Difference between revisions of "Paddlefish" - New World Encyclopedia

From New World Encyclopedia
m
 
(33 intermediate revisions by one other user not shown)
Line 1: Line 1:
 +
{{Images OK}}{{Approved}}{{copyedited}}
 +
 
{{Taxobox
 
{{Taxobox
 
| name = Paddlefishes
 
| name = Paddlefishes
Line 4: Line 6:
 
| image_width = 250px
 
| image_width = 250px
 
| image_caption = [[American Paddlefish]], ''Polyodon spathula''
 
| image_caption = [[American Paddlefish]], ''Polyodon spathula''
−
| fossil_range = {{Fossil range|Late Cretaceous|Recent}}<ref name=FB>{{FishBase_family|family=Polyodontidae|year=2009|month=January}}</ref>
+
| fossil_range = {{Fossil range|Late Cretaceous|Recent}}<ref name=FB>R. Froese and D. Pauly, eds., [http://www.fishbase.org/Summary/FamilySummary.php?Family=Polyodontidae Family Polyodontidae: Paddlefishes ], ''Fishbase'' (2009). Retrieved August 23, 2012.</ref>
 
| regnum = [[Animal]]ia
 
| regnum = [[Animal]]ia
 
| phylum = [[Chordate|Chordata]]
 
| phylum = [[Chordate|Chordata]]
Line 13: Line 15:
 
| subdivision_ranks = Genera
 
| subdivision_ranks = Genera
 
| subdivision =  
 
| subdivision =  
−
''[[American paddlefish|Polyodon]]''<br />
+
''[[Paddlefish#American paddlefish|Polyodon]]''<br />
−
''[[Chinese paddlefish|Psephurus]]''<br />
+
''[[Paddlefish#Chinese paddlefish|Psephurus]]''<br />
 
}}
 
}}
  
−
'''Paddlefish''' (family '''Polyodontidae''') are primitive [[Chondrostean]] [[ray-finned fish]]es. The paddlefish can be distinguished by its large [[mouth]] and its elongated, [[spatula]]-like [[snout]], called a [[rostrum (anatomy)|rostrum]], which is longer than the rest of the head.  These fish are not closely related to [[shark]]s, which are in a different [[class (biology)|taxonomic class]], but they do have some body parts that resemble those of sharks such as their skeletons, primarily composed of [[cartilage]], and their deeply forked heterocercal [[Fish anatomy#Types of fin|tail fin]]s. This type of fish's age is hard to determine but many scientists{{Who|date=March 2009}} think that they live 50 years or more.
+
'''Paddlefish''' is the common name for the [[ray-finned fish]] comprising the family Polyodontidae of the Order Acipenseriformes, characterized by an elongated, paddle-like snout with minute barbels, large mouth with minute teeth, and long gill rakers. The other extant family in the Acipenseriformes order is that of the sturgeons, [[Acipenseridae]], but the [[sturgeon]]s lack teeth in adults, have fewer than 50 gill rakers, and have a flattened rostra, among other differences. In some areas in the United States, paddlefish are referred to as "spoonbills," "spoonbill catfish," or "spoonies."
  
−
Froese, Rainer, and Daniel Pauly, eds. (2009). "Polyodontidae" in FishBase. January 2009 version.
+
There are only two modern species of these fish: the [[plankton]]-feeding American paddlefish (''Polyodon spathula''), found in the [[Mississippi River]] drainage system, and the piscivorous Chinese paddlefish (''Psephurus gladius''), found in the Yangtze River; however, there are concerns that the Chinese species may now be extinct.  
  
−
paddlelike snout; body lacking large scutes of acipenerids but small "scales" in sme regions; minute barbels on snout; long gill rakes; minute tteth;
+
Paddlefish provide important economic, ecological, and aesthetic values. During the last century, paddlefish and [[sturgeon]] have been commercially exploited for their eggs ([[roe]]), called [[caviar]]. Paddlefish and sturgeon are two of the most important fish for freshwater caviar. The large number of eggs produced by females also mean they can be important in [[food chain]]s, with the young providing a food resource for predators. Their unique shape and large size also adds to the joy of [[nature]] for humans, including sports fishing. However, exploitation and habitat changes, among other factors, have significantly reduced the populations of paddlefish, with the Chinese paddlefish not having a confirmed sighting since 2007 and the American paddlefish no longer found in the Great Lakes region.  
−
 
 
−
 
 
−
* example: '''Sturgeon''' is the [[common name]] for any of the anadromous and freshwater [[fish]] comprising the family '''Acipenseridae''' of the Order Acipenseriformes of the Class [[Actinopterygii]], characterized by an elongated body, largely cartilaginous skeleton, rows of bony scutes or plates on the body, four barbels in front of the mouth, and protrusible mouth.
 
−
 
 
−
There are only two modern species of these fish: the Chinese paddlefish ''(Psephurus gladius)'' and the American paddlefish ''(Polyodon spathula).''  Both have declined greatly in abundance, and the Chinese species may now be extinct. In some areas, paddlefish are referred to as "Spoonbill", "Spoonies" or "Spoonbill Catfish".
 
  
 
==Overview and description==  
 
==Overview and description==  
 +
[[Image:Paddlefish.jpg|thumb|left|[[American Paddlefish]], ''Polyodon spathula'']]
 +
The Order Acipenseriformes includes two extant families: the paddlefishes (family Polyodontidae) and the [[sturgeon]]s (family Acipenseridae). Members of this order are characterized by a largely [[cartilage|cartilaginous]] structure, an elongated body, an [[intestine]] with spiral valve, a heterocercal caudal fin, the absence of gulars, lack of vertebral central, and fin rays more numerous than their basals (Nelson 2006).
  
 +
The paddlefish family, Polyodontidae, is characterized by its members having an elongated, [[spatula]]-like [[snout]], called a [[rostrum (anatomy)|rostrum]], which is longer than the rest of the head. It takes it common name, and the American paddlefish (''Polyodon spathula'') takes its scientific name from this distinctive paddle-shaped snout. Other characteristics include minute barbels on the snout; long gill rakers, which can reach the hundreds in ''Polyodon''; minute teeth; and a body lacking large scutes, but having small "scales" in some regions (Nelson 2006).  The piscivorous Chinese paddlefish, ''Psephurus gladius'', is characterized by a protrusible mouth, while the plankton-feeding American paddlefish (''Polyodon spathula'') has a nonprotrusible mouth. Members of the sturgeon family, Acipenseridae, differ from the paddlefish in that the acipenserids lack teeth in adults, have five rows of large bony scutes or plates on the body, have fewer than 50 gill rakers; and have a flattened rostra (Nelson 2006). 
  
−
The Order Acipenseriformes includes two extant families: the sturgeons (family Acipenseridae) and the [[paddlefish]]es (family Polyodontidae). Members of this order are characterized by a largely [[cartilage|cartilaginous]] structure, an elongated body, an [[intestine]] with spiral valve, a heterocercal caudal fin, the absence of gulars, lack of vertebral central, and fin rays more numerous than their basals (Nelson 2006).
+
Paddlefish are not closely related to [[shark]]s, which are in a different [[class (biology)|taxonomic class]], but they do have some body parts that resemble those of sharks such as their skeletons, primarily composed of [[cartilage]], and their deeply forked heterocercal [[Fish anatomy#Types of fin|tail fin]]s. As in many of the distantly related shark class, the paddlefish's rostrum contains [[Electroreception|electroreceptors]] that can detect weak [[electrical field]]s.
−
 
 
−
The sturgeon family, Acipenseridae, is characterized by five rows of bony scutes or plates on the body, rather than [[scale (zoology)|scales]]; four barbels that precede the inferior and protrusible mouth; the absence of teeth in adults; a large swim bladder; fewer than 50 gill rakers; and pectoral fins with anterior spinous ray made up of fused rays (Nelson 2006). They also have a flattened [[Rostrum (anatomy)|rostra]] and elongated upper tail lobes. Collectively, the Acipenseridae family is also known as the ''true sturgeons''. Members of the Acipenseridae differ from the paddlefish family Polyodontidae in that the latter have a paddlelike snout with minute barbels, the presence of minute teeth, and lack the large scutes of the acipenserids but have small "scales" in some regions; in some cases, paddlefish also have long gill rakers, including hundreds of gill rakers in the plankton-feeding ''Polyodon''  (Nelson 2006).
 
