Oceanic whitetip shark (Carcharhinus longimanus)

Oceanic whitetip shark
Carcharhinus longimanus

TAXONOMY AND NAMING

Class : Chondrichthyes
Order : Carcharhiniformes
Clade : Neoselachii
Family : Carcharhinidae
Genus/species : Carcharhinus
Common names :
English : Oceanic whitetip shark
Spanish : Tiburón oceánico
French : Requin longimane

ANATOMY AND MORPHOLOGY

Carcharhinus longimanus is a large-bodied shark species from the family Carcharhinidae (requiem sharks). This species can reach a maximum size of 325-346 cm, with most specimens measuring between 150 and 205 cm. C. longimanus can easily be distinguished from other shark species by its large, rounded fins and the white mottled markings on the tips of the fins.

BEHAVIOUR AND LIFE HISTORY

Longevity was estimated to be 25 years. Like other carcharhinid-species, female C. longimanus reproduces viviparously. After a gestation period of 12 months, the female produces a litter of 1 to 14 pups (mean : 6). Like other large shark species, C. longimanus feeds close to the top of the marine food web (trophic level 4.2), occupying a top predator position along with other large pelagic teleost species. The species has exhibited site fidelity in the Bahamas where large pelagic teleosts are abundant, potentially for feeding purposes.

DISTRIBUTION, ABUNDANCE AND CONSERVATION STATUS

Carcharhinus longimanus is a circumtropical species and the only true oceanic species within the Carcharhinus-genus, occurring in waters between the 30ºN and 35ºS latitudes. The species occurs mostly in epipelagic zones, from the surface waters to a depth of 20 meters. It is considered to be one of the most widespread shark species, ranging across all tropical and subtropical waters.

The oceanic whitetip shark was characterized historically as one of the most abundant oceanic sharks in tropical seas worldwide. Currently, there is no global population size estimates available ; however, numerous lines of evidence indicate that the oceanic whitetip shark has experienced significant population declines throughout a majority of its global range, with an overall reduction in numbers of 98% and a decrease of over 75% since the late 1970’s. The 2019 IUCN red list update assessed Oceanic White Tip as Critically Endangered globally.

Oceanic whitetip shark (Carcharhinus longimanus) geographic range©IUCN red list

THREATS

Studies show that populations of C. longimanus are threatened by overfishing on a global scale. Life history parameters of this species and its specific biology indicate that it is a species with low resilience to fishing and low productivity. Although oceanic whitetip sharks are not typically a target species in fisheries, the biggest threat to the species is that they are caught incidentally as bycatch in virtually all parts of their range. The main driver for the fishery (directed and bycatch) is the high value of the fins on the international market. C. longimanus is a preferred and highly valuable species in the international shark fin trade in Hong Kong, the largest international fin market.

PROTECTION STATUS

Most Regional Fisheries Management Organizations have developed management measures banning the retention of oceanic white tip shark. Since 2010, the International Convention for the Conservation of Atlantic Tunas has prohibited retention, transshipment, storage, and landing of Oceanic White Tip sharks. The IUCN recognizes oceanic whitetip sharks as “Vulnerable” worldwide and "Critically Endangered" in the Northwest and Western Central Atlantic.

SPAW Protocol : yes since 2017 _ Annex III

International Plans of Actions for Conservation and Management of Sharks (IPOA-Sharks) : yes since 1999

CMS : yes

CITES : yes_ Annex II

Memorandum of Understanding on the Conservation of Migratory Sharks (Sharks MoU) : yes since 2016 _ Annex I

Highly Migratory Species, of the UN Convention on the Law of the Sea : yes _ Annex I

Bibliography

Proposal for the uplisting of Oceanic whitetip shark from Annex III to Annex II of the SPAW Protocol