Ginglymostoma cirratum (Western Atlantic subpopulation)
|Scientific Name:||Ginglymostoma cirratum (Western Atlantic subpopulation)|
|Red List Category & Criteria:||Near Threatened ver 3.1|
|Assessor(s):||Rosa, R.S., Castro, A.L.F., Furtado, M., Monzini, J. & Grubbs, R.D.|
|Reviewer(s):||Kyne, P.M., Cavanagh, R.D. & Musick, J.A. (Shark Red List Authority)|
Extreme population reduction (and in some cases localized extinction) of the species from the southern portion of its range in the Western Atlantic has been reported (Rosa 2002). Gadig (1994) noted that the impact of coastal fisheries is the primary cause of the observed decline of Nurse Sharks along the Brazilian coast. Recently it became a target of the commercial aquarium fisheries in Brazil. The species was assessed as Vulnerable in Brazil by a commission of the Brazilian Society for the Study of Elasmobranchs (SBEEL) in 2002, following the application of the IUCN Red List criteria. Its inclusion in the Official List of Endangered Animals in Brazil as a Vulnerable species was recommended to the Brazilian Ministry of the Environment in 2003. The species occurs in some marine parks in Brazil, however, effective management, including policing of these areas is essential. Similar declines are inferred across its range in South America, given heavy fishing pressure on the coastal zone in this region, and although more information is certainly required, the Nurse Shark is assessed as Vulnerable off South America due both to observed and inferred declines from heavy coastal fisheries and habitat destruction. For Central America information is more limited, though coastal fisheries are known to be intense in many areas as is habitat destruction. Nurse Sharks are actively targeted for fins and meat by artisanal fishers in Panama with lines and gillnets, here, juveniles are also collected for the aquarium trade. Fished by artisanal fishers for their skin and meat along the Colombian coast with nets and lines, the Colombian government is in fact considering a ban on the G. cirratum fishery together with an extensive habitat protection campaign. Nurse sharks are managed as part of the Large Coastal Species complex in the Atlantic and Gulf of Mexico waters of the US. They represent only about 2% of the sharks captured in the directed bottom longline fishery (NMFS 2003). They are of very low economic value in the US and are rarely retained with very high post-capture survivorship. In addition, a fishery independent survey in Bimini, Bahamas suggested an increase in Nurse Shark CPUE between 1995-2004 (Gruber and Grubbs unpublished data). The species is therefore assessed as Least Concern in the US NW Atlantic and Bahamas. The overall assessment for the Western Atlantic subpopulation is therefore Near Threatened, this is based on its Vulnerable status off South America, the likelihood of threats to the species throughout many areas of Central America and the Caribbean, and its Least Concern status off the US and Bahamas.
|Range Description:||Rhode Island, USA to southern Brazil, including the Gulf of Mexico, Caribbean and the Antilles. |
Extreme population reduction (and in some cases localized extinction) of the species from the southern portion of its range in the Western Atlantic has been reported (Rosa 2002). The species is no longer found in the southern portion of its Brazilian range, being declared locally extinct in Rio de Janeiro Municipality (Rio de Janeiro 2000).
Native:Anguilla; Antigua and Barbuda; Aruba; Bahamas; Barbados; Belize; Bermuda; Bonaire, Sint Eustatius and Saba (Saba, Sint Eustatius); Brazil; Cuba; Dominica; French Guiana; Grenada; Guadeloupe; Guyana; Haiti; Honduras; Jamaica; Martinique; Mexico; Montserrat; Panama; Puerto Rico; Saint Kitts and Nevis; Saint Lucia; Saint Martin (French part); Saint Vincent and the Grenadines; Sint Maarten (Dutch part); Trinidad and Tobago; Turks and Caicos Islands; United States (Florida, Georgia, North Carolina, Rhode Island, South Carolina, Texas); Venezuela, Bolivarian Republic of; Virgin Islands, British; Virgin Islands, U.S.
|FAO Marine Fishing Areas:|
Atlantic – western central; Atlantic – southwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Population size in Atol das Rocas, Brazil was estimated in 368 individuals (SD = 68), with Petersen-Bailey estimator, and 339 individuals (SD = 95) with Jolly-Seber estimator (Castro 2000a, Castro and Rosa 2005). This population is protected in a biological reserve. Other protected populations in Brazil include those of Marine State Park of Parcel Manuel Luiz (Maranhão State), Marine State Park of Risca do Meio (Ceará State), National Marine Park of Fernando de Noronha (Pernambuco State) and National Marine Park of Abrolhos (Bahia State). |
Glover’s Atol, Belize: Nurse Sharks are the most common elasmobranch on this offshore atol. They made up 68% of the elasmobranch catch in a fishery independent shark survey conducted in 2000 (Grubbs et al. 2000).
