Pallid sturgeon: Difference between revisions

Pallid sturgeon
	File:Pallid.jpg
Conservation status
	; Endangered (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Acipenseriformes
Family:	Acipenseridae
Subfamily:	Scaphirhynchinae
Genus:	Scaphirhynchus
Species:	S. albus
Binomial name
	Scaphirhynchus albus ; (Forbes and Richardson, 1905)
	Pallid sturgeon range
Synonyms
	Parascaphirhynchus albus Forbes and Richardson, 1905

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The pallid sturgeon (Scaphirhynchus albus) is an endangered species of ray-finned fish, endemic to the waters of the Missouri and lower Mississippi River basins of the United States. Named for its pale coloration, the pallid sturgeon is closely related to the relatively common shovelnose sturgeon (Scaphirhyncus platorhynchus), but is much larger, averaging between 30 and 60 inches (76 and 152 cm) in length and weighing 85 pounds (39 kg) at maturity.^[2]^[3] The Pallid sturgeon take a long time to mature and spawns infrequently, but it can live up to 100 years. A member of the Acipenseridae (sturgeon) family of fish that originated during the Cretaceous period 70 million years ago, the pallid sturgeon has remained relatively unchanged. The species is considered to be a relic of the dinosaur era, and has been called "one of the ugliest fish in North America".^[4]

In 1990, the U.S. Fish and Wildlife Service placed the pallid sturgeon on the endangered species list because few young pallid sturgeons had been observed in the preceding decade, and sightings of the fish had greatly decreased.^[5] Due to such a reduction in numbers, the pallid sturgeon is rarely seen in the wild. It was the first fish species in the Mississippi River drainage area to be listed as endangered, and a loss of its habitat is thought to be responsible for its decline. The vast majority of the Mississippi River drainage system has been channeled and dammed, reducing the gravel deposits and slow-moving side channels that are its favored spawning areas. Until the middle of the 20th Century, the fish was relatively common and anglers found landing such large fish in fresh water a rewarding experience. The species is also considered to be an excellent-tasting fish, and like many sturgeon, the eggs have been used as caviar, though this use was never common with this species.^[6]

Efforts to restore the species have yet to be successful. The capture of a young pallid sturgeon has become rare since the 1980s. With the major alterations to natural spawning areas described above, restoration of these areas throughout the Mississippi River drainage basin is required if the species is to survive in the wild. Active attempts at preservation using fish hatcheries for spawning may aid in the survival of the species, but this survival would be heavily dependent on human assistance. In an effort to better understand pallid sturgeon behavior, researchers have implanted GPS transmitters to track their movements and help identify possible spawning areas.

Taxonomy and etymology

Taxonomists S.A. Forbes and R. E. Richardson classified the pallid sturgeon in 1905, grouping it in the Scaphirhynchus genus and the Acipenseridae family, which includes all sturgeon worldwide. The pallid sturgeon's closest relatives are the shovelnose sturgeon (Scaphirhyncus platorhynchus), which is still relatively common, and the critically endangered Alabama sturgeon (Scaphirhynchus suttkusi), which may soon become extinct.^[7]^[8] These three species belong to the Scaphirhynchinae subfamily which has only one other genera, namely the Pseudoscaphirhynchus genus, represented by three more fish species found in west-central Asia.

The word pallid means "deficient in color",^[9] and compared to other species of sturgeon, the pallid is noticeably paler.^[10] The scientific name for the fish is derived from Scaphirhynchus, a Greek word meaning "spade snout" and albus which is Latin for the color white.^[11]

Biology

DNA studies

To better protect pallid sturgeons from extinction, research on its DNA and that of other closely related species was conduced to assess differences within various populations of pallid sturgeon, as well as the differences between them and the shovelnose sturgeon. Early DNA research indicated that the pallid sturgeon and the shovelnose sturgeon were the same species.^[12] However, in 2000, one study comparing DNA sequencing in all three species in the Scaphirhynchus genus (pallid, shovelnose and Alabama sturgeon) showed that the three species are distinct.^[13] Between 2001 and 2006, several studies examined two populations of pallid sturgeon located in the upper Great Plains section of the Missouri River and compared them to those found in the lower Mississippi River. These DNA studies concluded that the northern populations of pallid sturgeon are reproductively isolated and are genetically distinct from a southern population located in the Atchafalaya River in Louisiana. However, the genetic variability among pallid sturgeon was found to be far less than that between them and the shovelnose sturgeon.^[14]^[15]

Another reason for DNA testing was to determine the rates of hybridization between pallid and shovelnose sturgeons. The southern populations have more hybrids than are found in the middle sections of the Missouri River basin, while the northernmost populations have had few reports of hybrids.^[15] Hybrids are most common in the Atchafalaya River in Louisiana and DNA sequencing in these hybrids showed a genetic distinction from pallid sturgeons, but based on the genetic markers assessed, they were genetically indistinguishable from shovelnose sturgeons.^[14] Because of this ability of two species to hybridize, some biologists have expressed concern that it is a violation of the Endangered Species Act to protect one species that may not be genetically isolated from another.^[13] It is not known if the hybrids are able to reproduce or not, although they appear to be the result of of pallid sturgeon eggs being fertilized by shovelnose sturgeon males.^[12]

Physical characteristics

The pallid sturgeon is one of the largest freshwater fish species in North America. They are generally between 30 and 60 inches (76 and 152 cm) in length and weigh as much as 85 pounds (39 kg).^[2]^[3] The species is ancient and has remained virtually unchanged for 70 million years, since the Cretaceous period. The pallid sturgeon has a distinctive appearance that has been referred to as "primitive", "dinosaur-like" and even "ugly".^[4] Although visually similar, the shovelnose sturgeon is much smaller and usually weighs no more than 5 pounds (2.3 kg). Pallid sturgeons are much paler in coloration with grayish white backs and sides, while shovelnose sturgeons are brown.^[6] Pallid sturgeons turn whiter as they age and younger specimens are easily confused with adult shovelnoses sturgeon since they are similar in color.^[16] Like the shovelnose sturgeon, their tails are heterocercal, with the top tail fin being longer than the bottom fin, though this is more pronounced in pallid sturgeons.^[17]

As with other sturgeons, pallid sturgeons are lacking the scales or bones found in more modern species of fish. Instead, they have cartilaginous skeletons with 5 rows of thick cartilage plates that extend along their sides, undersides and backs, as well as over most of the head. These thick cartilage plates are covered by the skin and serve as a protective armor.^[17] The bony cartilage also extends along the backside, from the dorsal fin to the tail.^[11]

The pallid sturgeon's snout and head are longer than that of the shovelnose sturgeon.^[16] In both species, the mouth is located well back from the tip of the snout. Lacking teeth they use their extendable mouths to suck up small fish, mollusks and other food sources from river bottoms. Both species also have four barbels which descend from the snout near the front of the mouth. The barbels are believed to be sensory features to locate food sources.^[17] On pallid sturgeons, the two inner barbels are approximately half as long as the outer ones, while on the shovelnose sturgeon, all four barbels are the same length.^[6] The inner barbels of the pallid sturgeon are positioned in front of the outer ones, whereby those on the shovelnose sturgeon are all located in essentially a straight line. The length and positioning of the barbels is one of the best ways to distinguish the two species.^[16]

Reproduction and life cycle

The immature larva of a pallid sturgeon being raised in a fish hatchery

Pallid sturgeons have a long lifespan, living in excess of 50 years and perhaps as long as 100 years.^[18]^[19]^[20] They lack bones and scales which makes it more difficult to establish their age and determine exactly how long they live.^[21] As is true for many long-lived species, pallid sturgeons reach reproductive maturity relatively late.^[22] Males reach sexual maturity between the ages of 5 and 7 years, while females are believed to become capable of reproduction when they are at least 15 years old. One study of 9 females indicated that they begin egg development between the ages of 9 and 12 years, but do not reach reproductive maturity until they are 15 years old. Reproduction does not take place every year; the average interval between spawnings is three years, although other studies suggest an interval as long as ten years.^[23]^[24] Spawning usually takes place between the months of May and July.^[25]

Prior to the construction of dams on the Missouri, pallid sturgeon migrated hundreds of miles upstream to spawn,^[26] and would seek out rocky or hard surfaces to deposit hundreds of thousands of eggs.^[25] One female pallid sturgeon that was caught in the upper Missouri River was estimated to be carrying 170,000 eggs, representing over 11 percent of its total body weight.^[27] After fertilization, pallid sturgeon eggs hatch in 5 to 8 days,^[6] after which the larvae drift back downstream for several weeks. As the larvae develop tails, they seek out slower moving waterways and slowly mature over a period of a dozen years.^[26] The rate of survival to maturity for pallid sturgeon larvae is extremely low and of the hundreds of thousands of eggs spawned, only a small handful lives to adulthood.^[19]

