|Scientific Name:||Carcharhinus brachyurus (Günther, 1870)|
|Infra-specific Taxa Assessed:|
Carcharhinus acarenatus Morenos & Hoyos, 1983
Carcharhinus improvisus Smith, 1952
Carcharhinus remotoides Deng, Xiong & Zhan, 1981
Carcharhinus rochensis Abella, 1972
Carcharias brachyurus Günther, 1870
Carcharias lamiella Jordan & Gilbert, 1882
Eulamia ahenea Stead, 1938
|Taxonomic Source(s):||Eschmeyer, W.N. (ed.). 2015. Catalog of Fishes. Updated 6 April 2015. Available at: http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp. (Accessed: 6 April 2015).|
|Taxonomic Notes:||Synonyms = Galeolamna greyi [synonymy uncertain] Owen, 1853; Carcharias lamiella Jordan & Gilbert, 1882; Carcharias lamia: Lahille (1928), Marini (1929), Pozzi & Bordalé (1935); Eulamia ahenea Stead, 1938; Galeolamna brachyurus: Whitley (1940); Galeolamna ahenea: Whitley (1940); Galeolamna (Galeolamnoides) eblis: Whitley (1944); Carcharhinus improvisus Smith, 1952; Carcharhinus remotus: López (1963, 1965), López & Castello (1972), Menni et al. (1984), Menni (1986); Carcharhinus rochensis Abella, 1972; Carcharhinus greyi: Scott, Glover & Southcott (1974); Carcharhinus remotoides Deng, Xiong & Zhan, 1981; Carcharhinus acarenatus, Morenos & Hoyos, 1983. References: Whitley (1940), Garrick (1982), Compagno (1984), Cappo (1992), and Chiaramonte (1998).|
|Red List Category & Criteria:||Near Threatened ver 3.1|
|Assessor(s):||Duffy, C. & Gordon, I. (SSG Australia & Oceania Regional Workshop, March 2003)|
|Reviewer(s):||Fowler, S., Lea, R., Ebert, D, Musick, J.A. & Cavanagh, R.D. (Shark Red List Authority)|
Carcharhinus brachyurus is a large coastal shark with low productivity. Although widespread, regional populations appear to be discrete, and movement of individuals between them is thought infrequent or absent, and it does not appear to be naturally abundant anywhere. C. brachyurus is assessed as Vulnerable in East Asia due to intensive fisheries and the apparent widespread collapse of fisheries for large coastal sharks. Coastal multispecies fisheries in the region are likely to continue to depress the population by taking pregnant females and juveniles. Coastal nursery areas in this region are also at risk from development and pollution.
Catches appear to be stable in Australia. In New Zealand, although there may have been some reduction in population size due to fishing, C. brachyurus is apparently still common throughout its range. Management of this species in New Zealand, Australia and South Africa is simplified by having most, if not all of the population resident within each nation's EEZ, and the species is assessed as Least Concern in these regions. However, it is assessed as Data Deficient in the East Pacific, where there is no information and it appears to be uncommon or rare.
Throughout its range, it is known to be exploited by fisheries, but landings are grouped together with other Carcharhinus species, meaning any population declines are likely to go unnoticed, and its coastal nursery areas are potentially vulnerable to development and pollution. This, together with life history characteristics that make it especially vulnerable to overfishing has led to the global assessment of C. brachyurus as Near Threatened. The situation must be monitored as this species could soon qualify for a threatened category, on the basis of population declines due to fisheries exploitation, in other areas.
