Shovelnose sturgeon
Encyclopedia
The shovelnose sturgeon, Scaphirhynchus platorynchus, is the smallest species of freshwater sturgeon
native to the United States of America. It is often called "hackleback", "sand sturgeon", or "switchtail." Switchtail refers to the long filament found on the upper lobe of the caudal fin (often broken off as adults). Shovelnose sturgeon are the most abundant sturgeon
, found in the Missouri River
and Mississippi River
systems, and the only commercially fished sturgeon in the United States of America (Pflieger 1997).
s along the sides and back and four barbels on the underside of the rostrum
. A total of 25 extant species of sturgeon are recognized, including 17 within the genus Acipenser. Sturgeon are distributed around the northern part of the Northern Hemisphere
(holarctic diston
) and have marine
, freshwater
, and anadromous members. Sturgeons, including the shovelnose, are highly regarded for their flesh and their roe
, from which premium grades of caviar
are made (Barton 2007).
The scientific name Scaphirhynchus, Greek, means "spade snout," and platorynchus, Greek, means "broad snout." The shovelnose sturgeon is characterized by a long slender filament on the upper lobe of the caudal fin. They have a flattened rostrum (modified snout) that is also shovel shaped. There are four fringed barbels on the ventral side of the rostrum that can be found in a straight line, which is equidistant from the mouth opening to the tip of the snout, unlike pallid sturgeon
. The belly of the shovelnose sturgeon is covered with scale-like plates, which is another distinguishing factor from pallid sturgeon whom have p
. The Missouri River
and the Mississippi River
systems tend to carry high sediment loads. Here the sturgeon inhabits the open channel or main channel areas of the large rivers. It lives on the bottom, often in areas with swift current and sand or gravel bottom. As with many riverine fish species, the shovelnose sturgeon does not have a restricted home range and may travel long distances (Pflieger 1997).
The shovelnose sturgeon feeds on the bottom, using its highly protrusible mouth to suck up its food. The diet is mainly aquatic insect larvae, consisting principally of mayflies, true flies (Diptera
), and caddisflies. The sturgeon also feed on crustaceans, worms, and small fish (Carlson et al. 1985;Held 1969). As a result to bottom feeding it is a host to the glochidia (larvae) of several species of freshwater mollusc, including Quadrula pustulosa
(Pimpleback), Obovaria olivaria
(Hickorynut) and Lampsilis teres (Yellow sandshell). It is the only known host to the hickorynut mussel.
A typical sturgeon's life history includes a migration from feeding grounds to breeding grounds in large rivers. During spawning, behavior changes and swimming near the surface occurs. Females do not spawn every year and spawning chronology is not readily evident. Spawning takes place over gravel in fairly swift water. Eggs hatch after 3 to 5 days, and the larvae—about 1 cm long—drift downstream to suitable rearing areas in the river (Barton 2007). Carlson et al. (1985) found that growth of the shovelnose sturgeon is relatively slow, at 21.3 inches (54.1 cm) in five years.
and Black Sea
sturgeon caviar have become endangered
, roe from shovelnose sturgeon and paddlefish
have recently become commercially important. The flesh of the sturgeon is widely considered a delicacy, especially smoked sturgeon. Poaching of the shovelnose sturgeon is becoming a problem, as they must be 8–10 years old before spawning can occur, and females are only gravid once every 3 years. There is some interest in marketing the shovelnose sturgeon as an aquarium species.
Sturgeon
Sturgeon is the common name used for some 26 species of fish in the family Acipenseridae, including the genera Acipenser, Huso, Scaphirhynchus and Pseudoscaphirhynchus. The term includes over 20 species commonly referred to as sturgeon and several closely related species that have distinct common...
native to the United States of America. It is often called "hackleback", "sand sturgeon", or "switchtail." Switchtail refers to the long filament found on the upper lobe of the caudal fin (often broken off as adults). Shovelnose sturgeon are the most abundant sturgeon
Sturgeon
Sturgeon is the common name used for some 26 species of fish in the family Acipenseridae, including the genera Acipenser, Huso, Scaphirhynchus and Pseudoscaphirhynchus. The term includes over 20 species commonly referred to as sturgeon and several closely related species that have distinct common...
, found in the Missouri River
Missouri River
The Missouri River flows through the central United States, and is a tributary of the Mississippi River. It is the longest river in North America and drains the third largest area, though only the thirteenth largest by discharge. The Missouri's watershed encompasses most of the American Great...
and Mississippi River
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
systems, and the only commercially fished sturgeon in the United States of America (Pflieger 1997).
Physical description
The sturgeons of the family Acipenseridae have bony scuteScute
A scute or scutum is a bony external plate or scale, as on the shell of a turtle, the skin of crocodilians, the feet of some birds or the anterior portion of the mesonotum in insects.-Properties:...
s along the sides and back and four barbels on the underside of the rostrum
Rostrum (anatomy)
The term rostrum is used for a number of unrelated structures in different groups of animals:*In crustaceans, the rostrum is the forward extension of the carapace in front of the eyes....
. A total of 25 extant species of sturgeon are recognized, including 17 within the genus Acipenser. Sturgeon are distributed around the northern part of the Northern Hemisphere
Northern Hemisphere
The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...
(holarctic diston
Holarctic
The Holarctic ecozone refers to the habitats found throughout the northern continents of the world as a whole. This region is divided into the Palearctic, consisting of Northern Africa and all of Eurasia, with the exception of Southeast Asia and the Indian subcontinent, and the Nearctic,...