For several decades, no natural reproduction of pallid sturgeons was observed, since all the pallid sturgeons that had been captured were older specimens. However, in the late 1990s, young pallid sturgeons were discovered living in a restored riparian area of the lower Missouri River. This was the first documented example of wild spawned pallid sturgeons in 50 years.^[19] In 2007, two female pallid sturgeons were also reported to have spawned in the Missouri National Recreational River area located downstream from Gavins Point Dam on the Missouri River.^[28]

Ecology

Distribution

The pallid sturgeon's historical range spanned the entire Missouri and into the Mississippi Rivers. Historically, the species was rare to nonexistent in the upper Mississippi, probably due to a lack of proper habitat. Currently, the species is considered critically imperiled throughout its entire range.^[29] As of 2008, pallid sturgeons can still be found throughout their original range, but their population numbers have severely declined from the mid 20th century. The Missouri and Mississippi Rivers from Montana to Louisiana, as well as the Atchafalaya River in Louisiana, continue to harbor an aging population of pallid sturgeons.^[22] Pallid sturgeons have never been very common; as early as 1905 when the species was first identified, they represented only 1 in 5 of all sturgeon in the lower Missouri River and as few as 1 in 500 where the Illinois River meets the Mississippi.^[30] Recently, between 1985 and 2000, the ratio of pallid sturgeons to all sturgeon netted declined from 1 in about 400 to 1 in nearly 650. A 1996 study concluded that between 6,000 and 21,000 pallid sturgeons remained in their natural habitat at that time.^[1]

Six areas were studied for wild pallid sturgeon population estimates and recovery recommendations by the United States Fish and Wildlife Service (USFWS) between 1990, when the species was declared endangered, and 2006. The USFWS has referred to these six areas of wild pallid sturgeon population studies as Recovery Priority Management Areas (RPMA's). In the northernmost region of the study, known as RPMA 1, located between the Marias River in Montana to the western reaches of Fort Peck Reservoir, only 45 wild (non-hatchery) individuals remain. Of these, no juveniles were observed and the population was declining. In RPMA 2, located between Fort Peck Dam, the headwaters of Lake Sakakawea and the lower Yellowstone River up to the confluence of the Tongue River, Montana, only 136 wild specimens remain. In RPMA 3, stretching from upstream of the Niobrara River to Lewis and Clark Lake along the Missouri River, no native populations were recorded. All collected specimens appeared to be hatchery raised. However, the hatchery raised specimens were apparently maturing and adjusting well to this section of the river. RPMA 4 extends from Gavins Point Dam to the confluence of the Missouri and Mississippi Rivers. This region also includes the Platte River. Here, at least 100 unique non-hatchery specimens were collected during the study period. There is also evidence that some wild reproduction is ongoing in this region. In RPMA 5, between the confluence of the Missouri and Mississippi and the Gulf of Mexico, several hundred specimens were documented. Here again, some evidence suggests that natural reproduction is occurring, as demonstrated by the recovery of a few examples of immature, non-hatchery raised individuals. The Atchafalaya River basin is designated as RPMA 6 and the findings there were similar to those in Recovery Priority Management Areas 4 and 5 but with greater numbers of unique individuals, near 500 in total.^[15]

Habitat

Pallid sturgeons prefer moderate to swift river currents and most captured specimens have been recovered in rivers and streams in which the current averages between 0.33 and 2.9 feet per second (0.10 and 0.88 m/s). They also prefer turbid waterways and water depths between 3 and 25 feet (0.91 and 7.62 m). The species is more commonly found where sandy substrates are plentiful but also lives in waterways that are predominately rocky. Pallid sturgeons prefer swift river currents more often than do shovelnose sturgeon.^[22]

In a study based in Montana and North Dakota conducted on both the pallid and shovelnose sturgeon, both species were fitted with radio transmitters. Pallid sturgeons were found to prefer wider river channels, mid-channel sandbars and numerous islands and were most commonly recorded in water depths between 2 and 47 feet (0.61 and 14.33 m). The study also showed that the pallid sturgeon moved as much as 13 miles (21 km) a day and up to 5.7 miles per hour (9.2 km/h).^[31] Pallid sturgeon are believed to have preferred the muddy and generally warmer waters that existed prior to Missouri River dam construction.^[26]

Food preferences

Pallid sturgeons are generally bottom feeders, skimming the sandy reaches of the various rivers and streams in their habitat. Though little is known about the precise eating habits of the species, they are thought to be opportunistic feeders.^[22] One study which examined the contents from the stomachs of juvenile pallid sturgeons revealed that their diets were seasonally dependent. Various insects were consumed during some seasons and various fish species during others. These results support the description of the pallid sturgeons' eating habits as opportunistic.^[32] Fish is a more important dietary staple for pallid sturgeon than it is for shovelnose sturgeon.^[33] In one study comparing dietary tendencies between adult shovelnose sturgeon and immature pallid sturgeon, the pallid sturgeon was found to consume far greater numbers of small fish such as Cyprinids (minnows).^[32] In another study conducted in the upper Missouri River region, an examination of the stomach contents of hatchery reared pallid sturgeons showed that 82% of the wet weight was small fish and the balance was mosquito-like insects, mayflies and caddis flies and small amounts of detritus and plant material.^[34]

Conservation

Though never believed to be common, pallid sturgeon populations nosedived during the late 20th century and the species was listed as endangered on September 6, 1990.^[6] The U.S. Government and most of the states with pallid sturgeon populations have commenced restoration efforts to save the species from extinction. Wild reproduction of pallid sturgeon is rare to nonexistent in most areas; therefore, human intervention is needed to ensure the survival of the species.^[35]^[2] Pallid sturgeon were previously considered a prized trophy game fish species, until their numbers declined and they were placed on the endangered species list. All captured pallid sturgeon must now be released back to the wild. The species was known for being very palatable and the roe from females was used as caviar.^[10]

The route and the environmental characteristics of Missouri River in the northern Great Plains states of North and South Dakota, Nebraska and Montana, have been significantly altered. The resultant changes to the Missouri River in the upper Great Plains from channelization and impoundment prevent upstream migration. The reduced water flow rates and sediment loads and has brought an end to the seasonal flooding of the flood plains in the region. Since the construction of the Fort Peck Dam in Montana in 1937, and subsequent damming and channelization, the Missouri river has lost over 90 percent of its wetland and sandbar ecosystems. More than 2,000 miles (3,200 km) of the Missouri River has been altered and only that stretch of the river above Fort Peck Reservoir in Montana remains relatively unchanged.^[36] These alterations of the river have had a detrimental impact on a number of native fish species. In the 13 U.S. states that the pallid sturgeon is found, only a few other fish species are listed as endangered.^[37] Although substantial efforts are being implemented to ensure the survival of this species, the rarity of self-sustaining populations of pallid sturgeons ensures that it will remain federally protected for many decades.

Extinction threats

Two populations of pallid sturgeons in the Missouri and Yellowstone Rivers of Montana are both at risk of extinction and current projections are that wild pallid sturgeon populations in Montana will be extinct by 2018.^[2] Though a vigorous stocking effort was implemented in 1996, until pallid sturgeon females reach reproductive maturity sometime after they are 15 years of age, recovery efforts in Montana will not be readily measurable. The U.S. Bureau of Reclamation has been conducting spring pulse water releases from the Tiber dam every 4 to 5 years to try and recreate a semblance of an annual spring flood to restore and rejuvenate downstream floodplains. These pulse releases are done in an effort to restore suitable habitat for numerous fish species.^[38]

In Nebraska, a small number of pallid sturgeons have been captured along the lower reaches of the Platte River. Unlike most rivers in the Mississippi-Missouri river system, the Platte River has only a few dams and they are well upstream from its confluence with the Missouri River. The lower Platte River is shallow with numerous sand bars and small islands. Though pallid sturgeons prefer more turbulent and deeper rivers than the Platte River, between 1979 and 2003 over a dozen pallid sturgeons, including some from hatcheries, have been captured from the Platte River.^[39] A number of these pallid sturgeons have been fitted with radio transmitters which track their return to the Platte River when water levels and turbidity conditions are favorable. Coinciding with the majority of the pallid sturgeons that have been captured, this period that is generally most favorable is during the spring and early summer months. By mid-summer, a reduction in water levels and turbidity on the Platte River encourages pallid sturgeons to return to the Missouri River.