|Range Description:||The range and biology of C. brachyurus is poorly known due to confusion with other large Carcharhinus species, particularly C. obscurus which often replaces it in subtropical waters (Garrick 1982, Compagno 1984, Compagno et al. 1989). Although widely distributed in warm temperate and subtropical waters, populations of C. brachyurus are disjoint and there is probably little interchange between them. Verified records from tropical regions are infrequent and very patchy but include Equatorial Guinea and possibly the Gulf of Thailand (Garrick 1982, Compagno 1984, Vidthayanon 2002). C. brachyurus was also reported to be common in the Seychelles by Marshall (in Rose 1996), however, this requires confirmation given this species preference for temperate shelf habitats. No estimates of population size or biomass are available. Global population structure is unknown. Stock structure is not known for any fished population. |
C. brachyurus is widespread in the Mediterranean but only sporadically reported possibly due to misidentification and lower abundance relative to other large sharks (Fergusson and Compagno 1995). C. brachyurus was the least abundant of the five pelagic sharks sampled in the northeast Atlantic and western Mediterranean by Muñoz-Chápuli (1984). The relationship between the Mediterranean and northeast Atlantic populations is unknown but it seems likely that pregnant females migrate from the Atlantic to breeding grounds off Morocco (Muñoz-Chápuli 1984). Stock structure in the Mediterranean is unknown. Despite being listed as common in US Atlantic shark landings by Rose (1996, pg. 26) C. brachyurus is absent from the western North Atlantic (Garrick 1982, Compagno 1984, Russell 1993, Castillo-Génez et al. 1998, J. Castro, pers. comm., L. Natanson, pers. comm., M. Grace, pers. comm.). In the southwest Atlantic C. brachyurus is relatively common off northern Argentina during summer, and is the most abundant species of Carcharhinus in Agentina (Chiaramonte 1998a, b). It is also common off Namibia and the west coast of South Africa (Compagno et al. 1989). In the Indian Ocean it is common off Eastern Cape, South Africa ranging north to Richard's Bay, Natal although it is rare north of Durban (Compagno et al. 1989, Cliff and Dudley 1992).
Range and population size is poorly known in the eastern Pacific. Although Compagno (1984) speculated that it may occur in Chile there are no documented records or specimens of C. brachyurus in Museum collections there (I. Kong, pers. comm). Philippi (1887) described two species, Hypoprion isodus and H. heterodus from Chile on the basis of two dried jaws (Garrick 1982). Garrick (1982) considered both to be species dubia placing them in Carcharhinus. The upper teeth in both jaws are too broad and the tooth counts are too low for either to be brachyurus (Garrick 1982). Garrick (1982) considered H. heterodus was likely to be C. obscurus or galapagensis. Pequeño (1989) also considered it likely H. heterodus corresponds to C. obscurus (I. Kong, pers. comm). Despite the lack of records and specimens it seems likely that C. brachyurus at least occasionally reaches northern Chilean waters from Peru. Little is known of its occurrence in Peru other than the juvenile specimens reported by Garrick (1982). C. brachyurus appears to be uncommon or rare in Mexico (Gulf of California and Baja California) but confusion with other Carcharhinus species could be a problem (O. Sosa, pers. com., L. Castillo, pers. comm.). Although very small juveniles have been collected from a number of locations in southern California suggesting it may breed there, C. brachyurus is considered to be a rare visitor to the west coast of the US (Garrick 1982, R. Lea, pers. comm., D. Ebert, pers. comm., G. Cailliet, pers. comm.). There are no records of C. brachyurus north of Point Conception (R. Lea, pers. comm), although based on what is known of its ecology in the Southern Hemisphere it could be expected to be common as far north as Monterey Bay (D. Ebert, pers. comm). This apparent rarity does not appear to be due to confusion with other species of Carcharhinus as the genus itself is rare in California (R. Lea, pers. comm). It is worth noting here that although Garrick (1982) synonymised C. lamiella with brachyurus the characters referred to in the description of lamiella were those diagnostic of C. obscurus. Consequently most records of lamiella from California are not referable to C. brachyurus (Garrick 1982). The populations in the northeast and southeast Pacific appear to be disjunct (Compagno 1984).
