Basking Shark, Cetorhinus maximus (Gunnerus 1765)


Other Names: Sunfish

A Basking Shark, Cetorhinus maximus, with its mouth wide open straining plankton from the water column. Source: Chris Gotschalk / Wikimedia Commons. License: CC by Attribution

Summary:

Next to the mighty Whale Shark, the Basking Shark is the second largest living fish in the world, growing to a length of more than 12 metres. Despite its huge size and enormous mouth, the basking shark is a harmless pelagic filter feeder, straining zooplankton from the water with thousands of bristle-like gill rakers.

Basking sharks have a pointed snout with an enormous mouth and five huge gill slits that almost encircle the head. The first dorsal, pectoral and pelvic fins are large, while the second dorsal and anal fins are small; the caudal fin is lunate, or almost moon-shaped. The body is dark greyish-brown to almost black with a mottled pattern.

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Basking Shark breaching off Staffa, Inner Hebrides, Scotland.

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Article on marine debris caught around the snout of a Basking Shark in Scotland.


Cite this page as:
Bray, D.J. 2023, Cetorhinus maximus in Fishes of Australia, accessed 20 Jul 2024, https://fishesofaustralia.net.au/home/species/1847

Basking Shark, Cetorhinus maximus (Gunnerus 1765)

More Info


Distribution

Worldwide in cool temperate coastal seas and oceanic waters, occasionally venturing into subtropical waters.

Basking sharks are rare in Australian waters, being only known from scattered localities, mostly along the south coast - from north of Port Stephens (New South Wales) to Busselton (Western Australia), including Bass Strait and around Tasmania.

Although often seen at the surface, basking sharks undertake extensive vertical migrations to deep water. They may spend much of their time at mesopelagic depths, feeding on small fishes, invertebrates and zooplankton. One individual was recorded to a depth of over 1200 metres. Basking sharks usually occur near or at the surface in temperate waters, and at depths below the thermocline, in tropical waters.

Their habit of 'basking' at the surface may be a way of warming their bodies after long times feeding in cold waters below 200 metres.

Basking Sharks follow summer plankton blooms and are seasonally abundant in some parts of the world. 

Features

Vertebrae: 107-110 (precaudal 50-53)

Body stout, streamlined, head large, snout pointed, eye small; 5 extremely long gill slits extend from the top to the underside of the head; mouth huge, extending well beyond the eye, with rows of minute curved teeth in jaws; first dorsal, pectoral and pelvic fins large, second dorsal and anal fins small, caudal fin crescent-shaped, lower lobe somewhat smaller than upper lobe.

Size

Although basking sharks can grow to a length of more than 12 metres, and a weight of about 7 tonnes, most individuals are smaller. The smallest known Basking Shark measured about 1.7 metres, and very few young sharks have been encountered.

Colour

Dark greyish-brown to almost black with a mottled pattern.

Feeding

Basking sharks are ram filter feeders, and use thousands of bristle-like gill rakers to strain huge quantities of zooplankton from the water column. They are known to feed on crustacean larvae, copepods, euphasids, fish eggs, small fishes, chaetognaths and other zooplankton.

Biology

Despite being the second largest fish in the world and having been fished for centuries, much is yet to be learned about this huge filter-feeding shark. 

Basking sharks are aplacental viviparous (ovoviviparous). This means that the embryos develop within the uterus without a placenta to provide nourishment. Females produce a very large number of eggs, indicating that embryonic oophagy (egg-eating) may occur as it does with other lamniform sharks (the developing embryos feed on unfertilised eggs within the uterus). Females give birth to litters of up to 6 pups after a gestation period of more than one year. At birth the pups measure about 1.5-2 metres in length, and juveniles less than 3 metres in length are rarely encountered.

Male basking sharks mature between 5-7 metres in length, and females mature between 8-10 metres. 

Fisheries

Basking sharks were historically hunted for the oil in their livers which provided lighting (including for street lamps) and was used in early industries. The skin was also tanned for leather, and the flesh used for food or fishmeal.

The species has been fished for meat, liver oil and cartilage (Compagno 2001; Hoelzel 2001). Their large fins are also in high demand for sale in the Asian shark fin trade. Basking sharks are also taken as by-catch in a number of fisheries around the world.

Basking sharks are especially vulnerable to over-exploitation because they mature slowly, taking about 12–20 years, and females have long gestation periods (approx. 1-3 years) after which they give birth to few offspring (Compagno 2001).

Conservation

  • IUCN Red List: Endangered
  • CITES: listed under Appendix II

    The Basking Shark is CITES-listed due to the value of its fins in the international shark-fin trade. The species is also protected in some parts of the world.

    Basking sharks grow slowly, are slow to mature, and have a long gestation period - making the species extremely vulnerable to overfishing.

