Black-nosed shark
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Black-nosed shark ( Carcharhinus acronotus ) |
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| Carcharhinus acronotus | ||||||||||||
| ( Poey , 1860) |
The black-nosed shark ( Carcharhinus acronotus ) 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 black-nosed shark is a medium-sized shark with a maximum body length of around 200 cm and an average length of 125 cm and a weight of around 10 kg. It has a gray body color and a conspicuous black spot on the tip of the snout in the area of the nose or just below it. The stain is particularly pronounced in young animals and later fades. The second dorsal fin and the upper lobe of the caudal fin have dark to black spots.
It has an anal fin and two dorsal fins . The first dorsal fin is small and is slightly level with the free ends of the pectoral fins. These too are small compared to related species. Like all species of the genus, the animals have five gill slits and no injection hole .
The black-nosed shark resembles other species of the genus Carcharhinus with a long and rounded snout, but due to the conspicuous black tip of the snout, there is no risk of confusion.
Way of life
The black-nosed shark is a common coastal and shallow-water species that is found above all over sandy and coral-like subsoil. It feeds predatory on various fish of the shore zones such as the sea bream (Sparidae). He himself is hunted by larger species of shark.
The sharks are viviparous and form a yolk sac placenta ( placental viviparous ). After a gestation period of 8 to 9 months, the females have between 3 and 6 young animals with a length of about 40 to 50 cm in one litter. In the Florida region, the birth time is from January to April; no data are available for other populations. The females prefer areas near the coast, known as nursery grounds . The young animals reach sexual maturity within two years with a body length of about 100 centimeters.
distribution
The black-nosed shark is common in the western Atlantic Ocean in tropical waters in the area between latitudes 40 ° N - 37 ° S and longitudes 100 ° W - 33 ° W. It lives in the coastal areas of North America from South Carolina to Florida , on the Bahamas and the Gulf of Mexico as well as on the South American east coast to southern Brazil . It occurs mainly in shallow waters above the continental shelf .
Importance to humans
The blacknose shark is generally classified as harmless, while in this type as in the so-called other relatives was Drohschwimmen ( hunching ) observed.
Danger
In its entire range, this shark is likely bycatch and also a target for fishing. US trawls that are used to catch shrimp pose a problem; this method is used intensively in the entire Gulf of Mexico and on the Caribbean coast of South America. This leads to overfishing of this species and mostly kills young animals and represents the greatest threat to the stocks. In the mentioned distribution areas, however, there is no information about catch quotas or population developments. Available data come from north and north-east Brazil; these do not give any evidence of shrinking populations. Sexually mature animals are common in this region. Other developments are evident in the US populations. An increased decline has been recorded there since 2000. Measures must be taken to compensate for this decline.
Further data should be collected as it is not exactly clear what impact fishing generally has in the entire range. In addition, population growth rates should be monitored. Based on this decision-making basis, the black-nosed shark has been classified as potentially endangered by the IUCN since 2008 .
supporting documents
literature
- 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
Individual evidence
- ↑ a b Carcharhinus acronotus in the endangered Red List species the IUCN 2009 Posted by: Morgan, M., Carlson, J., Kyne, PM & Lessa, R, 01 December, 2008.
Web links
- Species portrait on hai.ch
- Black-nosed shark on Fishbase.org (English)
- Carcharhinus acronotus onthe IUCN Red List of Threatened Species 2013.1. Posted by: Morgan, M., Carlson, J., Kyne, PM & Lessa, R., 2008. Retrieved October 6, 2013.