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The pallid sturgeon (''Scaphirhynchus albus'') is an endangered species of
ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or h ...
,
endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...
to the waters of the
Missouri Missouri is a state in the Midwestern region of the United States. Ranking 21st in land area, it is bordered by eight states (tied for the most with Tennessee): Iowa to the north, Illinois, Kentucky and Tennessee to the east, Arkansas t ...
and lower
Mississippi river The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it fl ...
basins of the United States. It may have even reached the St. Croix River before colonization. Named for its pale coloration, it is closely related to the relatively common
shovelnose sturgeon 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 ...
(''Scaphirhynchus platorynchus''), but is much larger, averaging between in length and in weight at maturity. This species takes 15 years to mature and spawns infrequently, but can live up to a century. A member of the sturgeon family, Acipenseridae, which originated during the
Cretaceous period The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of t ...
70 million years ago, the pallid sturgeon has changed little since then. In 1990, the
U.S. Fish and Wildlife Service The United States Fish and Wildlife Service (USFWS or FWS) is an agency within the United States Department of the Interior dedicated to the management of fish, wildlife, and natural habitats. The mission of the agency is "working with othe ...
placed the pallid sturgeon on its endangered species list because few young individuals had been observed in the preceding decade and sightings had greatly diminished; the species is now rarely seen in the wild. It was the first fish species in the Missouri 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 Missouri River drainage system has been channeled and dammed, reducing the gravel deposits and slow-moving side channels that are its favored
spawning Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquat ...
areas. Until the middle of the 20th century, pallid sturgeon were common and anglers found catching such a large fish in fresh water a rewarding experience. The species is considered to be good-tasting, and its eggs have been used as
caviar Caviar (also known as caviare; from fa, خاویار, khâvyâr, egg-bearing) is a food consisting of salt-cured roe of the family Acipenseridae. Caviar is considered a delicacy and is eaten as a garnish or a spread. Traditionally, the te ...
, although less commonly than those of many other sturgeon. Efforts to prevent the species from becoming extinct have had modest success. Pallid sturgeon are actively being raised in a dozen
hatcheries A hatchery is a facility where eggs are hatched under artificial conditions, especially those of fish, poultry or even turtles. It may be used for ex-situ conservation purposes, i.e. to breed rare or endangered species under controlled condi ...
and the offspring are being released back to the wild every year. To better understand pallid sturgeon behavior, researchers have implanted radio transmitters to track their movements and help identify possible spawning areas. Federal and state agencies are working together to improve habitat by restoring spawning areas since restoration of these areas is required if the species is to survive in the wild.


Taxonomy and etymology

Taxonomists S. A. Forbes and R. E. Richardson classified the pallid sturgeon in 1905, grouping it in the
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
''Parascaphirhynchus'' and the
family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
Acipenseridae, which includes all sturgeon worldwide. Its closest relatives are the shovelnose sturgeon (''Scaphirhynchus platorynchus''), which is still relatively common, and the critically endangered Alabama sturgeon (''Scaphirhynchus suttkusi''), which may soon become extinct. These three species belong to the subfamily
Scaphirhynchinae Sturgeon is the common name for the 27 species of fish belonging to the family Acipenseridae. The earliest sturgeon fossils date to the Late Cretaceous, and are descended from other, earlier acipenseriform fish, which date back to the Early ...
, which has only one other genus, ''
Pseudoscaphirhynchus ''Pseudoscaphirhynchus'' is a genus of relatively small, highly threatened sturgeons that are restricted to the Aral Sea system (although extirpated from the Aral Sea itself), including the Amu Darya and Syr Darya river basins, in Central Asia. ...
'', represented by three species found in west-central
Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...
. The word pallid means "deficient in color", and compared to other species of sturgeon, the pallid is noticeably paler. The scientific name for the fish is derived from ''Scaphirhynchus'', a
Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...
word meaning "spade snout" and ''albus'' which is
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
for "white".


