FEATURE CREATURE

FEATURE CREATURE – TAWNY NURSE SHARK NEBRIUS FERRUGINEUS

Simone Caprodossi

RED LIST CATEGORY & CRITERIA: VULNERABLE Scientific Name: Nebrius ferrugineus Common Name: Tawny Nurse Shark Synonym: Scyllium ferrugineum Lesson, 1831

ASSESSMENT INFORMATION Justification: A widely distributed continental and insular shelf species of the Indian, west and central Pacific Oceans. Restricted to a narrow band of shallow water habitat (5 to 30 m, occasionally to 70 m) that is heavily fished throughout all its range except Australia. Taken in inshore fisheries (demersal trawls, floating and fixed bottom gill nets and baited hooks) in Indonesia, Thailand, Philippines, Pakistan and India. Although there are limited data on population declines in these areas, reports of local extinctions in India and Thailand, combined with its narrow habitat range, apparently limited dispersion and low fecundity, indicate that the species is highly susceptible to local inshore fisheries and has declined in a large proportion of its range. Within Australia it is assessed as Least Concern because it is widely distributed and abundant, captured only in very small numbers in gillnets and beach meshing.

GEOGRAPHIC RANGE Range Description: Found on continental and insular shelves of the Indo-Pacific, often in the intertidal zone and from the surf line down to a depth of 70 m but more commonly between 5 and 30 m.

Countries occurrence: Native: Australia (New South Wales, Northern Territory, Queensland, Western Australia); Bahrain; China; Djibouti; Egypt; Eritrea; India; Indonesia; Iran, Islamic Republic of; Japan; Kuwait; Madagascar; Malaysia; Maldives; Marshall Islands; Mauritius; Mozambique; New Caledonia; Palau; Papua New Guinea; Philippines; Qatar; Samoa; Saudi Arabia; Seychelles; Singapore; Somalia; South Africa; Sudan; Taiwan, Province of China; Thailand; United Arab Emirates; Viet Nam; Yemen.

FAO Marine Fishing Areas: Native: Indian Ocean - eastern, Indian Ocean - western, Pacific - eastern central, Pacific - northwest, Pacific - southwest, Pacific - western central.

POPULATION Current Population Trend: Decreasing

Simone Caprodossi

HABITAT AND ECOLOGY It occurs on or near the bottom in lagoons, in channels or along outer edges of coral and rocky reefs, in areas with seagrass and sand on reefs, sandy areas near reef and off sandy beaches. It prefers areas in crevices and caves. Young prefer crevices in shallow lagoons but adults are more wide ranging.

Life History: Ovoviviparous (aplacental viviparity) with uterine cannibalism in the form of oophagy. Pregnant females from Okinawa had one or two foetuses per uterus (297 to 595 mm) with the yolk sac reabsorbed and a greatly expanded stomach filled with yolky material in the larger fetuses and also had egg cases in the uterus (Teshima et al. 1995). It appears as though this species practices oophagy on relatively large, cased nutritive eggs (unlike lamnoids which have very small nutritive eggs) and is the first orectoloboid known to have uterine cannibalism. It is not known if the foetuses eat each other (adelphophagy) as with the grey nurse shark (Carcharias taurus).

Reproductive periodicity: Unknown Size at birth: 40 to 80 cm total length (TL)

Average litter size: At least four per uterus suggested from egg cases, but the large size differences between foetuses in a litter suggests the litters are smaller, possible only one per female (Compagno 2001). Size male maturity: 250 cm TL Size female maturity: 230 to 290 cm TL Max size: to at least 320 cm Systems: Marine

THREATS Threats within Australia are likely to be minimal, there are no target fisheries, although it is taken in inshore fisheries throughout much of the rest of its range.

In the Gulf of Thailand, it was historically more abundant and it may have been adversely affected by the use of explosives and poisons on reefs in the Indian Ocean and western Pacific, particularly Indonesia and the Philippines (Compagno 2001). Nebrius ferrugineus often form small aggregations during the day and have a limited home range, with individuals returning to the same area every day after foraging. This behaviour together with small litter size, large size at maturity and inshore habitat suggest that it is vulnerable to local population depletion in areas of heavy fishing pressure. Furthermore, its docility and habit of resting in caves and crevices during the day make it susceptible to capture and harassment by divers, and reef destruction.

CONSERVATION ACTIONS There are currently no conservation measures in place for this species.

CITATION Pillans, R. (SSG Australia & Oceania Regional Workshop, March 2003). 2003. Nebrius ferrugineus. The IUCN Red List of Threatened Species 2003. www.iucnredlist.org