|Scientific Name:||Heteronarce garmani|
|Species Authority:||Regan, 1921|
Heteronarce regani von Bonde & Swart, 1923
Narcine natalensis Fowler, 1925
|Red List Category & Criteria:||Vulnerable A2d+4d ver 3.1|
|Assessor(s):||de Carvalho, M.R. & McCord, M.E.|
|Reviewer(s):||Fowler, S.L. & Valenti, S.V. (Shark Red List Authority)|
Very few specimens of this apparently rare Southern African endemic electric ray have been caught since this species was described in 1921, despite much scientific sampling having occurred on the shelf and upper slope region. The status of the Natal Electric Ray (Heteronarce garmani) is of concern because it occurs from 73-329 m deep in an area of heavy commercial fishing pressure from both trawl and longline vessels in which it is known to be captured. Fishing pressure is unlikely to decrease or cease in this area. Discards of elasmobranchs in South African bottom trawl operations are estimated to be high (80-90%) and catches in the Natal prawn fishery are known to be dominated by small rays. Significant declines have been reported in similar species where they are heavily fished. Although little specific information is available on this species' population status, given its apparent rarity and known high, continuing fishing pressure throughout its limited range, it is assessed as Vulnerable on the basis of suspected declines of >30% as a result of continuing high levels of exploitation.
|Range Description:||Southeast Atlantic and southwest Indian Ocean: South Africa, found on the continental shelf from Algoa Bay to Natal (Compagno et al. 1989) and off southern Mozambique (Heemstra 1995).|
Native:Mozambique; South Africa
|FAO Marine Fishing Areas:||
Atlantic – southeast; Indian Ocean – western
|Lower depth limit (metres):||329|
|Upper depth limit (metres):||73|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Very few specimens of this apparently rare Southern African endemic electric ray have been caught since this species was described in 1921, despite much scientific sampling having occurred on the shelf and upper slope region.|
|Current Population Trend:||Unknown|
|Habitat and Ecology:||The Natal Electric Ray is caught in continental shelf waters of 73-329 m depth (Smith and Heemstra 1995). It has been recorded from canyons (at between 100 and 200 m depth) near Sodwana Bay, Natal. Nothing is known of the biology or life-history of this species; it reaches a maximum size of at least 25 cm total length (TL) (Smith and Heemstra 1995).|
Fisheries operate throughout this species' depth range, offering it little refuge from fishing pressure. H. garmani is caught as incidental bycatch in trawl and longline fisheries in areas that are historically and currently heavily fished.
Potentially the greatest impact on chondrichthyans in South African waters is from the large bottom-trawl fisheries directing at the Cape hakes Merluccius paradoxus and M. capensis (Japp 1999). The offshore and inshore fisheries target hake, sole and horse mackerel. Annual demersal landings, including all shark and other bycatch in the South African trawl fisheries varies from year to year and in 1995 approximated 180,000 t (In recent years this figure has been reported to be well above 200,000 t). Japp (1997) estimated discards of elasmobranchs in South African bottom trawl operations at between 80-98% (depending on the area), i.e., between 2-20% of those caught in trawl nets are processed (Japp 1999). Fennessey (1994) reported extensively on the elasmobranch bycatch in the Natal prawn fishery, and pointed out that catches were dominated by small rays.
All of South Africa's main commercial fisheries are believed to be fully exploited with the only possible exception being the mid-water directed fishery for Horse mackerel (Japp 1999). Although there are no species-specific catch data for H. garmani, and it is not known to be utilised, it is taken as bycatch in these fisheries.
Despite species-specific data on catches and population trends generally lacking for most electric rays, significant declines have been documented where data are available for species that have been heavily fished (e.g., Narcine bancroftii). The electric ray, N. bancroftii, occurs in the western Atlantic, matures at a very early age (two years) and is relatively fecund (up to 20 pups per litter). Despite this, Shepherd and Myers (2005) documented declines in N. bancroftii, to 2% (95% confidence intervals 0.5 to 5%) of its baseline abundance in 1972 in the Northern Gulf of Mexico, most probably caused by intense shrimp trawling. Similar declines were also documented in Narcine bancroftii in US trawl surveys and diver surveys off Florida (Carvalho et al. 2007).
There are a number of Marine protected areas (MPA's) implemented along the coast of South Africa that coincide with this species range (Wood 2007).
There are no species specific conservation measures in place. Further biological and fisheries data are required to assess any future conservation needs. Catches require monitoring.
The development and implementation of management plans (national and/or regional e.g., under the FAO International Plan of Action for the Conservation and Management of Sharks: IPOA-Sharks) are required to facilitate the conservation and management of all chondrichthyan species in the region.
|Citation:||de Carvalho, M.R. & McCord, M.E. 2009. Heteronarce garmani. The IUCN Red List of Threatened Species 2009: e.T161746A5494167. http://dx.doi.org/10.2305/IUCN.UK.2009-2.RLTS.T161746A5494167.en . Downloaded on 13 October 2015.|