Editing Chinese paddlefish

{{Short description|Extinct species of fish}}
{{Use dmy dates|date=July 2022}}
{{Speciesbox
| name = Chinese paddlefish
| image = A specimen of Psephurus gladius, Museum of Hydrobiological Sciences, Wuhan Institute of Hydrobiology (4).jpg
| image_upright = 1.2
| image_caption = Preserved specimens at Museum of Hydrobiological Sciences, [[Institute of Hydrobiology]], [[Wuhan]], China
| status = EX
| status_system = IUCN3.1
| status_ref = <ref name="iucn">{{cite iucn |last= Qiwei |first=W. |year=2022 |title=''Psephurus gladius'' |page=e.T18428A146104283 |doi=10.2305/IUCN.UK.2022-2.RLTS.T18428A146104283.en |access-date=21 July 2022}}</ref>
| taxon = Psephurus gladius
| extinct = 2022
| authority = ([[Eduard von Martens|von Martens]], 1862)
| parent_authority = [[Albert C. L. G. Günther|Günther]], 1873
| synonyms = * ''Polyodon gladius'' <small>von Martens, 1862</small>
* ''Spatularia'' (''Polyodon'') ''angustifolium'' <small>Kaup, 1862</small>
* ''Polyodon angustifolium'' <small>(Kaup, 1862)</small>
| synonyms_ref = <ref>{{Cite web |last1=Froese |first1=R. |last2=Pauly |first2=D. |year=2017 |title=Polydontidae |website=[[FishBase]] version (02/2017) |url=http://www.fishbase.se/Summary/FamilySummary.php?ID=33 |url-status=live |archive-url=https://web.archive.org/web/20170824024508/http://www.fishbase.se/Summary/FamilySummary.php?ID=33 |archive-date=24 August 2017 |access-date=18 May 2017}}</ref><ref>{{Cite web |title=Polydontidae |website=Deeplyfish- fishes of the world |url=http://deeplyfish.com/wp-content/uploads/2017/05/Family-Polyodontidae-PDF.pdf |url-status=live |archive-url=https://web.archive.org/web/20170824024507/http://deeplyfish.com/wp-content/uploads/2017/05/Family-Polyodontidae-PDF.pdf |archive-date=24 August 2017 |access-date=18 May 2017}}</ref>
}}

The '''Chinese paddlefish''' ('''''Psephurus gladius'''''; {{zh|t=白鱘|s=白鲟|p=báixún}}: literal translation: "white [[sturgeon]]"), also known as the '''Chinese swordfish''', is an [[Extinction|extinct]] [[species]] of fish that was formerly native to the [[Yangtze]] and [[Yellow River]] basins in China. With records of specimens over {{Convert|3|m|ft|0|spell=on}} and possibly {{cvt|7|m|ft}} in length, it was one of the [[List of largest fish|largest species of freshwater fish]]. It was the only species in the [[genus]] '''''Psephurus''''' and one of two [[Holocene|recent]] species of [[paddlefish]] (Polyodontidae), the other being the [[American paddlefish]] (''Polyodon spathula''). It was an [[anadromous]] species, meaning that it spent part of its adult life at sea, while migrating upriver to [[Spawn (biology)|spawn]].

