world: systematics and distribution. Society of Marine Mammalogy, Special Publication No. 4. ISBN 1891276034.
4. ↑ Rosenbaum, H. C.; R. L. Brownell Jr.; M. W. Brown; C. Schaeff; V. Portway; B. N. White; S. Malik; L. A. Pastene; N. J. Patenaude; C. S. Baker; M. Goto; P. Best; P. J. Clapham; P. Hamilton; M. Moore; R. Payne; V. Rowntree; C. T. Tynan; J. L. Bannister & R. Desalle (2000). "World-wide genetic differentiation of Eubalaena: Questioning the number of right whale species" (PDF). Molecular Ecology. 9 (11): 1793–802. doi:10.1046/j.1365-294x.2000.01066.x. PMID 11091315. [jam ne plu uzebla ligilo]
5. ↑ A note on the genetic diversity and phylogeny of western North Pacific and southern right whales based on mitochondrial and microsatellite DNA Alirita la 16an de Novembro 2018.
6. ↑ Palaeobiology and Biodiversity Research Group, University of Bristol, Alirita la 16an de Novembro 2018.
7. ↑ [www.marinemammalscience.org/index.php?option=com_content&view=article&id=645&Itemid=340 "List of Marine Mammal Species and Subspecies". Committee on Taxonomy. Society for Marine Mammalogy. 3a de Aprilo 2012. Alirita la 29an de Septembro 2012.
8. ↑ Müller, J. (1954)."Observations of the orbital region of the skull of the Mystacoceti" (PDF). Zoologische Mededelingen. 32: 239–90. Alirita la 16an de Novembro 2018.
9. ↑ (1998) Whales, Dolphins and Porpoises. Surry Hills, NSW: Reader's Digest. ISBN 0-86449-096-8.
10. ↑ Fig. S3. Stranded Pacific right whale Eubalaena japonica at Izu....
11. ↑ ^{11,0 11,1} Branch, G.M., Branch, M.L, Griffiths, C.L. kaj Beckley, L.E. 2010. Two Oceans: a guide to the marine life of southern Africa (ISBN 978-1-77007-772-0)
12. ↑ Antonio B. Greig (2001). “Stranding events of southern right whales, Eubalaena australis, in southern Brazil”, J. Cetacean Res. Manage Special Issue (2), p. 157–160.
13. ↑ http://www.doc.govt.nz/Documents/science-and-technical/sfc225a.pdf
14. ↑ Department of Sustainability and Environment. 1998. Southern Right Whale – Eubalaena australis En webarchive [1] 31a de Oktobro 2014. Action Statement-Flora and Fauna Guarantee Act 1988. No.94. Alirita en 31a de Oktobro. 2014
15. ↑ Southern Right Whale Species Guide. Whale and Dolphin Conservation.
16. ↑ Whale and Dolphin Conservation. Endangered Species – Southern Right Whale Eubalaena australis. Alirita la 31an de Oktobro. 2014
17. ↑ Eubalaena glacialis. Animal Diversity Web (2002). Alirita 27a de Junio 2009.
18. ↑ Waerebeek, V. K.; Santillán, L.; Suazo, E.; The Peruvian Centre for Cetacean Research (2009). "On The Native Status of the Southern Right Whale Eubaleaena australis in Peruournal=Boletín del Museo Nacional de Historia Natural, Chile" (PDF). 58: 75–82. Retrieved 2014-12-26. [www.vliz.be/imisdocs/publications/242935.pdf] Alirita la 16an de Novembro 2018.
19. ↑ Sathasivam K.. 2015. A Catalogue of Indian Marine Mammal Records (pdf)
20. ↑ The Marine Mammal Conservation Network of India. Sightings and Strandings – Species – Black Right Whale. Alirita la 19an de Aprilo, 2017

La ballena franca austral (Eubalaena australis) es una especie de cetáceo misticeto de la familia Balaenidae propia del Hemisferio Sur.

Descripción

Se pueden observar callosidades, que son áreas de piel elevadas de más de 18 cm de grosor aproximadamente, de consistencia córnea, situadas en distintas partes de la cabeza. La distribución, dimensión y forma de los callos varían de una ballena a otra pero no cambian con el crecimiento. Funcionando como huellas dactilares, identifican a cada animal durante toda la vida. Estas callosidades, desarrolladas en la etapa fetal y de color rosa oscuro, presentan densas poblaciones de pequeños crustáceos anfípodos llamados ciámidos (pitos de las ballenas) y en algunas ocasiones se intercalan con cirrípedos que hacen que las callosidades luzcan blancas, amarillas, anaranjadas o rosa claro. Normalmente, se reparten a lo largo del margen superior del labio inferior, mandíbula, superficie dorsal del rostro y sobre los ojos. El callo de mayor importancia por su tamaño es el "bonete", ubicado en la punta del hocico.