In Australian waters C. brachyurus is infrequently recorded north of Sydney or Perth, being most abundant between Albany (Western Australia) and Bass Strait (Last and Stevens 1994, R. McAuley, pers. comm., C. Simpfendorfer, pers. comm., J. Stevens, pers. comm.). It is the commonest Carcharhinus species in South Australia and Victoria (Cappo 1992). C. brachyurus has not been recorded from Lord Howe and Norfolk Islands (Last and Stevens 1994). In New Zealand waters C. brachyurus is common around the northern half of North Island, including Three Kings Islands, Middlesex Bank and Three Kings Rise, ranging south to Cook Strait in summer (Illingworth 1961, Garrick 1982, Francis 2001). Pregnant females and pups have been recorded as far south as Waimea Inlet, Nelson (about 41°S, C.D. unpublished data). C. brachyurus has not been recorded from the Kermadec Islands or the islands of the tropical southwest Pacific (Garrick 1982, Compagno 1984, Last and Stevens 1994, Cox and Francis 1997).
Native:Albania; Algeria; Argentina; Australia (New South Wales, South Australia, Tasmania, Victoria, Western Australia); Bosnia and Herzegovina; Brazil; China (Hebei, Jiangsu, Liaoning, Shandong, Zhejiang); Croatia; Equatorial Guinea; France; Greece; Italy; Japan (Honshu); Korea, Democratic People's Republic of; Korea, Republic of; Malta; Mauritania; Mexico (Baja California); Montenegro; Morocco; Namibia; New Zealand (North Is.); Peru; Portugal; Russian Federation; South Africa; Spain (Canary Is.); Turkey; United States (California); Uruguay
|FAO Marine Fishing Areas:|
Atlantic – eastern central; Atlantic – southeast; Atlantic – southwest; Indian Ocean – western; Indian Ocean – eastern; Mediterranean and Black Sea; Pacific – southwest; Pacific – northwest; Pacific – eastern central; Pacific – southeast
|Range Map:||Click here to open the map viewer and explore range.|
|Current Population Trend:||Unknown|
|Habitat and Ecology:||Carcharhinus brachyurus is an essentially warm temperate and subtropical species (Garrick 1982, Compagno 1984, Muñoz-Chápuli 1984, Smale 1991, Cappo 1992, Cliff and Dudley 1992, Chiaramonte 1998). It is a widespread but patchily distributed coastal and shelf species, occasionally reported from oceanic areas close to the continental shelf (Amorim et al. 1998, Marín et al. 1998, Bagley et al. 2000). It readily enters shallow water, and individuals and aggregations are often sighted in shallow bays, the surf zone and in harbour channels during summer (Ayling and Cox 1982, Cappo 1992, Last and Stevens 1994). It also occurs in brackish or freshwater in the lower reaches of large rivers and estuarine bays (Last 2002). Maximum reported depth is 100 m but it is likely to range deeper (Compagno 1984, Smale 1991, Last and Stevens 1994). Diet includes a wide variety of bottom-living and pelagic cephalopods and fishes including squid (Loligo spp.), cuttlefish, octopus, spiny dogfish (Squalus spp.), stingrays, electric rays, sawfish, gurnard, flatfish, hake, catfish, ling, jacks, kahawai/Australian salmon, mullet, sea bream, sardines and anchovy (Illingworth 1961, Compagno 1984, Comapgno et al. 1989, Smale 1991, Cliff and Dudley 1992, Last and Stevens 1994, Francis 2001). Juveniles also feed on jellyfishes (Scyphozoa) and benthic crustacea (Callianasa spp. and Penaeid shrimps) (Smale 1991). Other elasmobranchs are taken with greatest frequency by sharks over 2 m total length (Smale 1991, Cliff and Dudley 1992). |
