|Scientific Name:||Carcharhinus longimanus (Poey, 1861)|
Carcharhinus maou (Lesson, 1831)
Carcharias insularum Snyder, 1904
Carcharias longimanus (Poey, 1861)
Carcharias obtusus (Poey, 1861)
Pterolamiops budkeri Fourmanoir, 1961
Pterolamiops longimanus (Poey, 1861)
Pterolamiops magnipinnis Smith, 1958
Squalus longimanus Poey, 1861
Squalus maou Lesson, 1831
|Taxonomic Source(s):||Compagno, L.J.V. 1973. Carcharhinidae. In: J.-C. Hureau and T. Monod (eds), Check-list of the fishes of the north-eastern Atlantic and of the Mediterranean (CLOFNAM). Volume 1, pp. 23-31. Unesco, Paris.|
|Red List Category & Criteria:||Endangered A2b (Regional assessment) ver 3.1|
|Assessor(s):||Walls, R., Soldo, A. & Buscher, E.|
|Contributor(s):||Fordham, S., Baum, J.K., Medina, E., Musick, J. & Smale, M.|
|Facilitator/Compiler(s):||Walls, R. & Dulvy, N.|
European regional assessment: Endangered (EN)
This formerly widespread and abundant, large oceanic shark is subject to fishing pressure throughout its range. It is caught in large numbers as a bycatch in pelagic fisheries, with pelagic longlines, probably pelagic gillnets, handlines and occasionally pelagic and even bottom trawls. Catches, particularly in international waters, are inadequately monitored. Its large fins are highly prized in international trade although the carcass is often discarded. Declines of 90% according to observer data from the Pacific are probably the most reliable available data on this species today, and with the same types of fishery in operation throughout its habitat worldwide, it is realistic to assume that it might be faring similarly in the Atlantic Ocean.
Estimates from the Northwest Atlantic are available and indicate a decline of 80-85% from 1950s-2000, but these are contended and may not reflect the status of the European subpopulations. Therefore, it is estimated that the species has declined by at least 50% for the three generation period (46 years) in European waters, therefore qualifying as Endangered under criterion A2b. It should be noted that this region only represents a portion of the Atlantic-wide subpopulation, which likely spans the entire Atlantic Ocean. For this reason, this information should be updated following further analyses of relevant Atlantic fisheries data.
This is one of the most widespread shark species, ranging across entire oceans in tropical and subtropical waters, usually found far offshore between about 30°N and 35°S in all oceans. In the Northeast Atlantic it occurs from southern Portugal to Madeira. There are several unconfirmed records of this species from the Mediterranean Sea but all have been considered as invalid (Serena 2005, Bradaï et al. 2012). Its depth range is zero to 152 m.
Native:Morocco; Portugal (Azores, Madeira, Portugal (mainland)); Spain (Canary Is., Spain (mainland))
|FAO Marine Fishing Areas:|
Atlantic – eastern central; Atlantic – northeast
Oceanic Whitetip Shark (Carcharhinus longimanus), together with Silky Shark (Carcharhinus falciformis) and Blue Shark (Prionace glauca), was once described as one of the three most abundant species of oceanic sharks and large marine animals (Compagno 1984, Taniuchi 1990, Bonfil 1994, Castro et al. 1999); it was formerly nearly ubiquitous in water deeper than 180 m and above 20°C (Castro et al. 1999). Recent observations however indicate that this species is now only occasionally recorded (e.g., Baum and Myers 2004, Domingo 2004).
In the Gulf of Mexico, this pelagic shark allegedly declined by > 99% between the 1950s and 1990s (Baum and Myers 2004). This study however excluded a number of key considerations from the analysis, including the shift in average gear depth from 72 m in the 1950s to 110 m in the 1990s, which could have significantly affected the exploitation of this species given that it primarily inhabits waters < 100 m depth (Burgess et al. 2005). The large decline in Oceanic Whitetip Shark globally is undeniable, but it is as yet unclear what the extent really is, so an inference of the Northeast Atlantic subpopulation status from the Northwest Atlantic status in this case may not be entirely reliable.