Dentro de su boca de forma curva, la mandíbula superior sostiene unas 1567 placas o barbas córneas llamadas originariamente "baleen", de donde se deriva el nombre en castellano de ballena. Estas barbas llegan a medir unos 2,50 m de largo. Cuando las ballenas se alimentan, sirven de filtros o coladores para retener su comida principal, el krill.

Los machos poseen los órganos sexuales de mayor tamaño de todo el reino animal. Sus testículos pueden llegar a pesar hasta 525 kg cada uno, con unas dimensiones de 2 m x 78 cm (casi un 1 % de su peso corporal, 10 veces más grandes que los de la ballena azul), y su pene puede alcanzar una longitud de 2.7 m.^[2]​

Los científicos han relacionado estas proporciones con la denominada competición espermática, presente en esta y otras especies.^[3]​^[4]​

Hábitat

La ballena franca austral habita una amplia franja que va de los 20° a los 60° de latitud en los océanos Pacífico sur, Atlántico sur e Índico sur.

La caza indiscriminada de este ejemplar lo llevó a ser declarado en peligro de extinción. Desde el siglo XIX, su población original se redujo hasta en un 90 %. En la actualidad existen aproximadamente 8000 ejemplares. Si bien se las encuentra en el hemisferio y polo sur, las ballenas se reproducen en aguas cálidas durante el invierno. Por este motivo se reúnen en varios lugares del mundo los cuales son:

• Argentina (península Valdés)
• Australia
• Chile
• Uruguay^[5]​
• Tristán de Acuña (dependencia británica de ultramar)
• Nueva Zelanda

Caza

Debido a que es un animal que nada lento y que flota una vez muerto (a diferencia de otros mamíferos) es muy fácil de cazar, y sumado a que su cuerpo rinde el equivalente a 40 barriles de aceite (7200 litros).

Solo tienen cría cada tres años, promedio que perjudica su protección, que en la actualidad contabiliza solo unos 10000 individuos, de los cuales el 20 % han sido registrados en jurisdicción de Argentina.

Monumento natural

El 28 de septiembre de 1984 se sancionó la ley n.º 23094 que declaró monumento natural a todas las ballenas francas que se visualicen en aguas jurisdiccionales de Argentina. Tal decisión se fundamenta en la imperiosa necesidad de otorgarle la debida protección. Se reproduce y amamanta a sus crías en aguas australes.^[6]​ La provincia de Río Negro también la declaró monumento natural provincial mediante la ley n.º 4066 sancionada el 6 de abril de 2006^[7]​ y la provincia de Santa Cruz mediante la n.º 2643 sancionada el 13 de marzo de 2003.^[8]​ También es monumental natural de Chile mediante el decreto supremo N°230 sancionado el 20 de junio del 2008 junto a todos los demás cetáceos del país.

Se insiste con la posibilidad de crear un santuario para la preservación de esta especie en el Atlántico Sur.^[9]​

Véase también

• Ballena franca pigmea
• Península Valdés
• Cetáceos de Chile

Referencias

Balea austral (Eubalaena australis) Eubalaena generoko animalia da. Artiodaktiloen barruko Balaenidae familian sailkatuta dago.

Erreferentziak

• 'Eubalaena australis'ri buruzko informazioa Mammals of The World datubasean

Ikus, gainera

• Balaenidae

Etelänmustavalas ^[3] (Eubalaena australis) on eteläisellä pallonpuoliskolla elävä valaslaji. Laji on nykyään toipumassa sitä verottaneesta pyynnistä. Etelänmustavalaat syövät eläinplanktonia ja vaeltavat etelästä pohjoiseen vuodenaikojen mukaan. Etelänmustavalas luokiteltiin aiemmin samaan lajiin kuin sen pohjoiset sukulaiset mustavalas (Eubalaena glacialis) ja tyynenmeren alueen mustavalas Eubalaena japonica, mutta sen asema omana lajinaan on nykyään yleisesti hyväksytty^[4].