Juvenile and adult C. brachyurus segregate by size and sex (Muñoz-Chápuli 1984, Smale 1991, Cliff and Dudley 1992, Chiaramonte 1998). Juveniles occur in shallow water (less than 30 m depth) year round, whereas adults are most abundant inshore during spring and summer. Adults and sub-adults are found over the shelf and around offshore islands and banks throughout the year. The movement of adult females inshore in spring is related to breeding. Nursery areas tend to be large and ill defined but include shallow banks, large shallow bays, inlets and harbours as well as the open coast (Muñoz-Chápuli 1984, Smale 1991, Cappo 1992, Chiaramonte 1998b, Fergusson and Compagno 1995). These areas also tend to be nurseries for other common coastal sharks such as Smoothhound (Mustelus spp.), School Shark (Galeorhinus galeus) and Smooth Hammerhead (Sphyrna zygaena). In New Zealand pregnant females and neonates have been reported as far south as Waimea Inlet (41°20'S) on the west coast and Hawke Bay (40°S) on the east coast (Garrick 1982, C.D. unpublished data). In Australia neonates and small juveniles (less than 1 m total length) have been reported from Albany (Western Australia), Port Lincoln, the upper Gulf St. Vincent and Robe (South Australia), and Port Phillip Bay (Victoria) (Cappo 1992, R. McAuley pers. comm., T. Walker pers. comm., I.G. pers. obs). In South Africa the waters of the Eastern Cape are considered to be the main nursery area for this species (Smale 1991, Cliff and Dudley 1992). Elsewhere neonates and small juveniles have been recorded from: Rhodes, Nice and the banks off Al Hoceima (West Alboran Basin) in the Mediterranean (Garrick 1982, Muñoz-Chápuli 1984, Fergusson and Compagno 1995); Rio de Oro, Pulpito Bay, northwest Africa (Garrick 1982); Rio de Janeiro, Brazil (Garrick 1982); Bahia Blanca and Bahia San Blas, Distrito Bonaerense, Argentina (Chiaramonte 1998b); Paita and Guanape Cove, Peru (Garrick 1982); Bahia Sebastian Vizcaino, Baja California (Garrick 1982); San Diego Bay and Oceanside, California (Garrick 1982); near Niigata, Sea of Japan (Garrick 1982).
Segregation also occurs along latitudinal gradients (Muñoz-Chápuli 1984, Smale 1991, Cliff and Dudley 1992). Adult males are present in subtropical regions throughout the year, whereas females and immature C. brachyurus migrate into these regions during winter. Most adult females return to temperate regions to breed in the spring. The males also appear to migrate to higher latitudes in late winter-spring presumably to mate (Cliff and Dudley 1992). Mating probably occurs offshore as the females disperse from the nursery areas. Post-partum females bearing unhealed mating scars have been caught over the shelf (about 100 m depth) in early February off Hawke Bay, New Zealand (C.D. pers. obs). C. brachyurus inhabiting temperate areas also range into higher latitudes during the summer (Ayling and Cox 1982, Compagno 1984, Compagno et al. 1989, Cappo 1992, Last and Stevens 1994, Chiaramonte 1998b). These latitudinal movements may be in response to changes in water temperature or prey migrations (Compagno 1984, Comapgno et al. 1989, Cliff and Dudley 1992, Chiaramonte 1998b). In South Africa female C. brachyurus appear to follow the sardine run from the Eastern Cape to Natal during winter (Compagno et al. 1989, Cliff and Dudley 1992). The mean distance travelled by tagged C. brachyurus in South Africa is 163 km during 162 days at liberty, the maximum distance travelled was 1,320 km (Cliff and Dudley 1992). In South Australia tagged adults have been resighted at their tagging location after a year at liberty suggesting this species, like other Carcharhinids, is philopatric (I.G. pers. obs). Movement between New Zealand and Australia, or other regional populations has not been documented.
C. brachyurus occur singly and in loose schools sometimes numbering hundreds of individuals (Smale 1991, Cappo 1992, Cliff and Dudley 1992, C.D. unpublished data). In New Zealand and Australia these aggregations are most conspicuous in shallow water near shore during spring and summer, and in South Africa during the winter sardine run. Divers and sport fishers also report aggregations of C. brachyurus around offshore islands and banks off northern New Zealand during winter. Aggregations of large sharks reported in the surf zone near the entrances to harbours in northern New Zealand during spring may be related to breeding however at other times schooling may be a response to a local abundance of prey (Compagno et al. 1989, Cappo 1992).
