Scaphirhynchus platorynchus

Scaphirhynchus platorynchus
Scaphirhynchus platorynchus
Systematics
Subclass : Cartilage organoids (chondrostei) Order : Sturgeon (Acipenseriformes) Family : Sturgeon (Acipenseridae) Subfamily : Shovel sturgeon (Scaphirhynchinae) Genre : Scaphirhynchus Type : Scaphirhynchus platorynchus
Scientific name
Scaphirhynchus platorynchus
( Rafinesque , 1820)

The shovel sturgeon ( Scaphirhynchus platorynchus ; English: shovelnose sturgeon , also: hackleback , sand sturgeon , switchtail ) is an endangered species of fish from the family of sturgeon (Acipenseridae) in the United States . It is the smallest species of freshwater sturgeon and is endemic to the Missouri and Mississippi Rivers . It is fished commercially.

Surname

The German and English as well as the scientific name refer to the shovel-shaped rostrum . Scaphirhynchus means "spade snout " and platorynchus also means "broad- snouted ". The English "switch tail" refers to a long ray of the caudal fin , which is often lost in older specimens.

features

Blade sturgeon

The sturgeons are characterized by rows of bone plates along the sides and four barbels on the underside of the rostrum. These barbels are at the same distance from the tip of the snout and the mouth. In contrast to the white shovel sturgeon ( S. albus ), the shovel sturgeon has no scales on its belly. Shovel sturgeons can reach 1 m in length and 4.8 kg in weight. Most specimens are only 50-85 cm long and 2.5 kg heavy. A special feature of the shovel sturgeon is a long, thin fin ray on the upper caudal fin lobe , which is often lost in older specimens. The color varies between light brown and leather colors with a white belly. The sturgeon is commercially fished for its tasty meat and its roe , which is processed into premium caviar .

distribution and habitat

The shovel sturgeon can only be influenced slightly by cloudy water. The Missouri River and the Mississippi River continuously transport large amounts of sediment. In these murky waters, the animals live mainly in the main arms near the bottom and like to stay in areas with fast currents and sand or gravel bottoms. The fish often migrate over long distances.

The sturgeons feed on insect larvae ( caddis flies , mayflies, etc.), as well as crustaceans , worms and small fish. They are also hosts of glochidia (larvae) of several freshwater molluscs , including Quadrula pustulosa (Pimpleback), Obovaria olivaria (Hickorynut) and Lampsilis teres (Yellow sandshell). The shovel sturgeon is the only known host of the hickorynut clam .

behavior

Usually the fish migrate back and forth between the feeding grounds and the breeding grounds in the large rivers. While they tend to stay at the bottom of the water during the year, the animals come closer to the water surface during spawning time. The females do not spawn every year, but there are no records of spawning behavior either. The spawn is deposited over gravelly ground in relatively fast flowing waters. The young hatch after 3–5 days with a length of approx. 1 cm and the larvae drift down the river, where they find suitable habitats to grow up. Carlson writes that growth is relatively slow. The animals grow approximately 21.3  inches (54.1 cm) in five years.

Commercial importance

The roe of the shovel sturgeon is sold as hackleback caviar . Since the caviar production in the Caspian Sea and the Black Sea becomes low, the caviar production of Shovelnose and paddlefish commercially interesting. The sturgeon meat is widely regarded as a delicacy and is also often smoked. Poaching is becoming more and more of a problem, especially since the animals have to be 8-10 years old to spawn for the first time. Sometimes shovel sturgeons are also kept as aquarium fish.

Diseases

The shovel sturgeon , like the white shovel sturgeon, is parasitized by the Missouri River sturgeon iridovirus (MRSIV).

literature

• Michael Barton: Bond's Biology of Fishes . Thompson Brooks / Cole, Belmont, California 2007.
• Douglas M. Carlson, William L. Pflieger, Linden Trial, Pamela S. Haverland: Distribution, biology, and hybridization of Scaphirhynchus albus and S. platorynchus in the Missouri and Mississippi rivers . In: Env. Biol. Fishes 14 (1) 1985, pp. 51-59, doi: 10.1007 / BF00001576
• John W. Held: Some early summer foods of the shovelnose sturgeon in the Missouri River . In: Trans. Am. Fish. Soc. 98 (3), July 1969, pp. 514-517, doi : 10.1577 / 1548-8659 (1969) 98 [514: SESFOT] 2.0.CO; 2
• William L. Pflieger: The Fishes of Missouri . Conservation Commission of the State of Missouri (Missouri Dept. of Conservation), Jefferson City, Missouri 1997. ISBN 1-887247-11-4 , ISBN 978-1-887247-11-5 , paperback: 372 pages

Individual evidence

1. ↑ Pflieger 1997.
2. ↑ Pflieger, 1997.
3. ↑ Barton 2007.
4. ↑ Pflieger 1997.
5. ↑ Carlson 1985; Hero 1969.
6. ↑ ^{a b} Shovelnose Sturgeon brochure , US Fish and Wildlife Service, Onalaska , Wisconsin, May 16, 2001
7. ↑ Barton 2007;
8. ↑ American Hackleback Caviar.

Web links

Commons : Scaphirhynchus platorynchus  - collection of images, videos and audio files

• Scaphirhynchus albus in the endangered Red List species the IUCN 2006. Posted by: Krentz, S., 2006. Retrieved on December 18, 2013 ..
• Scaphirhynchus platorynchus on Fishbase.org (English)
• Scaphirhynchus platorynchus in the Integrated Taxonomic Information System (ITIS)