Koko ja ulkonäkö

Täysikasvuinen etelänmustavalas on 16–18 metrin pituinen ja painaa 36–73 tonnia. Naaraat ovat hieman koiraita suurempia. Niiden ruumis on pyöreähkö ja ympärysmitaltaan suuri verrattuna ruumiinpituuteen. Pään pituus on noin kolmannes ruumiinpituudesta. Päätä ja sen ympäristöä täplittävät valkoiset, äyriäisiin kuuluvat valasrokot. Väritys on tasaisen musta.^[5] Vatsapuolella on erikokoisia valkoisia läikkiä, jotka keskittyvät ruumiin keskiosaan.^[6] Evät ovat leveät ja lyhyet. Muiden silovalaiden tapaan etelänmustavalailta puuttuvat selkäevä ja leuan uurteet.^[5] Etelänmustavalailla on 205—270 mustaa hetulaa, joiden pituus voi olla jopa 2,2 metriä.^[6]

Levinneisyys ja elinympäristö

Etelänmustavalasta tavataan nimensä mukaisesti eteläisellä pallonpuoliskolla. Levinneisyys ulottuu kesäisin jopa 65. leveysasteelle Antarktiksella, mutta useimmat yksilöt viettävät kesänsä 40.–50. leveysasteen tienoilla. Lisääntymisalueet ovat pohjoisempana rannikon läheisyydessä eteläisessä Australiassa, Uudessa-Seelannissa, eteläisessä Afrikassa ja Etelä-Amerikan Atlantin puoleisella rannikolla Brasiliassa ja Argentiinassa. Pieni alapopulaatio elää myös keskisen Chilen ja Perun alueella ja Madagaskarissa.^[1] Ne elävät subantarktisissa vesissä ja välttelevät päiväntasaajan lämpimiä vesiä ja pysyttelevät mieluiten mantereiden saarten ympäristössä. Etelänmustavalaat vaeltavat talveksi pohjoiseen lisääntymään.^[5]

Etelänmustavalas hyppäämässä Etelä-Afrikassa

Elintavat

Etelänmustavalas on hidas uimari ja etenee korkeintaan reilun 15 kilometrin tuntinopeudella, tuolloinkin lyhytaikaisesti. Emon ja poikasen uintivauhti on vain 2,7–4,2 kilometriä tunnissa. Laji elää pieninä ryhmin tai yksin.^[5] Valaat viestivät keskenään tuottamalla lyhyitä ja matalataajuista vaikerointia ja pulsseja. Ne myös puhaltelevat sekä veden alla että pinnalla. Yleisin ääni on röyhtäisyn tapainen keskimäärin 1,4 sekunnin lausahdus. Sen taajuus on alle 500 Hz. Ne tuottavat myös suppeampia ja monimutkaisempia ääniä, jotka toistuvat sointuina. Lisäksi ne tuottavat ääniä läiskyttämällä vedenpintaa pyrstöllään ja evillään etenkin lisääntymiskauden aikana. Etelänmustavalailla on tapana ottaa pystysuora asento ilmaan ja keinua selällään, ne tekevät sitä noin 2 minuuttia kerralla. Se on luultavasti joko lepoasento tai liittyy lisääntymiseen. Ne myös nousevat usein puoliksi pintaan ja lysähtävät veteen joko selälleen tai sivulle. Ne saattavat näin yrittää poistaa loisia ja se voi olla myös esitys lisääntymisaikana.^[7] Aikuisella, terveellä yksilöllä ei ole muita vihollisia kuin miekkavalas. Poikasia ja sen emoa sen sijaan saattavat uhata myös hait, joiden puremia niistä on löytynyt. Pienet poikaset saattavat joskus rantautua, mutta aikuisille niin käy vain harvoin. Elinikä on tuntematon, mutta luultavasti se on ainakin yli 50 vuotta.^[6]

Etelänmustavalas Valdésin niemimaan edustalla Argentiinassa

Ravinto

Etelänmustavalaiden pääravintoa ovat krillit ja hankajalkaiset. Ravinnon koostumus vaihtelee sen mukaan millä leveysasteilla ne liikkuvat. Hankajalkaiset ovat tärkeintä saalista 40°S lähtien pohjoisessa ja etelämpänä lähinnä krillit.^[6] Ne syövät myös äyriäisten toukkia. Etelänmustavalailla on kaksi pyyntitekniikkaa. Ne ruokailevat pinnalla ja avaavat suunsa ammollaan ja siivilöivät hetuloidensa läpi yhteen pakkautuneen planktonparven tai ruokailevat sukelluksissa tiheiden planktonesiintymien luona.^[5]