The lower reaches of the Platte River, a more than 30-mile (48 km) stretch from the Elkhorn River to its confluence with the Missouri River, has suitable spawning habitat for pallid sturgeons, although no conclusive evidence has been found that spawning is occurring in this region.^[39] Along with the lower Yellowstone River, the lower Platte River was identified as one of the best of the remaining regions with the potential for the natural spawning.^[15] In an effort to help restore habitat, two large river water pulse releases are planned for the months of March and May 2009 from Gavins Point Dam, located on the border of Nebraska and South Dakota. Although the amount of water released from the dam will be dependent on both upstream reservoir levels and downstream river levels, and will be regulated to ensure that downstream flooding will not occur, some restoration of the historic ebb and flow of the river will occur and that will benefit the spawning of the pallid sturgeon.^[40]

In Missouri, at the Lisbon Bottoms section of the Big Muddy National Fish & Wildlife Refuge, wild pallid sturgeon larvae were collected in 1998. These non-hatchery raised larvae were the first recovered on the lower Missouri River in the previous 50 years. The recovery was made along a side channel of the Missouri River that had been developed to provide suitable habitat for pallid sturgeon and other fish spawning.^[41] The side channel was apparently being used by the larva pallid sturgeons for protection from the swifter currents of the Missouri River.^[42]

In 2007, the U.S. Fish and Wildlife Service concluded that hatchery-based reproduction efforts should be continued, along with monitoring of any population changes, to determine the effectiveness of human intervention. The 2007 findings also emphasized the need to determine the most likely areas of spawning. The goal of this recommendation was to identify any parasite or disease that may be impacting the reproductive capabilities of pallid sturgeon and to examine engineering possibilities that may permit recreation of suitable habitats without reducing the Serivice's ability to protect people from harmful and destructive flooding, and to maintain its ability to provide adequate water impoundment for irrigation and recreation purposes.^[15]

References

^ ^a ^b "Scaphirhynchus albus". The IUCN Red List of Threatened Species. International Union for Conservation of Nature and Natural Resources. 2004. Retrieved 2008-11-19.
^ ^a ^b ^c ^d "Pallid Sturgeon - Scaphirhynchus albus". Montana Fish, Wildlife and Parks. Retrieved 2008-11-19.
^ ^a ^b "The Pallid Sturgeon (Scaphirhynchus albus)". Platte River Endangered Species Partnership. Retrieved 2008-11-19.
^ ^a ^b "The Pallid Sturgeon, a Missouri River "Dinosaur"". Feature Series, Vol I, No. 4. U.S. Fish and Wildlife Service. Retrieved 2008-11-19.
^ "Operation and Maintenance of the Upper Mississippi River 9-Foot Channel". Endangered Species Program. U.S. Fish and Wildlife Service. November 18, 2008. Retrieved 2008-11-19.
^ ^a ^b ^c ^d ^e "Threatened and Endangered Species: Pallid Sturgeon Scaphirhynchus Fact Sheet". U.S. Department of Agriculture. November 16, 2005. Retrieved 2008-11-19.
^ Template:IUCN2008
^ "The Desperate Dozen: Fishes on the Brink" (pdf). Southeastern Fishes Council. November, 2008. Retrieved 2008-12-09. {{cite news}}: Check date values in: |date= (help)
^ "Pallid". Merriam-Webster. 2008. Retrieved 2008-11-19.
^ ^a ^b "Pallid Sturgeon". Animal Field Guide. Montana Fish, Wildlife and Parks. Retrieved 2008-11-19.
^ ^a ^b Riis, Jim (1993). "Pallid Sturgeon (Scaphirhynchus albus)". South Dakota Department of Game, Fish and Parks. Retrieved 2008-11-19.
^ ^a ^b Tranah, G. J. (2004). "Genetic Evidence for Hybridization of Pallid and Shovelnose Sturgeon". Journal of Heredity. 95 (6). The American Genetic Association: 474–480. doi:10.1093/jhered/esh077. Retrieved 2008-12-14. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ ^a ^b Campton, Donald E. (March 2000). "Genetic distinction of pallid, shovelnose, and Alabama sturgeon: emerging species and the US Endangered Species Act". Conservation Genetics. 1 (1). Springer Netherlands: 17–32. doi:10.1023/A:1010121417487. Retrieved 2008-12-14. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ ^a ^b Tranah, G. J. (March 2001). "Reproductive isolation in sympatric populations of pallid and shovelnose sturgeon" (PDF). North American Journal of Fisheries Management. 21. American Fisheries Society: 367–373. Retrieved 2008-11-19. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ ^a ^b ^c ^d ^e "Pallid Sturgeon (Scaphirhynchus albus) 5-Year Review Summary and Evaluation" (pdf). U.S. Fish and Wildlife Service. 2007. pp. 24–28. Retrieved 2008-11-19.
^ ^a ^b ^c "Endangered Sturgeon Struggle for Survival". The Sturgeon of Missouri Missouri's Aquatic Dinosaurs. Conservation Commission of Missouri. 2008. Retrieved 2008-11-19. {{cite web}}: Cite has empty unknown parameter: |1= (help)
^ ^a ^b ^c Johnsgard, Paul A. (April 1, 2005). The Nature of Nebraska. Lincoln, Nebraska: Bison Books. pp. 169–170. ISBN 978-0803276215.
^ "Upper Missouri Pallid Sturgeon" (pdf). National Wildlife Federation. Retrieved 2008-11-19.
^ ^a ^b ^c Burton, Ken (January/April 2000). "New Hope for the Pallid Sturgeon" (pdf). Endangered Species Bulletin. U.S. Fish and Wildlife Service. Retrieved 2008-11-19. {{cite web}}: Check date values in: |date= (help)
^ "Abnormal Cells found in Pallid Sturgeon at Gavins Point National Fish Hatchery Prohibit Stocking these Fish in the Wild". U.S. Fish and Wildlife Service. September 26, 2007. Retrieved 2008-11-19.
^ Holm, Rob (April–May 2002). "Prehistoric Presence The Pallid Sturgeon" (pdf). North Dakota Outdoors. Retrieved 2008-11-19.{{cite web}}: CS1 maint: date format (link)
^ ^a ^b ^c ^d "Status and Life History of the Pallid Sturgeon" (pdf). U.S. Environmental Protection Agency. August 31, 2007. Retrieved 2008-11-19.
^ Keenlyne, K.D. (1993). "Age at Sexual Maturity of the Pallid Sturgeon". American Fisheries Society. 122 (3). American Fisheries Society: 393–396. Retrieved 2008-11-19. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
^ "Pallid Sturgeon: The Road to Recovery". U.S. Fish and Wildlife Service. July 15, 2008. Retrieved 2008-11-19.
^ ^a ^b Kallemeyn, Larry (1983). "Status of the Pallid Sturgeon Scaphirhynchus albus" (subscription required). Fisheries. 8. American Fisheries Society: 3–9. Retrieved 2008-11-19.
^ ^a ^b ^c McKean, Andrew (May/June 2006). "A Whisker Away from Winking Out". Montana Outdoors. Retrieved 2008-11-19. {{cite web}}: Check date values in: |date= (help)
^ Keenlyne, K.D. (1992). "Fecundity of the Pallid Sturgeon". American Fisheries Society. 121 (1). American Fisheries Society: 139–140. Retrieved 2008-11-19. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
^ "Sturgeon Research Update: Confirmed Pallid sturgeon Sturgeon Spawning in the Missouri River in 2007" (pdf). U.S. Geological Survey. 2007. Retrieved 2008-11-19. {{cite web}}: Unknown parameter |month= ignored (help)
^ "Pallid Sturgeon (Scaphirhynchus albus)" (pdf). Louisiana Department of Wildlife and Fisheries. Retrieved 2008-11-19.
^ Grady, Joanne (2001). "Pallid and Shovelnose Sturgeon in the Lower Missouri and Middle Mississippi Rivers" (pdf). U.S. Fish and Wildlife Service. Retrieved 2008-11-19. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
^ Bramblett, Robert (2001). "Habitat Use and Movements of Pallid and Shovelnose Sturgeon in the Yellowstone and Missouri Rivers in Montana and North Dakota". Transactions of the American Fisheries Society. 130 (6). Bethesda, Maryland: American Fisheries Society: 1006–1025. {{cite journal}}: |access-date= requires |url= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ ^a ^b Wanner, Greg (2007). "Food Habits of Juvenile Pallid Sturgeon and Adult Shovel nose Sturgeon in the Missouri River Downstream of Fort Randall Dam, South Dakota" (pdf). Journal of Freshwater Ecology. 22 (1). La Crosse, Wisconsin: Oikos Publishers: 81–92. Retrieved 2008-11-19. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
^ "Pallid Sturgeon". The Iowa Department of Natural Resources. Retrieved 2008-11-19.
^ Wilson, Ryan (April 2004). "Pallid Sturgeon Recovery Update" (pdf). U.S. Fish and Wildlife Service. Retrieved 2008-12-6. {{cite web}}: Check date values in: |accessdate= (help)
^ Wildhaber, Mark L. (2007). "A Conceptual Life-History Model for Pallid and Shovelnose Sturgeon" (pdf). U.S. Geological Survey. Retrieved 2008-11-19. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ Power, Greg (2006). "The Missouri River System's "Other" Fish". U. S. Geological Survey. Retrieved 2008-11-19.
^ "How many species are listed in each state (based on published population data)?". Threatened & Endangered Species System. U.S. Fish and Wildlife Service. 2008. Retrieved 2008-11-19.
^ "Pallid Sturgeon — Scaphirhynchus albus". State of Montana. Retrieved 2008-11-19.
^ ^a ^b Committee on Endangered and Threatened Species in the Platte River Basin (2004). Endangered and Threatened Species of the Platte River. Washington, D. C.: The National Academies Press. pp. 225–239. ISBN 978-0-309-09230-2.
^ Hendee, David (October 3, 2009). "Missouri River plan calls for '09 water pulses". Omaha World Herald. {{cite news}}: |access-date= requires |url= (help); Italic or bold markup not allowed in: |publisher= (help)
^ Ikenson, Ben (May 31, 2006). "Biologists struggle to keep the pallid sturgeon from going extinct". Reviving the Missouri River's dinosaur. ESPN. Retrieved 2008-11-19. {{cite news}}: Italic or bold markup not allowed in: |publisher= (help)
^ "Pallid Sturgeon, Scaphirhynchus albus". Mississippi Interstate Cooperative Resource Association. Retrieved 2008-11-19.