The Chinese paddlefish was officially declared extinct in 2022, with an estimated time of extinction to be by 2005, and no later than 2010, although it had become [[functionally extinct]] by 1993.<ref name="iucn" /><ref name="Zhang Jarić Roberts He 2020 p=136242">{{Cite journal |last1=Zhang |first1=Hui |last2=Jarić |first2=Ivan |last3=Roberts |first3=David L. |last4=He |first4=Yongfeng |last5=Du |first5=Hao |last6=Wu |first6=Jinming |last7=Wang |first7=Chengyou |last8=Wei |first8=Qiwei |year=2020 |title=Extinction of one of the world's largest freshwater fishes: Lessons for conserving the endangered Yangtze fauna |journal=Science of the Total Environment |issn=0048-9697 |publisher=Elsevier BV |bibcode=2020ScTEn.71036242Z |doi=10.1016/j.scitotenv.2019.136242 |pmid=31911255 |s2cid=210086307 |volume=710 |page=136242}}</ref> The main cause of its extinction was the construction of the [[Gezhouba Dam|Gezhouba]] and [[Three Gorges Dam|Three Gorges]] [[dam]]s, causing [[population fragmentation]] and blocking the anadromous spawning migration. Overfishing also played a significant role in its demise. Fishing of the Chinese paddlefish dates back centuries, with annual harvests reaching 25 tons by the 1970s. Since the 1990s, the species was officially listed by the [[International Union for Conservation of Nature]] (IUCN) as [[critically endangered]], and was last seen alive in 2003. A 2019 paper including scientists from the [[Chinese Academy of Fishery Sciences|Yangtze River Fisheries Research Institute]] found the species to be extinct.<ref name="Zhang Jarić Roberts He 2020 p=136242" /> It was unanimously agreed to be extinct by the Species Survival Commission Sturgeon Specialist Group of the IUCN on 15 September 2019,<ref name=IUCN2019>{{Cite web |date=September 2019 |title=The Chinese paddlefish was reevaluated to be extinct |website=IUCN |url=https://www.iucn.org/commissions/ssc-groups/fishes/sturgeon-specialist-group/about-us/regional-activities |url-status=dead |archive-url=https://web.archive.org/web/20200823183129/https://www.iucn.org/commissions/ssc-groups/fishes/sturgeon-specialist-group/about-us/regional-activities |archive-date=2020-08-23}}</ref> with its conservation status being formally updated by the [[IUCN Red List]] in July 2022.<ref name=Master2022>{{cite news |work=Reuters |first1=Farah |last1=Master |first2=Albee |last2=Zhang |editor-first=Neil |editor-last=Fullick |date=22 July 2022 |title=Chinese Paddlefish and wild Yangtze Sturgeon extinct - IUCN |language=en |url=https://www.reuters.com/business/environment/chinese-paddlefish-wild-yangtze-sturgeon-extinct-iucn-2022-07-22/ |access-date=22 July 2022 |url-status=live |archive-url=https://web.archive.org/web/20220723155510/https://www.reuters.com/business/environment/chinese-paddlefish-wild-yangtze-sturgeon-extinct-iucn-2022-07-22/ |archive-date=23 July 2022}}</ref>

==Description==
[[File:A specimen of Psephurus gladius, Museum of Hydrobiological Sciences, Wuhan Institute of Hydrobiology (3).jpg|left|thumb|A specimen at Museum of Hydrobiological Sciences, [[Wuhan Institute of Hydrobiology]]]]