Lisääntyminen

Etelänmustavalasnaaraat saavat yhden poikasen yleensä kolmen vuoden välein. Väli on kuitenkin pidempi jos ravintoa on huonosti saatavilla.^[1] Kiima on heinä-elokuussa. Naaraalla saattaa jopa kahdeksan koirasta, joiden kanssa se parittelee. Koiraiden välillä on silti erittäin vähän aggressioita toisiaan kohtaan. Kantoaika on 11–12 kuukautta, ja naaraat synnyttävät kesä-elokuussa. Naaraan täytyy olla 4 kuukautta syömättä talvikuukausien aikana.^[8] Poikanen on syntyessään 1 000–1 500-kiloinen ja 5–6-metrinen^[5] Emo hoitaa ja imettää poikastaan suojaisissa matalissa vesissä, joissa ne ovat hyvin turvassa valkohailta ja miekkavalailta.^[8] Poikasta imetetään 4–6 kuukautta. Se kasvaa kolme senttiä päivässä. Sukukypsyys saavutetaan noin 10-vuotiaana.^[5]

Uhat ja suojelu

Etelänmustavalaita katsomaan tulleita matkailijoita lähellä Valdésin niemimaata Patagoniassa, Argentiinassa

Etelänmustavalas ei ole nykyään uhanalainen, mutta ne ovat ennen kärsineet kaupallisesta valaanpyynnistä. Niitä pyydettiin muun muassa lihan ja öljyn vuoksi.^[5] Etelänmustavalaiden pyynti alkoi 1600-luvun alussa ja se kasvoi voimakkaasti 1700- ja 1800-luvulla. Vuosien 1770-1900 välisenä aikana tapettiin arviolta 150 000 etelänmustavalasta, joista 48 000–60 000 1830-luvulla. Pyynti jatkui vuoteen 1935, jolloin laji rauhoitettiin kansainvälisesti. Kanta kääntyi hitaaseen nousuun, mutta laiton pyynti alkoi 1960-luvulla, kun neuvostoliittolaiset pyysivät yli 3 000 valasta, mikä oli luultavasti yli puolet silloisesta populaatiosta. Pyynti jatkui myös hieman Etelä-Amerikan valtioiden taholta ja laiton pyynti loppui vasta 1970-luvulle tultaessa. Etelänmustavalaita kuolee nykyään törmäyksissä laivojen kanssa ja takertuu kalastusvälineisiin, joskaan ne eivät ole paljoakaan haitanneet kannan elpymistä. Kannan kooksi arvioitiin vuonna 1997 7 500 yksilöä. Kokonaiskannan elpymisestä huolimatta Perun-Chilen noin 50 yksilön populaatio on äärimmäisen uhanalainen. Nyttemmin valaat ovat saaneet rauhoitusalueita, joilla ne voivat lisääntyä rauhassa ja sukukypsien naaraiden lukumäärän arvioidaan kaksinkertaistuneen vuodesta 1997 vuoteen 2007. Laji kuuluu CITES-sopimuksen liitteeseen I.^[1] 1990-luvulta lähtien valaita on hyödynnetty valasmatkailun muodossa. Sen tuomat rahat ovat antaneet hyvän syyn suojella lajia.^[5]

Lähteet

Aiheesta muualla

• Mitochondrial DNA Diversity and Population Structure among Southern Right Whales (Eubalaena australis)

Eubalaena australis

La baleine franche australe (Eubalaena australis) est une espèce de baleine franche (Balaenidae) de genre Eubalaena. Elle est aussi appelée baleine noire australe ou baleine australe. Sa population est estimée à environ 7 000 individus en 2020^[1].

Elle n'est pas la seule représentante du genre Eubalaena, la baleine noire de l'Atlantique, ou baleine franche de Biscaye (Eubalaena glacialis), en fait également partie.

Description

Elle est très similaire par ses formes (pas d'aileron) à la baleine franche du Groenland mais n'a pas de tache blanche au menton. En revanche, sa gueule est ornée d'énormes callosités où se fixent des crustacés parasites.

Elle mesure jusqu'à 18 m, pour un poids maximal de 80 tonnes.

Le baleineau tète près de 125 litres de lait maternel par jour.

Les scientifiques pensent que la baleine franche australe est très portée sur l'activité sexuelle. Cette déduction vient du fait que ses deux testicules peuvent peser jusqu'à une tonne et qu'elle possède le plus grand pénis du règne animal^[2],[3].

