Gymnura natalensis

• Overview
• Interesting Facts
• Common Names
• Description
• Taxonomy
• Similar Species
• More Info
• Further Reading
• Notes

Overview

Family : Butterfly rays ; Occurs off sandy beaches, muddy estuaries and offshore banks. Found singly or in large groups[1]. Feeds on a variety of fishes , crabs and polychaete worms[1]. Ovoviviparous[2]. Ability to change markings and color to blend into environment[3]. Caught by offshore trawlers [1]. Caught by shore anglers , it is prized for its strong fight when hooked , often released[1].

Interesting Facts

Common Names

Click on the language to view common names.

Description

Habitat

Typically found in water with a depth of 0 to -5,744 meters (0 to -18,845 feet).[4]

Ecology: Habitat
This species occurs close inshore , especially off sandy beaches as well as on offshore banks down to 75 m (Compagno et al. 1989, Smith 1991). Fennessy (1994) found that the species occurs more frequently in the deeper trawls (33 to 45 m) on the Tugela Bank. He observed no diel pattern for this species. Gymnura natalensis is also found in river estuaries (Wallace 1967, Compagno et al. 1989, Smith 1991) and lagoons (Wallace 1967).

Behaviour
Although normally solitary, large shoals have been spotted, often comprising animals of one sex (van der Elst 1988). Single rays tend to be found on the seabed, whereas shoals are often found in the midwater region (van der Elst 1988). Young (2001) found, between 1981 and 2001, 37 occurrences of three or more diamond rays caught in the same Natal Sharks Board (NSB) net installation in one or two days. The majority was of mixed sex and 19 groups were caught off Durban. Most of these multiple catches took place in October and November.

Seasonality
Gymnura natalensis occurs year round (common in Natal throughout the whole year; Wallace 1967) with a peak abundance in December/January (van der Elst 1988). Fennessy (1994) also found that in trawl catches diamond rays occurred more frequently during summer. This differs from the findings of Young (2001), who examined NSB net captures between 1981 and 2000. She found that catches occurred throughout the year, but peaked in October and November (40.5% of total catch) and declined sharply in December. Despite a slight increase during June and July, catches remained low for the rest of the year. Females outnumbered males during warmer months (December to May), while males were more numerous during the cooler period. However, overall both sexes were more common in catches during the cooler months and this association was significant (Young 2001). The sex ratio of NSB catches between 1981 and 2000 was 1:0.92 (m:f) (Young 2001).

Reproduction and Maturity
Wallace (1967) examined a shoal of 28 male specimens caught in Durban nets October 1964. Animals ranged between 109.7and 131.4 cm DW and appeared to be sexually mature . Gravid females (146.2 and 188.0 cm DW) with 5 to 9 embryos were recorded in Durban Bay during January, February, March, June and August. The largest embryo was 38.2 cm DW/453.6 g. A number of the glandular villi, which clothe the uterine walls of the mother, are always found inserted into the spiracular openings of the embryos, suggesting that some of the uterine ?milk? is absorbed this way (Wallace 1967). Van der Elst (1988) states gestation period is one year. The smallest mature male dissected at the NSB was 96.4 cm DW and the smallest mature female was 166.9 cm DW (NSB, unpubl. data ).

According to the length-age curve of van der Elst (1988), diamond rays are ~24 years old at ~250 cm DW /120 kg . Using the above maturity lengths from Wallace (1967), males mature at approximately two years (~100 cm DW/10 kg) and females at approximately six years (~150 cm DW/25 kg).

Smallest free-swimming specimen: 46.8 cm DW (Wallace 1967); 37 to 39 cm field length (NSB unpubl. data).
Largest embryo: 38.2 cm DW (Wallace 1967).
Maximum reported size: 250 cm DW (Smith 1991).
Largest observed animal: 182 cm DW (Wallace 1967); 250 cm DW, 200 cm field length (dubious!) (NSB, unpubl. data).
South Africa angling record : 89.8 kg (Wallace 1967, van der Elst 1988).

