Shovelnose sturgeons search for food by manipulating their large barbels which have taste buds and electrorecptors. These barbels hang below the mouth and feel the bottom as the sturgeon swims. This allows them to sense when food or other obstacles are below.
Communication Channels: tactile
Perception Channels: tactile ; chemical
Other fishes, such as catfishes and burbots, probably eat the young shovelnose sturgeons. The main predator of adult shovelnose sturgeons is man. Presently, about 25 tons of shovelnose sturgeon are harvested annually. Sixty percent come from the Mississippi River upstream of St. Louis, Missouri. They are harvested in late fall and early winter for both meat and highly valued roe. The alteration of large rivers, and construction of locks and dams for navigational purposes has contributed significantly to the decline of the species by blocking access to ancestral spawning grounds, and by eliminating its required habitat.
Known Predators:
Shovelnose sturgeons have an elongated body with five rows of sharply keeled body plates: 14-19 dorsal plates, 38-47 lateral, 10-14 ventrolateral. They are olive to yellowish-brown in color on the top with lighter sides, and white on the bottom. The head contains bony plates with short spines at the tip of the snout and anterior to the eye. The snout is rounded and pointed up. The caudal peduncle is long, depressed, and fully armored. The tail is heterocercal, with the upper lobe containing long, thread-like filaments. All four barbels are evenly spaced under the jaw, unlike the related pallid sturgeon, which has barbels unevenly spaced under the jaw. The most readily distinguishing characteristic of the shovelnose is its small size and dark color. They rarely exceed 5 lbs (2.3 kg) or over 28 inches (70 cm)in length.
Range mass: .050 to 8.170 kg.
Average mass: 2.500 kg.
Range length: 6.0 to 106.2 cm.
Average length: 91.0 cm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: female larger
The largest shovelnose sturgeon recorded weighed 13.72 lbs (6.2 kg). Most are not expected to live over 30 years of age.
Range lifespan
Status: wild: 61 (high) years.
Average lifespan
Status: captivity: 70 years.
Average lifespan
Status: wild: 30 years.
Shovelnose sturgeons are primarily bottom dwellers, preferring high turbidity in large waters, and are usually found in pools downstream of sandbars or along the main channel border. The flowing freshwater is between 18-20 deg C. During low water or in the warm summer months, these sturgeons seek cooler, deep channel areas.
Average elevation: known to inhabit low elevations m.
Range depth: 2 to 7 m.
Average depth: 4 m.
Habitat Regions: temperate ; freshwater
Aquatic Biomes: benthic ; rivers and streams
Shovelnose sturgeons are a freshwater species historically found in most portions of the Mississippi and Missouri river basins. This area ranges from Montana south to Louisiana, and from Pennsylvania west to New Mexico. However, shovelnose sturgeons are no longer found in Pennsylvania, New Mexico, and large parts of Kansas, Kentucky, and Tennessee where they were once abundant. The main cause for the restriction of range is the construction of dams on many of their native waterways.
Biogeographic Regions: nearctic (Native )
Scaphirhynchus platorynchus are opportunistic feeders, eating mostly aquatic insects, mussels, worms and crustaceans. Altered stream flow can affect the sturgeon’s ability to find food and also influences the abundance of prey organisms. The barbels detect prey, and then the sucker type mouth easily picks up the food organisms. Most food is found over sand and gravel substrates.
Animal Foods: insects; mollusks; terrestrial worms; aquatic or marine worms
Foraging Behavior: filter-feeding
Primary Diet: carnivore (Insectivore , Eats non-insect arthropods, Molluscivore , Vermivore)
Shovelnose sturgeons have many benefits to humans. They have been commercially harvested since 1987, and the meat is considered a delicacy, especially when smoked. They are also considered a sport fish in 12 of the 24 states in which they occur. The roe is used as an acceptable caviar and it has also been introduced as a potential aquarium fish.
Positive Impacts: pet trade ; food
There are no known adverse affects of shovelnose sturgeons on humans.
Eggs are deposited over cobble, gravel, or rock, becoming adhesive and attaching to the bottom substrates. After five to eight days, the eggs hatch and the young begin to search for food on the river bottom. Females grow significantly faster than males.
Development - Life Cycle: indeterminate growth
Shovelnose sturgeons are considered extirpated in three states, fully protected in four, and rare, or of special concern in eight states as of 1996. However, they are not currently listed as federally threatened or endangered.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: vulnerable
Rafinesque described this species as the 97th species described in his book, "Ichthyologia Ohiensis: Natural History of the Fishes Inhabiting the River Ohio and Its Tributary Streams," published in 1820.