Reproductive periodicity is probably biennial like most other large Carcharhinids (Castro et al. 1999). In the Southern Hemisphere parturition probably occurs from June to January, with a peak in October and November (Smale 1991, Cliff and Dudley 1992, Chiaramonte 1998b). Reproduction is viviparous, with a yolk sac placenta. Litters range from 7 to 24, with an average of 15 reported from South Africa (Garrick 1982, Smale 199, Cliff and Dudley 1992, Chiaramonte 1998b). Size at birth is about 60 cm total length (range 55-67 cm total length) (Garrick 1982, Smale 1991, Cliff and Dudley 1992). Cliff and Dudley (1992) estimated gestation lasts about 12 months. However their data show two embryonic size classes are present in the January and June-July samples, and a better description of embryonic growth is obtained if a 15 to 21 month gestation period is assumed (r² = 0.798 cf. 0.628). Males mature between 206 and 235 cm total length, and females from 227 to 244 cm total length. Age at maturity in South Africa is estimated to be 13 to 19 years for males, and 19-20 years for females (Walter and Ebert 1991). Maximum size of C. brachyurus is at least 295 cm total length and it is reported to reach 350 cm total length (Ayling and Cox 1982, Compagno 1984, Last and Stevens 1994). Maximum age is unknown. Productivity is estimated to be low to very low, with a minimum population doubling time of more than 14 yrs (K=0.04) (Froese and Pauly 2002, Fish Base).
The life-history of this large Carcharhinid makes it vulnerable to over fishing by directed fisheries and as bycatch in fisheries targeted at more productive species (Walker 1998, Castro et al. 1999, Vidthayanon 2002). C. brachyurus is mainly taken as bycatch in gill net and bottom longline fisheries for bony fishes and other sharks, particularly Mustelus spp. and Galeorhinus galeus (Compagno et al. 1989, Cappo 1992, Bentley in Rose 1996, Chiaramonte 1998a, b). It is also taken by bottom trawl and pelagic longline but only forms a minor component of the catch in these fisheries (Compagno et al. 1989, Parry-Jones 1996, Amorim et al. 1998, Marín et al. 1998, Bagley et al. 2000).
C. brachyurus is fished commercially in New Zealand (Francis 1998, Bagley et al. 2000, Ministry of Fisheries catch effort data), Australia (Cappo 1992), South Africa (Compagno et al.1989), Brazil (Amorim et al. 1998), Uruguay (Marín et al. 1998), Argentina (Chiaramonte 1998a, b), Mexico (Appelgate et al. 1993) and China (Parry-Jones 1996). C. brachyurus was not reported in trade from any of its Mediterranean range states by Rose (1996) but it is taken in net fisheries here and is usually lumped with other Carcharhinids (e.g., C. plumbeus) when landed (Fergusson and Compagno 1995). Little data is available for these fisheries. In Western Australia the "bronze whaler fishery" actually targets juvenile dusky shark (C. obscurus) (Heald 1987, Simpfendorfer 2001). C. brachyurus only constitutes about 3% of total reported landings in this fishery (R. McAuley pers. comm.). Carcharhinus spp. are also taken as bycatch in the Southern Shark Fishery (Victoria, Tasmania, South Australia). Between 1996-2001 mean annual landed catch of Carcharhinus spp. in this fishery was 71.5 tonnes (range 44-106 tonnes) (T. Walker pers. comm). The bulk of this (97-100%) was landed in South Australia, where landings increased from less than 20 tonnes a year in the early 1980s to 60-70 tonnes a year between 1988 and 1990 (Stevens in Castro et al. 1999). During the 1990s the landed catch has remained stable at around 70 tonnes a year, although a maximum of 105 tonnes was landed in 1999 (T. Walker pers. com.). The species composition of the bronze whaler catch in South Australia is unknown but is likely to be predominately C. brachyurus (Cappo 1992). In New Zealand reported commercial landings increased from 10 tonnes in 1989/90 to about 48 tonnes in 1995/96. Since then landings have declined steadily to about 20 tonnes in the 2001/02 fishing year (Ministry of Fisheries catch effort data). Most of the catch is taken by set net in the Hauraki Gulf and Firth of Thames. Reported landings from this area have been declining since 1992/93. No CPUE analysis of this fishery has been performed so it is uncertain if the decline in landings represents a decline in abundance or a change in fishing practice.