Clarke et al. (2006) calculated a simple ocean basin area proportion for the Atlantic relative to the world ocean (0.2506); this was considered a proxy for habitat area, and hence for the potential area of catch of pelagic sharks. Clarke (2008) then tried to estimate historical total removals of pelagic sharks from the Atlantic using this calculation and global shark fin trade data. The peak year for the area- and effort-proportioned series was 2003, during which an estimated 80-210,000 individuals, or 5-12,000 tonnes of the species were removed from the Atlantic Ocean solely for the finning trade. It should however be noted that the suitability of this basin area proportion calculation to this particular species is not certain; alternative measures of Oceanic Whitetip Shark habitat in the Atlantic (and globally) therefore need to be considered.
In the western and central Pacific, annual longline catch rates decreased by 90% from 1996 to 2009; uncertainty in the estimates was low as this information comes from observers onboard commercial fishing vessels. This represents a significant 17% decline per year during this time. Declines in purse seine fisheries in this region resembled those in the longline fishery (Clarke et al. 2013). Other data sets from Japan and Hawaii over the same time period showed declines consistent with these (Clarke et al. 2011, Walsh and Clarke 2011) and the observed declining sizes of individuals also served to confirm the depleted state of the species’ stock in this region (Clarke et al. 2011, Clarke et al. 2013).
It is highly likely that in the Northeast Atlantic region this nomadic species represents only a fraction of an Atlantic-wide stock, though population size and trends are unknown in European waters owing to a lack of reliable data from high seas fisheries. It can however be inferred that the Northeast and Eastern central Atlantic portion of the wider subpopulation is in decline, based on the global Vulnerable status of the species, the declines shown in observer data from the Pacific, the declines in the western Atlantic, and the unsustainable level of fishing that has occurred historically and still occurs in European waters relative to other parts of the world.
When trends in abundance from the former analyses (1992-2000; Baum et al. 2003) are extrapolated back to the mid-1950s, they match the latter analysis (Baum and Myers 2004) of abundance declines (Baum et al. 2006). It is likely that the population of this low-productivity species is at least 15-20% of baseline (1950s) in the northwest Atlantic Ocean (CITES 2013). Considering a decline of 80-85% from the mid-1950s-2000 (~45-50 years), there has been an annual rate of decline of 0.96, and the species is estimated to have declined by 85% over the three generation period (46 years). However, these estimated declines in the Northwest Atlantic are contended (see Baum and Blanchard 2010) and may not reflect the status of the European populations. Therefore, it is estimated that the species has declined by at least 50% for the three generation period in European waters.
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||This is one of the most widespread oceanic-epipelagic sharks, ranging across entire oceans in tropical and subtropical waters. It is normally found in surface waters, although it has been recorded to 152 m. It has occasionally been recorded inshore, but is more typically found offshore or around oceanic islands and areas with narrow continental shelves (Fourmanoir 1961, Last and Stevens 1994). It regularly occurs in waters of 18 to 28°C, usually > 20°C.|
Development is viviparous and embryos have a yolk sac placenta that attaches to the uterine wall of the mother (Bigelow and Schroeder 1948). The average litter size is five to six (Ebert and Stehmann 2013), although 15 foetuses were recorded from a female of 245 cm total length (TL) from the Red Sea (Gohar and Mazhar 1964); larger females appear to carry more young, although there may be regional variation (Bass et al. 1975). Pups are born at ~ 55 to 77 cm TL after a gestation period of about nine to 12 months (Ebert and Stehmann 2013). Males mature at about 168 to 198 cm TL and females at 170 to 200 cm TL (Seki et al. 1998, Ebert and Stehmann 2013). Oceanic Whitetip Shark usually grows to < 3 m TL, with some individuals reaching 350-395 cm TL (Ebert and Stehmann 2013).