Habitat

Elle habite surtout l'Antarctique mais également le sud du Pacifique et de l'océan Indien, la Peninsula Valdes en Argentine où elle se nourrit de plancton.

Annexes

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), Baleine franche australe page 26
2. ↑ « FRANCE 5 - Programmes, vidéos et replay - Pluzz FRANCE 5 », sur france5.fr (consulté le 1^er septembre 2020).
3. ↑ «Eubalaena australis. TONS of FUN ! » sur bioweb.uwlax.edu(consulté le 28 mai 2016)

Ainmhí mór is ea an ceartmhíol mór an deiscirt.

Is síol ainmhí é an t-alt seo. Cuir leis, chun cuidiú leis an Vicipéid.
Má tá alt níos forbartha le fáil i dteanga eile, is féidir leat aistriúchán Gaeilge a dhéanamh.

Calosidades na cabeza de Eubalaena australis.

Sopro en forma de "V" característico.

Escultura de Eubalaena australis en Tasmania.

Observadores de baleas cerca da península Valdés.

A balea franca austral,^[2] Eubalaena australis (Desmoulins, 1822), é unha especie de cetáceo misticeto da familia dos balénidos, descrita en 1822 por Desmoulins como Balaena australis.^[3]

É unha das tres especies do xénero Eubalaena, as coñecidas como baleas francas, que anteriormente foron clasificadas como unha soa especie,^[4] e que son denominadas así (baleas francas = baleas fáciles de cazar) porque nadan lentamente, son moi confiadas e, cando morren, flotan na auga, o que facilita moito os labores dos baleeiros que as cazaban. Por iso, na nomenclatura internacional, coñécese como balea franca austral.

Características

As proincipais caracetrísticas de Eubalaena australis son as seguintes:^[5]

• Moi semellante ás outras baleas francas ten o corpo repoludo, de até os 13 ou 15 m nos machos e ao redor dos 16 nas femias, e un peso que oscila entre as 30 e as 80 t. Ao naceren miden de 3 a 5 m, e pesan ao redor dunha tonelada.
• A cabeza é e grande, e presenta calosidades, zonas de pel elevadas de máis de 5 cm de grosor e consistencia córnea. A distribución, dimensións e forma destes calos varían dunha balea a outra pero non cambian co crecemento, polo que funcionan a xeito de pegadas dactilares que identifican a cada animal durante toda a súa vida. Estas calosidades, desenvolvidas xa na etapa fetal, son de cor gris escuro, e presentan densas poboacións de pequenos crustáceos anfípodos ciámidos (ou piollos das baleas) que, nalgunhas ocasións, se intercalan con cirrípedes que fan que as calosidades se vexan brancas, amarelas, alaranxadas ou de cor rosa clara.
• Dentro da boca, de forma curva, a mandíbula superior sostén unhas 260 barbas de até uns 2,50 m de longo, coas que filtran o krill e outros pequenos crustáceos dos que se alimentan.

Distribución

Eubalaena australis é unha especie de distribución circumpolar, rexistrándose a súa presenza polo menos entre os 20º S e os 55º S. Reprodúcense en inverno nas costas do subcontinente suramericano, principalmente nas da Arxentina e do Brasil, aínda que tamén algúns individuos o fan nas de Chile e o Perú, e nas da illa de Tristan da Cunha, sur de África, principalmente nas da República Surafricana, chegando até Mozambique e as costas occidentais de Madagascar, sur de Australia, Tasmania e Nova Zelandia, migrando en verán cara ás augas frías da Antártida,^[5][6] onde se encontran principalmente entre as latitudes 40º S e 50º S,^[6] aínda que tamén se puideron ver, especialmente nos últimos anos, tan ao sur como nos 65° S,^[7] e nos arredores de Xeorxia do Sur.^[8]

Poboación

A Comisión Baleeira Internacional realizou a súa última revisión importante das baleas francas austrais en 1998 (CBI 2001), constatando que, tras o grave esgotamento histórico pola caza comercial, varias subpoboacións reprodutoras (Arxentina, Brasil, Suráfrica e Australia) mostraron evidencias dunha forte recuperación, cun tempo de duplicación de 10-12 anos.^[9][10][11]

As outras subpoboacións de cría aínda son moi pequenas, e os datos dispoñíbeis son insuficientes para determinar se se están a recuperar. Calcúlase que el tamaño total da poboación a partir de 1997 era de 7 500 animais (dos cales 1 600 eran femias maduras, incluíndo 547 da Arxentina e 659 de Suráfrica), e as tres principais subpoboacións continuaron aumentando a unha taxa similar desde entón.^[12][13]

As capturas ilegais da Unión Soviética (principalmente na década de 1960) inhibiron temporalmente a recuperación, pero en xeral a poboación parece que medrou bastante desde entón.