The Chinese paddlefish had a white underbelly, and its back and head were grey.<ref name=":2" /> Its [[dorsal fin|dorsal]] and [[anal fin]]s were situated considerably far back on the body. The paddle-like [[Rostrum (anatomy)|rostrum]] was narrow and pointed, and was between a quarter and up to a third of total body length.<ref name="FAO fact sheet">{{Cite web |title=Species Fact Sheets: Psephurus gladius (Martens, 1862) |url=https://www.fao.org/fishery/en/species/14620/en |url-status=unfit |archive-url=https://web.archive.org/web/20091003115813/http://www.fao.org/fishery/species/14620/en |archive-date=3 October 2009 |access-date=1 February 2019 |publisher=Food and Agricultural Organization of the United Nations}}</ref> Its eyes were small and round.<ref name=":2">{{Cite journal |last1=Gao |first1=Xin |last2=Wang |first2=Jian Wei |last3=Brosse |first3=Sébastien |date=April 2009 |title=Threatened fishes of the world: Psephurus gladius (Martens, 1862) (Acipenseriformes: polyodontidae) |language=en |journal=Environmental Biology of Fishes  |issn=0378-1909 |doi=10.1007/s10641-009-9443-1 |s2cid=38833459 |volume=84 |issue=4 |pages=421–422|bibcode=2009EnvBF..84..421G }}</ref> The [[Caudal fin|tail fin]] was [[heterocercal]] (spine extending into the upper lobe), with the lower lobe being well developed.<ref name="FAO fact sheet" /> The skull is more elongate and narrower than that of the American paddlefish, and lacks the sculpturing present on the skull bones of other paddlefish, with the stellate (star-shaped) bones on the rostrum less numerous than those of the American paddlefish.<ref name=Grande1991>{{Cite journal |last1=Grande |first1=Lance |last2=Bemis |first2=William E. |date=1991-03-28 |title=Osteology and Phylogenetic Relationships of Fossil and Recent Paddlefishes (Polyodontidae) with Comments on the Interrelationships of Acipenseriformes |language=en |journal=Journal of Vertebrate Paleontology |issn=0272-4634 |doi=10.1080/02724634.1991.10011424 |volume=11 |issue=sup001 |pages=1–121 |bibcode=1991JVPal..11S...1G |url=http://www.tandfonline.com/doi/abs/10.1080/02724634.1991.10011424|url-access=subscription }}</ref> The teeth were small, sharp, [[Canine tooth|canine]] shaped and inward curling, and became proportionally smaller relative to the jaw during growth, and in mature adults were completely fused into the bone. Compared to ''Polyodon'', the jaws were shorter, and had a proportionately narrower gape, and unlike the American paddlefish, but similar to fossil paddlefish, the upper jaw was not firmly attached to the [[braincase]].<ref name="Grande1991" /> Like other paddlefish, the skeleton was largely [[Cartilage|cartilaginous]].<ref>{{Citation |last=Miller |first=Michael J. |editor1-last=LeBreton |editor1-first=Greg T. O. |editor2-last=Beamish |editor2-first=F. William H. |editor3-last=McKinley |editor3-first=R. Scott |date=2005 |title=The Ecology and Functional Morphology of Feeding of North American Sturgeon and Paddlefish |language=en |work=Sturgeons and Paddlefish of North America |series=Fish & Fisheries Series |publisher=Kluwer Academic Publishers |place=Dordrecht |doi=10.1007/1-4020-2833-4_5 |isbn=978-1-4020-2832-8 |volume=27 |pages=87–102 |url=http://link.springer.com/10.1007/1-4020-2833-4_5 |access-date=22 July 2022 |url-status=live |archive-url=https://web.archive.org/web/20220725001401/https://link.springer.com/chapter/10.1007/1-4020-2833-4_5 |archive-date=25 July 2022|url-access=subscription }}</ref> The body lacked scales,<ref name=":2" /> except for small scales in the [[caudal peduncle]] and caudal fin.<ref name="FAO fact sheet" />

Juveniles attained a weight of around {{convert|1 to 1.5|kg|lb|0}} by their first winter and a length of {{cvt|1|m|ft|0}} and a weight of about {{cvt|3.3|kg|lboz}} by the time they were a year old. Beyond this length, proportional weight gain relative to body length dramatically increased, reaching a weight of about {{cvt|12.5|kg|lb|0}} by the time they were around {{cvt|1.5|m|ft|0}} long. They reached sexual maturity at a weight of around {{cvt|25|kg}}.<ref name=Chenan1988/> The maximum length of the Chinese paddlefish is often quoted as {{cvt|7|m|ft}}, with this estimate apparently being given by [[Bing Zhi|C. Ping]] (1931), though according to Grande and Bemis (1991), specimens over {{Convert|3|m|ft|0|spell=on}} had not been definitively measured.<ref name="Grande1991" /> Ping recorded that fishermen in [[Nanjing]] caught a Chinese paddlefish with a length of {{convert|7|m}} and a weight of {{convert|907|kg}}.<ref>{{cite book |title=Contributions from the Biological Laboratory of the Science Society of China: Zoological series |volume=7 |year=1931 |page=189}}</ref> [[FishBase]] and [[World Wide Fund for Nature]] gives a conservative maximum weight of {{cvt|300|-|500|kg}}.<ref name="fishbase">{{FishBase|genus=Psephurus|species=gladius|month=July|year=2010}}</ref><ref>{{cite web|title=River of Giants: Giant Fish of the Mekong|year=2012|publisher=WWF for Nature|url=https://d2ouvy59p0dg6k.cloudfront.net/downloads/new_river_of_giants_report_14_may_2010_web_version.pdf}}</ref> Female fish are suggested to have grown larger than male fish once sexually mature, though they grew at similar rates prior to this.<ref>J. Ma, Z. Deng, X. Deng, M. Cai [http://ssswxb.ihb.ac.cn/article/app/id/14e3f46d-f929-4188-84d5-6e63aef4acf6?pageType=en Age determination and growth of Chinese paddlefish ''Psephurus gladius''] Acta Hydrobiologica Sinica, 20 (2) (1996), pp. 150–159 (in Chinese with English abstract)</ref> The lifespan has been estimated at 29–38 years, though the theoretical maximum lifespan is likely to have been significantly higher, as the estimate reflects anthropogenic impacts on the population.<ref name="Zhang Jarić Roberts He 2020 p=136242" />