) and have marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
, freshwater
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...
, and anadromous members. Sturgeons, including the shovelnose, are highly regarded for their flesh and their roe
Roe
Roe or hard roe is the fully ripe internal egg masses in the ovaries, or the released external egg masses of fish and certain marine animals, such as shrimp, scallop and sea urchins...
, from which premium grades of caviar
Caviar
Caviar, sometimes called black caviar, is a luxury delicacy, consisting of processed, salted, non-fertilized sturgeon roe. The roe can be "fresh" or pasteurized, the latter having much less culinary and economic value....
are made (Barton 2007).
The scientific name Scaphirhynchus, Greek, means "spade snout," and platorynchus, Greek, means "broad snout." The shovelnose sturgeon is characterized by a long slender filament on the upper lobe of the caudal fin. They have a flattened rostrum (modified snout) that is also shovel shaped. There are four fringed barbels on the ventral side of the rostrum that can be found in a straight line, which is equidistant from the mouth opening to the tip of the snout, unlike pallid sturgeon
Pallid sturgeon
The pallid sturgeon is an endangered species of ray-finned fish, endemic to the waters of the Missouri and lower Mississippi River basins of the United States...
. The belly of the shovelnose sturgeon is covered with scale-like plates, which is another distinguishing factor from pallid sturgeon whom have p
Distribution, habitat, and reproduction
The shovelnose sturgeon, as its distribution represents, is impacted very little by turbidityTurbidity
Turbidity is the cloudiness or haziness of a fluid caused by individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality....
. The Missouri River
Missouri River
The Missouri River flows through the central United States, and is a tributary of the Mississippi River. It is the longest river in North America and drains the third largest area, though only the thirteenth largest by discharge. The Missouri's watershed encompasses most of the American Great...
and the Mississippi River
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
systems tend to carry high sediment loads. Here the sturgeon inhabits the open channel or main channel areas of the large rivers. It lives on the bottom, often in areas with swift current and sand or gravel bottom. As with many riverine fish species, the shovelnose sturgeon does not have a restricted home range and may travel long distances (Pflieger 1997).
The shovelnose sturgeon feeds on the bottom, using its highly protrusible mouth to suck up its food. The diet is mainly aquatic insect larvae, consisting principally of mayflies, true flies (Diptera
Diptera
Diptera , or true flies, is the order of insects possessing only a single pair of wings on the mesothorax; the metathorax bears a pair of drumstick like structures called the halteres, the remnants of the hind wings. It is a large order, containing an estimated 240,000 species, although under half...
), and caddisflies. The sturgeon also feed on crustaceans, worms, and small fish (Carlson et al. 1985;Held 1969). As a result to bottom feeding it is a host to the glochidia (larvae) of several species of freshwater mollusc, including Quadrula pustulosa
Quadrula pustulosa
Quadrula pustulosa, common name the Pimpleback, is a species of freshwater mussel, an aquatic bivalve mollusk in the family Unionidae, the river mussels....
(Pimpleback), Obovaria olivaria
Obovaria olivaria
Obovaria olivaria is a species of freshwater mussel, an aquatic bivalve mollusk in the family Unionidae, the river mussels.This species is endemic to the United States.-References:* Bogan, A.E. 1996. . Downloaded on 7 August 2007....
(Hickorynut) and Lampsilis teres (Yellow sandshell). It is the only known host to the hickorynut mussel.
A typical sturgeon's life history includes a migration from feeding grounds to breeding grounds in large rivers. During spawning, behavior changes and swimming near the surface occurs. Females do not spawn every year and spawning chronology is not readily evident. Spawning takes place over gravel in fairly swift water. Eggs hatch after 3 to 5 days, and the larvae—about 1 cm long—drift downstream to suitable rearing areas in the river (Barton 2007). Carlson et al. (1985) found that growth of the shovelnose sturgeon is relatively slow, at 21.3 inches (54.1 cm) in five years.
Commercial importance
The roe of the shovelnose sturgeon is marketed as "hackleback" caviar. As old world sources of CaspianCaspian Sea
The Caspian Sea is the largest enclosed body of water on Earth by area, variously classed as the world's largest lake or a full-fledged sea. The sea has a surface area of and a volume of...
and Black Sea
Black Sea
The Black Sea is bounded by Europe, Anatolia and the Caucasus and is ultimately connected to the Atlantic Ocean via the Mediterranean and the Aegean seas and various straits. The Bosphorus strait connects it to the Sea of Marmara, and the strait of the Dardanelles connects that sea to the Aegean...
sturgeon caviar have become endangered
Beluga sturgeon
The beluga or European sturgeon is a species of anadromous fish in the sturgeon family of order Acipenseriformes. It is found primarily in the Caspian and Black Sea basins, and occasionally in the Adriatic Sea...
, roe from shovelnose sturgeon and paddlefish
Paddlefish
Paddlefish are primitive Chondrostean ray-finned fishes. The paddlefish can be distinguished by its large mouth and its elongated, spatula-like snout, called a rostrum, which is longer than the rest of the head...
have recently become commercially important. The flesh of the sturgeon is widely considered a delicacy, especially smoked sturgeon. Poaching of the shovelnose sturgeon is becoming a problem, as they must be 8–10 years old before spawning can occur, and females are only gravid once every 3 years. There is some interest in marketing the shovelnose sturgeon as an aquarium species.