Biology


DNA studies

To better protect the pallid sturgeon from extinction, research on its DNA and that of other closely related species was conducted to assess the differences within various populations of pallid sturgeon, and the differences between pallid and shovelnose sturgeon. Early DNA research indicated that pallid sturgeon and shovelnose sturgeon were a single species. However, a 2000 study comparing DNA sequences in the three members of the genus ''Scaphirhynchus''(pallid, shovelnose, and Alabama sturgeon) showed that the three are distinct species. 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 a southern population located in the
Atchafalaya River The Atchafalaya River ( french: La Rivière Atchafalaya, es, Río Atchafalaya) is a distributary of the Mississippi River and Red River in south central Louisiana in the United States. It flows south, just west of the Mississippi River, and ...
in
Louisiana Louisiana , group=pronunciation (French: ''La Louisiane'') is a state in the Deep South and South Central regions of the United States. It is the 20th-smallest by area and the 25th most populous of the 50 U.S. states. Louisiana is borde ...
. These DNA studies concluded that the northern populations of pallid sturgeon are
reproductively isolated The mechanisms of reproductive isolation are a collection of evolutionary mechanisms, behaviors and physiological processes critical for speciation. They prevent members of different species from producing offspring, or ensure that any offsprin ...
and are genetically distinct from the Atchafalaya population. However, the genetic variability among pallid sturgeon was found to be far less than that between them and the shovelnose sturgeon. Another reason for DNA testing was to determine the rates of hybridization between pallid and shovelnose sturgeon. 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. Hybrids are most common in the Atchafalaya River in Louisiana, and DNA sequencing in these hybrids showed a genetic distinction from pallid sturgeon, but based on the genetic markers assessed, they were genetically indistinguishable from shovelnose sturgeon. 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. It is not known if the hybrids are able to reproduce or not, although they appear to be the result of pallid sturgeon
eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...
being fertilized by shovelnose sturgeon males.


Physical characteristics

The pallid sturgeon is one of the largest freshwater fish species in North America. They are generally between in length and weigh as much as . The species is ancient and has remained virtually unchanged for 70 million years, since the
Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
period. The pallid sturgeon has a distinctive appearance that has been referred to as "primitive", "dinosaur-like" and even "ugly". Although visually similar, the shovelnose sturgeon is much smaller and usually weighs no more than . Pallid sturgeon are much paler in coloration with grayish white backs and sides, while shovelnose sturgeon are brown. Pallid sturgeon turn whiter as they age and younger specimens are easily confused with adult shovelnose sturgeon since they are similar in color. Like the shovelnose sturgeon, their tails are
heterocercal Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as s ...
, with the top tail fin being longer than the bottom fin, though this is more pronounced in pallid sturgeon. As with other sturgeon, pallid sturgeon lack the
scales Scale or scales may refer to: Mathematics * Scale (descriptive set theory), an object defined on a set of points * Scale (ratio), the ratio of a linear dimension of a model to the corresponding dimension of the original * Scale factor, a number w ...
or bones found in more "modern" species of fish. Instead, they have
cartilaginous Cartilage is a resilient and smooth type of connective tissue. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck a ...
skeletons with five 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. The bony cartilage also extends along the backside, from the
dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through c ...
to the tail. The pallid sturgeon's snout and head are longer than that of the shovelnose sturgeon. 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 Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000  extant species of molluscs are recognized. The number of fossil species is e ...
s, and other food sources from river bottoms. Both species also have four
barbels In fish anatomy and turtle anatomy, a barbel is a slender, whiskerlike sensory organ near the mouth. Fish that have barbels include the catfish, the carp, the goatfish, the hagfish, the sturgeon, the zebrafish, the black dragonfish and some s ...
which descend from the snout near the front of the mouth. The barbels are believed to be sensory features to locate food sources. On pallid sturgeon, the two inner barbels are about half as long as the outer ones, while on the shovelnose sturgeon, all four barbels are the same length. The inner barbels of the pallid sturgeon are positioned in front of the outer ones, but 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.


Reproduction and lifecycle

Pallid sturgeon have a long lifespan, living in excess of 50 and perhaps as long as 100 years. They lack bones and scales, which makes it more difficult to establish their age and determine exactly how long they live. As is true for many long-lived species, pallid sturgeon reach reproductive maturity relatively late. 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 nine 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 10 years. Spawning usually takes place May to July. Prior to the construction of dams on the Missouri, pallid sturgeon migrated hundreds of miles upstream to spawn, and sought out rocky or hard surfaces to deposit hundreds of thousands of eggs. One female pallid sturgeon caught in the upper Missouri River was estimated to be carrying 170,000 eggs, representing over 11 percent of its total body weight. After fertilization, pallid sturgeon eggs hatch in 5 to 8 days, 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. The rate of survival to maturity for pallid sturgeon larvae is extremely low, and of the hundreds of thousands of eggs spawned, only a few live to adulthood. For several decades, no natural reproduction of pallid sturgeon was observed, since all the fish that had been captured were older specimens. In the late 1990s, young pallid sturgeon were discovered living in a restored riparian area of the lower Missouri River. This was the first documented example of wild spawned pallid sturgeon in 50 years. In 2007, two female pallid sturgeon were also reported to have spawned in the
Missouri National Recreational River The Missouri National Recreational River is a National Recreational River located on the border between Nebraska and South Dakota. The designation was first applied in 1978 to a 59-mile section of the Missouri River between Gavins Point Dam and ...
area located downstream from
Gavins Point Dam Gavins Point Dam is a long embankment rolled-earth and chalk-fill dam which spans the Missouri River and impounds Lewis and Clark Lake. The dam joins Cedar County, Nebraska with Yankton County, South Dakota a distance of 811.1 river miles (1,30 ...
on the Missouri River.