Scaphirhynchus platorynchus feed on invertebrates, stirring up and loosening bottom substrates. The shovelnose sturgeon harbors a newly discovered virus called the Missouri River Sturgeon Iridovirus or MRSIV. The shovelnose sturgeon is host to the hickory-nut Obovaria olivaria, and may possibly be hosts for other pearly mussels including commercial species. Lamprey also parasitize the fish.
Shovelnose sturgeons migrate upstream, sometimes as far as 540 km if unimpeded, in a search for acceptable reproduction habitat and mates. Due to proximate cues, such as day length, water flow, and water temperature, all adults of reproducing age gather at spawning sites in large numbers. Although these fish are usually bottom dwellers, they rise to the surface during this time. Commonly, the same sites are used for spawning over the years. Once at the spawning area, mating begins, and fertilization of eggs occurs.
Not all females spawn every year. The frequency is determined by food supply and ability to store adequate fat to produce mature gametes. Males however, always spawn if physically possible.
Mating System: polygynandrous (promiscuous)
Breeding begins when females are around seven years of age and the males are approximately five. Mature shovelnose sturgeons travel upstream to spawn over rocky substrates in flowing water between 17-21 deg C, usually downstream from a dam in April to early July. The male and female swim side by side while they release eggs and sperm. Once the eggs are fertilized, they adhere to the rocky substrates. It is very important that there is a continuous stream of water flowing over them, and that the substrate is not too fine, so that it does not settle over the eggs and suffocate them. After 5 to 8 days the dark gray eggs, measuring 2 to 3 mm in diameter, hatch. Within approximately three months, when the young are 15 to 20 cm, they are independent, and leave their natal habitat.
Breeding interval: Females do not spawn every year, and frequency is influenced by food supply and fat storage. If spawning does occur, once at the breeding location, breeding lasts for a few days, and then eggs are deposited.
Breeding season: April to early July
Average number of offspring: 50,000 eggs at one time for each female.
Range gestation period: 5 to 8 days.
Average gestation period: 7 days.
Average time to independence: 3 months.
Average age at sexual or reproductive maturity (female): 7 years.
Average age at sexual or reproductive maturity (male): 5 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization (External ); broadcast (group) spawning; oviparous
These sturgeons have to use a great deal of energy to swim upstream for long distances to spawning areas. Once at the spawning areas, and fertilization of eggs has occurred the female deposits approximately 50,000 eggs per spawning season. The parental involvement is very limited after eggs have been deposited. Both male and female return downstream to their original home range, leaving un-hatched eggs attached to bottom substrates at spawning areas to develop independently.
Parental Investment: pre-fertilization (Provisioning); pre-hatching/birth (Provisioning: Female)
The shovelnose sturgeon (Scaphirhynchus platorynchus)[5] is the smallest species of freshwater sturgeon native to North 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 were formerly a commercially fished sturgeon in the United States of America (Pflieger 1997). In 2010, they were listed as threatened under the U.S. Endangered Species Act due to their resemblance to the endangered pallid sturgeon (S. albus),[6] with which shovelnose sturgeon are sympatric.[6][7]
The sturgeons of the family Acipenseridae have bony scutes 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 distribution) 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).
They can reach 1 metre (39 in) in length and up to 4.8 kilograms (11 lb) in weight but 50–85 centimetres (20–33 in) and 2.5 kilograms (5.5 lb) is more common.
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 who have primarily scaleless bellies. Coloration of the shovelnose sturgeon ranges from a light-brown to buff with a white belly (Pflieger 1997).
The shovelnose sturgeon, as its distribution represents, is impacted very little by turbidity. 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 of the hickorynut mussel.[7]
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 the growth of the shovelnose sturgeon is relatively slow, reaching 21.3 inches (54 cm) in five years.
The roe of the shovelnose sturgeon was marketed as "hackleback" caviar. As old-world sources of Caspian and Black Sea sturgeon caviar became overfished, especially in the wake of the collapse of the Soviet Union, roe from shovelnose sturgeon became commercially important.[7] 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 do not become gravid every year. There has some interest in marketing the shovelnose sturgeon as an aquarium species.[7] In 2010, the shovelnose sturgeon was listed as threatened under the U.S. Endangered Species Act due to its resemblance to the endangered pallid sturgeon (Scaphirhynchus albus),[6] with which shovelnose sturgeon are sympatric.[6][7]
The shovelnose sturgeon (Scaphirhynchus platorynchus) is the smallest species of freshwater sturgeon native to North 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 were formerly a commercially fished sturgeon in the United States of America (Pflieger 1997). In 2010, they were listed as threatened under the U.S. Endangered Species Act due to their resemblance to the endangered pallid sturgeon (S. albus), with which shovelnose sturgeon are sympatric.
