Degraer, Steven

Messiaen, Marlies

Vandendriessche, Sofie

Vincx, Magda

English

Ghent University Academic Bibliography

Belg. J. Zool., 135 (1) : 101-102 January 2005Juvenile Hippocampus guttulatus from a neuston tow atthe French-Belgian borderSofie Vandendriessche, Marlies Messiaen, Magda Vincx and Steven DegraerMarine Biology Section, Biology Department, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumE-mail corresponding author : Sofie.Vandendriessche@UGent.beKEY WORDS : Seahorse, neuston, floating debris.The long-snouted seahorse Hippocampus guttulatusCuvier, 1829 occurs mostly in shallow inshore watersamong algae and eel grass (Zostera or Posidonia) andalso in littoral lagoons (1). The species can be found inthe Eastern Atlantic from the British Isles to Morocco,including the Canary Islands, Madeira and the Azores (2).The presence of the long-snouted seahorse in Belgianwaters was already suspected (see CITES appendix II)but never confirmed. Hippocampus ramulosus Leach,1814 is regarded as an invalid synonym of this species,although this name is still widely used for what is now H.guttulatus (2).The sampling station where Hippocampus guttulatuswas found is situated between the sandbanks Buiten Ratelen Oost Dyck (UTM 5674450 - 460236.7), on the French-Belgian border (Fig. 1). This station was investigated dur-ing a sampling campaign on August 20th (2003) with theresearch vessel ‘Zeeleeuw’. The sample was taken with arectangular neuston net (2m x 1m, 1mm mesh) fromwhich only the lower 50cm is immersed, thereby sam-pling the upper 50cm of the water column. Identificationsof the specimens, which were preserved in a 10% formal-dehyde-seawater solution, are based on characteristicsdescribed by LOURIE et al. (2).The neuston sample contained two well-preservedjuveniles (approximately 3 to 4 weeks old) of the speciesHippocampus guttulatus. Most of the examined charac-teristics (Table 1) are within the range for both Hippoc-ampus guttulatus and H. hippocampus (i.e. number oftrunk rings, number of tail rings, number of pectoral finrays, number of dorsal fin rays). However, the ratio ofsnout length to head length (> 1/3) certainly suggests thatthese specimens are H. guttulatus or the European long-snouted seahorse, and the number of pectoral fins on oneof the specimens is consistent with it being H. guttulatus.Both specimens lack a mane of thick skin fronds on neckand head, usually seen in adults (Fig. 2).460000 470000 480000 490000 500000 510000Easting (m) 572000057100005700000569000056800005670000 )m( gnihtroNNUTM-zone 31 (ED-50)OostendeZeebruggeFig. 1. – Sampling station Hippocampus guttulatus (blackcross) and fishermen’s catches of Hippocampus hippocampus(grey areas) in Belgian marine waters (border represented byblack lines)TABLE 1Examined identification characteristicsfor both specimensSpecimen 1 Specimen 2Overall height 2.93 cm 3.51 cmNumber of trunk rings 11 11Number of tail rings 36 37Snout length / head length 0.42 0.42Coronet Rounded knobsSpine development Blunt and well-developedPectoral fin rays 15 16Dorsal fin rays 18 18Cheek spine Low and bluntEye spine Prominent, roundedFig. 2. – Photograph of specimen 2Sofie Vandendriessche, Marlies Messiaen, Magda Vincx and Steven Degraer102This is the first reported catch of Hippocampus guttula-tus for the Belgian waters, and the origin of the specimensis unclear. Although there are numerous records forsouthern Britain, it is unlikely that specimens could reachthe Belgian coast due to their poor swimming ability andthe lack of assisting currents (3). On the other hand, thepresence of a local population seems unlikely becausefrom 1997 onwards, only Hippocampus hippocampuswas occasionally caught by local fishermen (Table 2,Fig. 1). As the specimens were caught near the sea sur-face, it is likely that they were carried to the Belgiancoastal zone through the English Channel in associationwith floating debris (the sample contained decaying duck-weed, plant seeds and pieces of plastic). However, thepresence of