External links

Pallid Sturgeon Recovery Plan (10mb file)

[IUCN-1] "Scaphirhynchus albus". The IUCN Red List of Threatened Species. International Union for Conservation of Nature and Natural Resources. 2004. Retrieved 2008-11-19.

[montana-2] "Pallid Sturgeon - Scaphirhynchus albus". Montana Fish, Wildlife and Parks. Retrieved 2008-11-19.

[Platte-3] "The Pallid Sturgeon (Scaphirhynchus albus)". Platte River Endangered Species Partnership. Retrieved 2008-11-19.

[dinosaur-4] "The Pallid Sturgeon, a Missouri River "Dinosaur"". Feature Series, Vol I, No. 4. U.S. Fish and Wildlife Service. Retrieved 2008-11-19.

[endangered-5] "Operation and Maintenance of the Upper Mississippi River 9-Foot Channel". Endangered Species Program. U.S. Fish and Wildlife Service. November 18, 2008. Retrieved 2008-11-19.

[NRCS-6] "Threatened and Endangered Species: Pallid Sturgeon Scaphirhynchus Fact Sheet". U.S. Department of Agriculture. November 16, 2005. Retrieved 2008-11-19.

[AlabamaIUCN-7] Template:IUCN2008

[AlabamaSEFC-8] "The Desperate Dozen: Fishes on the Brink" (pdf). Southeastern Fishes Council. November, 2008. Retrieved 2008-12-09. {{cite news}}: Check date values in: |date= (help)

[Merriam-9] "Pallid". Merriam-Webster. 2008. Retrieved 2008-11-19.

[Guide-10] "Pallid Sturgeon". Animal Field Guide. Montana Fish, Wildlife and Parks. Retrieved 2008-11-19.

[Riis-11] Riis, Jim (1993). "Pallid Sturgeon (Scaphirhynchus albus)". South Dakota Department of Game, Fish and Parks. Retrieved 2008-11-19.

[Tranah1-12] Tranah, G. J. (2004). "Genetic Evidence for Hybridization of Pallid and Shovelnose Sturgeon". Journal of Heredity. 95 (6). The American Genetic Association: 474–480. doi:10.1093/jhered/esh077. Retrieved 2008-12-14. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Campton-13] Campton, Donald E. (March 2000). "Genetic distinction of pallid, shovelnose, and Alabama sturgeon: emerging species and the US Endangered Species Act". Conservation Genetics. 1 (1). Springer Netherlands: 17–32. doi:10.1023/A:1010121417487. Retrieved 2008-12-14. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Tranah2-14] Tranah, G. J. (March 2001). "Reproductive isolation in sympatric populations of pallid and shovelnose sturgeon" (PDF). North American Journal of Fisheries Management. 21. American Fisheries Society: 367–373. Retrieved 2008-11-19. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Billings-15] "Pallid Sturgeon (Scaphirhynchus albus) 5-Year Review Summary and Evaluation" (pdf). U.S. Fish and Wildlife Service. 2007. pp. 24–28. Retrieved 2008-11-19.

[Missouri-16] "Endangered Sturgeon Struggle for Survival". The Sturgeon of Missouri Missouri's Aquatic Dinosaurs. Conservation Commission of Missouri. 2008. Retrieved 2008-11-19. {{cite web}}: Cite has empty unknown parameter: |1= (help)

[Johnsgard-17] Johnsgard, Paul A. (April 1, 2005). The Nature of Nebraska. Lincoln, Nebraska: Bison Books. pp. 169–170. ISBN 978-0803276215.

[NWF-18] "Upper Missouri Pallid Sturgeon" (pdf). National Wildlife Federation. Retrieved 2008-11-19.

[Burton-19] Burton, Ken (January/April 2000). "New Hope for the Pallid Sturgeon" (pdf). Endangered Species Bulletin. U.S. Fish and Wildlife Service. Retrieved 2008-11-19. {{cite web}}: Check date values in: |date= (help)

[Gavins-20] "Abnormal Cells found in Pallid Sturgeon at Gavins Point National Fish Hatchery Prohibit Stocking these Fish in the Wild". U.S. Fish and Wildlife Service. September 26, 2007. Retrieved 2008-11-19.

[Holm-21] Holm, Rob (April–May 2002). "Prehistoric Presence The Pallid Sturgeon" (pdf). North Dakota Outdoors. Retrieved 2008-11-19.{{cite web}}: CS1 maint: date format (link)

[EPA-22] "Status and Life History of the Pallid Sturgeon" (pdf). U.S. Environmental Protection Agency. August 31, 2007. Retrieved 2008-11-19.

[Keenlyne1-23] Keenlyne, K.D. (1993). "Age at Sexual Maturity of the Pallid Sturgeon". American Fisheries Society. 122 (3). American Fisheries Society: 393–396. Retrieved 2008-11-19. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)

[Recovery-24] "Pallid Sturgeon: The Road to Recovery". U.S. Fish and Wildlife Service. July 15, 2008. Retrieved 2008-11-19.

[Kallemeyn-25] Kallemeyn, Larry (1983). "Status of the Pallid Sturgeon Scaphirhynchus albus" (subscription required). Fisheries. 8. American Fisheries Society: 3–9. Retrieved 2008-11-19.

[McKean-26] McKean, Andrew (May/June 2006). "A Whisker Away from Winking Out". Montana Outdoors. Retrieved 2008-11-19. {{cite web}}: Check date values in: |date= (help)

[Keenlyne2-27] Keenlyne, K.D. (1992). "Fecundity of the Pallid Sturgeon". American Fisheries Society. 121 (1). American Fisheries Society: 139–140. Retrieved 2008-11-19. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)

[USGS-28] "Sturgeon Research Update: Confirmed Pallid sturgeon Sturgeon Spawning in the Missouri River in 2007" (pdf). U.S. Geological Survey. 2007. Retrieved 2008-11-19. {{cite web}}: Unknown parameter |month= ignored (help)

[Louisiana-29] "Pallid Sturgeon (Scaphirhynchus albus)" (pdf). Louisiana Department of Wildlife and Fisheries. Retrieved 2008-11-19.

[Grady-30] Grady, Joanne (2001). "Pallid and Shovelnose Sturgeon in the Lower Missouri and Middle Mississippi Rivers" (pdf). U.S. Fish and Wildlife Service. Retrieved 2008-11-19. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)

[Bramblett-31] Bramblett, Robert (2001). "Habitat Use and Movements of Pallid and Shovelnose Sturgeon in the Yellowstone and Missouri Rivers in Montana and North Dakota". Transactions of the American Fisheries Society. 130 (6). Bethesda, Maryland: American Fisheries Society: 1006–1025. {{cite journal}}: |access-date= requires |url= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Wanner-32] Wanner, Greg (2007). "Food Habits of Juvenile Pallid Sturgeon and Adult Shovel nose Sturgeon in the Missouri River Downstream of Fort Randall Dam, South Dakota" (pdf). Journal of Freshwater Ecology. 22 (1). La Crosse, Wisconsin: Oikos Publishers: 81–92. Retrieved 2008-11-19. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)

[Iowa-33] "Pallid Sturgeon". The Iowa Department of Natural Resources. Retrieved 2008-11-19.

