Leopard shark  (Triakis semifasciata)

The leopard shark is classified as Least Concern (LC) on the IUCN Red List (1).

The leopard shark (Triakis semifasciata) is named for its striking patterning, consisting of dark saddles and splotches on the fins and upper body, set against an overall silver or bronzed grey body colouration (2) (3). The snout is relatively broad and short, and the body features a prominent, rounded first dorsal fin, roughly mid-way along the body and a smaller pointed dorsal fin, situated towards the rear. The caudal fin is also distinctive, with an elongated upper lobe featuring a conspicuous notch. Leopard shark teeth are arranged in overlapping rows, forming a broad, ridged and pointed surface on the upper and lower jaws (2).

The leopard shark inhabits the eastern Pacific Ocean, occurring in waters off the coast of Oregon, south to the Gulf of California, Mexico. It is a relatively common species, occurring in large numbers in San Francisco Bay and other large estuaries (1) (2).

The leopard shark inhabits cool and temperate inshore and offshore waters, typically on or near the bottom in shallow water, from the intertidal zone to depths of four metres, although it has been recorded at depths of up to 91 metres. This species’ preferred habitats include sandy areas, mud flats, estuaries, and rock strewn bottoms near rocky reefs and kelp beds (1).

Active during the day and night (3), the leopard shark is often encountered in large, nomadic schools, sometimes mixed with grey and brown smoothhound sharks (Mustelus californicus and Mustelus henlei) and piked dogfish (Squalus acanthias) (1). A large variety of prey is taken, including crabs, shrimps, octopi, fat innkeeper worms (Urechis caupo), fish and fish eggs (2) (4). Burrowing marine invertebrates are one of the most commonly taken food sources, and are extracted by means of the shark grasping exposed parts with its specialised teeth (2).

Recent research indicates that the leopard shark has smaller and more numerous red blood cells than related shark species. This adaptation allows the shark to absorb oxygen more easily and may confer a competitive advantage over some of its close relatives in low oxygen environments such as estuaries (2).

The leopard shark is an ovoviviparous species, which means that it produces eggs that develop and hatch internally, and therefore gives birth to live young (5). Following a gestation period of between 10 and 12 months, a litter of 4 to 33 pups are born, usually between April and May (2). The young measure around 20 centimetres at birth, and grow slowly, only reaching reproductive maturity at an age of around ten years (5).

The leopard shark’s meat is used for human consumption, and it is therefore commonly taken by both commercial and recreational fishers. Like most sharks, as a result of slow growth, late maturity and low reproductive output, this species is vulnerable to overexploitation. Nevertheless at the current time the leopard shark is not considered to be threatened. A rise in spearfishing has possibly caused some declines in areas of California, but due to recent implementation of shark management plans, there is little cause for concern. The status of the leopard shark in Mexico is less clear, as there is little information available regarding catch rates or population size (1).

Thanks to management plans introduced in U.S.A. waters in recent decades, the core population of the leopard shark in the waters around California and Oregon is protected from overfishing (1).

View information on this species at the UNEP World Conservation Monitoring Centre.

Learn more about the conservation of sharks and rays: 

• Save Our Seas Foundation:
  www.saveourseas.com
• IUCN Shark Specialist Group:
  www.iucnssg.org
• Shark Research Institute:
  www.sharks.org
• Shark Trust:
  www.sharktrust.org