Although no fishery data is available for C. brachyurus in East Asia (i.e., Sea of Japan, Yellow Sea, East China Sea) directed shark fisheries have operated in the region since at least the 1950s, and sharks are a component of multi-species fisheries for more highly valued species such as tuna and swordfish (Parry-Jones and others in Phipps 1996). All directed fisheries for large coastal sharks in this region appear to have ceased during the 1970s due to declining catches and a shift in effort into offshore fisheries for tuna and salmon (Parry-Jones, and Kiyono in Phipps 1996). Parry-Jones (1996) observed that shark landings from coastal fisheries in China consisted mainly of small immature sharks (i.e., 90% <100 cm total length and 1 kg weight). The only C. brachyurus observed in markets during that survey was a juvenile weighing 5.5 kg in Fujian Province. Fishers from Fujian Province reported that large sharks were relatively common during the 1960s but are seldom caught now (Parry-Jones 1996). Fishing vessels from China, Taiwan, Hong Kong, Japan, South Korea, the Philippines and Viet Nam all operate in the South China Sea, East China Sea and Yellow Sea (Parry-Jones 1996). C. brachyurus is not reported to be an important component of Taiwan's shark fishery, either within Taiwanese waters, its distant-water shark fishing areas in Papua New Guinea, Indonesia and Mozambique, or its tuna longline and trawler fleets. The latter fishes waters of the South China Sea, Yellow Sea, East China Sea, India and northwest Africa (Chen et al. 2002).
In Argentina the main commercial fishery is located at Necochea. Reported annual landings range from 0 to 336 sharks (Chiaramonte 1998a). Chiaramonte (1998a) reported only two vessels targeted C. brachyurus, and observed that catches indicated this species was not sufficiently abundant to support a directed fishery should the school shark (G. galeus) stock collapse. In Chile directed shark fisheries are confined to the northern part of the country where artisanal fishers target shortfin mako (Isurus oxyrinchus) and blue shark (Prionace glauca) and may occasionally take Carcharhinus spp. (I. Kong pers. com.). Little information is available on the elasmobranch fisheries in Peru other than landings are dominated by smoothhounds (Mustelus spp) and batoids (Bonfil 1994). In 1990/91 landings crashed from over 25,000 tonnes to about 5,000 tonnes p.a. The reason for this crash is unknown and may not reflect a collapse of the fishery (Bonfil 1994). Mexican shark fisheries are the largest in America and the Pacific coast contributes about 60% of total landings (Bonfil 1994). There is also a significant bycatch of elasmobranchs in large scale trawl fisheries in the Mexican Pacific (Bonfil 1994). The Gulf of California represents one of the major fishing grounds in the Pacific and supports directed fisheries for Carcharhinus spp. (C. altimus, C. brachyurus, C. falciformis, C. leucus, C. limbatus, C. obscurus, C. porosus) (Appelgate et al. 1993, Bonfil 1994). Although information on stock size and species specific fishing mortality was limited or non-existent Bonfil (1994) considered it likely, given the level of exploitation that many shark stocks in the Gulf of California were close to their maximum sustainable yield or overfished. Neither Applegate et al. (1993) or Bonfil (1994) listed C. brachyurus as being heavily fished. However, as it is vulnerable to the same types of gear and may be naturally less abundant than those Carcharhinus spp. that dominate the landings, the effects of fishing on C. brachyurus may be more serious than its representation in the catch suggests. C. brachyurus and other Carcharhinus spp. are rare in California and do not support any directed fisheries (Bonfil 1994, Hanson 1999, R. Lea pers. comm., D. Ebert pers. comm., G. Cailliet pers. comm.).