−
 
 
−
 
 
  
 +
==Classification==
 
There are two currently or recently [[extant taxon|extant]] genera in this family and four (if not five) [[extinct]] genera:
 
There are two currently or recently [[extant taxon|extant]] genera in this family and four (if not five) [[extinct]] genera:
−
 
+
'''Polyodontidae'''
 +
*Subfamily [[extinction|†]]Paleopsephurinae
 +
**Genus †''[[Paleopsephurus]]'' <small>MacAlpin, 1947</small>
 +
***Species †''[[Paleopsephurus|Paleopsephurus wilsoni]]'' <small>MacAlpin, 1947</small> [[Image:Protopsephurus liui.JPG|thumb|''[[Protopsephurus|Protopsephurus liui]]'' fossils]]
 +
*Subfamily Polyodontinae
 +
**Genus †''[[Crossopholis]] <small>[[Edward Drinker Cope|Cope]], 1883</small>
 +
***Species †''[[Crossopholis|Crossopholis magnicaudatus]]'' <small>Cope, 1883</small>
 
**Genus ''[[Polyodon]]'' <small>[[Bernard Germain de Lacépède|Lacépède]], 1797</small>
 
**Genus ''[[Polyodon]]'' <small>[[Bernard Germain de Lacépède|Lacépède]], 1797</small>
 
***''[[Polyodon spathula]]'' <small>[[Johann Julius Walbaum|Walbaum]], 1792</small> [[American paddlefish]]
 
***''[[Polyodon spathula]]'' <small>[[Johann Julius Walbaum|Walbaum]], 1792</small> [[American paddlefish]]
 +
***†''[[Polyodon tuberculata]]'' <small>Grande & Bemis, 1991</small>
 
**Genus ''[[Psephurus]]'' <small>[[Albert Günther|Günther]], 1873</small>
 
**Genus ''[[Psephurus]]'' <small>[[Albert Günther|Günther]], 1873</small>
 
***''[[Psephurus|Psephurus gladius]]'' <small>[[Eduard von Martens|E. von Martens]], 1862</small> [[Chinese paddlefish]] (Not recently verified extant, and perhaps now extinct)
 
***''[[Psephurus|Psephurus gladius]]'' <small>[[Eduard von Martens|E. von Martens]], 1862</small> [[Chinese paddlefish]] (Not recently verified extant, and perhaps now extinct)
 +
*Subfamily †Protopsephurinae <small>Grande & Bemis, 1996</small>
 +
**Genus †''[[Protopsephurus]]'' <small>Lu, 1994</small>
 +
***Species †''[[Protopsephurus|Protopsephurus liui]]'' <small>Lu, 1994</small>
  
−
[[Image:Paddlefish.jpg|thumb|left|[[American Paddlefish]], ''Polyodon spathula'']]
+
Fossils of other kinds of paddlefish have been found. One such species is ''Crossopholis magnicaudatus'', from the [[Eocene|Eocene-age]] Green River Shale deposit in [[Wyoming]].
−
Early investigators{{Who|date=March 2009}} once thought that paddlefishes used their snouts to dig vegetation from the bottom of lakes and rivers. In fact, they feed by filtering out [[zooplankton]] from the water, using filaments on their gill arches called gill rakers, and in  this respect appear similar to the [[basking shark]].
 
−
 
 
−
As in many of the distantly related shark class, the paddlefish's rostrum contains [[Electroreception|electroreceptors]] that can detect weak [[electrical field]]s, suggesting that they use their rostrum as an [[Antenna (biology)|antenna]] to detect [[zooplankton]].<ref name=EoF>{{cite book |editor=Paxton, J.R. & Eschmeyer, W.N.|author= Wiley, Edward G.|year=1998|title=Encyclopedia of Fishes|publisher= Academic Press|location=San Diego|pages= 77–78|isbn= 0-12-547665-5}}</ref> Even though the rostrum seems to help the fish feed, fish with severely damaged or missing rostrums are able to feed and appear to be just as healthy as other fish with them intact.
 
−
 
 
−
The rostrum also helps the fish to feed by acting as a stabilizer. As the fish moves through the water with its mouth open, the rostrum creates lift, much like a wing of an airplane. This helps the fish by keeping its head in a steady position and helps it keep from diving to the bottom.
 
−
 
 
−
Paddlefish lay their [[Egg (biology)|egg]]s in midstream over bare rocks or gravel. The eggs are adhesive and stick to the rocky substrate. The young are swept downstream after hatching and grow to adulthood in deep freshwater pools.<ref name=EoF/>
 
  
  
 
==American paddlefish==
 
==American paddlefish==
 +
[[Image:Paddlefish Polyodon spathula.jpg|240px|thumb|American paddlefish, ''Polyodon spathula'']]
  
 +
The American paddlefish, ''Polyodon spathula'', also known as the Mississippi paddlefish, lives in slow-flowing waters of the [[Mississippi River]] drainage system. This includes slow-flowing waters of the [[Mississippi River]] itself, as well as various tributaries, including the [[Missouri River]], [[Ohio River]], [[Yellowstone River]], [[Wisconsin River]], [[Des Moines River]], and [[Arkansas River]] systems.  These fish were also found historically in [[Lake Erie]], in the [[Great Lakes]], but appears to have become extinct in that area. In May 2000, the Canadian Species at Risk Act listed the paddlefish as being extirpated in [[Canada]].
  
−
{{Taxobox
+
The American paddlefish is one of the largest freshwater fish in North America. They commonly reach 5 feet (1.5 meters) or more in length and can weigh more than 60 pounds (27 kilograms). The largest American paddlefish on record, weighing 144 pounds (65 kg), was caught by Clinton Boldridge in the Atchison Watershed in [[Kansas]].
−
| name = American Paddlefish
 
−
| status = VU | status_system = IUCN3.1
 
−
| trend = unknown
 
−
| image = Paddlefish Polyodon spathula.jpg
 
−
| image_width = 240px
 
−
| regnum = [[Animal]]ia
 
−
| phylum = [[Chordata]]
 
−
| classis = [[Actinopterygii]]
 
−
| ordo = [[Acipenseriformes]]
 
−
| familia = [[Paddlefish|Polyodontidae]]
 
−
| genus = '''''Polyodon'''''
 
−
| genus_authority = [[Bernard Germain de Lacépède|Lacépède]], 1797
 
−
| species = '''''P. spathula'''''
 
−
| binomial = ''Polyodon spathula''
 
−
| binomial_authority = ([[Johann Julius Walbaum|Walbaum]] in [[Peter Artedi|Artedi]], 1792)
 
−
}}
 
−
 
 
−
The '''American paddlefish''', ''Polyodon spathula'', also called the '''Mississippi paddlefish''' or '''spoonbill''', is a [[paddlefish]] living in slow-flowing waters of the [[Mississippi River]] drainage system. It appears to have been extirpated from [[Lake Erie]] and its tributaries.  They are closely related to the [[sturgeon]]s. This large [[Chondrostean]] freshwater fish may grow to 220&nbsp;cm (7&nbsp;feet) and weigh up to 100&nbsp;kg (220&nbsp;pounds).  The paddlefish takes its common and scientific names from its distinctive snout, which is greatly elongated and flattened into a paddle shape. The American paddlefish is believed to use sensitive [[electroreceptor]]s on its paddle to detect [[prey]], as well as to navigate while migrating to spawning sites. The American paddlefish feeds primarily on [[zooplankton]] but also feeds on [[crustaceans]] and [[Bivalvia|bivalve]]s. ''Polyodon spathula'' is one of two living species of [[Paddlefish]];  the other is the possibly extinct [[Chinese Paddlefish]], ''Psephurus gladius.''
 