Parece que hai un intercambio substancial entre os criadeiros do mesmo continente, por exemplo entre Arxentina e Brasil,^[14] pero a taxa de intercambio é moito menor entre subpoboacións afastadas xeograficamente, por exemplo, entre as de Australia e Nova Zelandia,^[15] e entre as da Arxentina e Tristán da Cunha.^[16]

Comportamento

Como as outras baleas francas, Eubalaena australis nada lentamente, pero tamén pode facer acrobacias: saltos, golpes na auga coas aletas pectorais e diversos movementos coa aleta caudal, coa que pode facer o pino, axitando a cola perpendicularmente ao vento até 2 minutos utilizándoa como vela de navegación, posto que a manobra fai que seo animal se deslice libremente pola auga. Isto parece que se trata dunha forma de xogo, xa que polo xeal nadan atçé o punto de partida para repetir o deslizamento.^[5]

Cando efectúan as inmersións, a cabeza sae moito da auga, mostrando as súas calosidades, e lanzando o típico sopro en "V" das baleas francas, que adoita ter unha altura duns 5 m; despois a cabeza desaparece por debaixo da superficie, e o único que se ve é o dorso ancho, liso, sen aleta dorsal e sen calosidades.^[5]

Ameazas e medidas de protección

As baleas francas austrais foron cazadas intensamente por baleeiros premodernos a partir de principios do século XVII, pero especialmente nos séculos XVIII e XIX por baleeiros americanos e europeos.

Aínda que non se conservan moitos rexistros, pénsase que o número total de animais capturados entre 1770 e 1900 foron uns 150 000, dos cales entre 48 000 e 60 000 foron tan só na década de 1830.^[17]

Cando comezou a caza de baleas moderna, a principios do século XX, a especie xa era moi rara, e as capturas até que as baleas comezaron a estar algo protexidas a partir de 1935 ascenderon a só uns 1 600 exemplares. Sobre 3 000 animais foron capturados ilegalmente polas frotas baleeiras soviéticas na década de 1960.^[18]

A poboación hemisférica en 1770 estímase entre 55 000 e 70 000 individuos, e se cre que descendeu até un mínimo de cerca de 300 animais na década de 1920.

A especie probabelmente comezou a recuperarse despois de protección iniciada en 1935, pero as capturas ilegais soviéticas na década de 1960 fixeron que, segundo estimacións, se eliminara á metade da poboación existente neses momentos, e que se atrasara a súa recuperación.^[17]

Debido á intensa caza da que foi obxecto, chegou, por tanto, e como a súa conxénere do norte, Eubalaena glacialis, case a extinguirse. No século XIX, a súa poboación se reducira até un 90 %. Pero desde a moratoria de 1986 a poboación da especie experimentou un aumento aproximado do 7 % nos últimos anos (ver máis arriba), e na actualidade existen aproximadamente 8 000 exemplares.

Para protexer esta especie, en 1984 a Arxentina sancionou a lei 23094 pola que se declaraba Monumento natural a todas as baleas francas austrais que se visualicen nas súa augas xurisdicionais. Tal decisión se fundamentou na imperiosa necesidade de outorgarlle a debida protección a esta especie animal que se reproduce en aguas austrais, e que é motivo da práctica do moderno turismo de avistamento de baleas na península Valdés, na Patagonia. Hai un crecente interese na posibilidade de crear un santuario para la preservación de esta especie no Atlántico sur.^[19]

Estado de conservación

Nos anos 1990, o status da poboación de Eubalaena australis era considerado como vulnerábel:

• 1994 – Vulnerábel (Groombridge 1994)
• 1990 – Vulnerábel (IUCN 1990)
• 1988 – Vulnerábel (IUCN Conservation Monitoring Centre 1988)

Nos últimos tempos a IUCN, dado o tamaño da poboación estimada recente (1 600 femias maduras en 1997 e aproximadamente o duplo deste número en 2007), e o forte incremento da taxa observada nalgunhas partes moi estudadas da área de distribución da especie, a poboación actual, aínda que sendo escasa en relación coa súa riqueza histórica, non se considera ameazada a nivel hemisférico. Estímase que a poboación agora é maior do que era hai tres xeracións (87 anos, supoñendo un tempo de xeración de 29 anos).^[20]