Sport fisheries taking Carcharhinus spp. occur in New Zealand, Australia, South Africa, Argentina, Mexico and California (Stevens 1984, Compagno et al. 1989, Cappo 1992, Pepperell 1992, Appelgate et al. 1993, Francis 1998, Chiaramonte 1998a, b). In New Zealand C. brachyurus is the most commonly landed Carcharhinus species. It is only infrequently taken by anglers targeting marlin and swordfish off the northeast North Island. Most of these fish are unwanted and are released. However there is a small summer boat and shore-based sport fishery for C. brachyurus centered on the large harbours in the northern North Island. Most of the sharks taken in this fishery are pregnant and post-partum females and are tagged and released. A small number are retained and landed during fishing competitions. C. brachyurus are also occasionally taken by bow-hunters in some North Island harbours, and there are incidental catches of juveniles and adults in recreational gill net fisheries for rig (Mustelus lenticulatus), mullet, snapper and flatfish. The size of this bycatch is unknown but is probably minor. C. brachyurus is a minor component of sport fishing catches in southern New South Wales between Port Stephens and Narooma but is likely to dominate "bronze whaler" catches in Victoria and South Australia (Stevens 1984, Cappo 1992). No information on these fisheries was available at the time of writing. In South Africa this species is regularly taken by shore-based fishers in the Eastern Cape. These fishers take mainly neonates and juveniles less than 2 m total length (Smale 1991). There is also a land-based tag and release fishery for adult C. brachyurus in Nambia (S. Fowler pers. comm.).
C. brachyurus is commonly taken in protective shark control programs off Natal, South Africa and presumably Australia (New South Wales), although catches of Carcharhinus spp. are not identified to species in Australia (Cliff and Dudley 1992, Reid and Krogh 1992, Dudley 1997, Dudley et al. 1998). The mean annual catch in the Natal shark nets between 1978 and 1990 was 138 (range 9 to 421). Large annual fluctuations in catch meant no trend was evident over that period (Cliff and Dudley 1992). C. brachyurus is also killed as a pest species in and around fish farms, notably southern bluefin tuna pens in South Australia (I.G. pers. obs). The shallow coastal nursery areas of C. brachyurus are also potentially vulnerable to habitat loss and pollution arising from coastal development. The effects of this are likely to be greatest in parts of the Mediterranean Sea and East Asia. Expansion of marine aquaculture in New Zealand also potentially threatens nursery areas of C. brachyurus.
Castro et al. (1999) listed this species as Category 3 (i.e., a species that is exploited by directed fisheries or bycatch, and has a limited reproductive potential, and/or life history characteristics that makes it especially vulnerable to over fishing). Vidthayanon (2002) listed it as vulnerable in Thailand.
A prohibition on taking school and gummy sharks in shark nursery areas in Tasmania, and bans on gillnetting in some of these, may indirectly benefit some C. brachyurus but most of these areas are outside the main part of the species range (Williams and Schaap 1992, Last and Stevens 1994). Victorian coastal waters out to three nautical miles are almost completely closed to commercial shark fishing (Stevens 2002).
C. brachyurus may not be target fished in Quota Management Areas 1, 3, 4, 5, 6, 9. Management measures that are likely to indirectly benefit this species include closure of most harbours and semi-enclosed bays in northern New Zealand to trawling and Danish seining, and a permanent ban on gill netting out to five nautical miles from shore off the northwest North Island (Fisheries statistical areas 41 and 42) to protect endangered North Island Hector's dolphin.
|Citation:||Duffy, C. & Gordon, I. (SSG Australia & Oceania Regional Workshop, March 2003). 2003. Carcharhinus brachyurus. The IUCN Red List of Threatened Species 2003: e.T41741A10551730.Downloaded on 22 September 2017.|
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