Elops machnata

Status_ne_offStatus_dd_offStatus_lc_onStatus_nt_offStatus_vu_offStatus_en_offStatus_cr_offStatus_ew_offStatus_ex_off

Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA ACTINOPTERYGII ELOPIFORMES ELOPIDAE

Scientific Name: Elops machnata
Species Authority: (Forsskål, 1775)
Synonym(s):
Argentina machnata Forsskål, 1775
Elops capensis Smith, 1838-47
Taxonomic Notes: E. machnata and E. hawaiensis occur sympatrically in the Western Pacific and possibly the Hawaiian Islands, so further research appears warranted.  In the northern south China Sea, for example, Shao et al. (2008) claim that E. hawaiensis historically reported in the region are misidentifications of E. machnata.    Wang et al. (2002) state that genetic data is now available to discriminate between E. machnata and E. hawaiensis.

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2012
Date Assessed: 2011-03-30
Assessor(s): Adams, A., Guindon, K., Horodysky, A., MacDonald, T., McBride, R., Shenker, J. & Ward, R.
Reviewer(s): Harwell, H. & Raynal, M.
Facilitator/Compiler(s): Harwell, H.
Justification:

Elops machnata is distributed in the Indo-West Pacific from the Red Sea to East Africa, South Africa, Seychelles, Madagascar and western Mascarenes east to Philippines. The unknown extent of commercial fisheries and the magnitude of harvest suggest a potential threat to this species. Its early stages use estuary and lagoonal habitats, which are prone to anthropogenic alterations but this species exhibits a broad range of habitat plasticity. Population trends are currently stable in eastern Africa, Indian Ocean but are unknown throughout the rest of its expansive range. We therefore globally consider this species as Least Concern in the absence of known threats. However, a number of questions remain regarding its taxonomic uncertainty, population status, fisheries interactions and potential threats in the eastern part of its range. Future monitoring is needed, particularly in the Coral Triangle, where significant declines in other Elopiformes has been inferred.

Geographic Range [top]

Range Description:Elops machnata is distributed in the Indo-West Pacific from the Red Sea to East Africa, South Africa, Seychelles, Madagascar and western Mascarenes (extinct in Réunion) east to Philippines; possibly Hawaiian Islands (Eschmeyer and Fong 2008).



 


Countries:
Native:
Australia; Bangladesh; Cambodia; China; Djibouti; Egypt; Eritrea; India (Andaman Is., Nicobar Is.); Indonesia; Israel; Japan; Jordan; Kenya; Malaysia; Maldives; Mozambique; Myanmar; Philippines; Saudi Arabia; Singapore; Somalia; South Africa; Sri Lanka; Sudan; Taiwan, Province of China; Tanzania, United Republic of; Thailand; Viet Nam; Yemen
FAO Marine Fishing Areas:
Native:
Atlantic – southeast; Indian Ocean – eastern; Indian Ocean – western; Pacific – northwest; Pacific – western central
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population: Overall population trends are currently stable in eastern Africa, Indian Ocean but are unknown throughout the rest of its expansive range.

Elops machnata
was dominant in mangrove clear-cut areas in Tanzania, but was found in relatively low abundances compared to the undisturbed areas. Results of the study done by Mwandya et al. (2009) indicate that mangrove habitat loss and changes in environmental conditions caused by salt farm developments will decrease fish densities, biomass and species numbers as well as alter the overall fish assemblage composition in the salt farm area but not downstream in the creek. Also in the St. Lucia Estuary, South Africa, Mann et al. (2002) ranked E. machnata eigth by numbers and fifth by weight in the recreational catch. Catch per unit effort (CPUE) was stable from 1986 to 1989.

In Thukela Estuary, South Africa, a trend of declining fish abundance with increasing river flow was observed. CPUE (average number of fish sampled per seine haul) for E. machnata was recorded at 28 individuals per haul in 1997 and 0 in 1999. This decline is probably due to a combination of high river discharge and zero salinities throughout the system, with many marine species then finding temporary refuge in the sea. The pattern observed in Thukela Estuary of declining fish abundance and lack of colonization of the estuary during high river flow conditions has been observed in other estuaries and river mouths of southern Africa (Whitfield and Paterson 1995, Ter Morshuizen et al. 1996, and South America (Garcia et al. 2001, Garcia and Vieira 2002).