−
 
 
−
The [[American paddlefish]] ''(Polyodon spathula)'' is currently known from the [[Mississippi River|Mississippi River watershed]] in the [[United States]], including slow-flowing waters of the [[Mississippi River]] itself, as well as various tributaries including the [[Missouri River]], [[Ohio River]], [[Yellowstone River]], [[Wisconsin River]], [[Des Moines River]], and [[Arkansas River]] systems.  These fish were also found historically in [[Lake Erie]], in the [[Great Lakes]], but in May 2000, the Canadian Species at Risk Act listed the paddlefish as being extirpated in [[Canada]].
 
  
−
The American paddlefish is one of the largest freshwater fish in North America. They commonly reach {{convert|5|ft|m}} or more in length and can weigh more than {{convert|60|lb|kg}}. The largest American paddlefish on record, weighing {{convert|144|lb|kg}}, was caught by Clinton Boldridge in the Atchison Watershed in [[Kansas]]. The largest unofficial record was 206 pounds from [[Lake Cumberland]] in [[Kentucky]];{{Citation needed|date=January 2009}} postcards from the 1960s{{Which?|date=June 2010}} show a photo of this huge fish.
+
Paddlefish take many years before they are able to spawn. A female may take eight to twelve years, and males spawn when about seven years old (range from about 5-9 years old) and they are about 40 inches inches long when they start to spawn. The female releases adhesive eggs randomly over the water bottom and abandons them. They are capable of producing over a half million eggs a year, but they may not spawn every year.  
  
−
===Population decline===
+
The American paddlefish is believed to use sensitive [[electroreceptor]]s on its paddle to detect [[prey]], as well as to navigate while migrating to spawning sites. The American paddlefish feeds primarily on [[zooplankton]] but also feeds on [[crustaceans]] and [[Bivalvia|bivalve]]s.  
−
[[File:Paddlefish.jpg|left|thumb|235px|''Polyodon spathula'']]
 
−
Though the American paddlefish was once common throughout the [[Midwest]], overfishing and habitat changes have caused major population declines; both the meat and [[roe]] of ''Polyodon spathula'' are desirable as food. Dams and other barriers can prevent the fish from recolonizing places where they once occurred and can deny them access to important critical [[habitat]]s such as spawning areas. Until about 1900, the species was also found in [[Lake Erie]] and in river systems tributary thereto in the U.S. and [[Canada]]. Invasive species such as [[zebra mussel]]s have reduced the number of [[zooplankton]] in the Great Lakes to such low levels that any hypothetical reintroduction program would seem likely to fail. Recently, paddlefish were spotted in the [[Danube]] river. It has not been determined whether these fished escaped from [[Romania]]n or [[Bulgaria]]n [[Fish farming|fish farms]] during the [[2006 European floods]], or whether they were let into the Danube earlier and matured in the river.
 
−
<br clear="left" />
 
  
−
===Sport fishing===
+
====Population decline====
−
The American paddlefish remains a popular [[sport fish]] in those parts of its range where populations are sufficient to allow harvesting. Since they are filter-feeders, paddlefish will not accept bait or [[Fishing lure|lures]] and must be caught by snagging. Several states, including [[Missouri]], have enacted stocking programs for these fish in reservoirs where the resident populations were low or nonexistent, or in areas where historical populations are no longer naturally sustainable. Paddlefish roe is occasionally sold as "American Sevruga Caviar"[http://www.affordablecaviar.com/paddlefishcaviar].
+
[[File:Paddlefish.jpg|left|thumb|240px|''Polyodon spathula'']]
 +
Paddlefish were at one time very abundant in most central U.S. river systems, but populations have declined greatly due to [[overharvesting]], [[sedimentation]], river modification, and other factors.  
  
−
===References===
+
Paddlefish need free-flowing rivers that have shallow pools with sandy, rocky bottoms for their spawning, and modification of rivers by the construction of [[dam]]s and dredging, as well as water removal for [[agriculture|agricultural use]], has reduced paddlefish spawning grounds. Dams and other barriers block paddlefish migration routes that are very important to the fish for spawning and can prevent the fish from recolonizing places where they once occurred. Notably, [[fish ladder]]s that could allow paddlefish to navigate around dams are avoided because of the metal [[rebar]] used in construction, which disrupts their electro-magnetic sense organs.
−
* {{IUCN2006|assessors=Grady|year=2004|id=17938|title=Polyodon spathula|downloaded=11 May 2006}} Database entry includes a lengthy justification of why this species is vulnerable
 
−
* {{ITIS |id=161088 |taxon=Polyodon spathula |accessdate=30 January 2006}}
 
−
* {{FishBase_species|genus=Polyodon|species=spathula|year=2005|month=10}}
 
−
*'''Barry Patrick M., Robert F. Carline, David G. Argent, William G. Kimmel.''' 2007. Movement and Habitat Use of Stocked Juvenile Paddlefish in the Ohio River System, Pennsylvania. North American Journal of Fisheries Management 27:1316-1325
 
−
*'''Bettoli Phillip W., George D. Scholten, William C. Reeves.''' 2007. Protecting Paddlefish from Overfishing: A Case History of the Research and Regulatory Process. Fisheries, American Fisheries Society 32:390-397
 
−
*'''Boone, E.A., and T.J. Timmons.''' 1994. Density and natural mortality of paddlefish,''Polyodon spathula'', in an unfished Cumberland River subimpoundment, South Cross Reservoir, TN. Journal of Freshwater Ecology 10: 421-431
 
−
*'''Cheblukov V. P., V. Ye. Kharin.''' 2009. The First  Finding of the American Paddlefish "Polyodon Spathula" (Polyodontidae)in waters of the Russian Far East. Russian Journal of Marine Biology 35:611-613
 
−
*'''Miller S. E., D. L. Scarnecchia.''' 2008. Adult paddlefish migrations in relation to spring river conditions of the Yellowstone and Missouri rivers, Montana and North Dakota, USA. Journal of Applied Icthiology 24:221-228
 
−
*'''Onders Richard J., Steven D. Mims, Carl D. Webster, Ann L. Gannam.''' 2009. Apparent digestibility coefficients of protein, lipid and carbohydrate in practical diets fed to paddlefish, "polyodon spathula" (Walbaum). Wiley Interscience 40:1785-1788
 
−
*'''Pitman, V.M., and J.O. Parks.''' 1994. Habitat use and movement of young paddlefish, ''Polyodon spathula''. Journal of Freshwater Ecology 33:181-190
 
−
*'''Rosen, R.A., and D.C. Hales.''' 1981. Feeding of paddlefish,''Polyodon spathula''. Copeia 2:441-455
 
−
*'''Russell, D.F., L.A. Wilkens, and F. Moss.''' 1999. Use of behavioural stochastic resonance by paddlefish for feeding. Nature 402:291-294
 
−
*'''Scholten, G.D., and P.W. Betoli.''' 2005. Population characteristics and assessment of overfishing for an exploited paddlefish population in the lower Tennessee River. Transactions of the American Fisheries Society 134:1285-1298
 
−
*'''Zigler, S.J., M.R. Dewey, B.C. Knights, A.L. Runstrom, and M.T. Steingraeber.''' 2004. Hydrologic and hydraulic factors affecting passage of paddlefish through dams in the upper Missouri River. Transactions of the American Fisheries Society 133:160-172
 