Tagged by NSB between 1996 and 2002: 25 animals, no recaptures to date (NSB, unpubl. data). Tagged by shore anglers between 1984 and 2002: 1,766 animals, 10 recaptures (0.57% recapture rate), which includes washed-up tags . Maximum distance moved: 151 km , maximum time at liberty: 330 days (Bullen et al. 2003).

Diet : flat-fish, sardine, gurnard, mole crabs, worms, crabs and squid (van der Elst 1988, Compagno et al. 1989, Smith 1991, Smale et al. 2001). (Ref. 275892).

List of Habitats:

•     9     Marine Neritic   
  
•     9.1     Marine Neritic - Pelagic   
  
•     9.10     Marine Neritic - Estuaries   
  
•     10     Marine Oceanic   
  
•     10.1     Marine Oceanic - Epipelagic (0-200m)   
  
•     13     Marine Coastal/Supratidal   
  
•     13.4     Marine Coastal/Supratidal - Coastal Brackish/Saline Lagoons/Marine Lakes   
[more info]

Taxonomy

Synonyms

Gymnura natalensis • Pteroplatea natalensis • Pteroplatea natalensis Gilchrist & Thompson, 1911 • Pteroplatea natalensis Gilchrist & Thompson • Urogymnus natalensis (Gilchrist & Thompson

Notes

Name Status: Accepted Name .

Last scrutiny: Data last modified by FishBase 19-Oct-2000

See Wallace (1967) and Smith (1991).[5].

Similar Species

Members of the genus Gymnura

ZipcodeZoo has pages for 13 species and subspecies in this genus:

G. altavela (Spiny Butterfly Ray) · G. australis (Australian Butteryfly Ray) · G. bimaculata (Twin-Spot Butterfly Ray) · G. crebripunctata (Longsnout Butterfly Ray) · G. hirundo (Madeira Butterfly Ray) · G. japonica (Japanese Butterfly Ray) · G. marmorata (California Butterfly Ray) · G. micrura (Smooth Butterfly Ray) · G. natalensis (Backwater Butterfly Ray) · G. poecilura (Long-Tailed Butterfly Ray) · G. tentaculata (Tentacled Butterfly Ray) · G. zonura (Zonetail Butterfly Ray) · G. poecilura (Madeira Butterfly Ray)