[Wilson-34] Wilson, Ryan (April 2004). "Pallid Sturgeon Recovery Update" (pdf). U.S. Fish and Wildlife Service. Retrieved 2008-12-6. {{cite web}}: Check date values in: |accessdate= (help)

[Wildhaber-35] Wildhaber, Mark L. (2007). "A Conceptual Life-History Model for Pallid and Shovelnose Sturgeon" (pdf). U.S. Geological Survey. Retrieved 2008-11-19. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Power-36] Power, Greg (2006). "The Missouri River System's "Other" Fish". U. S. Geological Survey. Retrieved 2008-11-19.

[Tess-37] "How many species are listed in each state (based on published population data)?". Threatened & Endangered Species System. U.S. Fish and Wildlife Service. 2008. Retrieved 2008-11-19.

[montana2-38] "Pallid Sturgeon — Scaphirhynchus albus". State of Montana. Retrieved 2008-11-19.

[Platte2-39] Committee on Endangered and Threatened Species in the Platte River Basin (2004). Endangered and Threatened Species of the Platte River. Washington, D. C.: The National Academies Press. pp. 225–239. ISBN 978-0-309-09230-2.

[Herald-40] Hendee, David (October 3, 2009). "Missouri River plan calls for '09 water pulses". Omaha World Herald. {{cite news}}: |access-date= requires |url= (help); Italic or bold markup not allowed in: |publisher= (help)

[Ikenson-41] Ikenson, Ben (May 31, 2006). "Biologists struggle to keep the pallid sturgeon from going extinct". Reviving the Missouri River's dinosaur. ESPN. Retrieved 2008-11-19. {{cite news}}: Italic or bold markup not allowed in: |publisher= (help)

[Mississippi-42] "Pallid Sturgeon, Scaphirhynchus albus". Mississippi Interstate Cooperative Resource Association. Retrieved 2008-11-19.

