Leopard Sharks, Triakis semifasciata
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Description & Behavior
Leopard sharks, Triakis semifasciata (Girard, 1855), are members of the Houndsharks Family, Triakidae. Zebra sharks, Stegostoma fasciatum, are commonly confused with leopard sharks and share the same common name in Australia and SE Asia. Leopard sharks have short, broadly-rounded snouts, their first dorsal fins are moderately large and its origin is over their pectoral fins' inner margins. Their second dorsal fin is nearly as large as the first one (height is about 3/4 of the first dorsal fin) and their anal fins are much smaller than their second dorsal fins. Their pectoral fins are broadly triangular and they have very conspicuous dark saddles and dots on their bodies. They have gray to bronze-gray upper bodies with light ventral (under) surfaces. Their average size is between 1.2-1.5 m and their maximum total length is about 1.8 m. Leopard sharks can weigh up to 18.4 kg and live as long as 30 years.
World Range & Habitat
Leopard sharks are found in the Eastern Pacific Ocean: from Oregon to the Gulf of California, Mexico. They are currently an abundant species in cool and warm-temperate waters. They are found inshore and offshore in continental littoral waters. Most common on or near the bottom in shallow waters, between 4-90 m. They prefer sandy or muddy bays. They are active, strong swimmers and are known to form large schools that seem to be nomadic. The swimming motion of this species is described as undulating. Leopard sharks are often seen together with brown smooth-hounds, Mustelus henlei, and gray smooth-hounds, Mustelus californicus, or the piked dogfish, Squalus acanthias.
Feeding Behavior (Ecology)
Leopard sharks, Triakis semifasciata, feed primarily on bottom-living invertebrates. Other small sharks have also been found in their stomachs. Their diet seems to change with seasons and their age/size.
Leopard sharks are aplacental viviparous (ovoviviparous) and they produce between 4-33 pups per litter after a gestation period of about 10-12 months. Their size at birth is about 20 cm, usually in April-May, and they grow very slowly. They reach maturity at an age of about 10 years, males at a size between 0.7-1.2 m, females at approximately 1.1-1.3 m, respectively.
Ovoviviparous: eggs are retained within the body of the female in a brood chamber where the embryo develops, receiving nourishment from a yolk sac. This is the method of reproduction for the "live-bearing" fishes where pups hatch from egg capsules inside the mother's uterus and are born soon afterward. Also known as aplacental viviparous.
Conservation Status & Comments
Leopard sharks are harmless to humans. This mid-sized coastal shark is fairly common in bays and estuaries and are taken both commercially and by recreational anglers.
Although a slow-growing, late-maturing shark with low productivity, management introduced in recent decades has reportedly protected the core of the population in California and Oregon waters from overfishing. Little is known of the stock status in Mexico.
Leopard sharks, Triakis semifasciata, are listed as Least Concern on the IUCN Red List of Threatened Species:
LEAST CONCERN (LC) - A taxon is Least Concern when it has been evaluated against the criteria and does not qualify for Critically Endangered, Endangered, Vulnerable or Near Threatened. Widespread and abundant taxa are included in this category.
References & Further Research
Research Triakis semifasciata » Barcode of Life ~ BioOne ~ Biodiversity Heritage Library ~ CITES ~ Cornell Macaulay Library [audio / video] ~ Encyclopedia of Life (EOL) ~ ESA Online Journals ~ FishBase ~ Florida Museum of Natural History Ichthyology Department ~ GBIF ~ Google Scholar ~ ITIS ~ IUCN RedList (Threatened Status) ~ Marine Species Identification Portal ~ NCBI (PubMed, GenBank, etc.) ~ Ocean Biogeographic Information System ~ PLOS ~ SIRIS ~ Tree of Life Web Project ~ UNEP-WCMC Species Database ~ WoRMS
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