Algunhas subpoboacións, en particular s de Chile e Perú, aínda son moi pequenas e poden necesitar protección especial pata que se restableza. Porén, a UICN cualificou en 2013 o estado global da especie como "LC" (pouco preocupante).^[17]

Notas

Véxase tamén

Bibliografía

• Carwardine, Mark (1995): Ballenas, delfines y marsopas. Barcelona: Ediciones Omega. ISBN 84-282-1037-3.
• Perrin, William F., Bernd Wursig & J. G. M. Thewissen (eds.) (2002): Encyclopedia of Marine Mammals. 2ª ed. San Diego, California: Academic Press. ISBN 978-0-12-373553-9.
• Schokkenbroek, Joost C. A. (2008): Trying-out: An Anatomy of Dutch Whaling and Sealing in the Nineteenth Century, 1815-1885. Amsterdam: Aksant Academic Publishers. ISBN 978-90-5260-283-7.
• Tönnesen, J. N. & Arne Odd Johnsen (1982): The history of modern Whaling. London: C. Hurst & Co. ISBN 978-0-905838-23-6; Canberra: Australian National University Press. ISBN 978-0-7081-0749-2; Berleley: University of California Press. ISBN 0-520-03973-4.
• Wilson, D. E. & Reeder, D. M. (eds.) (2005): Mammal Species of the World. A Taxonomic and Geographic Reference. Third edition. ISBN 0-8018-8221-4.

Outros artigos

• Cetáceos
• Misticetos
• Balénidos
• Eubalaena

La balena franca australe (Eubalaena australis (Desmoulins, 1822)) è un mammifero marino appartenente alla famiglia Balaenidae. A causa della lentezza e del suo modo fluttuante di nuotare è stata una delle specie di cetacei maggiormente cacciata nel periodo compreso tra il XVII ed il XX secolo^[2]. Dalla carcassa di un solo esemplare, che aveva la caratteristica di galleggiare appena ucciso, si ottenevano grandi quantità di olio. È una specie protetta dal 1937.

Descrizione

La balena australe ha un corpo grasso e tozzo e la pelle è liscia. Il colore prevalente è il nero, con macchie bianche distribuite in modo casuale sul ventre e, raramente, sulla schiena. Sono stati comunque osservati individui di colore blu-nero, marron chiaro e perfino bianco scuro. La testa è grossa fino ad un quarto del corpo e caratterizzata da appariscenti callosità (escrescenze di pelle dura), che formano disegni diversi in ogni individuo e, per tale ragione, sono utilizzate dai ricercatori per l'identificazione degli animali. Il corpo è inoltre ricoperto dai pidocchi delle balene. La lunghezza complessiva è compresa fra i 14 ed i 18 metri, per un peso medio di 54 tonnellate. Non è presente la pinna sul dorso e le pinne pettorali assumono la forma di un ventaglio, mentre la pinna caudale è ampia e arrotondata. La bocca è dotata di un numero di fanoni variabile tra i 200 ed i 270, molto stretti, lunghi fino a tre metri e di colore variabile dal grigio scuro al nero^[3].

Biologia

Comportamento

Come avviene per altre specie di balene, anche la balena franca australe è una specie migratrice, compiendo spostamenti di lungo raggio che possono raggiungere distanze medie superiori ai 1000 chilometri. Durante l'estate vivono a sud, nelle acque dell'Australia occidentale, della Georgia del Sud e della Penisola Antartica, preferendo zone di acque profonde, con elevata concentrazione di zooplancton e caratterizzate da fondali ripidi. Durante l'inverno migrano a nord, a latitudini più temperate, nelle acque oceaniche temperate sub-antartiche della Nuova Zelanda, dove partoriscono in acque calme e poco profonde in prossimità della costa. Si muovono in gruppi composti da un numero di esemplari compreso tra due e sette, prevalentemente formati da individui di sesso maschile, ma guidati da una femmina^[4].

Alimentazione

La specie si nutre di copepodi e krill^[4].

Riproduzione

Le femmine raggiungono la maturità sessuale all'età di nove anni e partoriscono ogni tre anni circa. Il corteggiamento avviene durante l'inverno, in prossimità della costa, ed il periodo di gestazione ha la durata di circa un anno. I piccoli, alla nascita, hanno una lunghezza media di 5,5-6 metri. Le femmine tendono a partorire e ad allattare la prole in determinati siti. Il periodo di svezzamento è compreso tra i 303 ed i 419 giorni^[4].

