Species Details

Details of Tawny nurse shark will be displayed below

Tawny nurse shark   

Common Name: Tawny nurse shark
Scientific Name: Nebrius ferrugineus
Local Name: Nidhan miyaru
Dhivehi Name: ނިދަންމިޔަރު
Animalia  (Kingdom)
Chordata  (Plylum)
Nebrius   (Genus)

Tawny nurse shark's description

The most remarkable feature of the tawny nurse shark is probably its curious ability to change colour between grey and sandy brown depending on the colour of its surroundings. The tawny nurse shark is uniformly grey to tan-brown on its upper surfaces, paling slightly on the belly. Juveniles can be distinguished from adults by the presence of small dark spots on the skin. This large shark has a broad, flattened head with a squarish snout and tiny eyes. There are two angular dorsal fins close to the tail, the pectoral fins curve backwards, and the long, narrow tail has a large upper lobe and almost no distinct lower lobe.


Tawny nurse shark habitat

The Tawny Nurse Shark occurs on or near coral reefs, particularly in crevices and caves, and seagrass lagoonal habitat at depths of less than 70 m. It is mainly nocturnal and often has a limited home range (Ebert et al. 2013). The species reaches a maximum size of at least 320 cm total length (TL), with males mature at 225–250 cm TL and females mature at 230–290 cm TL (Ebert et al. 2013). Reproductive biology appears to vary regional being aplacental viviparous in Australia with litter sizes of up to 26 pups (maximum of 32 pups) whereas in Japan oophagy is reported with much smaller litter sizes of 1–4 pups (Last and Stevens 2009, Ebert et al. 2013). Size-at-birth of 40–60 cm TL (Teshima et al. 1995, Compagno 2001, Ebert et al. 2013). Generation length is estimated at 30 years based on age data from Ginglymostoma cirratum (Carrier and Luer 1990).

Tawny nurse shark threats

The Tawny Nurse Shark is caught throughout its range in industrial and small-scale longline, gillnet, trawl, and handline fisheries that occur in the waters around coral reefs and other complex habitats. There is little species-specific information on catches, and the magnitude of catches is poorly understood, especially in those areas where population reductions have been the greatest. The species is rarely targeted, except for use as an aquarium display species, because its meat and fins are considered of low value. It is often discarded, but is retained in some nations, including India, Indonesia, Philippines, and Sri Lanka. In recent years, it has only been rarely observed at fish landing sites in Indonesia where it is caught mostly by demersal longline and coastal gillnet vessels. For example, Winter et al. (2020) reporting it made up 0.1% of the elasmobranch catch landed at the port of Muncar in 2017–2018. In the Andaman Islands (India) it is caught mostly in the grouper demersal longline fishery, but also occasionally in trawls. In India, this species is caught in line and gillnet fisheries with landings ranged between from 1 to 84 t per year on the west coast for 2010–2015 (K.K. Bineesh unpubl. data 2020). In Sri Lanka, this species is caught incidentally, and the meat is considered to be of low quality and value. This is a common display species in public and private aquaria. It is exported live from countries such as Australia and Indonesia to aquaria worldwide, but this trade is small compared to catches in fisheries.

The reliance of this species on coral reefs makes it susceptible to declines in habitat quality. Global climate change has already resulted in large-scale coral bleaching events with increasing frequency causing worldwide reef degradation. Almost all warm-water coral reefs are projected to suffer significant losses of area and local extinctions, even if global warming is limited to 1.5ºC (IPCC Report, 2019). Destructive fishing practices in some nations (e.g., dynamite fishing) (McManus 1997) and declining water quality (MacNeil et al. 2019) have also led to the decline in coral reef habitat.

Tawny nurse shark's status