Bare nose shark
| Bare nose shark | ||||||||||||
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Bigeye shark ( Carcharhinus altimus ) |
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| Scientific name | ||||||||||||
| Carcharhinus altimus | ||||||||||||
| ( Springer , 1950) |
The bigeye shark ( Carcharhinus altimus ) is a species of the genus Carcharhinus within the Requiem sharks (Carcharhinidae). The species is common in the waters of the east coast of North and South America and in the Gulf of Mexico .
Appearance and characteristics
The bare nose shark is a relatively large shark with a maximum body length of around 280 cm and average lengths of 240 cm. He has a brown-gray body color without any noticeable body markings or markings. The muzzle is large and round and has a clearly defined nasal lobe.
It has an anal fin and two dorsal fins . Like all species of the genus, the animals have five gill slits and no injection hole . A pronounced interdorsal ridge is present. The pectoral fins are almost straight, the beginning of the dorsal fin is at the level of the rear attachment point of the pectoral fins .
Way of life
The bigeye shark is a form of deep water that occurs primarily in the area of the continental shelf slope at depths between 250 and 430 meters. It is often close to the ground and rarely in open water. It feeds predatory on various bony fish as well as on smaller sharks ( dogfish , dogfish ) and rays .
The sharks are viviparous and form a yolk sac placenta ( placental viviparous ). The females get between 3 and 15 young animals with a length of about 70 to 90 cm in one litter. The birth time varies from region to region and is in the Mediterranean from August to September and in the area around Madagascar from September to October. The females prefer areas near the coast, known as nursery grounds . The young sharks reach sexual maturity with a body length of about 216 (females) or 220 centimeters (males).
distribution
The bare nose shark has a worldwide distribution and occurs in the Atlantic , Pacific and Indian Oceans . The distribution is very irregular and often limited to relatively small areas. It can be found in the western Atlantic off North Carolina to Florida and around the Bahamas and in the eastern Atlantic off Senegal , Ghana and South Africa . In the Pacific it comes from Hawaii and California down to Peru and Ecuador and in the Indian Ocean it lives in the coastal waters of Madagascar and off southern India . In the Mediterranean it is rarely encountered and can be used both in the western Mediterranean off Spain (relatively common) as occur in the eastern Mediterranean.
Danger
This species is not specifically fished. This shark is caught as bycatch by longline fishing, which actually fish for tuna. In addition, the bare nose shark is occasionally caught by bottom trawls, also as bycatch. The reported catches are small but not all catches are reported and no specific data are available. It is generally believed that these fishing activities are causing stocks to shrink and put under pressure. This assumption justifies the classification of the species as potentially endangered in the distribution area Northwest Atlantic . There is more pressure from fishing in Southeast Asia and the fins of the great nosed shark have been confirmed in the Hong Kong fin market. In the Indian Ocean, the Maldives reported sharply falling catch quotas.
At present there is not enough information to assess this species beyond the status of insufficient data basis worldwide. This assessment has been maintained by the IUCN since 2008 . Possibly a dangerous situation similar to that of the sandbar shark prevails , so the population of these animals would be in a worrying state. Adequate data collection should now be a priority.
literature
- Alessandro de Maddalena, Harald Bänsch: Sharks in the Mediterranean , Franckh-Kosmos Verlags-GmbH, Stuttgart 2005; Pages 178–179 ( ISBN 3-440-10458-3 )
- Kuno Sch. Steuben : The sharks of the seven seas: species, way of life and sporting catch. Parey, Berlin 1989; Pages 85 and 98. ISBN 3-490-44314-4
Web links
- Species portrait on hai.ch
- Bare nose shark on Fishbase.org (English)
- Carcharhinus altimus inthe IUCN 2013 Red List of Threatened Species . Listed by: Pillans, R., Amorim, A., Mancini, P., Gonzalez, M. & Anderson, C., 2008. Retrieved December 4, 2013 and May 3, 2020.