There was an increase in gill net CPUE in the Sundays and Swartkops estuaries of South Africa between late 1970s and 1992–1993. There was also an increase in percentage composition of anglers' catches from 1.9% in 1972–78 to 2.2% in 1988–93 in Swartkops estuary (Mann and Radebe 1999).

Pradervand and Baird (2002) report a creel survey for one year (1996–1997) in Eastern Cape, South Africa.
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: Elops machnata adults inhabit shallow coastal areas and commonly enter estuaries, particularly larger subtropical estuaries which are permanently open. Harrison and Whitfield (2006) categorized E. machnata as a eurythermic tropical species found widely into subtropical and warm temperate regions. Whitfield (2005) reports no Elops spp. in cool-temperate estuaries. It may be found in turbid water and has a wide salinity tolerance. Juveniles are common in warm, turbid estuaries on which they are dependent as nursery areas (Mann and Radebe 1999). Elops machnata was recorded from 0–90 ppt in St. Lucia Estuary, South Africa (Whitfield et al. 2006). Maximum size recorded is 118 cm FL (International Game Fish Association 2001).

Elops machnata is piscivorous (Marais 1984). Whitfield and Blaber (1978) report that crustaceans and molluscs are also consumed.

Alikunhi and Rao (1951) describe leptocephalus metamorphosis and early growth of E. machnata (erroneously called E. saurus) in an estuary of the Bay of Bengal in India.
Systems: Marine

Use and Trade [top]

Use and Trade: In South Africa, this species is an important component of estuarine sport anglers' catches. It is also taken by rock and surf anglers, recreational skiboat anglers and spearfishers. It is particularly popular with saltwater fly anglers. It is caught by subsistence and artisanal fishers using fish traps and gill-nets (Mann and Radebe 1999). Kemp et al.  (2009) state that this species is a no sale species in South Africa. In Hong Kong, Elops spp. are harvested from shrimp farm ponds (Cha et al. 1997). The flesh has been described as "insipid and full of bones" (Smith and Heemstra 2003).

Threats [top]

Major Threat(s): Results of the study done by Mwandya et al. (2009) indicate that mangrove habitat loss and changes in environmental conditions caused by salt farm developments will decrease fish densities, biomass and species numbers as well as alter the overall fish assemblage composition in the salt farm area but not downstream in the creek. The unknown extent of commercial fisheries and the magnitude of harvest suggest a potential threat to this species. Its early stages use estuary and lagoon habitats, which are prone to anthropogenic alterations. However, population trends are currently stable in St. Lucia Estuary, South Africa and this species is exhibits a broad range of habitat plasticity.

In South Africa, this species is an important component of estuarine sport anglers' catches. It is also taken by rock and surf anglers, recreational skiboat anglers and spearfishers. It is particularly popular with saltwater fly anglers. It is caught by subsistence and artisanal fishers using fish traps and gill-nets (Mann and Radebe 1999).

Conservation Actions [top]

Conservation Actions: In South Africa, there is a bag limit of five fish/per person/day. There is no sale for this species (Crook and Mann 2002).

Its distribution overlaps with a number of marine reserves in parts of its range.

Bibliography [top]

Alikunhi, K.H. and Rao, S.N. 1951. Notes on the metamorphosis of Elops saurus Linn, and Megalops cyprinoides (Broussonet) with observations on their growth. Journal of the Zoological Society of India 3: 99-109.

Cha, M.W., Young, L. and Wong, K.M. 1997. The fate of traditional extensive (gei wai) shrimp farming at the Mai Po Marshes Nature Reserve, Hong Kong. Hydrobiologia 352: 295-303.

Crook, B.J.S. and Mann, B.Q. 2002. A critique of and recommendations for a subsistence fishery, Lake St Lucia, South Africa. Biodiversity and Conservation 11: 1223-1225.

Eschmeyer, W.N. and Fong, J.D. 2008. Species by Family/subfamily in the Catalog of Fishes . Available at: http://research.calacademy.org/research/ichthyology/catalog/SpeciesByFamily.asp. (Accessed: March 29, 2011).