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||A coastal shark found in tropical and subtropical waters of continental and insular shelves, often near patch reefs, both coralline and rocky, where it hides and rests during day hours (Cervigón and Alcalá 1999, Compagno 2001). Found from depths of 1m or less down to 130 m (Compagno 2001). Activity is more intense at night (Compagno 2001), but strong swimming in adults also occurs during the day (R. Rosa pers. obs. in Atol das Rocas). Fidelity to day resting sites such as caves and crevices, has been reported in the literature, as well as an aggregation behavior in such sites (Castro 2000a, Castro 2000b, Compagno 2001). Group behavior related to sexual activity is also reported in the literature (Carrier et al. 1994). |
Size at birth is from 27 to 30 cm TL. Females attain maturity at 223 to 231 cm TL (Castro 2000b) or 230 to 240 cm TL (Compagno 2001) and males mature at 210 cm TL (Compagno 2001) or 214 cm TL (Castro 2000b). Maximum cited total lengths exceeding 450 cm TL are possibly greatly exaggerated (Castro 2000b). The largest reliably reported specimen was 308 cm TL (Compagno 2001).
Reproduction is aplacental viviparous, the retained eggs possessing a large amount of yolk (Compagno 2001). Number of intrauterine eggs 20 to 30, gestation period from five to six months, and reproduction occurs every other year (Compagno 2001). Brood sizes up to 50 young were reported by Castro (2000b), with a mean number of 34. Age at maturity estimated to be 10 to 15 years (males) and 15 to 20 years (females) (Carrier 1991, Carrier and Luer 1999, Compagno 2001).
Diet studies based on examination of stomach contents indicate small teleosts, cephalopods, gastropods, bivalves, sea urchins and crustaceans as the main prey items. Pieces of coral debris and algae occasionally occur in the stomachs (Castro 2000b, Compagno 2001). Such data indicate that the nurse shark is an opportunistic benthic predator.
Life history parameters
Age at maturity: Female: 15 to 20 years; Male: 10 to 15 years.
Size at maturity (total length): Female: 223 to 231 cm TL or 230 to 240 cm TL; Male: 210 to 214 cm TL.
Longevity (years): Unknown.
Maximum size (total length): 450 cm TL? Reliably 308 cm TL.
Size at birth: 27 to 30 cm TL.
Average reproductive age (years): Unknown.
Gestation time: 5 to 6 months.
Reproductive periodicity: Biennial.
Average annual fecundity or litter size: Average: 34 pups/litter.
Annual rate of population increase: Unknown.
Natural mortality: Unknown.
Although edible, the nurse shark is not usually prized as market food. In Brazil the Nurse Shark is consumed locally by fishermen, who incidentally or actively capture the species. In Venezuela it is marketed salt dried (Cervigón and Alcalá 1999). Major threats include incidental and deliberate capture in coastal fisheries, spear fishing and capture for the ornamental fish trade, and indirectly, the impacts on the coastal zone, particularly on reef areas which constitute its preferred habitat. Actively targeted by Panamanian artisanal fishers with lines and gillnets. Fished by artisanal fishers along the Colombian coast with nets and lines. Nurse sharks are also harvested in parts of the Caribbean for their skin.
In the United States, they are occasionally captured in the bottom longline fishery, however, nearly all are released and post-release survivorship is high.
Nurse sharks are fished in Panama for their fins and meat (US$ 0.75 per Lb) (Monzini 2004). In Colombia nurse sharks are mostly targetted for the skin while meat is usually transformed into animal food (Cervigon et al. 1999). In Panama, juveniles are also collected for public and private aquarium (Monzini 2004).
Nurse Sharks are managed as part of the Large Coastal Species complex in the Atlantic and Gulf of Mexico waters of the United States.
The Colombian government is considering a ban on the G. cirratum fishery together with an extensive habitat protection campaign (Mejia et al. 2002).
The species was listed as Vulnerable in São Paulo State (Brazil) by participants at a workshop organized by the State Secretary of the Environment (SEMA/SP) using IUCN criteria. (São Paulo 1998), and later assessed as Vulnerable in Brazil by a commission of the Brazilian Society for the Study of Elasmobranchs (SBEEL) in 2002, also using IUCN Red List criteria. Its inclusion in the Official List of Endangered Animals in Brazil as a Vulnerable species was recommended to the Brazilian Ministry of the Environment in 2003.
Conservation measures should include:
Establishment of no fishing marine conservation units, encompassing reef formations, which include mating and breeding grounds; regulation of spear-fishing activity, both commercial and sporting, with restriction of capture; regulation of the marine ornamental fish trade, with restriction of capture; bycatch control, with mandatory release of live by-caught individuals; and, development and effective implementation of management plans (national and/or regional e.g., under the FAO International Plan of Action for the Conservation and Management of Sharks: IPOA-Sharks) in order to facilitate the conservation and sustainable management of all chondrichthyan species in the region. See Anon. (2004) for an update of progress made by nations in the range of G. cirratum.
|Citation:||Rosa, R.S., Castro, A.L.F., Furtado, M., Monzini, J. & Grubbs, R.D. 2006. Ginglymostoma cirratum (Western Atlantic subpopulation). The IUCN Red List of Threatened Species 2006: e.T60224A12327471.Downloaded on 19 April 2018.|