  • Remarks

    In November 1883, a Basking Shark was captured off Portland Victoria and transported to Melbourne via the railway. In his Prodromus of the Zoology of Victoria, Frederick McCoy describes this specimen, and tells the tale of it being hauled up Swanston Street, Melbourne to be put on display during race week (in the heat)!

    "The extraordinary circumstances of the individual I have here figured and described having come so far south gives special interest to this specimen, which was caught in November, 1883, at Portland, on the Western coast of Victoria. It, as often happens in the northern hemisphere, to which, until this occurrence, it was supposed to be confined, was found entangled in the nets of the fisherman, and having wrapped the nets round itself by rolling and struggling, it became exhausted and was killed. In other countries where fisherman have recorded their meetings with this monster, the accounts agree in showing it to be a quiet, sluggish creature quite destitute of the ferocity of the other Sharks, swimming along showing its back and dorsal fin above the water, and with its mouth open to catch its small, floating food, like a Whale, and when basking quietly on the surface being so indifferent to the approaching of a boat that the man may feel it without any alarm or movement or anger on the part of the Shark, unless harpooned, when it darts to the bottom with great force and velocity, and unlike a Whale, which must come up to breathe, it stays below, making it a dangerous captive for any ordinary fishing vessel.

    I have here noted, the red pulpy mass filling the intestines of our example being altogether composed of body and shells of a species of the Cuvieria or Triptera, rather less than a line long, fusiform, pointed, and slightly arched at the posterior end, mouth contracted, oblique (which might be named Cuvieria minor), the mass being tinted of a "boiled-shrimp" red from the remains of the soft parts, colored like the much larger Triptera rosea of Quoy and Gaimard. I owe the knowledge of this food to my vigilant friend, Mr. M. Dusting, of Portland, who sent me a sample he had taken from the intestines when giving me notice of the capture of this Shark, the species of which he correctly recognised.

    This is the largest species of the whole class of Fishes, and as, like many Whales, and unlike other Sharks, it migrates in shoals of one to two hundred individuals, each of which is worth from 30 pounds to 50 pounds, it is of great value where any peculiarity in the ocean induces it to come regularly within reach of the fishermen. The liver only is taken. The liver weighs about two tons, and yields 10 or 12 barrels (eight to the ton) of the finest oil, like spermaceti. The specimen figured, after its liver was taken out, was brought by railway to Melbourne, and attracted crowds in the streets as it came up Swanston-street on two of the largest lorries fastened together, drawn by a long train of horses to a stable-yard, where it was exhibited during the race week; the hot weather rendering it useless as a specimen for the Museum afterwards. The teeth and portion of skin were preserved, and all the measurements and drawings completed before it defied approach."

    Some teeth and a small piece of skin, all that remains of this mighty specimen, are registered in the Fish Collection at Museum Victoria, in Melbourne, Australia.

    Etymology

    The specific name is from the Latin maximus (= great). 

    Species Citation

    Squalus maximus Gunnerus 1765, Det Trondhiemske Selskabs Skrifter: 33, Pl. 2 Type locality: Nordland County, northern Norway

    Author

    Bray, D.J. 2023

    Resources

    Atlas of Living Australia

    Australian Faunal Directory

    Catalog of Fishes

    Basking Shark, Cetorhinus maximus (Gunnerus 1765)

    References


    Ali, M., Saad, A., Reynaud, C. & Capapé, C. 2012. Occurrence of Basking Shark, Cetorhinus maximus (Elasmobranchii: Lamniformes: Cetorhinidae), off the Syrian coast (Eastern Mediterranean) with first description of egg case. Acta Ichthyologica et Piscatoria 42 (4): 335-339. http://dx.doi.org/10.3750/AIP2012.42.4.07

    Compagno, L.J.V. 2001. Sharks of the world: an annotated and illustrated catalogue of shark species known to date. Volume 2. Bullhead, Mackerel and Carpet Sharks (Heterodontiformes, Lamniformes and Orectolobiformes). FAO. Rome, Italy.

    Duffy, C.A.J. 2015. 12 Family Cetorhinidae. pp. 68-69 in Roberts, C.D., Stewart, A.L. & Struthers, C.D. The Fishes of New Zealand. Wellington : Te Papa Press Vol. 2 pp. 1-576.

    Francis, M.P. & Duffy, C. 2002. Distribution, seasonal abundance and bycatch composition of basking sharks Cetorhinus maximus, in New Zealand, with observations on their winter habitat. Marine Biology 140(4): 831-842.

    Francis, M.P. & Duffy, C. 2002. Distribution, seasonal abundance an dbycatch composition of basking sharks Cetorhinus maximus in New Zealand, with observations on their winter habitat. Marine Biology 140(4): 831-842.