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@@ Line 18: / Line 18: @@
 | synonyms = ''Parascaphirhynchus albus'' <small>Forbes and Richardson, 1905</small>
 }}
-The '''pallid sturgeon''' (''Scaphirhynchus albus'') is an [[endangered species]] of [[Actinopterygii|ray-finned fish]], [[Endemism|endemic]] to the waters of the [[Missouri River|Missouri]] and lower [[Mississippi River]] basins of the United States.  Named for its pale coloration, the pallid sturgeon is closely related to the relatively common [[shovelnose sturgeon]] (''Scaphirhyncus platorhynchus''), but is much larger, averaging between {{convert|30|and|60|in|cm}} in length and weighing {{convert|85|lb|kg}} at maturity.<ref name="montana">{{cite web| title = Pallid Sturgeon - Scaphirhynchus albus| publisher = Montana Fish, Wildlife and Parks| url = http://fwp.mt.gov/wildthings/tande/pallid.html| accessdate = 2008-11-19}}</ref><ref name="Platte">{{cite web| title = The Pallid Sturgeon (Scaphirhynchus albus)| publisher = Platte River Endangered Species Partnership| url = http://www.platteriver.org/backgr/sturg.htm| accessdate =2008-11-19}}</ref>  The Pallid sturgeon take years to mature and  spawns infrequently, but it can live up to 100&nbsp;years. A member of the [[Sturgeon|Acipenseridae (sturgeon)]] family of fish that originated during the [[Cretaceous period]] 70&nbsp;million years ago, the pallid sturgeon has remained relatively unchanged. The species is considered to be a relic of the [[dinosaur]] era, and has been called "one of the ugliest fish in North America".<ref name="dinosaur">{{cite web| title = The Pallid Sturgeon, a Missouri River "Dinosaur"| work = Feature Series, Vol I, No. 4| publisher = U.S. Fish and Wildlife Service| url = http://www.r6.fws.gov/feature/sturgeon.html| accessdate = 2008-11-19}}</ref>
+The '''pallid sturgeon''' (''Scaphirhynchus albus'') is an [[endangered species]] of [[Actinopterygii|ray-finned fish]], [[Endemism|endemic]] to the waters of the [[Missouri River|Missouri]] and lower [[Mississippi River]] basins of the United States.  Named for its pale coloration, the pallid sturgeon is closely related to the relatively common [[shovelnose sturgeon]] (''Scaphirhyncus platorhynchus''), but is much larger, averaging between {{convert|30|and|60|in|cm}} in length and weighing {{convert|85|lb|kg}} at maturity.<ref name="montana">{{cite web| title = Pallid Sturgeon - Scaphirhynchus albus| publisher = Montana Fish, Wildlife and Parks| url = http://fwp.mt.gov/wildthings/tande/pallid.html| accessdate = 2008-11-19}}</ref><ref name="Platte">{{cite web| title = The Pallid Sturgeon (Scaphirhynchus albus)| publisher = Platte River Endangered Species Partnership| url = http://www.platteriver.org/backgr/sturg.htm| accessdate =2008-11-19}}</ref>  The Pallid sturgeon take a long time to mature and  spawns infrequently, but it can live up to 100&nbsp;years. A member of the [[Sturgeon|Acipenseridae (sturgeon)]] family of fish that originated during the [[Cretaceous period]] 70&nbsp;million years ago, the pallid sturgeon has remained relatively unchanged. The species is considered to be a relic of the [[Triassic|dinosaur]] era, and has been called "one of the ugliest fish in North America".<ref name="dinosaur">{{cite web| title = The Pallid Sturgeon, a Missouri River "Dinosaur"| work = Feature Series, Vol I, No. 4| publisher = U.S. Fish and Wildlife Service| url = http://www.r6.fws.gov/feature/sturgeon.html| accessdate = 2008-11-19}}</ref>
-In 1990, the [[U.S. Fish and Wildlife Service]] placed the pallid sturgeon on the endangered species list because  few young pallid sturgeons had been observed in the preceding decade, and  overall sightings of the fish had greatly decreased.<ref name="endangered">{{cite web| title = Operation and Maintenance of the Upper Mississippi River 9-Foot Channel| work = Endangered Species Program| publisher = U.S. Fish and Wildlife Service| date = November 18, 2008| url = http://www.fws.gov/midwest/Endangered/section7/pallid.html| accessdate = 2008-11-19}}</ref> With such reduction in numbers, the pallid sturgeon is rarely seen in the wild. It was the first fish species in the Mississippi River drainage area to be listed as endangered, and  a loss of habitat is thought to be responsible for its decline. The vast majority of the Mississippi River drainage system has been [[River engineering|channeled and dammed]], reducing the gravel deposits and slow-moving side channels that are favored [[Spawn (biology)|spawning]] areas. Until the middle of the 20th Century, the fish was relatively common  and anglers found landing such  large fish in fresh water a rewarding experience. The species is also considered to be an excellent-tasting fish, and like many sturgeon, the eggs have been used as [[caviar]], though this use was never common with this species.<ref name="NRCS">{{cite web| title = Threatened and Endangered Species: Pallid Sturgeon Scaphirhynchus Fact Sheet | publisher = U.S. Department of Agriculture| date = November 16, 2005| url = http://www.mt.nrcs.usda.gov/news/factsheets/pallidsturgeon.html| accessdate = 2008-11-19}}</ref>
+In 1990, the [[U.S. Fish and Wildlife Service]] placed the pallid sturgeon on the endangered species list because  few young pallid sturgeons had been observed in the preceding decade, and  sightings of the fish had greatly decreased.<ref name="endangered">{{cite web| title = Operation and Maintenance of the Upper Mississippi River 9-Foot Channel| work = Endangered Species Program| publisher = U.S. Fish and Wildlife Service| date = November 18, 2008| url = http://www.fws.gov/midwest/Endangered/section7/pallid.html| accessdate = 2008-11-19}}</ref> Due to such a reduction in numbers, the pallid sturgeon is rarely seen in the wild. It was the first fish species in the Mississippi River drainage area to be listed as endangered, and  a loss of its habitat is thought to be responsible for its decline. The vast majority of the Mississippi River drainage system has been [[River engineering|channeled and dammed]], reducing the gravel deposits and slow-moving side channels that are its favored [[Spawn (biology)|spawning]] areas. Until the middle of the 20th Century, the fish was relatively common  and anglers found landing such  large fish in fresh water a rewarding experience. The species is also considered to be an excellent-tasting fish, and like many sturgeon, the eggs have been used as [[caviar]], though this use was never common with this species.<ref name="NRCS">{{cite web| title = Threatened and Endangered Species: Pallid Sturgeon Scaphirhynchus Fact Sheet | publisher = U.S. Department of Agriculture| date = November 16, 2005| url = http://www.mt.nrcs.usda.gov/news/factsheets/pallidsturgeon.html| accessdate = 2008-11-19}}</ref>
 Efforts to restore the species have yet to be successful. The capture of a young pallid sturgeon has become rare since the 1980s. With the major alterations to natural spawning areas described above, restoration of these areas throughout the Mississippi River drainage basin is required if the species is to survive in the wild. Active attempts at preservation using [[Fish hatchery|fish hatcheries]] for spawning may aid in the survival of the species, but this survival would be heavily dependent on human assistance. In an effort to better understand pallid sturgeon behavior, researchers have implanted [[Global Positioning System|GPS]] transmitters to track their movements and help identify possible spawning areas.
 == Taxonomy and etymology ==
-Taxonomists [[Stephen Alfred Forbes|S.A. Forbes]] and R. E. Richardson classified the pallid sturgeon in 1905, grouping it in the ''[[Scaphirhynchus]]'' [[genus]] and the ''[[Acipenseridae]]'' [[Family (biology)|family]], which includes all [[sturgeon]] worldwide. The pallid sturgeon's closest relatives are the shovelnose sturgeon (''Scaphirhyncus platorhynchus''), which is still relatively common, and the critically endangered [[Alabama sturgeon]] (''Scaphirhynchus suttkusi''), which may soon become extinct.<ref name="AlabamaIUCN">{{IUCN2008| title=''Scaphirhynchus suttkusi'' | assessors=Parauka, F.M. |year=2004 | id=19942 | downloaded = 08 Dec 2008}}</ref><ref name="AlabamaSEFC">{{cite news | title = The Desperate Dozen: Fishes on the Brink | publisher = Southeastern Fishes Council | date = November, 2008 | url = http://www.flmnh.ufl.edu/fish/organizations/sfc/DesDoz_report.pdf | format = pdf | accessdate = 2008-12-09}}</ref> These three species belong to the ''[[Scaphirhynchinae]]'' subfamily which has only one other genera, namely the ''[[Pseudoscaphirhynchus]]'' genus, represented by three more fish species found in west-central [[Asia]].
+Taxonomists [[Stephen Alfred Forbes|S.A. Forbes]] and R. E. Richardson classified the pallid sturgeon in 1905, grouping it in the ''[[Scaphirhynchus]]'' [[genus]] and the ''[[Acipenseridae]]'' [[Family (biology)|family]], which includes all [[sturgeon]] worldwide. The pallid sturgeon's closest relatives are the shovelnose sturgeon (''Scaphirhyncus platorhynchus''), which is still relatively common, and the critically endangered [[Alabama sturgeon]] (''Scaphirhynchus suttkusi''), which may soon become [[Extinction|extinct]].<ref name="AlabamaIUCN">{{IUCN2008| title=''Scaphirhynchus suttkusi'' | assessors=Parauka, F.M. |year=2004 | id=19942 | downloaded = 08 Dec 2008}}</ref><ref name="AlabamaSEFC">{{cite news | title = The Desperate Dozen: Fishes on the Brink | publisher = Southeastern Fishes Council | date = November, 2008 | url = http://www.flmnh.ufl.edu/fish/organizations/sfc/DesDoz_report.pdf | format = pdf | accessdate = 2008-12-09}}</ref> These three species belong to the ''[[Scaphirhynchinae]]'' subfamily which has only one other genera, namely the ''[[Pseudoscaphirhynchus]]'' genus, represented by three more fish species found in west-central [[Asia]].
 The word ''pallid'' means "deficient in color",<ref name="Merriam">{{cite web| title = Pallid| work = | publisher = Merriam-Webster| year = 2008| url = http://www.merriam-webster.com/dictionary/pallid| accessdate = 2008-11-19}}</ref> and compared to other species of sturgeon, the pallid is noticeably paler.<ref name="Guide">{{cite web| title = Pallid Sturgeon| work = Animal Field Guide| publisher = Montana Fish, Wildlife and Parks| url = http://fwp.mt.gov/fieldguide/detail_AFCAA02010.aspx| accessdate = 2008-11-19}}</ref> The scientific name for the fish is derived from ''Scaphirhynchus'', a Greek word meaning "spade snout" and ''albus'' which is [[Latin]] for the color white.<ref name="Riis">{{cite web| last = Riis| first = Jim| title = Pallid Sturgeon (Scaphirhynchus albus) | publisher = South Dakota Department of Game, Fish and Parks| year = 1993| url = http://www.northern.edu/natsource/ENDANG1/Pallid1.htm| accessdate = 2008-11-19}}</ref>
@@ Line 31: / Line 31: @@
 == Biology ==
 ===DNA studies===