Garcia, A.M. and Vieira, J. 2002. The link between El Niño, freshwater outflow and the dynamics of an estuarine fish assemblage in south Brazil. In: Shepton Mallet: Wood and Woods (eds), Bulletin Number 41. Estuarine and Coastal Sciences Association.

Garcia, A.M., Vieira, J.P. and Winemiller, K.O. 2001. Dynamics of the shallow-water fish assemblage of the Patos Lagoon Estuary (Brazil) during cold and warm ENSO episodes. Journal of Fish Biology 59: 1218-1238.

Harrison, T.D., Whitfield, A.K. 2006. Estuarine typology and the structuring of fish communities in South Africa. Environmental Biology of Fishes 75: 269-293.

International Game Fish Association (IGFA). 2001. Database of IGFA angling records until 2001. IGFA, Fort Lauderdale, USA.

IUCN. 2012. IUCN Red List of Threatened Species (ver. 2012.2). Available at: http://www.iucnredlist.org. (Accessed: 17 October 2012).

Kemp, L.V., Branch, G.M., Attwood, C.A. and Lamberth, S.J. 2009. The ‘fishery’ in South Africa’s remaining coastal stonewall fish traps. African Journal of Marine Science 31: 55-62.

Mann, B.Q. and Radebe, P.V. 1999. Elops machnata. In: B.Q. Mann (ed.), Southern African Marine Linefish Status Reports, pp. 265. South African Association for Marine Biological Research, Marine Parade.

Mann, B.Q., James, N.C. and L.E. Beckley. 2002. An assessment of the recreational fishery in the St Lucia estuarine system, KwaZulu-Natal, South Africa. South African Journal of Marine Science 24: 263-279.

Marais, J.F.K. 1984. Feeding ecology of major carnivorous fish from four eastern Cape estuaries. South African Journal of Zoology 19(3): 210-223.

Martin, T.J., Cyprus, D.P. and Forbes, A.T. 1992. Episodic events: the effects of cyclonic flushing on the ichthyoplankton of St. Lucia estuary on the southeast coast of Africa. Netherlands Journal of Sea Research 30: 273-278.

Mwandya, A.W., Gullström, M., Öhman, M.C., Andersson, M.H., Mgaya, Y.D. 2009. Fish assemblages in Tanzanian mangrove creek systems influenced by solar salt farm constructions. Estuarine, Coastal and Shelf Science 82(2): 193–200.

Pradervand, P. and Baird, D. 2002. Assessment of the recreational linefishery in selected Eastern Cape estuaries: trends in catches and effort. South African Journal of Marine Science 24: 87-101.

Smith, M.M. and Heemstra, P.C. 1986. Smith's Sea Fishes. Spinger-Verlag, Grahamstown.

Ter Morshuizen, L.D., Whitfield, A.K. and Paterson, A.W. 1996. Influence of freshwater flow regime on fish assemblages in the Great Fish River and estuary. South African Journal of Aquatic Sciences 22: 52-61.

Whitfield, A.K. 2005. Preliminary documentation and assessment of fish diversity in sub-Saharan African estuaries. African Journal of Marine Science 27: 307-324.

Whitfield, A.K. and Blaber, S.J.M. 1978. Food and feeding ecology of piscivorous fishes at Lake St Lucia, Zululand. Journal of Fish Biology 13(6): 675?691.

Whitfield, A.K. and Harrison, T.D. 2003. River flow and fish abundance in a South African estuary. Journal of Fish Biology 62: 1467-1472.

Whitfield, A.K. and Paterson, A.W. 1995. Flood-associated mass mortality of fishes in the Sundays estuary . Water South Africa 21: 385-389.

Whitfield, A.K., Taylor, R.H., Fox, C. and Cyrus, D.P. 2006. Fishes and salinities in the St Lucia system — a review. Reviews in Fish Biology and Fisheries 16: 1-20.


Citation: Adams, A., Guindon, K., Horodysky, A., MacDonald, T., McBride, R., Shenker, J. & Ward, R. 2012. Elops machnata. In: The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 25 July 2014.
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