Ecology


Distribution

The pallid sturgeon's historical
range Range may refer to: Geography * Range (geographic), a chain of hills or mountains; a somewhat linear, complex mountainous or hilly area (cordillera, sierra) ** Mountain range, a group of mountains bordered by lowlands * Range, a term used to i ...
spanned the entire Missouri River and into the Mississippi River. Historically, the species was rare to nonexistent in the upper Mississippi, probably due to a lack of proper habitat. Currently, the species is considered imperiled throughout its entire range. As of 2008, pallid sturgeon 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 Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columb ...
to Louisiana, as well as the Atchafalaya River in Louisiana, continue to harbor an aging population of pallid sturgeon. Pallid sturgeon have never been very common; as early as 1905 when the species was first identified, they represented only one in five of all sturgeon in the lower Missouri River and as few as one in 500 where the Illinois River meets the Mississippi. Between 1985 and 2000, the ratio of pallid sturgeon to all sturgeon netted declined from one in about 400 to one in nearly 650. A 1996 study concluded that between 6,000 and 21,000 pallid sturgeon remained in their natural habitat at that time. 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 population studies as "recovery priority management areas" (RPMAs). In the northernmost region of the study, known as RPMA 1, located between the
Marias River The Marias River is a tributary of the Missouri River, approximately 210 mi (338 km) long, in the U.S. state of Montana. It is formed in Glacier County, in northwestern Montana, by the confluence of the Cut Bank Creek and the Two Med ...
in Montana and the western reaches of Fort Peck Reservoir, only 45 wild (nonhatchery) 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 Lake Sakakawea is a large reservoir in the north central United States, impounded in 1953 by Garrison Dam, a U.S. Army Corps of Engineers dam located in the Missouri River basin in central North Dakota. Named for the Shoshone-Hidatsa woman Sa ...
, and the lower
Yellowstone River The Yellowstone River is a tributary of the Missouri River, approximately long, in the Western United States. Considered the principal tributary of upper Missouri, via its own tributaries it drains an area with headwaters across the mountains a ...
up to the confluence of the Tongue River, Montana, only 136 wild specimens remain. In RPMA 3, stretching from upstream of the
Niobrara River The Niobrara River (; oma, Ní Ubthátha khe, , literally "water spread-out horizontal-the" or "The Wide-Spreading Water") is a tributary of the Missouri River, approximately long,U.S. Geological Survey. Many early settlers, such as Mari Sando ...
to
Lewis and Clark Lake Lewis and Clark Lake is a 31,400 acre (130 km²) reservoir located on the border of the U.S. states of Nebraska and South Dakota on the Missouri River. The lake is approximately in length with over of shoreline and a maximum water dep ...
along the Missouri River, no native populations were recorded. All collected specimens appeared to be hatchery-raised. However, these specimens were apparently maturing and adjusting well to this section of the river. Recovery priority management area 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 nonhatchery specimens were collected during the study period. Evidence also indicates some wild reproduction is going on in this region. In RPMA 5, between the confluence of the Missouri and Mississippi and the
Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United ...
, several hundred specimens were documented. Again, some evidence suggests natural reproduction is occurring, as demonstrated by the recovery of a few examples of immature, nonhatchery-raised individuals. The Atchafalaya River basin is designated as RPMA 6 and the findings there were similar to those in RPMAs 4 and 5, but with greater numbers of unique individuals, near 500 in total.


Habitat

Pallid sturgeon prefer moderate to swift river currents and most captured specimens have been recovered in rivers and streams in which the current averages between . They also prefer
turbid Turbidity is the cloudiness or haziness of a fluid caused by large numbers of 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. Fluids can ...
waterways and water depths between . The species is more commonly found where sandy substrates are plentiful, but also lives in predominately rocky waterways. Pallid sturgeon prefer swift river currents more often than do shovelnose sturgeon. In a study based in Montana and North Dakota conducted on both the pallid and shovelnose sturgeon, both species were fitted with radio transmitters so researchers could track their swimming habits. Pallid sturgeon were found to prefer wider river channels, midchannel sandbars, and numerous islands, and were most commonly recorded in water depths between . The study also showed that the pallid sturgeon moved as much as per day and up to . Pallid sturgeon are believed to have preferred the muddy and generally warmer waters that existed prior to Missouri River dam construction.