    Gilmore, R.G. 1993. Reproductive biology of lamnoid sharks. Environmental Biology of Fishes 38: 95-114.

    Gore, M.A., Rowat, D., Hall, J., Gell, F.R. & Ormond, R.F. 2008. Transatlantic migration and deep mid-ocean diving by basking shark. Biology Letters 4(4): 395–398.

    Harvey-Clark, C. J., Stobo, W. T., Helle, E. & Mattison, M. 1999. Putative mating behaviour in basking sharks off the Nova Scotia coast. Copeia 1999: 780-782.

    Hoelzel, A.R., M.S. Shivji, J. Magnussen & M.P. Francis. 2006. Low worldwide genetic diversity in the basking shark (Cetorhinus maximus). Biology Letters 2: 639-642. https://doi.org/10.1098/rsbl.2006.0513

    Izawa, K. & Shibata.T. 1993. A young basking shark, Cetrohinus maximus, from Japan. Japanese Journal of Ichthyology 40(2): 237-245, figs 1-4.

    Johnston, E.M., Halsey, L.G., Payne, N.L, Kock, A.A., Iosilevskii, G., Whelan, B. & Houghton, J.D.R. 2018. Latent power of basking sharks revealed by exceptional breaching events. Biology Letters 14 20180537; DOI: https://doi.org/10.1098/rsbl.2018.0537

    Kempster, R.M. & Collin, S.P. 2011. Electrosensory pore distribution and feeding in the basking shark Cetorhinus maximus (Lamniformes: Cetorhinidae). Aquatic Biology 12: 33-36.

    Last, P.R. & Stevens, J.D. 2009. Sharks and Rays of Australia. Collingwood : CSIRO Publishing Australia Edn 2, 550 pp.

    Maguire, J.-J., Sissenwine, M.P., Csirke, J., Grainger, R.J.R. & Garcia, S.M. 2006. The state of world highly migratory, straddling and other high seas fisheries resources and associated species. Fisheries Technical Report. FAO, Rome.

    Natanson, L.J., Wintner, S.P., Johansson, F., Piercy, A., et al. 2008. Ontogenetic vertebral growth patterns in the basking shark Cetorhinus maximus. Marine Ecology Progress Series 361: 267-278.

    Parker, H.W. & Stott, F.C. 1965. Age, size and vertebral calcification in the basking shark Cetorhinus maximus (Gunnerus). Zoological Mededelingen 40: 305-319.

    Pirotta, V., Grech, A., Jonsen, I.D., Laurance, W.F. & Harcourt, R.G. 2019. Consequences of global shipping traffic for marine giants. Frontiers in Ecology and the Environment 17(1): 39-47.

    Priede, I.G. & Miller, P.I. 2009. A basking shark (Cetorhinus maximus) tracked by satellite together with simultaneous remote sensing II: New analysis reveals orientation to a thermal front. Fisheries Research 95: 370-372.

    Rigby, C.L., Barreto, R., Carlson, J., Fernando, D., Fordham, S., Francis, M.P., Herman, K., Jabado, R.W., Liu, K.M., Marshall, A., Romanov, E. & Kyne, P.M. 2021. Cetorhinus maximus (amended version of 2019 assessment). The IUCN Red List of Threatened Species 2021: e.T4292A194720078. https://dx.doi.org/10.2305/IUCN.UK.2021-1.RLTS.T4292A194720078.en. Accessed on 18 July 2023.

    Sims, D.W. 1999. Threshold foraging behaviour of basking sharks on zooplankton: life on an energetic knife edge? Proceedings of the Royal Society of London B 266: 1437-1443.

    Sims, D.W. 2000. Filter feeding and cruising swimming speeds of basking sharks compared with optimal models: they filter-feed slower than predicted for their size. Journal of Marine Biology and Ecology 249: 65-76.

    Sims, D.W. & Merrett, D.A. 1997. Determination of zooplankton characteristics in the presence of surface feeding basking sharks Cetorhinus maximus. Marine Ecological Progress Series 158: 297-302.

    Sims, D.W., E J Southall, G.A. Tarling & J D Metcalfe. 2005. Habitat specific normal and reverse diel vertical migration in the plankton-feeding basking shark. Journal of Animal Ecology 74: 755-761.

    White, W. 2008. Shark Families Heterodontidae to Pristiophoridae. pp. 32-100 in Gomon. M.F., Bray, D.J. & Kuiter, R.H (eds). Fishes of Australia's Southern Coast. Sydney : Reed New Holland 928 pp.

    Quick Facts


    CAAB Code:37011001

    Biology:Live bearer

    Conservation:IUCN Endangered; CITES Listed

    Depth:0-1264 m

    Habitat:Oceanic, pelagic

    Max Size:1200+ cm TL

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    CAAB distribution map