== Taxonomy and evolutionary history ==
[[File:Psephurus gladius.jpg|thumb|Scientific drawing of ''Psephurus gladius'' from 1868 (resource: ''Nouvelles Archives du [[National Museum of Natural History, France|Muséum national d'histoire naturelle]]'')]]
The species was first named as a species of ''[[Polyodon]]'' by [[Eduard von Martens]] in 1862.<ref>{{cite journal |title=Über einen neuen ''Polyodon'' aus dem Yantsekiang und über die sogenannten ''Glaspolypen'' |journal=Monatsberichte der Königlichen Preussischen Akademie der Wissenschaften zu Berlin |volume=1861 (pt. 1) |date=2 May 1861 |access-date=29 July 2022 |pages=476–479 |url=https://archive.org/details/monatsberichtede18611knig/page/476/mode/1up }}</ref> It was placed into a separate, [[Monotypic taxon|monotypic]] genus by [[Albert Günther]] in 1873.<ref>{{cite journal |last=Günther |first=Albert |year=1873 |title=Report on a collection of fishes from China |journal=Annals and Magazine of Natural History |series=4 |volume=12 |issue=69 |pages=239–250 |doi=10.1080/00222937308680749 |url=https://www.biodiversitylibrary.org/page/19214311 }}</ref> The species was also given a different name, ''Spatularia angustifolium'' by [[Johann Jakob Kaup]] also in 1862,<ref>{{cite journal|last=Kaup |first=J.J. |year=1862 |title=Eine neue Art von Spatularia |journal=Archiv für Naturgeschichte |volume=28 |issue=1 |pages=278–281 |url=https://books.google.com/books?id=2ktKAAAAYAAJ&pg=PA278 }}</ref> but this is considered a [[Synonym (taxonomy)|junior synonym]] of ''P. gladius.''<ref name="FAO fact sheet" />