Maturity occurs between four and seven years for both males and females, and the maximum age on record is 11 to 13 years with a maximum estimated age of 22 years (Ebert and Stehmann 2013). Rapid growth and early maturation give this shark a moderate rebound potential (Smith et al. 1998). Camhi et al. (2009) reported an intrinsic rate of increase as 0.081 and population growth rate as 1.117 for this species. Its generation length is estimated to be 15.3 years (unpublished data, M.J. Juan Jorda pers. comm. 2015).
|Generation Length (years):||15.3|
|Use and Trade:||This shark is used fresh, smoked and dried salted for human consumption, for hides, for fins (processed into the ingredients for shark-fin soup), and for liver oil (extracted for vitamins) and fishmeal (Ebert and Stehmann 2013). Along with Blue Shark (Prionace glauca), thresher sharks (Alopias spp.) and hammerhead sharks (Sphyrna spp.), Oceanic Whitetip Shark makes up the bulk of fins sold in the global shark fin trade (Clarke et al. 2006).|
Oceanic Whitetip Shark is primarily taken as bycatch in large pelagic longline and purse seine fisheries targeting tuna and swordfish. It is also caught in pelagic gillnets, hand-lines and occasionally pelagic and even bottom trawls (Ebert and Stehmann 2013). The lack of reliably reported national landings of this species leads to significant underestimations of catches.
Oceanic Whitetip Shark is more likely to be retained by longline fisheries than finned, which implies that recent finning regulations requiring the entire carcass to be landed with fins attached may not even benefit this species (Clarke et al. 2011). Tagging studies have determined that this species has a high chance of surviving capture on pelagic longline fishing gear if carefully released (CITES 2013), so retention bans could potentially benefit the species more than finning bans.
Cortés et al. (2010) carried out an ecological risk assessment of pelagic sharks caught in Atlantic pelagic longline fisheries, concluding that Oceanic Whitetip Shark is among the species most sensitive to overexploitation. Calculations were based on the species’ productivity (intrinsic rate of increase) and ‘susceptibility’; ‘susceptibility’ was calculated based on availability of the species to the fleet, encounterability of the gear given the species vertical range, gear selectivity and post-capture mortality.
Fishing pressure on this species must be considerably decreased through reduction in fishing effort, catch limits, measures to enhance chances of survival after capture and possibly also through the implementation of large-scale oceanic non-fishing areas. Precautionary adaptive collaborative management of target and bycatch fisheries is urgently needed for this biologically vulnerable shark. It is also essential to improve data collection and develop stock assessments for this species. Listing on international resource management agreements, such as the recent 2014 listing on Appendix II of the Convention on Migratory Species could help drive improvements in national and regional management and facilitate collaboration between states, for this species and other migratory sharks. Oceanic Whitetip Shark is listed as a highly migratory species under the 1995 United Nations (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 listed species. Also of relevance is the Fisheries and Aquaculture Organisation’s (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.
Oceanic Whitetip Shark is currently the only shark species subject to protections under all the world’s tuna-focused Regional Fishery Management Organisations (RFMOs). Pursuant to these agreements, European Union (EU) fishermen are not allowed to retain, transship or land any part or whole carcass of the species taken in any fishery.
Oceanic Whitetip Shark was listed under Appendix II of the Convention on International Trade in Endangered Species in 2013. This requires international trade (among Parties not taking a Reservation) to be monitored and derived from sustainably managed fisheries, beginning in September 2014.
In 2013, the European Union (EU) banned removal of shark fins on board vessels through Regulation No. 605/2013, in line with advice from the International Union for Conservation of Nature Species Survival Commission’s Shark Specialist Group and other shark fishery experts, in order to enhance enforcement of the 2003 EU ban on shark finning (Regulation No. 1185/2003) and facilitate improved shark fishery data collection.
|Citation:||Walls, R., Soldo, A. & Buscher, E. 2015. Carcharhinus longimanus. The IUCN Red List of Threatened Species 2015: e.T39374A48919886.Downloaded on 24 February 2018.|
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