|Scientific Name:||Carcharhinus altimus|
|Species Authority:||(Springer, 1950)|
Eulamia altima Springer, 1950
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Assessor/s:||Pillans, R., Amorim, A., Mancini, P., Gonzalez, M. & Anderson, C.|
|Reviewer/s:||Soldo, A., Valenti, S.V., Kyne, P.M. & IUCN SSG Pelagic Shark Red List Workshop participants (Shark Red List Authority)|
The Bignose Shark (Carcharhinus altimus) is a deepwater, diurnally migrating (12?430 m) whaler shark which probably has a circumglobal distribution on the continental shelf edge in tropical and warm seas, although records are patchy. There are no target fisheries for this species, although it is taken as bycatch in deep set pelagic longlines including widespread tuna longline fisheries, and occasionally in bottom trawls. Reported catches are small, but shark bycatch in longline fisheries is not reported fully throughout the species? range and cannot be used to assess mortality or population trends. It is closely related to the Sandbar Shark (Carcharhinus plumbeus), which it may often be mistaken for (by both fishers and biologists), and which has been heavily depleted by fishing pressure in the northwest Atlantic. Although no specific data are available for Bignose Shark, it is suspected that this species has also been impacted by longline fisheries operating in this region, warranting an assessment of Near Threatened in the northwest Atlantic based on a suspected decline. Fishing pressure is also high in Southeast Asia, where this species is utilized whole. Its presence is also confirmed in the Hong Kong fin trade. The Bignose Shark is taken in bottom trawls in the western Indian Ocean, probably by line or gillnet off India and in nearshore pelagic longlines around the Maldives. Catch rates reported by fishermen in the Maldives have declined significantly in recent years. In Australia this species is not commercially fished, where it is assessed as Least Concern. At present there is insufficient information to assess this species beyond Data Deficient globally. However, given that it may have similarly vulnerable life history characteristics to the related Sandbar Shark, evidence for declines in some regions and high fishing pressure in large parts of its range, its status is of concern and data collection and precautionary adaptive collaborative management should be a priority.
|Range Description:||This species is circumglobal, but patchily recorded in tropical and warm seas (Compagno in prep, White et al. 2006).
Western central and southwest Atlantic: reported from Florida, Bahamas, Cuba, Nicaragua, Costa Rica, Venezuela, Brazil (Compagno in prep.). Eastern central Atlantic: Senegal, Gambia, Sierra Leone, Ivory Coast and Ghana, and also in the Mediterranean Sea (Golani 2002, Compagno in prep). Indian Ocean: South Africa, Madagascar, India, Maldives, Red Sea and possibly also Sri Lanka (Compagno in prep.). Northwest and western central Pacific: China, Thailand, Indonesia, Philippines (Compagno et al. 2005, Compagno in prep., White et al. 2006). Eastern central and southeast Pacific: Gulf of California, southern Mexico, Colombia, Peru, Ecuador, Revillagigedo Islands (Compagno in prep.). Also occurs off Australia, in the Indian and Pacific Oceans and Hawaii, in the Central Pacific (Compagno in prep.).
A transboundary/migratory species that has been tagged travelling distances between 1,000 and 2,000 miles (Kohler et al. 1998).
Native:Australia; Bahamas; Brazil; China; Colombia; Costa Rica (Costa Rica (mainland)); Côte d'Ivoire; Cuba; Ecuador (Ecuador (mainland)); Egypt; Eritrea; Gambia; Ghana; India (Kerala, Tamil Nadu); Madagascar; Maldives; Mexico (Jalisco, Nayarit, Sinaloa, Sonora); Nicaragua (Nicaragua (mainland)); Philippines; Saudi Arabia; Senegal; Sierra Leone; South Africa (Eastern Cape Province); Spain (Spain (mainland)); Sudan; United States (Florida, Hawaiian Is.); Venezuela, Bolivarian Republic of (Venezuela (mainland)); Yemen
|FAO Marine Fishing Areas:||
Atlantic – eastern central; Atlantic – western central; Indian Ocean – eastern; Indian Ocean – western; Mediterranean and Black Sea; Pacific – eastern central; Pacific – northwest; Pacific – southeast; Pacific – southwest; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The low tag and recapture rate (5.3%) of Bignose Shark (Carcharhinus altimus) does not necessarily reflect a low abundance of this species, but may be due to this species being undesirable or inaccessible to the main body of fishing and tagging effort in the Atlantic Ocean (Kohler et al. 1998). Soto (2001) notes that it is uncommon in Brazil, but that it is probably distributed offshore along the entire Brazilian coast. The species is reported as rare in the Mediterranean Sea (Serena 2005).|
|Habitat and Ecology:||
This species occurs mainly on the edge of continental shelves in deep water (12?430 m), and is more common between 80 and 220 m with very occasional captures in shallow water (Tester 1969). Between North Carolina and Florida, USA, it has a depth range from 12?200 m (Commercial Shark Fishery Observer Program unpubl data). Individuals have been caught at night near the surface over deep water in Hawaii, Maldives, Australia, Brazil and Sri Lanka. Therefore the species is thought to display diurnal vertical migrations (Anderson and Stevens 1996).
Average reproductive age is ~21 years. Males reach maturity at 216 cm total length (TL) and females at 226 cm TL. Maximum size is 282 cm TL and size at birth is 70?90 cm TL (Compagno 1984, Kohler et al. 1995, Jensen et al. 1996). Females give birth to 1?13 pups per litter.