More Info

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Further Reading

• Al Sakaff, H. and M. Esseen (1999). Occurrence and distribution of fish species off Yemen (Gulf of Aden and Arabian Sea). Naga ICLARM Q. 22(1):43-47.
• Anonymous. 2004. Report on the implementation of the UN FAO International Plan of Action for Sharks (IPOA?Sharks). AC20 Inf. 5. Twentieth meeting of the CITES Animals Committee, Johannesburg (South Africa), 29 March?2 April 2004.
• Begg, G.W. 1993. Initial assessment concerning the potential environmental impact of removing shark nets from the marine environment (March 1993). Environmental Advisory Services Investigational Report 361:1?16.
• Bianchi, G. 1985. Field guide to the commercial marine and brackish-water species of Tanzania. FAO species identification sheets for fishery purposes. Food and Agriculture Organization of the United Nations (FAO), Rome, Italy.
• Bianchi, G., Carpenter, K.E., Roux, J.-P., Molloy, F.J., Boyer, D. and Boyer, H.J. 1999. Field guide to the living marine resources of Namibia. FAO, Rome, Italy.
• Bullen, E., Mann, B.Q. and Everett, B.I. (eds). 2003. ORI Tagging News (16):12pp.
• Compagno, L.J.V., D.A. Ebert and M.J. Smale (1989). Guide to the sharks and rays of southern Africa. New Holland (Publ.) Ltd., London. 158 p.
• Compagno, L.J.V., Ebert, D.A. and Smale, M.J. 1989. Guide to the sharks and rays of Southern Africa. Struik, Cape Town. 160 pp.
• Eschmeyer, William N., ed. 1998. Catalog of Fishes. Special Publication of the Center for Biodiversity Research and Information, no. 1, vol 1-3. California Academy of Sciences. San Francisco, California, USA. 2905. ISBN: 0-940228-47-5.
• Fennessy, S.T. 1994. Incidental capture of elasmobranchs by commercial prawn trawlers on the Tugela Bank, Natal, South Africa. South African Journal of Marine Science 14:287-296.
• Fischer, W., Sousa, I., Silva, C., de Freitas, A., Poutiers, J.M., Schneider, W., Borges, T.C., Feral, J.P. and Massinga, A. 1990. Fichas FAO de identificaçao de espécies para actividades de pesca. Guia de campo das espécies comerciais marinhas e de águas salobras de Moçambique. Publicaçao preparada em collaboraçao com o Instituto de Investigaçao Pesquiera de Moçambique, com financiamento do Projecto PNUD/FAO MOZ/86/030 e de NORAD. Food and Agricultural Organization of the United Nations (FAO), Rome, Italy.
• Heemstra, P.C. 1995. Additions and corrections for the 1995 impression. In: M.M Smith and P.C Heemstra (eds). Revised edition of Smiths' sea fishes. pp:v?xv. Springer-Verlag, Berlin.
• Hutchings, K. and Lamberth, S.J. 2002. Bycatch in the gillnet and beach-seine fisheries in the Western Cape, South Africa, with implications for management. South African Journal of Marine Science 24: 227?241.
• IUCN SSC Shark Specialist Group. Specialist Group website. Available at: http://www.iucnssg.org/.
• IUCN. 2006. 2006 IUCN Red List of Threatened Species. www.iucnredlist.org. Downloaded on 04 May 2006.
• Lamberth, S.J., Bennett, B.A. and Clark, B.M. 1994. Catch composition of the commercial beach-seine fishery in False Bay, South Africa. South African Journal of Marine Science 14:69?78.
• Pradervand, P. 1999. National Marine Linefish System: Recorded catches of cartilaginous fishes in the KwaZulu-Natal recreational linefishery (1995?1998). Data Report 1999/99.2:4pp+x. (Durban, South Africa).
• Pradervand, P. 2003. National Marine Linefish System: Temporal trends in catches of dominant elasmobranch species in the shore-based competition fishery along the KwaZulu-Natal coast. Data Report 2003/5:4pp+III. (Durban, South Africa).
• Pradervand, P. 2004. Long-term trends in the shore fishery of the Transkei coast, South Africa. African Zoology 39(2):247?261.
• Pradervand, P. and Govender, R.D. 2003. Assessment of catches in shore angling competitions from the border region of the Eastern Cape, South Africa. African Zoology 38(1):1?14.
• Shark Specialist Group. For more information, see the Specialist Group website.
• Smale, M.J. 1997. Trade in sharks and shark products in South Africa. In: N.T. Marshall and R. Barnett (eds). The Trade in sharks and shark products in the Western Indian and Southeast Atlantic Oceans. pp:80?100. TRAFFIC East/Southern Africa, Nairobi.
• Smale, M.J., Sauer, W.H.H. and Roberts, M.J. 2001. Behavioural interactions of predators and spawning chokka squid off South Africa: towards quantification. Marine Biology 139(6):1095?1105.
• Smith, M.M. and Heemstra, P.C (eds.) 1991. Smiths? Sea Fishes. 1st edition. Southern Book Publishers, Johannesburg.
• Van der Elst, R. 1988. A guide to the common sea fishes of Southern Africa, 2nd edition. Struik, Cape Town
• Wallace, J.H. 1967. The batoid fishes of the east coast of southern Africa. II. Manta, eagle, duckbill, cownose, butterfly and sting rays. Investigational Report. Oceanographic Research Institute, Durban 16
• Young, N. 2001. An analysis of the trends in by-catch of turtle species, angelsharks and batoid species in the protective gillnets off KwaZulu-Natal, South Africa. MSc thesis, University of Reading

