Sand Tiger Shark

About the Sand Tiger Shark

Also known as the Sand Tiger Shark, Grey Nurse Shark, and Spotted Ragged-Tooth Shark. This species is a large, coastal shark with a disjunct distribution, occurring in most subtropical and warm temperate oceans, except for the Eastern Pacific.

Biology:

The maximum size of this species has been given variously as 3.2 m (10.5 ft), 2.75 m (9 ft)  and 142 Kg (313 lb), 3.2 m (10.5 ft), and 300 Kg (661 lb). Records from beach meshing have suggested that these sharks can grow to 4.3 m (14.1 ft), but this measure is doubtful and may be due to a misidentification. The Grey Nurse is a shark with a short, pointy snout, small eyes, spike-like teeth and equal size dorsal and anal fins. Feeds on bony fishes, small sharks, rays, squids, crabs, and lobsters

Reproduction:

The Grey Nurse Shark has a strong K-selected life history. They are ovoviviparous, meaning it produces young by means of eggs that hatch inside the mother’s body, and produce only two large pups per litter, this is because the remaining eggs and developing embryos are eaten by the largest and most advanced embryo in each horn of the uterus (this phenomenon is known as adelphophagy or uterine cannibalism). As a result of their annual rates of the population are very low, reducing its ability to sustain fishing pressure. The gestation period may last from 9-12 months and size at birth is relatively large, about 1 m (3.3 ft).

Behaviour:

The Grey Nurse shark occurs either alone or in small to medium-sized aggregations of 10-80 individuals. These sharks are often observed hovering motionless just above the seabed in or near deep sandy-bottomed gutters or rocky caves, generally found from the surf zone down to depths of around 25m (82 ft). They can also be found around coral reefs and shallow bays.

Conservation:

The current population of this species is unknown due to the fact that this one has been severely fragmented. Populations in several locations have been severely depleted by commercial fishing, spearfishing, and protective beach meshing, requiring the introduction of specific management measures.

The species is captured as target and bycatch in artisanal, recreational, and industrial fisheries across its range with multiple fishing gears including longline, gillnet, and trawl, and is mostly retained for its meat and fins, unless regulations prohibit retention. Species-specific population trend data reveal a subpopulation reduction of >80% in east Australia, with inferred subpopulation reductions of 30–49% in Northwest Atlantic and South Africa over the past three generation lengths (74 years). The species is suspected to be Critically Endangered in the Southwest Atlantic, Mediterranean, and the Arabian Seas region where it is either no longer or rarely encountered. It is suspected to have undergone similar levels of reduction of >80% over the past three generation lengths (74 years) in West Africa and Southeast Asia where there are high levels of historic and current inshore fishing pressure. Overall, the species is estimated and suspected to be declining across its entire range due to exploitation, except for west Australia, with signs of the onset of recovery evident where management measures have prohibited retention or reduced fishing mortality and have been in place for some time, that is in the Northwest Atlantic, South Africa, and east Australia. Globally, it is suspected that the Sand Tiger Shark has undergone a population reduction of >80% over the past three generations lengths (74 years) due to levels of exploitation, and it is assessed as Critically Endangered A2bd.

The species is used for it meat that is consumed fresh, frozen, smoked, and dried and salted. It is used for its fins which accounted for <1% of fin samples analysed in Hong Kong (Fields et al. 2018), and for its skin, liver oil, and for fish meal. It is popular in public aquaria and for dive tourism in the United States of America, South Africa, and Australia (Ebert et al. 2013).

Species-specific measures are in place in a number of countries and regions. In the United States (US), it was listed as a prohibited species in 1997 under the Fishery Management Plan for Atlantic Sharks (Carlson et al. 2009). In Australia, game fishers voluntarily banned capture of this species in Australian waters in 1979, it was protected in 1984 in New South Wales, and in 1997 it was listed as threatened under the national Environment Protection Biodiversity Conservation Act in 1997, making the take and retention of this species illegal throughout its Australian range. A National Recovery Plan for the species was adopted in 2002 and updated in 2014. From 2001 to 2009, 26 Marine Protected Areas were established in east Australia, at least in part, to manage interactions with the Sand Tiger Shark (Lynch et al. 2013).

In Argentina, the landing of this species is prohibited in recreational fisheries. In the Mediterranean, Parties to the Barcelona Convention agreed that the Sand Tiger Shark is prohibited to be retained and must be released unharmed and alive, to the extent possible. In South Africa, it was protected from commercial fishing through the Marine Living Resources Act of 1998, as a precautionary approach in response to declining population trends elsewhere in the world. In recent years, fishing effort by the Kwazulu-Natal bather protection program has been reduced in order to reduce captures of all exploited species.

To conserve the population and to permit recovery, a suite of measures will be required which may include species protection, spatial management, bycatch mitigation, and harvest and trade management measures (including international trade measures). Effective enforcement of measures will require ongoing training and capacity-building (including in the area of species identification). Catch monitoring is needed to help understand population trends and inform management.

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Sand Tiger Shark Gallery