Download 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.