[[Paddlefish]] (Polyodontidae) are one of two living families of [[Acipenseriformes]] alongside [[sturgeon]]s (Acipenseridae). The oldest records of Acipenseriformes date to the [[Early Jurassic]], over 190 million years ago. The oldest paddlefish fossil is that of ''[[Protopsephurus]]'' from the [[Early Cretaceous]] of China, dating to around 120 million years ago.<ref name=Grande2002>{{Cite journal |last1=Grande |first1=Lance |last2=Jin |first2=Fan |last3=Yabumoto |first3=Yoshitaka |last4=Bemis |first4=William E. |date=2002-07-08 |title=Protopsephurus liui , a well-preserved primitive paddlefish (Acipenseriformes: Polyodontidae) from the Lower Cretaceous of China |url=http://www.tandfonline.com/doi/abs/10.1671/0272-4634%282002%29022%5B0209%3APLAWPP%5D2.0.CO%3B2 |journal=Journal of Vertebrate Paleontology |language=en |volume=22 |issue=2 |pages=209–237 |doi=10.1671/0272-4634(2002)022[0209:PLAWPP]2.0.CO;2 |s2cid=86258128 |issn=0272-4634 |access-date=22 July 2022 |archive-date=16 July 2022 |archive-url=https://web.archive.org/web/20220716112521/https://www.tandfonline.com/doi/abs/10.1671/0272-4634%282002%29022%5B0209%3APLAWPP%5D2.0.CO%3B2 |url-status=live |url-access=subscription }}</ref> The oldest representatives of the genus containing the American paddlefish (''Polyodon'') date to around 65 million years ago, from the beginning of the [[Paleocene]].<ref name="Murray2020">{{cite journal |last1=Murray |first1=Alison M. |last2=Brinkman |first2=Donald B. |last3=DeMar |first3=David G. |last4=Wilson |first4=Gregory P. |date=3 March 2020 |title=Paddlefish and sturgeon (Chondrostei: Acipenseriformes: Polyodontidae and Acipenseridae) from lower Paleocene deposits of Montana, U.S.A. |journal=Journal of Vertebrate Paleontology |volume=40 |issue=2 |pages=e1775091 |doi=10.1080/02724634.2020.1775091 |bibcode=2020JVPal..40E5091M |s2cid=222213273}}</ref> Various [[molecular clock]] estimates have been given for the age of the [[Genetic divergence|divergence]] between the American and Chinese paddlefish, including 68 million years ago<ref>{{Cite journal |last1=Peng |first1=Zuogang |last2=Ludwig |first2=Arne |last3=Wang |first3=Dengqiang |last4=Diogo |first4=Rui |last5=Wei |first5=Qiwei |last6=He |first6=Shunping |date=March 2007 |title=Age and biogeography of major clades in sturgeons and paddlefishes (Pisces: Acipenseriformes) |url=https://linkinghub.elsevier.com/retrieve/pii/S1055790306003678 |journal=Molecular Phylogenetics and Evolution |language=en |volume=42 |issue=3 |pages=854–862 |doi=10.1016/j.ympev.2006.09.008 |pmid=17158071 |bibcode=2007MolPE..42..854P |access-date=22 July 2022 |archive-date=30 June 2022 |archive-url=https://web.archive.org/web/20220630180950/https://linkinghub.elsevier.com/retrieve/pii/S1055790306003678 |url-status=live |url-access=subscription }}</ref> 72 million years ago,<ref>{{Cite journal |last=Shedko |first=S. V. |date=June 2022 |title=Molecular Dating of Phylogeny of Sturgeons (Acipenseridae) Based on Total Evidence Analysis |url=http://dx.doi.org/10.1134/s1022795422060084 |journal=Russian Journal of Genetics |volume=58 |issue=6 |pages=718–729 |doi=10.1134/s1022795422060084 |s2cid=250059162 |issn=1022-7954|url-access=subscription }}</ref> and 100 million years ago,<ref>{{Cite journal |last1=Shen |first1=Yanjun |last2=Yang |first2=Na |last3=Liu |first3=Zhihao |last4=Chen |first4=Qiliang |last5=Li |first5=Yingwen |date=September 2020 |title=Phylogenetic perspective on the relationships and evolutionary history of the Acipenseriformes |journal=Genomics |language=en |volume=112 |issue=5 |pages=3511–3517 |doi=10.1016/j.ygeno.2020.02.017 |pmid=32105795 |s2cid=211555175 |doi-access=free }}</ref> all dating to the middle to [[Upper Cretaceous]].