  
−
==Chinese paddlefish==
+
Free-flowing lakes with [[reservoir (water)|reservoir]]s can also provide paddlefish breeding habitat. One such area is the [[Missouri River]]-[[Lake Sakakawea]] system in [[North Dakota]]. This area is capable of producing good paddlefish numbers because it is a free-flowing system with many good areas for paddlefish to spawn.
−
{{Taxobox
 
−
| name = Chinese Paddlefish
 
−
| status = PE
 
−
| status_system = iucn3.1
 
−
| image = Psephurus gladius.jpg
 
−
| image_width =
 
−
| regnum = [[Animal]]ia
 
−
| phylum = [[Chordata]]
 
−
| classis = [[Actinopterygii]]
 
−
| ordo = [[Acipenseriformes]]
 
−
| familia = [[Polyodontidae]]
 
−
| genus = '''''Psephurus'''''
 
−
| genus_authority = [[Albert C. L. G. Günther|Günther]], 1873
 
−
| species = '''''P. gladius'''''
 
−
| binomial = ''Psephurus gladius''
 
−
| binomial_authority = ([[Eduard von Martens|E. von Martens]], 1862)
 
−
| synonyms =
 
−
''Polyodon gladius''<br>
 
−
''Polyodon angustifolium''
 
−
}}
 
−
[[image:Psephurus gladius.jpg|240px|]]
 
  
−
'''Chinese Paddlefish''', '''''Psephurus gladius''''' ({{zh|t=白鱘|s=白鲟|p=báixún}}), also known as '''Chinese Swordfish''', are among the largest [[freshwater]] [[fish]]. It is one of two [[extant taxon|extant]] [[paddlefish]] species, the other being the [[American Paddlefish]] ''(Polyodon spathula).'' It is also called "elephant fish" (象魚; xiàngyú) because its snout resembles an [[elephant]] trunk. It is recorded sometimes in [[Classical Chinese]] as ''wěi''-fish (鮪). More poetically, it is sometimes referred to as the "Giant Panda of the Rivers", not because of any physical resemblance to a [[Giant Panda|panda]], but because of its rarity and protected status.
+
Paddlefish are protected by law over a large part of their range. In some regions, sports fishing is allowed, However, even in protected areas, paddlefish are sometimes argeted by poachers for their valuable eggs. Paddlefish are a protected species in [[Wisconsin]], where they occur in the Wisconsin River south of the [[Prairie du Sac, Wisconsin|Prairie du Sac]] hydroelectric dam and in the lower Saint Croix River in Pierce County.
  
−
*The [[Chinese paddlefish]] (''Psephurus gladius'') is (or was) known only from the [[Yangtze River]] in [[China]]. Nine-foot (3-meter) specimens weighing {{convert|300|kg|lb}} have been recorded, and reports of {{convert|7|m|ft}} fish exist,{{Citation needed|date=January 2009}} although the existence of such large specimens is doubtful. They may now be extinct, with a recently completed three-year survey of the Yangtze finding no specimens.<ref>{{cite news| url=http://dotearth.blogs.nytimes.com/2009/09/30/another-long-goodbye-chinese-paddlefish/ | work=The New York Times | title=For Chinese Paddlefish, a Long Goodbye | first=Andrew C. | last=Revkin | date=2009-09-30 | accessdate=2010-05-20}}</ref>
+
There are efforts to reintroduce paddlefish. [[Pennsylvania]] Fish and Boat Commissioners are reintroducing the species to historical habitats in the Ohio and [[Allegheny River|Allegheny]] rivers in an effort to establish a secure breeding population once again. Reintroduction efforts may take many years, since paddlefish mature slowly, lengthening the time required to establish a breeding population.  
  
−
September 30, 2009, 10:24 am 47 Comments
+
Until about 1900, the species was also found in [[Lake Erie]] and in associated river systems in the U.S. and [[Canada]]. Invasive species such as [[zebra mussel]]s have reduced the number of [[zooplankton]] in the Great Lakes to such low levels that any hypothetical reintroduction program would seem likely to fail.  
−
For Chinese Paddlefish, a Long Goodbye
 
−
By ANDREW C. REVKIN
 
  
−
"The Chinese paddlefish, a denizen of the Yangtze River, has not been seen alive for six years, despite thorough surveys."
+
Recently, American paddlefish were spotted in the [[Danube]] river. It has not been determined whether these fished escaped from [[Romania]]n or [[Bulgaria]]n [[Fish farming|fish farms]] during the [[2006 European floods]], or whether they were let into the Danube earlier and matured in the river.
  
−
The Chinese Paddlefish is the [[People's Republic of China]]'s first-level protected animal. Its belly is white and back and head grey. They live mostly in the middle or lower part of the [[Yangtze River|Yangtze]] (Chang Jiang), occasionally in large lakes. They feed on other fish, as well as small amounts of [[crabs]] and [[crayfish]]. Paddlefish are sexually mature at age seven or eight, with a typical body length of 2 metres and a weight of 25 kilograms.
+
====Sport fishing====
 +
The American paddlefish remains a popular [[sport fish]] in those parts of its range where populations are sufficient to allow harvesting. Because paddlefish are filter feeders, they do not take conventional lures. Taking paddlefish is done with a [[bowfishing|bow and arrow]], a [[spearfishing|spear]], or by [[snagging]] (deliberately foul-hooking the fish in the fins or tail). Snagging is the usual method.  
  
−
It is said that the zoologist Bǐng Zhì (秉志) recorded around the 1950s that some fishermen caught a paddlefish of 7-metres, although the authenticity of the story is unconfirmed.  It is said that the Chinese paddlefish can grow to 23 feet and weigh 1,100 pounds, but little research on a maximum size can be conducted today due to the species' scarcity.
+
In most of its range the paddlefish is a protected species, and fishing for paddlefish is illegal in many areas. Any paddlefish caught accidentally should be released unharmed as quickly as possible. However, a few states still allow sport fishing for paddlefish. Several states, including [[Missouri]], have enacted stocking programs for these fish in reservoirs where the resident populations were low or nonexistent, or in areas where historical populations are no longer naturally sustainable. [[Oklahoma]] has drastically reduced sportfish harvest of paddlefish to one per person per day to help sustain populations.  
  
−
Due to overfishing, the Chinese Paddlefish is [[species|critically endangered]] now, and officially recognized by the People's Republic in 1983 to prevent fishing of paddlefish young or adults. Paddlefish are also threatened by dams (such as the [[Three Gorges Dam]]) which divide the population into isolated groups. The fish are rarely seen, recently raising concerns that the species might already be extinct. During a three-year search conducted from 2006–2008 a research team from the [[Chinese Academy of Fisheries Science]] in [[Jingzhou]] failed to find even one specimen.<ref name=bbc20090929>{{cite news
+
Poachers also use these methods to target paddlefish in areas where paddlefish fishing is not legal. Suspect paddlefish fishing activity can be reported to fish and wildlife officers who will verify legality. Some jurisdictions pay a financial reward to citizens whose report leads to prosecution of a poacher. One example is the Iowa DNR, and their Turn In Poachers (TIP) Program which was started in August 1985.
−
  | last = Bourton
 
−
  | first = Jody
 
−
  | title = Giant fish 'verges on extinction'
 
−
  | newspaper = BBC News
 
−
  | location = London
 
−
  | publisher = BBC
 
−
  | date = 2009-09-29
 
−
  | url = http://news.bbc.co.uk/earth/hi/earth_news/newsid_8269000/8269414.stm#
 
−
| accessdate = 2009-09-29}}</ref> The last confirmed sighting of
 
−
the fish alive occurred January 24, 2003 on the Yangtze.<ref
 
−
name=bbc20090929/> However, a 3.6-meter, 250 kilogram specimen was captured
 
−
by illegal fishing on January 8, 2007, in Jiayu County. Local villagers contacted officials who rushed to the site.
 