-To better protect pallid sturgeons from extinction, [[DNA]] research was performed to assess differences within various populations of pallid sturgeon as well as the differences between them and shovelnose sturgeon. Early DNA research indicated that pallid sturgeon and shovelnose sturgeon were the same species.<ref name="Tranah1">{{cite journal| last = Tranah| first = G. J.| coauthors = D. E. Campton, and B. May | title = Genetic Evidence for Hybridization of Pallid and Shovelnose Sturgeon | journal = Journal of Heredity| volume = 95| issue = 6| pages = 474-480| publisher = The American Genetic Association| date = 2004| url = http://jhered.oxfordjournals.org/cgi/content/full/95/6/474| doi = 10.1093/jhered/esh077| accessdate = 2008-12-14}}</ref> However, in 2000, one study comparing DNA sequencing in all three species in the ''Scaphirhynchus'' genus (pallid, shovelnose and Alabama sturgeon) showed that the three species are distinct.<ref name="Campton">{{cite journal| last = Campton| first = Donald E.| coauthors = Anna L. Bass, Frank A. Chapman and Brian W. Bowen| title = Genetic distinction of pallid, shovelnose, and Alabama sturgeon: emerging species and the US Endangered Species Act| journal = Conservation Genetics| volume = 1| issue = 1| pages = 17-32| publisher = Springer Netherlands| location = | date = March 2000| url = http://www.springerlink.com/content/w76485t849537674/| doi = 10.1023/A:1010121417487| accessdate = 2008-12-14}}</ref> Between 2001 and 2006, several studies examined two populations of pallid sturgeon located in the upper [[Great Plains]] section of the Missouri River and compared them to those found in the lower Mississippi River. These DNA studies concluded that the northern populations of pallid sturgeon are [[Reproductive isolation|reproductively isolated]] and are genetically distinct from a southern population located in the [[Atchafalaya River]] in [[Louisiana]]. However, the genetic variability amongst pallid sturgeon was found to be far less than that between them and shovelnose sturgeon.<ref name="Tranah2">{{cite journal| last = Tranah| first = G. J.| coauthors = H. L. Kincaid, C. C. Krueger, D. E. Campton, and B. May| title = Reproductive isolation in sympatric populations of pallid and shovelnose sturgeon| journal = North American Journal of Fisheries Management | volume = 21 | pages = 367–373| publisher =  American Fisheries Society| date = March 2001| url = http://genome-lab.ucdavis.edu/Publications/2001TranahEtAl_NAJFM.pdf| accessdate = 2008-11-19}}</ref><ref name="Billings">{{cite web| title = Pallid Sturgeon (Scaphirhynchus albus) 5-Year Review Summary and Evaluation| publisher = U.S. Fish and Wildlife Service| date = 2007|pages = 24-28|url = http://www.uwyo.edu/enr/ienr/PSWorkshop2007/Pallid_Sturgeon_5year_Review_Final_June2007.pdf| format = pdf| accessdate = 2008-11-19}}</ref>
+To better protect pallid sturgeons from extinction,  research on its [[DNA]] and that of other closely related species was conduced to assess differences within various populations of pallid sturgeon, as well as the differences between them and the shovelnose sturgeon. Early DNA research indicated that the pallid sturgeon and the shovelnose sturgeon were the same species.<ref name="Tranah1">{{cite journal| last = Tranah| first = G. J.| coauthors = D. E. Campton, and B. May | title = Genetic Evidence for Hybridization of Pallid and Shovelnose Sturgeon | journal = Journal of Heredity| volume = 95| issue = 6| pages = 474-480| publisher = The American Genetic Association| date = 2004| url = http://jhered.oxfordjournals.org/cgi/content/full/95/6/474| doi = 10.1093/jhered/esh077| accessdate = 2008-12-14}}</ref> However, in 2000, one study comparing DNA sequencing in all three species in the ''Scaphirhynchus'' genus (pallid, shovelnose and Alabama sturgeon) showed that the three species are distinct.<ref name="Campton">{{cite journal| last = Campton| first = Donald E.| coauthors = Anna L. Bass, Frank A. Chapman and Brian W. Bowen| title = Genetic distinction of pallid, shovelnose, and Alabama sturgeon: emerging species and the US Endangered Species Act| journal = Conservation Genetics| volume = 1| issue = 1| pages = 17-32| publisher = Springer Netherlands| location = | date = March 2000| url = http://www.springerlink.com/content/w76485t849537674/| doi = 10.1023/A:1010121417487| accessdate = 2008-12-14}}</ref> Between 2001 and 2006, several studies examined two populations of pallid sturgeon located in the upper [[Great Plains]] section of the Missouri River and compared them to those found in the lower Mississippi River. These DNA studies concluded that the northern populations of pallid sturgeon are [[Reproductive isolation|reproductively isolated]] and are genetically distinct from a southern population located in the [[Atchafalaya River]] in [[Louisiana]]. However, the genetic variability among pallid sturgeon was found to be far less than that between them and the shovelnose sturgeon.<ref name="Tranah2">{{cite journal| last = Tranah| first = G. J.| coauthors = H. L. Kincaid, C. C. Krueger, D. E. Campton, and B. May| title = Reproductive isolation in sympatric populations of pallid and shovelnose sturgeon| journal = North American Journal of Fisheries Management | volume = 21 | pages = 367–373| publisher =  American Fisheries Society| date = March 2001| url = http://genome-lab.ucdavis.edu/Publications/2001TranahEtAl_NAJFM.pdf| accessdate = 2008-11-19}}</ref><ref name="Billings">{{cite web| title = Pallid Sturgeon (Scaphirhynchus albus) 5-Year Review Summary and Evaluation| publisher = U.S. Fish and Wildlife Service| date = 2007|pages = 24-28|url = http://www.uwyo.edu/enr/ienr/PSWorkshop2007/Pallid_Sturgeon_5year_Review_Final_June2007.pdf| format = pdf| accessdate = 2008-11-19}}</ref>
-Another reason for DNA testing was to determine the rates of [[Hybrid (biology)|hybridization]] between pallid and shovelnose sturgeons. The southern populations have more hybrids than are found in the middle sections of the Missouri River basin, while the northernmost populations have had few reports of hybrids.<ref name="Billings"/> Hybrids are most common in the Atchafalaya River in Louisiana and DNA sequencing in these hybrids showed a genetic distinction from pallid sturgeons, but based on the genetic markers assessed, they were genetically indistinguishable from shovelnose sturgeons.<ref name="Tranah2"/> Because of this ability of two species to hybridize, some biologists have expressed concern that it is a violation of the [[Endangered Species Act]] to protect one species that may not be genetically isolated from another.<ref name="Campton"/> It is not known if the hybrids are able to reproduce or not, yet they appear to be the result of of pallid sturgeon eggs being fertilized by shovelnose sturgeon males.<ref name="Tranah1"/>
+Another reason for DNA testing was to determine the rates of [[Hybrid (biology)|hybridization]] between pallid and shovelnose sturgeons. The southern populations have more hybrids than are found in the middle sections of the Missouri River basin, while the northernmost populations have had few reports of hybrids.<ref name="Billings"/> Hybrids are most common in the Atchafalaya River in Louisiana and DNA sequencing in these hybrids showed a genetic distinction from pallid sturgeons, but based on the genetic markers assessed, they were genetically indistinguishable from shovelnose sturgeons.<ref name="Tranah2"/> Because of this ability of two species to hybridize, some biologists have expressed concern that it is a violation of the [[Endangered Species Act]] to protect one species that may not be genetically isolated from another.<ref name="Campton"/> It is not known if the hybrids are able to reproduce or not, although they appear to be the result of of pallid sturgeon eggs being fertilized by shovelnose sturgeon males.<ref name="Tranah1"/>
 ===Physical characteristics===
 [[Image:Pallid Sturgeon head detail.JPG|thumb|right|Detail and measurement of head of a hatchery raised pallid sturgeon]]
-The pallid sturgeon is one of the largest freshwater fish species in North America. They are generally between {{convert|30|and|60|in|cm}} in length and weigh as much as {{convert|85|lb|kg}}.<ref name="montana"/><ref name="Platte"/> The species is ancient and has remained virtually unchanged for 70&nbsp;million years, since the Cretaceous period. The pallid sturgeon has a distinctive appearance that has been referred to as "primitive", "dinosaur-like" and even "ugly".<ref name="dinosaur"/> Although visually similar, the shovelnose sturgeon is much smaller and usually weighs no more than {{convert|5|lb|kg}}. Pallid sturgeons are much paler in coloration with grayish white backs and sides, while shovelnose sturgeons are brown.<ref name="NRCS"/> Pallid sturgeons turn whiter as they age and younger specimens are easily confused with  adult shovelnoses sturgeon since they are similar in color.<ref name="Missouri">{{cite web| | title = Endangered Sturgeon Struggle for Survival | work = The Sturgeon of Missouri Missouri's Aquatic Dinosaurs| publisher = Conservation Commission of Missouri| year = 2008| url = http://mdc.mo.gov/fish/sport/sturgeon/info/| accessdate = 2008-11-19}}</ref> Like the shovelnose sturgeon, their tails are heterocercal, with the top tail fin being longer than the bottom fin, though this is  more pronounced in pallid sturgeons.<ref name="Johnsgard">{{cite book| last = Johnsgard| first = Paul A.| title = The Nature of Nebraska| publisher = Bison Books| date = April 1, 2005| location = Lincoln, Nebraska| pages = 169–170| isbn = 978-0803276215}}</ref>
+The pallid sturgeon is one of the largest freshwater fish species in North America. They are generally between {{convert|30|and|60|in|cm}} in length and weigh as much as {{convert|85|lb|kg}}.<ref name="montana"/><ref name="Platte"/> The species is ancient and has remained virtually unchanged for 70&nbsp;million years, since the [[Cretaceous]] period. The pallid sturgeon has a distinctive appearance that has been referred to as "primitive", "dinosaur-like" and even "ugly".<ref name="dinosaur"/> Although visually similar, the shovelnose sturgeon is much smaller and usually weighs no more than {{convert|5|lb|kg}}. Pallid sturgeons are much paler in coloration with grayish white backs and sides, while shovelnose sturgeons are brown.<ref name="NRCS"/> Pallid sturgeons turn whiter as they age and younger specimens are easily confused with  adult shovelnoses sturgeon since they are similar in color.<ref name="Missouri">{{cite web| | title = Endangered Sturgeon Struggle for Survival | work = The Sturgeon of Missouri Missouri's Aquatic Dinosaurs| publisher = Conservation Commission of Missouri| year = 2008| url = http://mdc.mo.gov/fish/sport/sturgeon/info/| accessdate = 2008-11-19}}</ref> Like the shovelnose sturgeon, their tails are heterocercal, with the top tail fin being longer than the bottom fin, though this is  more pronounced in pallid sturgeons.<ref name="Johnsgard">{{cite book| last = Johnsgard| first = Paul A.| title = The Nature of Nebraska| publisher = Bison Books| date = April 1, 2005| location = Lincoln, Nebraska| pages = 169–170| isbn = 978-0803276215}}</ref>