Relationships of recent and fossil paddlefish genera, after Grande ''et al.'' (2002).<ref name=Grande2002/>
{{clade|{{clade
|label1=Polyodontidae
|1={{clade
   |1={{clade
      |1=†''[[Protopsephurus]]''
       }}      
    |2={{clade
     |label1=
      |1={{clade
        |1=†''[[Paleopsephurus]]''
         }}
       |label2=Polyodontinae
       |2={{clade
         |1=†'''''Psephurus''''' [[File:Psephurus gladius.jpg|70px]]
         |2={{clade
          |1=†''[[Crossopholis]]''
          |2=''[[Polyodon]]'' [[File:Paddlefish (white background).jpg|70px]]
          }}
        }}
      }}
    }}
  }}|style=font-size:100%;line-height:80%}}

==Distribution, habitat and ecology==
[[File:A_specimen_of_Psephurus_gladius,_Museum_of_Hydrobiological_Sciences,_Wuhan_Institute_of_Hydrobiology_(1).jpg|A specimen of ''Psephurus gladius'' exhibited in the Museum of Hydrobiological Sciences of [[Wuhan Institute of Hydrobiology]]|thumb|left]]

The Chinese paddlefish was native to the [[Yangtze River|Yangtze (Chang Jiang) River]] basin and its [[estuary]] at the [[East China Sea]]. Historically it was also recorded in the [[Yellow River]] basin (which is connected to the Yangtze by the [[Grand Canal (China)|Grand Canal]]) and its estuary at the [[Yellow Sea]].<ref name="FAO fact sheet" /><ref name="Xie2018">{{Cite journal |last1=Xie, J.Y. |last2=W.J. Tang |last3=Y.H. Yang |year=2018 |title=Fish assemblage changes over half a century in the Yellow River, China |journal=Ecology and Evolution |volume=8 |issue=8 |pages=4173–4182 |doi=10.1002/ece3.3890 |pmc=5916296 |pmid=29721289|bibcode=2018EcoEv...8.4173X }}<!-- see "Supporting Information" in Xie2018 --></ref><ref name="Li2015">{{Cite book |last=Li, S.Z. |title=Fishes of the Yellow River and Beyond |publisher=The Sueichan Press |year=2015 |isbn=9789578596771 |pages=61–63 |author-link=Li Sizhong (ichthyologist)}}</ref>  It primarily inhabited the large rivers, but sometimes travelled into large lakes.<ref name="iucn" /> Due to their anadromous nature, mature individuals were found in coastal waters of the East China Sea and the Yellow Sea; occasionally [[spring tides]] would bring individuals into the lower reaches of the [[Qiantang]] and [[Yong River (Zhejiang)|Yong]] rivers of [[Zhejiang]] province.<ref name=Chenan1988/>

The species spent part of its life in the lower section of the Yangtze, including the [[brackish]] water of its estuary, but [[Fish migration|migrated]] upriver and into major [[tributaries]] to congregate for [[Spawn (biology)|spawning]], which occurred in spring, from mid-March to early April. One spawning site on the [[Jinsha River]], located at the midpoint of the river, around {{cvt|60|m|ft|sigfig=1}} from the riverbank, was around {{cvt|500|m|ft}} in length, and had a max water depth of {{cvt|10|m|ft}} and rapid water flow, with the bottom sediments in the lower reaches being shingly and in the upper reaches muddy/sandy.<ref name=Chenan1988/> A study on a sample of spawning Chinese paddlefish found that they were all at least 8 years old.<ref name=Wei2002>{{Citation |last1=Wei |first1=Qiwei |last2=Ke |first2=Fu'en |last3=Zhang |first3=Jueming |last4=Zhuang |first4=Ping |last5=Luo |first5=Junde |last6=Zhou |first6=Rueqiong |last7=Yang |first7=Wenhua |year=2002 |title=Biology, fisheries, and conservation of sturgeons and paddlefish in China |work=Sturgeon Biodiversity and Conservation |series=Developments in Environmental Biology of Fishes |publisher=Kluwer Academic Publishers |place=Dordrecht |isbn=0-7923-4517-7 |doi=10.1007/0-306-46854-9_14 |volume=17 |pages=241–255 |url=http://dx.doi.org/10.1007/0-306-46854-9_14 |access-date=2022-07-24 |url-status=live |archive-url=https://web.archive.org/web/20220725001346/https://link.springer.com/chapter/10.1007/0-306-46854-9_14 |archive-date=25 July 2022|url-access=subscription }}</ref> Females likely sexually matured later than males, and probably did not spawn every year, likely every other year or somewhat less frequently, like other acipenseriforms.<ref>{{Cite journal |last=Scarnecchia |first=Dennis L. |date=2023-05-04 |title=The Extinction of the Chinese Paddlefish Psephurus gladius : Transnationalism, Technology Transfer, and Timescape |journal=Reviews in Fisheries Science & Aquaculture |volume=31 |issue=3 |language=en |pages=396–419 |doi=10.1080/23308249.2023.2201636 |issn=2330-8249|doi-access=free |bibcode=2023RvFSA..31..396S }}</ref> The ovaries of the female fish contained over 100,000 eggs, each approximately {{cvt|2.7|mm|in|frac=32|}} across. The developing [[zygote]]s and [[Juvenile fish|fry]] were restricted to the region of the Yangtze basin upstream of [[Luzhou]] in southeastern [[Sichuan]], while yearlings and adults were widely distributed throughout the Yangtze river proper from the lower to upper reaches.<ref name=Chenan1988/>[[File:Chinese paddlefish paddle closeup.jpg|thumb|Closeup of the tip of the rostrum, showing electrorecepting [[Ampullae of Lorenzini|ampullae]] |alt=]]

