Carcharhinus brachyurus (East Asia subpopulation)
|Scientific Name:||Carcharhinus brachyurus (East Asia subpopulation)|
|Red List Category & Criteria:||Vulnerable A2d+3d+4d 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.
|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. The East Asia subpopulation has been recorded from coastal waters of Japan (Tokyo and Niigata south), China (Yellow Sea, East China Sea), North and South Korea, and southern Siberia (Sea of Japan).|
Native:China; Japan; Korea, Democratic People's Republic of; Korea, Republic of; Russian Federation
|FAO Marine Fishing Areas:|
Pacific – northwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||No estimates of population size or biomass are available. Global population structure is unknown. Stock structure is not known for any fished population.|
|Current Population Trend:||Decreasing|
|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 1998b). 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 1998b). Juveniles occur in shallow water (<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). Neonates and small juveniles have been recorded from 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. 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).
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).
Reproductive periodicity is probably biennial like most other large Carcharhinids (Castro et al. 1999).
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 China (Parry-Jones 1996). 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).
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).
|Citation:||Duffy, C. & Gordon, I. (SSG Australia & Oceania Regional Workshop, March 2003). 2003. Carcharhinus brachyurus (East Asia subpopulation). The IUCN Red List of Threatened Species 2003: e.T41742A10552120.Downloaded on 22 October 2017.|