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Bigbelly Seahorse Hippocampus abdominalis Lesson, 1827
[CAAB 37 282120]

Distribution Map see an interactive map here (new window)

The Bigbelly Seahorse was, until recently, thought to be widely distributed throughout south-eastern Australia, from off NSW to the South Australian Gulf regions. The southern population is now considered to be Hippocampus bleekeri. Further research is required to clarify whether the two species are distinct.

Distribution, ecology and habitat:

Temperate waters of New Zealand and southeastern Australia, where it occurs from Newcastle to about Eden, NSW; pelagic juveniles may be carried further south by the Eastern Australian Current; benthic in shallow estuaries, usually on low rocky reefs where they cling to kelp holdfasts (Ecklonia radiata), in deep tidal channels usually clinging to sponges, or on deeper coastal reefs to more than 20 m.

Size:

Height to 180 mm.

Food and feeding:

Feeds by sucking up small epibenthic invertebrates such as carid and mysid shrimps and amphipods.

Reproduction and early life history:

Reproduction: The sexes are separate and reproduction is a form of viviparity or ovoviviparity, whereby the males give birth to tiny independent young. The female uses an ovipositor to transfer her eggs into an elaborate enclosed pouch under the abdomen of the male. The male not only fertilizes the eggs inside the pouch and provides physical protection for the developing embryos, he also osmoregulates and aerates the embryos and may provide some nourishment until the offfspring are born. Spawning occurs from October to January and young are born after a gestation period of about 4 weeks.
Eggs: Eggs undescribed; brood about 300, maximum over 700.
Larvae: Morphologically similar to adults; newly hatched larvae are slender, 16 mm in length, with a relatively straight body at birth, bending to adult form within 1-2 days; young rise to surface immediately after emerging from pouch and grasp debris with their tail; settle to the bottom at around 20-30 mm.

Characteristics:

Meristics: D 25-28; A 4; P 15-16; trunk rings 12-13; tail rings 44-45; subdorsal rings 3-4 + 1-2.
Head and body: Body slender, elongate; trunk of moderate depth to deep, distended ventrally in adult females; head small, at right angles to body; snout usually short; tail prehensile.
Spines and tubercles: Spines becoming progressively smaller in juveniles, remaining as low rugose tubercles in large adults. Subdorsal spines 4/0,0,1,1 or 5/0,0,1,1,1. Tubercles enlarged above eyes, on trunk mainly below the dorsal fin, and along shoulder ring at gill-opening with one of moderate size ventrally.
Coronet: Coronet very low, adults with a rugose apex.
Fins: Dorsal-fin base moderately long.
Lateral line: Lateral line visible as small indistinct pores with low papillae, usually only detectable intermittently, reaching posteriorly to about 30^th tail ring.

Colour:

Variable, overall whitish, grey, yellow or brown, usually with black spots on
head and trunk. Those in shallow bays usually brown with many dark spots, whilst those from deep water plain but with brighter colours similar to sponges on which they live. Tail sometimes with indistinct bands. In preservative - pale brown, head and trunk plain to spotted, tail sometimes with indistinct banding.

Similar species:

Very similar to H. bleekeri, differing in having a smaller head, a much shorter snout, fewer spines, no nape spine and in more commonly having head filaments.

Fisheries:

Specimens are occasionally taken as bycatch in commercial trawls. Captive-bred specimens are reared commercially in a number of Australian States and live individuals are collected as broodstock for aquaculture operations. Both wild caught and aquarium-reared individuals are sold within Australia and exported overseas for the live aquarium trade. Dried specimens are sold in Asia in the Traditional Medicine industry.

Conservation Status:

International: Listed under Appendix II of the Convention on the International Trade in Endangered Species of Wild Flora and Fauna (CITES).
Listed as Data Deficient on the 2008 IUCN Red List of Threatened species.

Australian Government Legislation: Marine Listed under the Federal Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act 1999).

Remarks:

Contention exists as to whether the east coast H. abdominalis is distinctly different from the more southern H. bleekeri. Genetic studies did not find strong evidence supporting more than one species Further research is needed to confirm these findings.

Other common names:

Big-bellied seahorse, Big-belly seahorse, Pot-bellied seahorse, Eastern pot-belly seahorse.

Original citation:

Hippocampus abdominalis Lesson 1827, Bull. Sci. nat Férussac 12: 127, New Zealand.

