Fishes · Sharks · Nurse sharks

Tawny Nurse Shark

Nebrius ferrugineus (Lesson, 1831)

syn. Ginglymostoma concolor, Ginglymostoma ferruginaea, Ginglymostoma ferruginea, Ginglymostoma ferrugineum, Ginglymostoma muelleri, Ginglymostoma rueppellii +9 more

3.2 m1-70 mVulnerable

1122

The tawny nurse shark (Nebrius ferrugineus) is a carpet shark species in the family Ginglymostomatidae and is the only extant member of the genus Nebrius. It is widely distributed in the Indo-Pacific region and can be found along coastlines, particularly reefs, sandy flats, and seagrass beds, in shallow waters up to a depth of 70 m (230 ft).

With its cylindrical body and broad, flattened head, the tawny nurse shark bears a resemblance to the nurse shark (Ginglymostoma cirratum) found in the Atlantic and East Pacific. However, it can be distinguished by its pointed-tipped dorsal fins and narrow, sickle-shaped pectoral fins. The maximum recorded length for this species is 3.2 m (10 ft).

The tawny nurse shark is nocturnal in nature and tends to rest during the day in groups of two dozen or more individuals inside caves or under ledges. At night, it becomes an active-swimming predator and uses a strong suction force to extract prey from holes and crevices. The diet of this species primarily consists of octopus, but it also consumes other invertebrates, small bony fishes, and occasionally sea snakes.

Reproductively, the tawny nurse shark is aplacental viviparous, which means the embryos hatch from egg capsules inside the mother. It is unique among carpet sharks in that the embryos are oophagous, feeding on eggs produced by the mother while still inside the uterus. The litter size can range from one to a few individuals based on the large size of near-term embryos.

Compared to the nurse shark, the tawny nurse shark has a more calm temperament and often allows divers to interact with it, including touching and playing. However, it is important to show respect to this species due to its powerful jaws and sharp teeth. The tawny nurse shark is frequently caught by commercial fisheries for purposes such as meat, fins, liver oil, leather, and fishmeal. It is also valued as a game fish off Queensland, 🇦🇺 Australia, known for its habit of spitting water at its captors. The International Union for Conservation of Nature (IUCN) has classified the tawny nurse shark as Vulnerable, with subpopulations in several areas already greatly reduced or extinct.

Overall, the tawny nurse shark is an important species in the Indo-Pacific region. Its distribution spans from the 🌊 Indian Ocean to the 🌊 Pacific Ocean, and it occupies a variety of habitats including sandy flats, seagrass beds, and coral or rocky reefs. It specializes in preying on octopus but also consumes a range of other food sources such as corals, sea urchins, crustaceans, squid, and small fishes. Divers often have pleasant interactions with tawny nurse sharks, as they tend to exhibit a more docile behavior compared to nurse sharks. Nonetheless, it is crucial to approach this species with caution due to their strength and powerful biting capabilities. Tawny nurse sharks are popular attractions for ecotourist divers in various locations such as 🇹🇭 Thailand and the 🇸🇧 Solomon Islands.

Why it's threatened

Biological resource use

Unintentional effects: (subsistence/small scale) [harvest] · Unintentional effects: (large scale) [harvest]

Climate change & severe weather

Habitat shifting & alteration · Temperature extremes

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.

Threat classification from the IUCN Red List.