Food preferences

Pallid sturgeon are generally
bottom feeder A bottom feeder is an aquatic animal that feeds on or near the bottom of a body of water. Biologists often use the terms ''benthos''—particularly for invertebrates such as shellfish, crabs, crayfish, sea anemones, starfish, snails, bristlewo ...
s, 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. One study which examined the contents from the stomachs of juvenile pallid sturgeon 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 sturgeon's eating habits as opportunistic. Fish is a more important dietary staple for pallid sturgeon than it is for shovelnose sturgeon. 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
cyprinid Cyprinidae is a family of freshwater fish commonly called the carp or minnow family. It includes the carps, the true minnows, and relatives like the barbs and barbels. Cyprinidae is the largest and most diverse fish family and the largest ver ...
s (minnows). In another study conducted in the upper Missouri River region, an examination of the stomach contents of hatchery-reared pallid sturgeon showed that 82% of the wet weight was small fish and the balance was mosquito-like insects,
mayflies Mayflies (also known as shadflies or fishflies in Canada and the upper Midwestern United States, as Canadian soldiers in the American Great Lakes region, and as up-winged flies in the United Kingdom) are aquatic insects belonging to the order ...
, and caddis flies and small amounts of detritus and plant material.


Conservation

Though never believed to be common, pallid sturgeon populations rapidly declined during the late 20th century and the species was listed as endangered on September 6, 1990. 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. 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 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, sea urchins and squid. As a seafood, roe is used both as a cooked in ...
from females was used as
caviar Caviar (also known as caviare; from fa, خاویار, khâvyâr, egg-bearing) is a food consisting of salt-cured roe of the family Acipenseridae. Caviar is considered a delicacy and is eaten as a garnish or a spread. Traditionally, the te ...
. 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 have brought an end to the seasonal flooding of the flood plains in the region. Since the construction of the
Fort Peck Dam The Fort Peck Dam is the highest of six major dams along the Missouri River, located in northeast Montana in the United States, near Glasgow, and adjacent to the community of Fort Peck. At in length and over in height, it is the largest h ...
in Montana in 1937, and subsequent damming and channelization, the Missouri River has lost over 90% of its wetland and sandbar ecosystems. More than of the Missouri River have been altered and only that stretch of the river above Fort Peck Reservoir in Montana remains relatively unchanged. These alterations of the river have had a detrimental impact on a number of native fish species. In the 13 U.S. states where the pallid sturgeon is found, only a few other fish species are listed as critically endangered. Although substantial efforts are being implemented to ensure the survival of this species, the rarity of self-sustaining populations of pallid sturgeon ensures that it will remain federally protected for many decades.


Species preservation efforts

Two populations of pallid sturgeon 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. 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 four to five years to try to 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. In Nebraska, a small number of pallid sturgeon have been captured along the lower reaches of the
Platte River The Platte River () is a major river in the State of Nebraska. It is about long; measured to its farthest source via its tributary, the North Platte River, it flows for over . The Platte River is a tributary of the Missouri River, which itsel ...
. 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 sturgeon prefer more turbulent and deeper rivers than the Platte, between 1979 and 2003, over a dozen pallid sturgeon, including some from hatcheries, have been captured from the Platte River. A number of these pallid sturgeon have been fitted with
radio transmitters In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna. The transmitter itself generates a radio frequency alternating current, which is applied to the ...
which track their return to the Platte River when water levels and turbidity conditions are favorable. Coinciding with the majority of the pallid sturgeon that have been captured, the period that is generally most favorable is during the spring and early summer. By midsummer, a reduction in water levels and turbidity on the Platte River encourages pallid sturgeon to return to the Missouri River. The lower reaches of the Platte River, a more than stretch from the
Elkhorn River The Elkhorn River is a river in northeastern Nebraska, United States, that originates in the eastern Sandhills and is one of the largest tributaries of the Platte River, flowing and joining the Platte just southwest of Omaha, approximately s ...
to its confluence with the Missouri River, has suitable spawning habitat for pallid sturgeon, although no conclusive evidence has been found that spawning is occurring in this region. 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. In Missouri, at the Lisbon Bottoms section of the
Big Muddy National Fish and Wildlife Refuge The Big Muddy National Fish and Wildlife Refuge was established in 1994, and has grown to over . Like pearls on a string, these acres are spread out as individual units along the Missouri River between Kansas City and St. Louis. These pearls of h ...
, wild pallid sturgeon larvae were collected in 1998. These nonhatchery-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. The side channel was apparently being used by the larva pallid sturgeon for protection from the swifter currents of the Missouri River. In 2007, the USFWS 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, 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 USFWS'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.


References


External links


Pallid Sturgeon Recovery Plan (10mb file)

Revised Recovery Plan for the Pallid Sturgeon

Pallid Sturgeon project in the Middle Mississippi River


NYTimes, 2015 {{Taxonbar, from=Q921461 Sturgeon Pallid Sturgeon Pallid Scaphirhynchus Articles containing video clips ESA endangered species Fish described in 1905 Freshwater fish of North America Taxa named by Stephen Alfred Forbes Taxa named by Robert Earl Richardson