−
Zeb Hogan of [[Monster Fish]] on National Geographic Channel and other conservationists transferred the
 
−
fish to a holding pen in hope that it would survive. But shortly afterwards it died due to unrecoverable injuries
 
−
sustained while thrashing in the net.<ref>{{cite news
 
−
  | title = Chinese Paddlefish Dies in Illegal Fishing
 
−
  | newspaper = CRIENGLISH.com
 
−
  | publisher = China Radio International
 
−
  | date = 2007-01-12
 
−
  | url = http://english.cri.cn/2946/2007/01/12/272@184212.htm
 
−
  | accessdate = 2009-09-29}}</ref>
 
  
−
===References===
+
==Chinese paddlefish==
−
*{{FishBase species|genus=Psephurus|species=gladius|month=July|year=2010}}
+
[[Image:Psephurus gladius.jpg|240px|thumb|240px]]
−
* {{IUCN2006|assessors=Sturgeon Specialist Group|year=1996|id=18428|title=Psephurus gladius|downloaded=11 May 2006}} Listed as Critically Endangered (CR A2cd v2.3)
 
−
{{reflist}}
 
  
−
==Classification==
+
The Chinese paddlefish, ''Psephurus gladius'' ({{zh|t=白鱘|s=白鲟|báixún}}), also known as Chinese swordfish and "elephant fish" (because its snout resembles an elephant trunk), is listed as one of two extant paddlefish species, although there are concerns it may be extinct. In modern days, they were found only in the [[Yangtze]] River Basin in China, mostly in the middle or lower part of the Yangtze (Chang Jiang), occasionally in large lakes.
−
There are two currently or recently [[extant taxon|extant]] genera in this family and four (if not five) [[extinct]] genera:
 
−
'''Polyodontidae'''
 
−
*Subfamily [[extinction|†]]Paleopsephurinae
 
−
**Genus †''[[Paleopsephurus]]'' <small>MacAlpin, 1947</small>
 
−
***Species †''[[Paleopsephurus|Paleopsephurus wilsoni]]'' <small>MacAlpin, 1947</small> [[Image:Protopsephurus liui.JPG|thumb|''[[Protopsephurus|Protopsephurus liui]]'' fossils]]
 
−
*Subfamily Polyodontinae
 
−
**Genus †''[[Crossopholis]] <small>[[Edward Drinker Cope|Cope]], 1883</small>
 
−
***Species †''[[Crossopholis|Crossopholis magnicaudatus]]'' <small>Cope, 1883</small>
 
−
**Genus ''[[Polyodon]]'' <small>[[Bernard Germain de Lacépède|Lacépède]], 1797</small>
 
−
***''[[Polyodon spathula]]'' <small>[[Johann Julius Walbaum|Walbaum]], 1792</small> [[American paddlefish]]
 
−
***†''[[Polyodon tuberculata]]'' <small>Grande & Bemis, 1991</small>
 
−
**Genus ''[[Psephurus]]'' <small>[[Albert Günther|Günther]], 1873</small>
 
−
***''[[Psephurus|Psephurus gladius]]'' <small>[[Eduard von Martens|E. von Martens]], 1862</small> [[Chinese paddlefish]] (Not recently verified extant, and perhaps now extinct)
 
−
*Subfamily †Protopsephurinae <small>Grande & Bemis, 1996</small>
 
−
**Genus †''[[Protopsephurus]]'' <small>Lu, 1994</small>
 
−
***Species †''[[Protopsephurus|Protopsephurus liui]]'' <small>Lu, 1994</small>
 
  
 +
The Chinese paddlefish has a white belly and its back and head is gray.  They feed on other fish, as well as small amounts of [[crabs]] and [[crayfish]]. It is suspected of being anadromous, spending time in marine waters but spawning in the Yangtze River; however, it is so rare that little is actually known about its habits (Bourton 2009).
  
−
Fossils of other kinds of paddlefish have been found. One such species is ''Crossopholis magnicaudatus'', from the [[Eocene|Eocene-age]] Green River Shale deposit in [[Wyoming]].
+
The Chinese paddlefish is a very large fish. Three-meter (9-feet) specimens weighing 300 kilograms (660 pounds) have been recorded. It is said that the zoologist Bǐng Zhì (秉志) recorded around the 1950s that some fishermen caught a paddlefish of 7 meters (23 feet), although the authenticity of the story is unconfirmed. It is said that the Chinese paddlefish can grow to a weight of 500 kilograms (1,100 pounds), but little research on a maximum size can be conducted today due to the species' scarcity. Paddlefish are sexually mature at age seven or eight, when they have reached a body length of about 2 meters (6 feet) and a weight of about 25 kilograms (55 pounds).
  
 +
Overfishing and habitat change are key factors in the decline of paddlefish populations. In 1983, the People's Republic of China official recognized the paddlefish as critical endangered in order to prevent fishing of paddlefish young or adults. Paddlefish are also threatened by dams (such as the Three Gorges Dam), which divide the population into isolated groups.
  
 +
The fish are rarely seen, recently raising concerns that the species might already be extinct. In 2009, Revkin reported that the Chinese paddlefish "has not been seen alive for six years, despite thorough surveys." During a three-year search conducted from 2006–2008, a research team from the Chinese Academy of Fisheries Science in Jingzhou failed to find even one specimen (Bourton 2009). There was a confirmed sighting of the fish alive on January 24, 2003 on the Yangtze (Bourton 2009). On January 8, 2007, a 3.6-meter, 250 kilogram specimen was captured by illegal fishing in Jiayu County (Gao et al. 2009). Local villagers contacted officials, who rushed to the site. Zeb Hogan of Monster Fish on National Geographic Channel and other conservationists transferred the fish to a holding pen in hope that it would survive. But shortly afterwards it died due to unrecoverable injuries sustained while thrashing in the net. This was the last known observation.
  
 +
==Notes==
 +
{{Reflist}}
  
 +
==References==
 +
* Barry, P. M., R. F. Carline, D. G. Argent, and W. G. Kimmel. 2007. Movement and habitat use of stocked juvenile paddlefish in the Ohio River System, Pennsylvania. ''North American Journal of Fisheries Management'' 27: 1316-1325.
  
 +
* Bettoli, P. W., G. D. Scholten, and W. C. Reeves. 2007. Protecting paddlefish from overfishing: A case history of the research and regulatory process. ''Fisheries'', American Fisheries Society 32: 390-397.
  
−
==Status==
+
* Boone, E. A., and T. J. Timmons. 1994. Density and natural mortality of paddlefish,''Polyodon spathula'', in an unfished Cumberland River subimpoundment, South Cross Reservoir, TN. ''Journal of Freshwater Ecology'' 10: 421-431.
−
Paddlefish were at one time very abundant in most central U.S. river systems, but populations have declined greatly due to [[overharvesting]], [[sedimentation]], and river modification. One of the major reasons for declining paddlefish numbers are the [[dam]]s constructed on many major U.S. river systems. Paddlefish avoid [[fish ladder]]s because of the metal [[rebar]] used in construction, which disrupts their electro-magnetic sense organs. The dams block paddlefish migration routes that are very important to the fish for spawning.
 
  
−
One other reason for the decreased numbers of paddlefish is overfishing. [[Pennsylvania]] Fish and Boat Commissioners are reintroducing the species to historical habitats in the Ohio and [[Allegheny River|Allegheny]] rivers in an effort to establish a secure breeding population once again. Reintroduction efforts may take many years, since paddlefish mature slowly, lengthening the time required to establish a breeding population. [[Oklahoma]] has drastically reduced sportfish harvest of paddlefish to one per person per day to help sustain populations. Paddlefish are a protected species in [[Wisconsin]], where they occur in the Wisconsin River south of the [[Prairie du Sac, Wisconsin|Prairie du Sac]] hydroelectric dam and in the lower Saint Croix River in Pierce County.
+
* Bourton, J. 2009. [http://news.bbc.co.uk/earth/hi/earth_news/newsid_8269000/8269414.stm# Giant fish 'verges on extinction.'] ''BBC News''. September 29, 2009. Retrieved August 29, 2012.
  