Notes

Contributors

• Bisby, F.A., Y.R. Roskov, M.A. Ruggiero, T.M. Orrell, L.E. Paglinawan, P.W. Brewer, N. Bailly, J. van Hertum, eds (2007). Species 2000 & ITIS Catalogue of Life: 2007 Annual Checklist. Species 2000: Reading, U.K.
• Brands, S.J. (comp.) 1989-present. The Taxonomicon. Universal Taxonomic Services, Zwaag, The Netherlands. Accessed January 15, 2012.
• FishBase 2006.
• FishBase. Release date: January 5, 2010
• Global Biodiversity Information Facility. Accessed March 01, 2008. http://www.gbif.org Mediated distribution data from 2 providers.
• IUCN 2012. IUCN Red List of Threatened Species. Version 2011.2. . Downloaded on January 28, 2012.
• McEachran, John (from FishBase).
• Ruggiero M., Gordon D., Bailly N., Kirk P., Nicolson D. (2011). The Catalogue of Life Taxonomic Classification, Edition 2, Part A. In: Species 2000 & ITIS Catalogue of Life: 2011 Annual Checklist (Bisby F.A., Roskov Y.R., Orrell T.M., Nicolson D., Paglinawan L.E., Bailly N., Kirk P.M., Bourgoin T., Baillargeon G., Ouvrard D., eds). DVD; Species 2000: Reading, UK.
• Wintner, S.P. 2006. Gymnura natalensis. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <www.iucnredlist.org>. Downloadedon 01February2012.
• Wintner, S.P. 2006. In IUCN 2008. 2008 IUCN Red List of Threatened Species. IUCNRedList.org. Downloaded July 18, 2008.

Data Sources

Accessed through GBIF Data Portal March 01, 2008:

• FishBase: FishBase DiGIR Provider - Philippine Server
• Institute of Marine and Coastal Sciences, Rutgers University: iziko South African Museum - Fish Collection
• Institute of Marine and Coastal Sciences, Rutgers University: iziko South African Museum - Shark Collection
• Institute of Marine and Coastal Sciences, Rutgers University: Marine and Coastal Management - Demersal Surveys (years 1986-1990)
• Institute of Marine and Coastal Sciences, Rutgers University: Marine and Coastal Management - Demersal Surveys (years 1991-1995)
• Institute of Marine and Coastal Sciences, Rutgers University: Marine and Coastal Management - Demersal Surveys (years 2001-2005)
• Institute of Marine and Coastal Sciences, Rutgers University: Marine and Coastal Management - Demersal Surveys (years 2006-)

Identifiers

• Biodiversity Heritage Library NamebankID: 128114
• Catalogue of Life Accepted Name Code: Fis-15849
• Fishbase Species ID: 5508
• Global Biodiversity Information Facility Taxonkey: 13527330
• Integrated Taxonomic Information System (ITIS) Taxonomic Serial Number (TSN): 564413
• IUCN ID: 212482
• Zipcode Zoo Species Identifier: 112005

Footnotes

1. Compagno, L.J.V., D.A. Ebert and M.J. Smale (1989). Guide to the sharks and rays of southern Africa. New Holland (Publ.) Ltd., London. 158 p. [back]
2. Dulvy, N.K. and J.D. Reynolds (1997). Evolutionary transitions among egg-laying, live-bearing and maternal inputs in sharks and rays. Proc. R. Soc. Lond. B 264:1309-1315. [back]
3. Compagno, L.J.V. (1986). Dasyatidae. p. 135-142. In M.M. Smith and P.C. Heemstra (eds.) Smiths' sea fishes. Springer-Verlag, Berlin. [back]
4. Mean = -169.490 meters (-556.070 feet), Standard Deviation = 887.750 based on 73 observations. Ocean depth information for each observation from British Oceanographic Data Centre. [back]
5. Wintner, S.P. 2006. Gymnura natalensis. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <www.iucnredlist.org>. Downloaded on 01 February 2012. [back]

©2004-2012 David Stang. All rights reserved.