Etymology:

Hippocampus is from the Greek, ippos = horse and kampe = curvature. The specific name abdominalis refers to the enlarged and prominent abdomen.

References:

Armstrong, P. 2001. Genetic and Morphological Variation in Pot-bellied Seahorses (Hippocampus abdominalis): Is there evidence for two species? Unpublished B.Sc. (Hons.) thesis, University of Tasmania.

Foster, S.J. & A.C.J. Vincent. 2004. Life history and ecology of seahorses: implications for conservation and management. J. Fish Biol. 65: 1-61.

Francis, M.P. 1998. Coastal fishes of New Zealand: an identification guide. Reed Books, Auckland, New Zealand.

Hoese, D.F., D.J. Bray, J.R. Paxton & G.R. Allen. 2006. Fishes. In: Beesley, P.L. & A. Wells. (eds.) Zoological catalogue of Australia. Volume 35. ABRS & CSIRO Publishing: Australia, 2178 pp.

Kuiter, R.H. 1993. Coastal Fishes of South-Eastern Australia. Crawford House, Bathurst, NSW, 437 pp.

Kuiter, R.H. 2000. Seahorses, pipefishes and their relatives. Chorleywood, UK: TMC Publishing, 240 pp.

Kuiter, R.H. 2001. Revision of the Australian Seahorse of the genus Hippocampus (Syngnathiformes: Syngnathidae) with descriptions of nine new species. Rec. Aust. Mus. 53: 293-340.

Lesson, R.P. 1827. Espèce nouvelle d'Hippocampe. Bull. Sci. Nat. Geol. (Férussac) 11: 127-128.

Lourie, S.A., S.J. Foster, E.W.T Cooper & A.C.J. Vincent. 2004. A Guide to the Identification of Seahorses. Project Seahorse and TRAFFIC North America, University of British Columbia and World Wildlife Fund, Washington D.C.

Lourie S.A., A.C.J. Vincent & H.J. Hall. 1999. Seahorses: an identification guide to the world's species and their conservation. Project Seahorse. London UK. 214 pp.

Martin-Smith, K.M. & A.C.J. Vincent. 2006. Exploitation and trade of Australian seahorses, pipehorses, sea dragons and pipefishes (Family Syngnathidae). Oryx, 40(2): 141-151.

Neira F.J., Miskiewicz A.G. & Trnski T. (1998) Larvae of temperate Australian fishes: laboratory guide for larval fish identification. University of Western Australia press, Nedlands, Western Australia.

Paulin, C. & C. Roberts. 1992. The Rockpool Fishes of New Zealand. Museum of New Zealand, Wellington.

Pogonoski, J.J., D.A. Pollard & J.R. Paxton. 2002. Conservation Overview and Action Plan for Australian Threatened and Potentially Threatened Marine and Estuarine Fishes. Canberra, Environment Australia, 375 pp.

Poortenaar , C.W., C.M.C. Woods, P.J. James, F.M. Giambartolomei & P.M. Lokman. 2004.  Reproductive biology of female big-bellied seahorses. J. Fish Biol. 64: 717-725.

Woods, C.M.C. 2000. Preliminary observations on breeding and rearing the seahorse Hippocampus abdominalis (Teleostei: Syngnathidae) in captivity. N. Z. J. Mar. Freshw. Res. 34: 475-485.

Woods, C.M.C. 2002. Natural diet of the seahorse Hippocampus abdominalis. N. Z. J. Mar. Freshw. Res. 36: 655-660.

Woods, C.M.C. 2003. Growth and survival of juvenile seahorse Hippocampus abdominalis reared on live, frozen and artificial foods. Aquaculture 220(2): 287-298.

Woods, C.M.C. 2005. Reproductive output of male seahorses, Hippocampus abdominalis, from Wellington Harbour, New Zealand: implications for conservation. N. Z. J. Mar. Freshw. Res. 39(4): 811-888.

Woods, C.M.C. & K.M. Martin-Smith. 2004. Visible Implant fluorescent Elastomer tagging of the big-bellied seahorse, Hippocampus abdominalis. Fisheries Res. 66(3): 363-371.

Woods, C.M.C., Morgan, S.K., Martin-Smith, K., Pogonoski, J.J., Paxton, J.R., Pollard, D.A. & Morgan, A.J. 2006. Hippocampus abdominalis. In: IUCN 2008. 2008 IUCN Red List of Threatened Species. <http://www.iucnredlist.org/>. Downloaded on 09 April 2009.