−
===Caviar harvest===
+
* Cheblukov, V. P., and V. Ye. Kharin. 2009. The first finding of the American Paddlefish, ''Polyodon spathula'' (Polyodontidae) in waters of the Russian Far East. ''Russian Journal of Marine Biology'' 35: 611-613.
−
During the last century, paddlefish and [[sturgeon]] have been commercially exploited for their eggs ([[roe]]), called [[caviar]]. Paddlefish and sturgeon are two of the most important fish for freshwater caviar. Paddlefish take many years before they are able to spawn. A female may take nine to ten years, when they are about 42&nbsp;inches long, and males seven-years-old and 40&nbsp;inches long are able to spawn. The female releases adhesive eggs randomly over the water bottom and abandons them. They are capable of producing over a half million eggs a year, but they may not spawn every year.
 
  
−
The [[Oklahoma]] Fish and Game Department set up Paddlefish Survey stations in various highly fished areas in the state. The Fish and Game biologists record length and weight measurements, and cut a portion of the lower jaw to determine age. To encourage participation in past surveys the Fish and Game Department has offered fish cleaning and preparation services, returning the cleaned fish in heat-sealed packaging, and has offered key tag souvenirs. The Fish and Game department keeps the eggs ([[roe]]) for licensed resale, with the proceeds keep the study funded without expense to the public.
+
* Gao X., Wang J.W. & Brosse S. (2009), Threatened fishes of the world: Psephurus gladius (Martens, 1862) (Acipenseriformes: Polyodontidae). Environmental Biology of Fishes. 84 : 421-422.
  
−
The Glendive Chamber of Commerce & Agriculture in [[Glendive, Montana]] sells Yellowstone Caviar. This caviar is harvested Paddlefish caviar that is processed from fish caught at Intake Fishing Area. The Intake Fishing Area is a fishing access site about eighteen miles north of Glendive in Eastern Montana.  This caviar has been harvested since 1989 with 70% of the proceeds going to the Glendive Chamber of Commerce & Agriculture and 30% going to the Montana Department of Fish, Wildlife and Parks.
+
* Miller, S. E., and D. L. Scarnecchia. 2008. Adult paddlefish migrations in relation to spring river conditions of the Yellowstone and Missouri rivers, Montana and North Dakota, USA. ''Journal of Applied Icthyology'' 24: 221-228.
  
−
===Current threats===
+
* Nelson, J. S. 2006. ''Fishes of the World'', 4th edition. Hoboken, NJ: John Wiley & Sons. ISBN 0471250317.
−
Paddlefish are targeted by poachers for their valuable eggs, and are protected by law over a large part of their range. Habitat destruction is also causing their numbers to decrease more rapidly. Paddlefish need free-flowing rivers that have shallow pools with sandy, rocky bottoms for their spawning. Water temperature is also important for spawning. Modification of rivers by the construction of [[dam]]s, dredging, and water removal for [[agriculture|agricultural use]] reduces paddlefish spawning grounds.
 
−
 
 
−
Free-flowing lakes with [[reservoir (water)|reservoir]]s can also provide paddlefish breeding habitat. One such area is the [[Missouri River]]-[[Lake Sakakawea]] system in [[North Dakota]]. This area is capable of producing good paddlefish numbers because it is a free-flowing system with many good areas for paddlefish to spawn.
 
  
−
==Fishing for paddlefish==
+
* Onders, R. J., S. D. Mims, C. D. Webster, and A. L. Gannam. 2009. Apparent digestibility coefficients of protein, lipid and carbohydrate in practical diets fed to paddlefish, ''Polyodon spathula'' (Walbaum). ''Wiley Interscience'' 40: 1785-1788.
−
{{Ref improve section|date=February 2010}}
 
−
In most of its range the paddlefish is a protected species, and fishing for paddlefish is illegal in many areas. Any paddlefish caught accidentally should be released unharmed as quickly as possible. However, a few states still allow sport fishing for paddlefish.<ref>[http://missoulian.com/news/state-and-regional/article_7741f2f8-61cd-11df-911d-001cc4c002e0.html Missoulian.com]</ref>  Because paddlefish are filter feeders, they do not take conventional lures. Taking paddlefish is done with a [[bowfishing|bow and arrow]], a [[spearfishing|spear]], or by [[snagging]] (deliberately foul-hooking the fish in the fins or tail). Snagging is the usual method.  
 
  
−
Poachers also use these methods to target paddlefish in areas where paddlefish fishing is not legal. Suspect paddlefish fishing activity can be reported to fish and wildlife officers who will verify legality. Some jurisdictions pay a financial reward to citizens whose report leads to prosecution of a poacher. One example is the Iowa DNR, and their Turn In Poachers (TIP) Program which was started in August 1985. The private TIP organization was established by concerned sportsmen and women under the guidance of the Iowa Department of Natural Resources Law Enforcement Bureau. Both groups recognized the need for an added dimension to fish and game law enforcement in the State of Iowa to aid in the fight against poaching.<ref>http://www.iowadnr.gov/InsideDNR/AboutDNR/ConservationLawEnforcement/TurnInPoachersTIP.aspx</ref>
+
* Pitman, V. M., and J. O. Parks. 1994. Habitat use and movement of young paddlefish, ''Polyodon spathula''. ''Journal of Freshwater Ecology'' 33: 181-190.
  
−
==References==
+
* Revkin, A. C. 2009. [http://dotearth.blogs.nytimes.com/2009/09/30/another-long-goodbye-chinese-paddlefish For Chinese paddlefish, a long goodbye]. ''New York Times'' September 30, 2009. Retrieved August 29, 2012.
−
{{Reflist}}
 
  
−
* Nelson, J. S. 2006. ''Fishes of the World'', 4th edition. Hoboken, NJ: John Wiley & Sons. ISBN 0471250317.
+
* Rosen, R. A., and D. C. Hales. 1981. Feeding of paddlefish,''Polyodon spathula''. ''Copeia'' 2: 441-455.
  
−
== External links ==
+
* Russell, D. F., L. A. Wilkens, and F. Moss. 1999. Use of behavioral stochastic resonance by paddlefish for feeding. ''Nature'' 402: 291-294.
  
−
* [http://www.capachi.com/paddlefish.htm The Chinese Paddlefish Website] - containing many photographs of ''Psepherus''.
+
* Scholten, G. D., and P. W. Betoli. 2005. Population characteristics and assessment of overfishing for an exploited paddlefish population in the lower Tennessee River. ''Transactions of the American Fisheries Society'' 134: 1285-1298.
−
* ARKive - [http://www.arkive.org/species/GES/fish/Polyodon_spathula/ images and movies of the paddlefish ''(Polyodon spathula)'']
 
−
* [http://www.fishbase.org/Summary/FamilySummary.cfm?ID=33 FishBase entry for Polyodontidae]
 
−
* [http://www.umesc.usgs.gov/aquatic/fish/paddlefish/main.html USGS UMESC Paddlefish Study]
 
−
* [http://sites.state.pa.us/PA_Exec/Fish_Boat/pafish/fishhtms/chap6.htm Sites.state.pa.us]
 
−
* [http://www.fisheries.org/AFSmontana/SSCpages/Paddlefish.htm Fisheries.org]
 
−
* [http://www.dnr.state.oh.us/wildlife/Fishing/aquanotes-fishid/padlfish.htm DNR.state.oh.us]
 
−
* [http://www.phy.ohiou.edu/~neiman/synchronization Stochastic synchronization of electroreceptors in the paddlefish]
 
  
 +
* Zigler, S. J., M. R. Dewey, B. C. Knights, A. L. Runstrom, and M. T. Steingraeber. 2004. Hydrologic and hydraulic factors affecting passage of paddlefish through dams in the upper Missouri River. ''Transactions of the American Fisheries Society'' 133: 160-172.
  