seahorses (and their fry) in the neuston isquite uncommon. Only Hippocampus erectus has alreadybeen reported from the neuston in association with float-ing debris and vegetation (4, 5, 6).As the entire genus Hippocampus is listed in AppendixII of CITES (Convention on International Trade inEndangered Species of Wild Fauna and Flora) and bothH. guttulatus and H. hippocampus are listed as Data Defi-cient by IUCN (World Conservation Union), it is mostimportant to gather information on the presence and per-sistence of local populations of seahorse species to formthe basis of legal protection and conservation. Hopefully,this note will be the starting point for a detailed record ofBelgian seahorse catches.ACKNOWLEDGEMENTSFirst, the authors would like to show their gratitude to NeilGarrick-Maidment, Sara Lourie and Janelle Curtis for theirassistance with the species identifications, and to Hans Hille-waert for editing the photograph. The list of seahorse catches byfishermen was composed by Eddy Eneman from the OostendeNorth Sea Aquarium. Special thanks go to André Cattrijsse ofthe Flanders Marine Institute (VLIZ), and to the crewmembersof the research vessel Zeeleeuw. The first author acknowledgesa specialisation grant from the ‘Flemish Institute for the Promo-tion of Scientific-Technological Research’ (IWT).REFERENCES1. LELONG, P. (1995). Hippocampe moucheté, Hippocampusramulosus. Océanorama (Institut Océanographique PaulRicard), 24 : 19-20.2. LOURIE, S.A., A.C.J. VINCENT & H.J. HALL (1999).Seahorses : an identification guide to the world’s species andtheir conservation. Project Seahorse, London.3. GARRICK-MAIDMENT, N. (1998). A note on the status ofindigenous species of seahorse. J. Mar. Biol. Ass. UK, 78 :691-692.4. POWELL, A.B., D.G. LINDQUIST & J.A. HARE (2000). Larvaland pelagic juvenile fishes collected with three types of gearin Gulf Stream and shelf waters in Onslow Bay, North Caro-lina, and comments on ichthyoplankton and hydrography.Fish. Bull. 98 : 427-438.5. CASTRO, J.J., J.A. SANTIAGO & A.T. SANTANA-ORTEGA(2001). A general theory on fish aggregation to floatingobjects : an alternative to the meeting point hypothesis.Reviews in fish biology and fisheries, 11(3) : 255-277.6. TEIXEIRA, R.L. & J.A. MUSICK (2001). Reproduction andfood habits of the lined seahorse, Hippocampus erectus(Teleostei : Syngnathidae) of Chesapeake Bay, Virginia.Brazilian Journal of Biology, 61(1) : 79-90TABLE 2Recent seahorse catches (Hippocampus hippocampus) by local fishermen in Belgian marine watersYear Date Num-berMethod of capture /vessel Capture site Destination of sea horses Remarks1997 May 4 Coastal fisheries – Oostende North Sea Aquar-iumalive1998 14-20 March 1 – 3 nautical miles from Zee-brugge– –1998 24 July 1 Shrimp fisheries / O.211 - Died and was discarded During night1998 22 September 7 Gill net / N.95 Between 51 12.70 N- 02 29.70E and 51 15.43N – 02 32.99Ereleased Associated with Alcyonidium1998 23 September 14 Aquarium of skipper-ship owner1998 24 September 33 Oostende North Sea Aquar-ium1998 25 September 66 Sealife Blankenberge1999 24 June 1 Coastal fisheries / O.101 – – –1999 10 July 1 Coastal fisheries / O.152 – – Dead but no signs of decay1999 14 July 1 O.20 – – Pregnant male1999 – – N.95 Between 51 12.70 N- 02 29.70E and 51 15.43N – 02 32.99E– Skipper is convinced of the presence of a local population2000 28 September 1 O.190 Westpit fishing grounds – Dead2001 17 February 1 Gill net / O.369 – – –2001 18 August 1 Coastal fisheries / O.190 – – –2001 25 September 1 Coastal fisheries / O.190 – – Male2002 11 September 1 O.191 Fishing grounds near Oosten-debank– –2004 20 April 1 O.190 Wenduinebank – –2004 21 May 1 O.20 3 nautical miles from Oost-ende– AliveReceived: June 8, 2004Accepted: December 10, 2004

Juvenile Hippocampus guttulatus from a neuston tow at the French-Belgian border

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Juvenile Hippocampus guttulatus from a neuston tow at the French-Belgian border

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