The fish was largely solitary, and occupied the lower-mid layers of the [[water column]]. Chinese paddlefish were noted for being strong swimmers. Unlike its relative the American paddlefish, which is a [[Planktivore|planktivorous]] filter feeder, the Chinese paddlefish was primarily [[Piscivore|piscivorous]], mainly feeding on small to medium-sized fishes like [[Anchovy|anchovies]] (''[[Coilia]])'', [[Cyprinidae|cyprinids]] (''[[Coreius]], [[Rhinogobio]]'')'','' [[Gobiidae|gobies]] (''[[Gobius]])'' as well as [[Bagridae|bagrid]] catfish and [[Bothidae|bothid]] flounders. Shrimp and crab were also eaten.<ref name=Chenan1988>{{Cite journal |last1=Chenhan |first1=Liu |last2=Yongjun |first2=Zeng |date=1988-05-18 |title=Notes on the Chinese Paddlefish, Psephurus gladius (Martens) |journal=Copeia |volume=1988 |issue=2 |pages=482 |doi=10.2307/1445891 |jstor=1445891}}</ref><ref name="FAO fact sheet" /> The jaws, unlike the American paddlefish but like sturgeons and fossil paddlefish, were capable of [[Jaw protrusion|protrusion]], a form of [[cranial kinesis]] allowing them to move relative to the rest of the skull, with the upper jaw being able to thrust downwards and forwards in order to seize prey.<ref name="Grande1991" /><ref name=Bemis2002>{{cite journal|last1=Bemis |first1=William E. |last2=Findeis |first2=Eric K. |last3=Grande |first3=Lance |editor1-last=Birstein |editor1-first=Vadim J. |editor2-last=Waldman |editor2-first=John R. |editor3-last=Bemis |editor3-first=William E. |date=2002 |title=An overview of Acipenseriformes |journal=Sturgeon Biodiversity and Conservation |series=Developments in Environmental Biology of Fishes |publisher=Kluwer Academic Publishers |place=Dordrecht |doi=10.1007/0-306-46854-9_4 |isbn=978-0-7923-4517-6 |volume=17 |pages=25–71 |url=http://link.springer.com/10.1007/0-306-46854-9_4 |access-date=2022-07-27 |quote=Living sturgeons and primitive paddlefishes (i.e.,polyodontids other than Polyodon) stand in sharpcontrast to all of these outgroup taxa. Their jaws are highly mobile, so that the upper jaw can be ‘projected’ far out to capture prey...|url-access=subscription }}</ref> Paddlefish, like other Acipenseriformes and several other groups of vertebrates, engage in passive [[Electroreception and electrogenesis|electroreception]] (the sensing of external [[electric field]]s) using structures called [[Ampullae of Lorenzini|ampullae]] that form an extension of the [[lateral line]] system of sensory organs. Passive electroreception (where electric fields are sensed but not generated, as in [[electric fish]]) is primarily used for detecting the weak electric fields generated by prey.<ref>{{Cite journal |last=Crampton |first=William G. R. |date=July 2019 |title=Electroreception, electrogenesis and electric signal evolution |journal=Journal of Fish Biology |language=en |volume=95 |issue=1 |pages=92–134 |doi=10.1111/jfb.13922 |pmid=30729523 |s2cid=73442571 |issn=0022-1112|doi-access=free |bibcode=2019JFBio..95...92C }}</ref> The head and rostrum of Chinese paddlefish, like those of other paddlefish, was densely packed with ampullae, indicating that enhancing electroreception was one of the rostrum's primary functions.<ref name="Grande1991" />