−
{{Acipenseriformes}}
 
  
 
[[Category:Life sciences]]
 
[[Category:Life sciences]]
Line 242: Line 140:
 
[[Category:Fishes]]
 
[[Category:Fishes]]
  
−
{{credit|Paddlefish|507980470|American_paddlefish|506810663}}
+
{{credit|Paddlefish|507980470|American_paddlefish|506810663|Chinese_paddlefish|505309718}}

Latest revision as of 17:27, 29 December 2014


Paddlefishes
Fossil range: Late Cretaceous–Recent
[1]
American Paddlefish, Polyodon spathula
American Paddlefish, Polyodon spathula
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Acipenseriformes
Family: Polyodontidae
Bonaparte, 1838
Genera

Polyodon
Psephurus

Paddlefish is the common name for the ray-finned fish comprising the family Polyodontidae of the Order Acipenseriformes, characterized by an elongated, paddle-like snout with minute barbels, large mouth with minute teeth, and long gill rakers. The other extant family in the Acipenseriformes order is that of the sturgeons, Acipenseridae, but the sturgeons lack teeth in adults, have fewer than 50 gill rakers, and have a flattened rostra, among other differences. In some areas in the United States, paddlefish are referred to as "spoonbills," "spoonbill catfish," or "spoonies."

There are only two modern species of these fish: the plankton-feeding American paddlefish (Polyodon spathula), found in the Mississippi River drainage system, and the piscivorous Chinese paddlefish (Psephurus gladius), found in the Yangtze River; however, there are concerns that the Chinese species may now be extinct.

Paddlefish provide important economic, ecological, and aesthetic values. During the last century, paddlefish and sturgeon have been commercially exploited for their eggs (roe), called caviar. Paddlefish and sturgeon are two of the most important fish for freshwater caviar. The large number of eggs produced by females also mean they can be important in food chains, with the young providing a food resource for predators. Their unique shape and large size also adds to the joy of nature for humans, including sports fishing. However, exploitation and habitat changes, among other factors, have significantly reduced the populations of paddlefish, with the Chinese paddlefish not having a confirmed sighting since 2007 and the American paddlefish no longer found in the Great Lakes region.

Overview and description

American Paddlefish, Polyodon spathula

The Order Acipenseriformes includes two extant families: the paddlefishes (family Polyodontidae) and the sturgeons (family Acipenseridae). Members of this order are characterized by a largely cartilaginous structure, an elongated body, an intestine with spiral valve, a heterocercal caudal fin, the absence of gulars, lack of vertebral central, and fin rays more numerous than their basals (Nelson 2006).

The paddlefish family, Polyodontidae, is characterized by its members having an elongated, spatula-like snout, called a rostrum, which is longer than the rest of the head. It takes it common name, and the American paddlefish (Polyodon spathula) takes its scientific name from this distinctive paddle-shaped snout. Other characteristics include minute barbels on the snout; long gill rakers, which can reach the hundreds in Polyodon; minute teeth; and a body lacking large scutes, but having small "scales" in some regions (Nelson 2006). The piscivorous Chinese paddlefish, Psephurus gladius, is characterized by a protrusible mouth, while the plankton-feeding American paddlefish (Polyodon spathula) has a nonprotrusible mouth. Members of the sturgeon family, Acipenseridae, differ from the paddlefish in that the acipenserids lack teeth in adults, have five rows of large bony scutes or plates on the body, have fewer than 50 gill rakers; and have a flattened rostra (Nelson 2006).

Paddlefish are not closely related to sharks, which are in a different taxonomic class, but they do have some body parts that resemble those of sharks such as their skeletons, primarily composed of cartilage, and their deeply forked heterocercal tail fins. As in many of the distantly related shark class, the paddlefish's rostrum contains electroreceptors that can detect weak electrical fields.

Classification

There are two currently or recently extant genera in this family and four (if not five) extinct genera: Polyodontidae

  • Subfamily †Paleopsephurinae
    • Genus †Paleopsephurus MacAlpin, 1947
      • Species †Paleopsephurus wilsoni MacAlpin, 1947
        Protopsephurus liui fossils
  • Subfamily Polyodontinae
    • Genus †Crossopholis Cope, 1883
      • Species †Crossopholis magnicaudatus Cope, 1883
    • Genus Polyodon Lacépède, 1797
      • Polyodon spathula Walbaum, 1792 American paddlefish
      • †Polyodon tuberculata Grande & Bemis, 1991
    • Genus Psephurus Günther, 1873
      • Psephurus gladius E. von Martens, 1862 Chinese paddlefish (Not recently verified extant, and perhaps now extinct)
  • Subfamily †Protopsephurinae Grande & Bemis, 1996
    • Genus †Protopsephurus Lu, 1994
      • Species †Protopsephurus liui Lu, 1994

Fossils of other kinds of paddlefish have been found. One such species is Crossopholis magnicaudatus, from the Eocene-age Green River Shale deposit in Wyoming.


American paddlefish

American paddlefish, Polyodon spathula

The American paddlefish, Polyodon spathula, also known as the Mississippi paddlefish, lives in slow-flowing waters of the Mississippi River drainage system. This includes slow-flowing waters of the Mississippi River itself, as well as various tributaries, including the Missouri River, Ohio River, Yellowstone River, Wisconsin River, Des Moines River, and Arkansas River systems. These fish were also found historically in Lake Erie, in the Great Lakes, but appears to have become extinct in that area. In May 2000, the Canadian Species at Risk Act listed the paddlefish as being extirpated in Canada.

The American paddlefish is one of the largest freshwater fish in North America. They commonly reach 5 feet (1.5 meters) or more in length and can weigh more than 60 pounds (27 kilograms). The largest American paddlefish on record, weighing 144 pounds (65 kg), was caught by Clinton Boldridge in the Atchison Watershed in Kansas.

Paddlefish take many years before they are able to spawn. A female may take eight to twelve years, and males spawn when about seven years old (range from about 5-9 years old) and they are about 40 inches inches long when they start to spawn. The female releases adhesive eggs randomly over the water bottom and abandons them. They are capable of producing over a half million eggs a year, but they may not spawn every year.

The American paddlefish is believed to use sensitive electroreceptors on its paddle to detect prey, as well as to navigate while migrating to spawning sites. The American paddlefish feeds primarily on zooplankton but also feeds on crustaceans and bivalves.

Population decline

Polyodon spathula

Paddlefish were at one time very abundant in most central U.S. river systems, but populations have declined greatly due to overharvesting, sedimentation, river modification, and other factors.

Paddlefish need free-flowing rivers that have shallow pools with sandy, rocky bottoms for their spawning, and modification of rivers by the construction of dams and dredging, as well as water removal for agricultural use, has reduced paddlefish spawning grounds. Dams and other barriers block paddlefish migration routes that are very important to the fish for spawning and can prevent the fish from recolonizing places where they once occurred. Notably, fish ladders that could allow paddlefish to navigate around dams are avoided because of the metal rebar used in construction, which disrupts their electro-magnetic sense organs.

Free-flowing lakes with reservoirs can also provide paddlefish breeding habitat. One such area is the Missouri River-Lake Sakakawea system in North Dakota. This area is capable of producing good paddlefish numbers because it is a free-flowing system with many good areas for paddlefish to spawn.

Paddlefish are protected by law over a large part of their range. In some regions, sports fishing is allowed, However, even in protected areas, paddlefish are sometimes argeted by poachers for their valuable eggs. Paddlefish are a protected species in Wisconsin, where they occur in the Wisconsin River south of the Prairie du Sac hydroelectric dam and in the lower Saint Croix River in Pierce County.