 As with other sturgeons, pallid sturgeons are lacking the [[Scale (zoology)|scales]] or bones found in more modern species of fish. Instead, they have [[cartilage|cartilaginous]] skeletons with 5&nbsp;rows of thick cartilage plates that extend along their sides, undersides and backs, as well as over most of the head. These thick cartilage plates are covered by the skin and serve as a protective armor.<ref name="Johnsgard"/>  The bony cartilage also extends along the backside, from the [[dorsal fin]] to the tail.<ref name="Riis"/>
-The pallid sturgeon's snout and head are longer than that of the shovelnose sturgeon.<ref name="Missouri"/> In both species, the mouth is located well back from the tip of the snout. Lacking teeth they use their extendable mouths to suck up small fish, [[mollusk]]s and other food sources from river bottoms. Both species also have four [[Barbel (anatomy)|barbel]]s which descend from the snout near the front of the mouth. The barbels are believed to be sensory features to locate food sources.<ref name="Johnsgard"/> On pallid sturgeons, the two inner barbels are approximately half as long as the outer ones, while on the shovelnose sturgeon, all four barbels are the same length.<ref name="NRCS"/> The inner barbels of the pallid sturgeon are positioned ahead of the outer ones, whereby those on the shovelnose sturgeon are all located in essentially a straight line. The length and positioning of the barbels is one of the best ways to distinguish the two species.<ref name="Missouri"/>
+The pallid sturgeon's snout and head are longer than that of the shovelnose sturgeon.<ref name="Missouri"/> In both species, the mouth is located well back from the tip of the snout. Lacking teeth they use their extendable mouths to suck up small fish, [[mollusk]]s and other food sources from river bottoms. Both species also have four [[Barbel (anatomy)|barbel]]s which descend from the snout near the front of the mouth. The barbels are believed to be sensory features to locate food sources.<ref name="Johnsgard"/> On pallid sturgeons, the two inner barbels are approximately half as long as the outer ones, while on the shovelnose sturgeon, all four barbels are the same length.<ref name="NRCS"/> The inner barbels of the pallid sturgeon are positioned in front of the outer ones, whereby those on the shovelnose sturgeon are all located in essentially a straight line. The length and positioning of the barbels is one of the best ways to distinguish the two species.<ref name="Missouri"/>
 ===Reproduction and life cycle===
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 == Conservation ==
-[[Image:Pallid Sturgeon released 1999.jpg|right|thumb|[[U.S. Fish and Wildlife Service]] employees release a hatchery-raised pallid sturgeon into the [[Yellowstone River]]]]
+[[Image:Pallid Sturgeon released 1999.jpg|right|thumb|[[U.S. Fish and Wildlife Service]] employees release a hatchery-raised pallid sturgeon into the [[Yellowstone River]].]]
-Though never believed to be common, pallid sturgeon populations nosedived during the late 20th century and the species was listed as endangered on September 6, 1990.<ref name="NRCS"/> The [[U.S. Government]] and most of the states with pallid sturgeon populations have commenced restoration efforts to save the species from extinction. Wild reproduction of pallid sturgeon is rare to nonexistent in most areas; therefore, human intervention is needed to ensure the survival of the species.<ref name="Wildhaber">{{cite web| last = Wildhaber| first = Mark L.| coauthors = Aaron J. DeLonay, Diana M. Papoulias, David L. Galat, Robert B. Jacobson, Darin G. Simpkins, Patrick J. Braaten, Carl E. Korschgen, and Michael J. Mac| title = A Conceptual Life-History Model for Pallid and Shovelnose Sturgeon| publisher = U.S. Geological Survey| date = 2007| url = http://www.uwyo.edu/enr/ienr/PSWorkshop2007/circ_1315.pdf| format = pdf| accessdate = 2008-11-19}}</ref><ref name="montana"/> Pallid sturgeon were previously considered a prized trophy game fish species, until their numbers declined and they were placed on the endangered species list. All captured pallid sturgeon must now be released back to the wild. The species was known as being very palatable and the [[roe]] from females was used as [[caviar]].<ref name="Guide"/>
+Though never believed to be common, pallid sturgeon populations nosedived during the late 20th century and the species was listed as endangered on September 6, 1990.<ref name="NRCS"/> The [[U.S. Government]] and most of the states with pallid sturgeon populations have commenced restoration efforts to save the species from extinction. Wild reproduction of pallid sturgeon is rare to nonexistent in most areas; therefore, human intervention is needed to ensure the survival of the species.<ref name="Wildhaber">{{cite web| last = Wildhaber| first = Mark L.| coauthors = Aaron J. DeLonay, Diana M. Papoulias, David L. Galat, Robert B. Jacobson, Darin G. Simpkins, Patrick J. Braaten, Carl E. Korschgen, and Michael J. Mac| title = A Conceptual Life-History Model for Pallid and Shovelnose Sturgeon| publisher = U.S. Geological Survey| date = 2007| url = http://www.uwyo.edu/enr/ienr/PSWorkshop2007/circ_1315.pdf| format = pdf| accessdate = 2008-11-19}}</ref><ref name="montana"/> Pallid sturgeon were previously considered a prized trophy game fish species, until their numbers declined and they were placed on the endangered species list. All captured pallid sturgeon must now be released back to the wild. The species was known for being very palatable and the [[roe]] from females was used as [[caviar]].<ref name="Guide"/>
 The route and the environmental characteristics of  Missouri River in the northern [[Great Plains]] states of North and [[South Dakota]], [[Nebraska]] and Montana, have been significantly altered. The resultant changes to the Missouri River in the upper Great Plains from channelization and impoundment prevent upstream migration. The reduced water flow rates and sediment loads and has brought an end to the seasonal flooding of the flood plains in the region. Since the construction of the [[Fort Peck Dam]] in Montana in 1937, and subsequent damming and channelization, the Missouri river has lost over 90&nbsp;percent of its wetland and sandbar ecosystems. More than {{convert|2000|mi|km}} of the Missouri River has been altered and only that stretch of the river above Fort Peck Reservoir in Montana remains relatively unchanged.<ref name="Power">{{cite web| last = Power| first = Greg| title = The Missouri River System's "Other" Fish | publisher = U. S. Geological Survey| date = 2006| url = http://www.npwrc.usgs.gov/resource/fish/othrfish/overview.htm| accessdate =2008-11-19 }}</ref> These alterations of the river  have had a detrimental impact on a number of native fish species. In the 13 [[U.S. state]]s that the pallid sturgeon is found, only a few other fish species are listed as endangered.<ref name="Tess">{{cite web| title = How many species are listed in each state (based on published population data)?| work = Threatened & Endangered Species System| publisher = U.S. Fish and Wildlife Service| date = 2008| url = http://ecos.fws.gov/tess_public/StateListing.do?state=all| accessdate = 2008-11-19}}</ref> Although substantial efforts are being implemented to ensure the survival of this species, the rarity of self-sustaining populations of pallid sturgeons ensures that it will remain federally protected for many decades.
+===Extinction threats===
-===Efforts to save the pallid sturgeon from extinction===
 Two populations of pallid sturgeons in the Missouri and [[Yellowstone River]]s of Montana are both at risk of extinction and current projections are that wild pallid sturgeon populations in Montana will be extinct by 2018.<ref name="montana"/> Though a vigorous stocking effort was implemented in 1996, until pallid sturgeon females reach reproductive maturity sometime after they are 15&nbsp;years of age, recovery efforts in Montana will not be readily measurable. The [[U.S. Bureau of Reclamation]] has been conducting spring pulse water releases from the [[Tiber dam]] every 4 to 5&nbsp;years to try and recreate a semblance of an annual spring flood to restore and rejuvenate downstream floodplains. These pulse releases are done in an effort to restore suitable habitat for numerous fish species.<ref name="montana2">{{cite web| title = Pallid Sturgeon — Scaphirhynchus albus| publisher = State of Montana| url = http://fieldguide.mt.gov/detail_AFCAA02010.aspx| accessdate =2008-11-19 }}</ref>
 [[Image:Radio transmitter implant in pallid sturgeon.jpg|right|thumb|Surgical implant of a radio transmitter in a sexually mature pallid sturgeon]]
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 In Missouri, at the Lisbon Bottoms section of the [[Big Muddy National Fish & Wildlife Refuge]], wild pallid sturgeon larvae were collected in 1998. These non-hatchery raised larvae were the first recovered on the lower Missouri River in the previous 50&nbsp;years. The recovery was made along a side channel of the Missouri River that had been developed to provide suitable habitat for pallid sturgeon and other fish spawning.<ref name="Ikenson">{{cite news | last = Ikenson| first = Ben | title = Biologists struggle to keep the pallid sturgeon from going extinct | work = Reviving the Missouri River's dinosaur| publisher = ''ESPN''| date = May 31, 2006| url = http://sports.espn.go.com/outdoors/general/columns/story?columnist=guest_columnist&page=c_col_Ikenson_sturgeon_pallid| accessdate = 2008-11-19}}</ref> The side channel was apparently being used by the larva pallid sturgeons for protection from the swifter currents of the Missouri River.<ref name="Mississippi">{{cite web| title = Pallid Sturgeon, Scaphirhynchus albus| publisher = Mississippi Interstate Cooperative Resource Association| url = http://wwwaux.cerc.cr.usgs.gov/MICRA/PALLIDST.HTM| accessdate = 2008-11-19}}</ref>
-The U.S. Fish and Wildlife Service concluded in 2007 that hatchery-based reproduction efforts should be continued, along with monitoring of any population changes to determine the effectiveness of human intervention. The 2007 findings also emphasized the need to determine the most likely areas of spawning, to identify any parasite or disease that may be impacting the reproductive capabilities of pallid sturgeon and to examine engineering possibilities that may permit recreation of suitable habitats without reducing the ability to protect people from harmful and destructive flooding, and maintaining the ability to provide adequate water impoundment for irrigation and recreation purposes.<ref name="Billings"/>
+In 2007, the  U.S. Fish and Wildlife Service concluded  that hatchery-based reproduction efforts should be continued, along with monitoring of any population changes, to determine the effectiveness of human intervention. The 2007 findings also emphasized the need to determine the most likely areas of spawning. The goal of this recommendation was to identify  any parasite or disease that may be impacting the reproductive capabilities of pallid sturgeon and to examine engineering possibilities that may permit recreation of suitable habitats without reducing the Serivice's ability to protect people from harmful and destructive flooding, and to  maintain its ability to provide adequate water impoundment for irrigation and recreation purposes.<ref name="Billings"/>
 == References ==