Salmon shark
| Salmon shark | ||||||||||||
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Salmon shark ( Lamna ditropis ) |
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| Scientific name | ||||||||||||
| Lamna ditropis | ||||||||||||
| Hubbs & Follett , 1947 |
The salmon shark ( Lamna ditropis ) is a species of the mackerel sharks (Lamnidae) and, together with the porbeagle shark ( L. nasus ), forms the genus of porbeagle sharks ( Lamna ). The species is found in cold to temperate waters of the northern Pacific .
Appearance and characteristics
The salmon shark reaches an average body length of over two meters and can grow to a maximum of three meters. It has a gray to gray-black body color and a white belly region with darker spots, while the underside of the snout is darkly colored in the adult animals. There is a distinct white spot at the base of the pectoral fins and the first dorsal fin ends in a black tip.
The snout is short and conical and the mouth, viewed from below, is broadly parabolic without labial folds. The eyes are large and are located relatively high on the head, the five gill slits are long and lie in front of the attachment of the pectoral fins.
It has an anal fin and two dorsal fins . The first dorsal fin is significantly larger than the second and begins above the pectoral fins. The anal fin is about the same size as the very small second dorsal fin. The tail stalk has conspicuous tail keels on both sides.
distribution
The salmon shark is common in cold to temperate waters of the northern Pacific , with males mainly in the eastern area and females in the western.
Its habitat is in the area of the coasts and the continental shelf in water depths of up to 225 meters.
Way of life
The salmon shark lives in small groups that are separated by age and gender. It feeds predatory on various schooling fish such as salmon , mackerel and herring , which it follows on their migrations.
The sharks are viviparous and do not form a placenta (aplacentally viviparous ). The females get between two and five young animals with a length of about 40 to 50 cm in one litter. The males are sexually mature at around two years of age and around 180 cm long, and the females at 220 cm.
Importance to humans
The salmon shark is generally classified as harmless, as a rule it avoids encounters with swimmers and divers.
It is caught and eaten relatively often off the coast of Alaska as well as in Asia; there is no estimate of the total number of catches, especially as bycatch or the influence on the population. In the IUCN Red List it is listed as “data deficient” due to the imprecise data situation. In 2007/2008 the IUCN announced that the salmon shark would be classified as "least concern" based on an investigation by the IUCN SSC Shark Specialist Group (SSG) into pelagic shark and ray species in front.
supporting documents
- ↑ Lamna ditropis in the endangered Red List species the IUCN 2013. Posted by: Goldman, K., Kohin, S., Cailliet, GM & Musick, JA, 2009. Retrieved on July 8, 2013.
literature
- Leonard Compagno , Marc Dando, Sarah Fowler: Sharks of the World. Princeton Field Guides, Princeton University Press , Princeton and Oxford 2005; Pp. 183-184, ISBN 978-0-691-12072-0 .
Web links
- Salmon shark on Fishbase.org (English)
- Salmon shark in the hai.ch database
- Brenda Roman: Salmon Shark. Florida Museum of Natural History. Accessed October 15, 2008