Distribuzione e habitat

La balena australe è diffusa soprattutto nelle acque subantartiche, tra i 20° ed 55° di latitudine sud. Migrano a sud durante l'estate, alla ricerca di zone con krill abbondante, ed a nord durante l'inverno, soprattutto lungo le coste dell'Australia, della Nuova Zelanda, dell'America meridionale e del Sudafrica, per accoppiarsi, partorire ed allattare. Durante l'inverno e la primavera sono maggiormente distribuite in prossimità della linea di costa^[5].

Le balene australi sono facilmente avvistabili, per un certo periodo dell'inverno e della primavera australi, da gran parte della costa del Sudafrica. La località di Hermanus, nella provincia di Western Cape, è particolarmente rinomata per il whale watching, perché le balene si spingono annualmente fin dentro la baia in cui sorge la città. Altro luogo eccellente per l'avvistamento è la Penisola di Valdés, in Argentina.

Conservazione

A livello internazionale la specie è protetta ai sensi dell'Accordo internazionale per la regolazione della caccia alla balena, sottoscritto a Londra nel 1937 ed al quale è seguita la Convenzione internazionale per la regolazione della caccia alla balena, firmata a Washington il 2 dicembre del 1946 dai delegati di Argentina, Australia, Brasile, Canada, Cile, Danimarca, Francia, Paesi Bassi, Nuova Zelanda, Norvegia, Perù, Regno Unito, Stati Uniti d'America, Unione delle Repubbliche Socialiste Sovietiche ed Unione Sudafricana. Secondo il Trattato ne è vietata la caccia^[6]. La specie è inserita nell'Appendice I del CITES, che ne proibisce ogni commercio; l'uso può essere concesso solo in circostanze eccezionali^[7]. È inoltre inserita nell'Appendice I della Convenzione sulle specie migratorie come specie migratoria minacciata di estinzione, vietandone il prelievo^[8]. Nel 2008 è stata inserita nella lista rossa IUCN e, benché la popolazione della specie sia in aumento, esistono ancora alcuni piccoli gruppi di individui, al largo delle coste del Cile e del Perù, che necessitano di una protezione speciale affinché il loro numero possa ristabilirsi^[1].

In Argentina, per effetto della legge N° 23.094 del 1984, tutti gli esemplari della specie che nuotano nelle acque territoriali argentine sono dichiarati monumento naturale nazionale e, per questa ragione, è garantito loro un elevato livello di protezione^[2].

Note

Bibliografia

• (EN) Thomas A. Jefferson, Stephen Leatherwood, Marc A. Webber, Balaenidae (PDF), in Marine mammals of the world, Roma, FAO, 1993, pp. 44-45, ISBN 92-5-103292-0. URL consultato l'8 novembre 2010.
• (EN) Cetacean Specialist Group 1996, Eubalaena australis, su IUCN Red List of Threatened Species, Versione 2020.2, IUCN, 2020.
• (EN) Randall R. Reeves, Brian D. Smith, Enrique A. Crespo, Giuseppe Notarbartolo di Sciara, Dolphins, Whales and Porpoises: 2002–2010 Conservation Action Plan for the World’s Cetaceans (PDF), Gland, Cambridge, IUCN, 2003, ISBN 2-8317-0656-4. URL consultato il 7 novembre 2010.
• (EN) D.E. Wilson e D.M. Reeder, Eubalaena australis, in Mammal Species of the World. A Taxonomic and Geographic Reference, 3ª ed., Johns Hopkins University Press, 2005, p. 723, ISBN 0-8018-8221-4.

Eubalaena australis (ang. Southern Right Whale) – bedantis banginis, viena iš trijų rūšių, priklausančių genčiai Eubalaena. Aptinkamas Pietų Pusrutulio vandenyse.

Aprašymas

Suaugęs individas siekia 15 m^[1] ir gali sverti iki 47 tonų.^[1] Eubalaena australis rūšies atstovų sėklidės yra didžiausios iš visų gyvūnų, kiekviena sveria apie 500 kg. Tai reiškia, jog spermatozoidų konkurencija yra svarbi poravimosi metu.^[2]

Elgesys

„Buriavimas“

Kaip ir kiti tikrieji banginiai, jie yra gana aktyvūs prie vandens paviršiaus. Vienas iš išskirtinių šių banginių bruožų yra jų „buriavimas“.

Šaltiniai

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