There are efforts to reintroduce paddlefish. Pennsylvania Fish and Boat Commissioners are reintroducing the species to historical habitats in the Ohio and Allegheny rivers in an effort to establish a secure breeding population once again. Reintroduction efforts may take many years, since paddlefish mature slowly, lengthening the time required to establish a breeding population.

Until about 1900, the species was also found in Lake Erie and in associated river systems in the U.S. and Canada. Invasive species such as zebra mussels have reduced the number of zooplankton in the Great Lakes to such low levels that any hypothetical reintroduction program would seem likely to fail.

Recently, American paddlefish were spotted in the Danube river. It has not been determined whether these fished escaped from Romanian or Bulgarian fish farms during the 2006 European floods, or whether they were let into the Danube earlier and matured in the river.

Sport fishing

The American paddlefish remains a popular sport fish in those parts of its range where populations are sufficient to allow harvesting. Because paddlefish are filter feeders, they do not take conventional lures. Taking paddlefish is done with a bow and arrow, a spear, or by snagging (deliberately foul-hooking the fish in the fins or tail). Snagging is the usual method.

In most of its range the paddlefish is a protected species, and fishing for paddlefish is illegal in many areas. Any paddlefish caught accidentally should be released unharmed as quickly as possible. However, a few states still allow sport fishing for paddlefish. Several states, including Missouri, have enacted stocking programs for these fish in reservoirs where the resident populations were low or nonexistent, or in areas where historical populations are no longer naturally sustainable. Oklahoma has drastically reduced sportfish harvest of paddlefish to one per person per day to help sustain populations.

Poachers also use these methods to target paddlefish in areas where paddlefish fishing is not legal. Suspect paddlefish fishing activity can be reported to fish and wildlife officers who will verify legality. Some jurisdictions pay a financial reward to citizens whose report leads to prosecution of a poacher. One example is the Iowa DNR, and their Turn In Poachers (TIP) Program which was started in August 1985.

Chinese paddlefish

Psephurus gladius.jpg

The Chinese paddlefish, Psephurus gladius (simplified Chinese: 白鲟; traditional Chinese: 白鱘), also known as Chinese swordfish and "elephant fish" (because its snout resembles an elephant trunk), is listed as one of two extant paddlefish species, although there are concerns it may be extinct. In modern days, they were found only in the Yangtze River Basin in China, mostly in the middle or lower part of the Yangtze (Chang Jiang), occasionally in large lakes.

The Chinese paddlefish has a white belly and its back and head is gray. They feed on other fish, as well as small amounts of crabs and crayfish. It is suspected of being anadromous, spending time in marine waters but spawning in the Yangtze River; however, it is so rare that little is actually known about its habits (Bourton 2009).

The Chinese paddlefish is a very large fish. Three-meter (9-feet) specimens weighing 300 kilograms (660 pounds) have been recorded. It is said that the zoologist Bǐng Zhì (秉志) recorded around the 1950s that some fishermen caught a paddlefish of 7 meters (23 feet), although the authenticity of the story is unconfirmed. It is said that the Chinese paddlefish can grow to a weight of 500 kilograms (1,100 pounds), but little research on a maximum size can be conducted today due to the species' scarcity. Paddlefish are sexually mature at age seven or eight, when they have reached a body length of about 2 meters (6 feet) and a weight of about 25 kilograms (55 pounds).

Overfishing and habitat change are key factors in the decline of paddlefish populations. In 1983, the People's Republic of China official recognized the paddlefish as critical endangered in order to prevent fishing of paddlefish young or adults. Paddlefish are also threatened by dams (such as the Three Gorges Dam), which divide the population into isolated groups.

The fish are rarely seen, recently raising concerns that the species might already be extinct. In 2009, Revkin reported that the Chinese paddlefish "has not been seen alive for six years, despite thorough surveys." During a three-year search conducted from 2006–2008, a research team from the Chinese Academy of Fisheries Science in Jingzhou failed to find even one specimen (Bourton 2009). There was a confirmed sighting of the fish alive on January 24, 2003 on the Yangtze (Bourton 2009). On January 8, 2007, a 3.6-meter, 250 kilogram specimen was captured by illegal fishing in Jiayu County (Gao et al. 2009). Local villagers contacted officials, who rushed to the site. Zeb Hogan of Monster Fish on National Geographic Channel and other conservationists transferred the fish to a holding pen in hope that it would survive. But shortly afterwards it died due to unrecoverable injuries sustained while thrashing in the net. This was the last known observation.

Notes

  1. ↑ R. Froese and D. Pauly, eds., Family Polyodontidae: Paddlefishes , Fishbase (2009). Retrieved August 23, 2012.

References
ISBN links support NWE through referral fees

  • Barry, P. M., R. F. Carline, D. G. Argent, and W. G. Kimmel. 2007. Movement and habitat use of stocked juvenile paddlefish in the Ohio River System, Pennsylvania. North American Journal of Fisheries Management 27: 1316-1325.
  • Bettoli, P. W., G. D. Scholten, and W. C. Reeves. 2007. Protecting paddlefish from overfishing: A case history of the research and regulatory process. Fisheries, American Fisheries Society 32: 390-397.
  • Boone, E. A., and T. J. Timmons. 1994. Density and natural mortality of paddlefish,Polyodon spathula, in an unfished Cumberland River subimpoundment, South Cross Reservoir, TN. Journal of Freshwater Ecology 10: 421-431.
  • Cheblukov, V. P., and V. Ye. Kharin. 2009. The first finding of the American Paddlefish, Polyodon spathula (Polyodontidae) in waters of the Russian Far East. Russian Journal of Marine Biology 35: 611-613.
  • Gao X., Wang J.W. & Brosse S. (2009), Threatened fishes of the world: Psephurus gladius (Martens, 1862) (Acipenseriformes: Polyodontidae). Environmental Biology of Fishes. 84 : 421-422.
  • Miller, S. E., and D. L. Scarnecchia. 2008. Adult paddlefish migrations in relation to spring river conditions of the Yellowstone and Missouri rivers, Montana and North Dakota, USA. Journal of Applied Icthyology 24: 221-228.
  • Nelson, J. S. 2006. Fishes of the World, 4th edition. Hoboken, NJ: John Wiley & Sons. ISBN 0471250317.
  • Onders, R. J., S. D. Mims, C. D. Webster, and A. L. Gannam. 2009. Apparent digestibility coefficients of protein, lipid and carbohydrate in practical diets fed to paddlefish, Polyodon spathula (Walbaum). Wiley Interscience 40: 1785-1788.
  • Pitman, V. M., and J. O. Parks. 1994. Habitat use and movement of young paddlefish, Polyodon spathula. Journal of Freshwater Ecology 33: 181-190.
  • Rosen, R. A., and D. C. Hales. 1981. Feeding of paddlefish,Polyodon spathula. Copeia 2: 441-455.
  • Russell, D. F., L. A. Wilkens, and F. Moss. 1999. Use of behavioral stochastic resonance by paddlefish for feeding. Nature 402: 291-294.
  • Scholten, G. D., and P. W. Betoli. 2005. Population characteristics and assessment of overfishing for an exploited paddlefish population in the lower Tennessee River. Transactions of the American Fisheries Society 134: 1285-1298.
  • Zigler, S. J., M. R. Dewey, B. C. Knights, A. L. Runstrom, and M. T. Steingraeber. 2004. Hydrologic and hydraulic factors affecting passage of paddlefish through dams in the upper Missouri River. Transactions of the American Fisheries Society 133: 160-172.

Credits

New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:

The history of this article since it was imported to New World Encyclopedia:

Note: Some restrictions may apply to use of individual images which are separately licensed.

Retrieved from https://www.newworldencyclopedia.org/p/index.php?title=Paddlefish&oldid=986091

Content is available under Creative Commons Attribution/Share-Alike License; additional terms may apply. See Terms of Use for details.
Copyright Logo
Powered by MediaWiki