Globally, C. altimus is taken in pelagic longline fisheries in deep water (Anderson and Stevens 1996) and is therefore susceptible to capture in widespread tuna longline fisheries. The species is occasionally caught in bottom trawls.
In the US northwestern Atlantic or Gulf of Mexico waters this species is not targeted. It is rarely caught in the US commercial bottom longline fishery (from New Jersey to Louisiana: 46 individuals recorded by fishery observers monitoring ~4% of the fishery during 1994 to 2003) or the US pelagic longline fishery (east coast of the US, Gulf of Mexico and Caribbean: 41 individuals observed recorded by fishery observers monitoring ~ 5% of the fishery during 1992 to 2000). There is no indication that catch rates for this species are increasing in either of these fisheries. However, this species is often misidentified by fishermen and biologists (J. Musick pers. comm.). It is related to the sandbar shark, which it may often be mistaken for, and which has been heavily depleted by fishing pressure in the Northwest Atlantic. Although no specific data are available for C. altimus, it is suspected that this species has also been impacted by longline fisheries operating in this region. It is possible non-US longline vessels targeting tuna (deeper sets) may catch this species as bycatch, however there are no data available to confirm this. In the Caribbean, this species is apparently taken on deep-set longlines (particularly off Cuba, but also southern Florida), and there it is utilized for fishmeal, oil and shagreen (Compagno in prep.).
In the eastern central and southeast Pacific, this species is taken as bycatch of gillnets, bottom longlines and trawls.
In the southwest Atlantic, off Brazil, C. altimus is taken incidentally by commercial fisheries on the outer continental shelf and continental slope. The species was first identified and recorded from the catches of tuna longliners operating out of Santos (São Paulo State, southern Brazil) by Sadowsky and Amorim (1977). They are seldom caught by this fleet but are retained when caught and sold as "other sharks" (Arfelli and Amorim 1994). The bignose shark is also taken in directed artisanal shark longline fisheries around Venezuelan oceanic islands (Tavares 2005).
It is also taken in bottom trawls in the western Indian Ocean and probably by line or gillnet off India. Taken by nearshore pelagic longline around the Maldives; catch rates reported by fishermen to have declined significantly in recent years (C. Anderson pers. comm. 2007). Whole individuals are consumed and traded at local markets in Thailand and the Philippines (Southeast Asian Fisheries Development Center 2006). In Indonesia this species is caught occasionally by shark longliners and is a utilized bycatch of gillnet fisheries (White et al. 2006). It has been confirmed as present in the shark fin trade through genetic testing of fins collected in Hong Kong (Clarke et al. 2006). This species is not commercially harvested in Australia.
In the Mediterranean this species is known to be important bycatch of the pelagic longline fishery operating from eastern Algerian ports (Fowler et al. 2005).
In US waters, under the Fishery Management Plan for Atlantic tunas, swordfish and sharks (National Marine Fisheries Service 2007), Carhcarhinus altimus, is currently listed as a Prohibited Species.
Collection of data and assessment of catches of this species is required throughout its range. This species is taken on the high seas, outside waters managed by coastal States. This species is listed as a highly migratory species under the 1995 UN Agreement on the Conservation and Management of Straddling Fish Stocks and Highly Migratory Fish Stocks (UNFSA). The Agreement specifically requires coastal States and fishing States to cooperate and adopt measures to ensure the conservation of these listed species. To date, there is little progress in this regard. See http://www.unclos.com for further details. Also of relevance is the FAO International Plan of Action for the Conservation and Management of Sharks (IPOA-Sharks) which specifically recommends that Regional Fisheries Organisations (RFO) carry out regular shark population assessments and that member States cooperate on joint and regional shark management plans. This is of particular importance for sharks such as C. altimus, whose stocks are exploited by more than one State on the high seas. Although steps are being taken by some RFOs, such as ICCAT, to collect species-specific data on pelagic sharks, and to ban the practise of shark finning, to date no RFO has limited shark catches or drafted a ?Shark Plan? as suggested in the IPOA-Shark guidelines.
The 2004 ICCAT shark stock assessment workshop (ICCAT 2005) reported that the current situation on submission of shark statistics indicates that the overall volume of catch reported to ICCAT does not represent the total removals of these sharks and the data are also very limited with respect to the size-, age- and sex- composition of the catch. It is noted that improvements in the ICCAT shark database can only be achieved if the Contracting Parties increase infrastructure investment into monitoring the overall catch composition and disposition of the overall catch of sharks and other by-catch species. Therefore, the workshop group recommended that larger monitoring and research investments directed at sharks in particular, and other by-catch species in general, need to be made by the Parties. Above and beyond this main recommendation, the group identified a number of research activities that could provide for improved advice on the status of these species, if implemented. See ICCAT (2005) for further details. This situation applies to all RFOs and is included here as a standard that needs to apply internationally for fisheries that capture pelagic sharks such as this.
Two RFOs, IATTC and ICCAT, have adopted finning (the removal of fins and discard of carcasses at sea) bans, as have several range states (e.g., USA, EU, Australia, Brazil etc.) and the EU. These bans only affect a limited part of the geographic range of this wide ranging shark at present.
Precautionary adaptive collaborative management of target and bycatch fisheries is needed for this potentially vulnerable shark.
|Citation:||Pillans, R., Amorim, A., Mancini, P., Gonzalez, M. & Anderson, C. 2009. Carcharhinus altimus. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 11 March 2014.|
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