Carcharhiniformes Triakidae (The Houndsharks)

Carcharhiniformes Triakidae (the houndsharks)

Jeff Guertin

10/30/07

9 Genera, ~39 species

·  Furgaleus (whiskery shark) - one species

·  Galeorhinus (school shark, oil shark, vitamin shark) - one species

·  Gogolia (sailback houndshark) - one species

·  Hemitriakis (whitefin tope sharks) - four species (plus 2 unnamed)

·  Hypogaleus (japanese tope shark) - one species

·  Iago (bigeye houndsharks) - two species

·  Mustelus (smooth hound sharks, smooth dogfishes, gummy sharks) ~22 species (plus 2 unnamed)

·  Scylliogaleus (flapnose houndshark) - one species

·  Triakis (leopard sharks) - 5 species

General Characteristics

·  Small to moderate-sized sharks

·  Some of the most abundant sharks off of Atlantic and Pacific coasts of North America

·  Horizontally oval eyes

·  Nictitating eyelids

·  Anterior nasal flaps

Distinctive Features

·  Small rounded teeth

·  Three to four separate cusps

·  First dorsal in front of the pelvic

·  No precaudal pits

·  Caudal fin may or may not have a strong ventral lobe

·  Two large-sized, spineless dorsal fins

·  Anal fin

·  T. semifasciata - distinctive markings provide camouflage against dappled ground; well developed spiracle; sometimes tinged with iridescence

·  M. canis - melanophores; spiracle is only of moderate size; pronounced sub-ocular fold

·  G. galeus - pronounced spiracles; first dorsal much larger than second dorsal

Habitat

·  Tropical and temperate seas worldwide

·  Mostly occur on continental and insular shelves

·  a few are deepwater slope dwellers (up to 2000m)

·  None are oceanic

·  Some seasonally migrate

·  Leopard Shark (Triakis semifasciata) - Eastern Pacific (Mexico to Oregon) but mostly in San Francisco Bay

·  Smooth dogfish (Mustelus canis) - Western Atlantic (Cape Cod to Uruguay)

·  Tope shark (Galeorhinus galeus) - Eastern Atlantic (largest inshore native shark in British waters); Oceania, South Africa, South America

Food Habits

·  Feed primarily on bottom and mid-water invertebrates and bony fishes

·  Worms, mollusks, crustaceans, octopuses

·  T. semifasciata - hunt in groups, sometimes with smooth-hound sharks

Size, Age, & Growth

·  T. semifasciata - born at a length of about 20 cm, max length of 180cm-200cm (avg. 150cm); maximum reported age about 50yrs

·  M. canis - max size roughly 150cm (avg. 122cm); males have a life span of 10yrs, females 16yrs; males mature 2-3yrs and females mature 3-4yrs

·  G. Galeus - max size roughly 190cm for males, 195cm for female; mature ~10-15yrs; life span up to 55 years

Reproduction

·  Live bearing (both viviparous and ovoviviparous)

·  Litters range from 1-52

·  T. semifasciata - migrate seasonally; aplacental viviparity (ovoviviparous); 4 to 33 pups per litter; Gestation is estimated at 10 to 12 months.

·  M. Canis - viviparous; 4-20 embryos of varying ages, not all born at once; ~10 month gestation

·  G. Galeus - aplacental viviparity; produce young every 2 yrs; 6-52 pups/litter

Predators

·  Marine mammals

·  Other large fish (Carcharodon carcharias in particular for leopard sharks)

·  Sharpnose Sevengill (Heptranchias perlo) is a primary predator of tope sharks

Conservation

·  T. semifasciata - Lower Risk according to IUCN; but actively sought by sport fishermen in the San Francisco Bay Area and in Monterey Bay for food

·  M. canis - Near Threatened according to IUCN; sought by small fisheries but mostly by-catch; often used as lab specimen and in aquaria

·  G. galeus - Vulnerable globally and Near Threatened in New Zealand according to IUCN; commercially harvested

Bibliography

·  Carrier, J,, Musick, J., and Heithaus, M. 2004. Biology of Sharks and Their Relatives. CRC Press, Boca Raton.

·  Cailliet, GM (1992). Demography of the central california population of the Leopard Shark (Triakis semifasciata). Australian Journal of Marine and Freshwater Research 43, 183–193.

·  Conrath CL and Musick JA. 2002. Reproductive Biology of the Smooth Dogfish, Mustelus canis, in the Northwest Atlantic Ocean. Environmental Biology of Fishes 64, 367-377.

·  Florida Museum of National History. <http://www.flmnh.ufl.edu/fish/>. Downloaded on 25 October 2007.

·  IUCN 2006. 2006 IUCN Red List of Threatened Species. <http://www.iucnredlist.org>. Downloaded on 25 October 2007.

·  Nelson, J. 1984. Fishes of the World. 2nd Ed. John Wiley & Sons, Inc., New York.

·  Parker, S. 1999. The Encyclopedia of Sharks. Firefly Books, Buffalo.

·  Perrine, D. 1999. Sharks and Rays of the World. Voyageur Press, Hong Kong.

·  Steel, R. 1985. Sharks of the World. Facts on File, Inc., New York.