==Decline and extinction==
The last records of Chinese paddlefish in the Yellow River basin and its estuary date back to the 1960s, although declines were realized between the 13th and 19th centuries.<ref name="Xie2018" /><ref name="Li2015" /><ref name=":0">{{Cite journal |last1=Zhang |first1=Hui |last2=Jarić |first2=Ivan |last3=Roberts |first3=David L. |last4=He |first4=Yongfeng |last5=Du |first5=Hao |last6=Wu |first6=Jinming |last7=Wang |first7=Chengyou |last8=Wei |first8=Qiwei |year=2020 |title=Extinction of one of the world's largest freshwater fishes: Lessons for conserving the endangered Yangtze fauna |journal=Science of the Total Environment |volume=710 |pages=136242 |bibcode=2020ScTEn.71036242Z |doi=10.1016/j.scitotenv.2019.136242 |issn=0048-9697 |pmid=31911255 |s2cid=210086307}}</ref><!-- see "Supporting Information" in Xie2018 --> Declines were significant throughout its primary range in the Yangtze basin, but annual captures of 25 tonnes continued into the 1970s.<ref name="Zhang Jarić Roberts He 2020 p=136242" /> In 1983, the Chinese government made fishing of the species illegal due to its decline in numbers.<ref name=Wei2002/> The species was still being found in small numbers in the 1980s (for example, 32 were caught in 1985), and young were seen as recently as 1995.<ref name="iucn" /> Due to the rarity of the fish by the time it was realised that it was in peril, and the fact that the adult fish were difficult to keep in captivity, attempts to create a captive breeding stock failed.<ref name=Wei2002/>[[File:ChinesePaddlefishZhengZhong.jpg|thumb|Depiction in the 17th-century work ''Searching the Mountains for Demons'' by Zheng Zhong]]

Since 2000, there have been only two confirmed sightings of the fish alive, both from the Yangtze basin: The first was a {{convert|3.3|m|ftin|adj=on}}, {{convert|117|kg|adj=on}} female caught at [[Nanjing]] in 2002 and the second a {{convert|3.52|m|ftin|adj=on}}, {{cvt|160|kg|lb}} female [[Bycatch|accidentally]] caught at [[Yibin]], Sichuan, on January 24, 2003, by fisherman Liu Longhua (刘龙华);<ref>{{Cite web |script-title=zh:"最后的长江白鲟"目击者：3.52米长 160公斤重 消失在宜宾江水中……-新华网 |url=http://www.xinhuanet.com/local/2020-01/07/c_1125428621.htm |url-status=dead |archive-url=https://web.archive.org/web/20200107055430/http://www.xinhuanet.com/local/2020-01/07/c_1125428621.htm |archive-date=January 7, 2020 |access-date=2020-01-09 |website=xinhuanet.com}}</ref> the former died despite attempts to save it and the latter was radio-tagged and released, but the tag stopped working after only 12 hours.<ref name="iucn" /><ref name="bbc20090929">{{Cite news |last=Bourton |first=Jody |date=2009-09-29 |title=Giant fish 'verges on extinction' |work=BBC News |publisher=BBC |location=London |url=http://news.bbc.co.uk/earth/hi/earth_news/newsid_8269000/8269414.stm# |url-status=live |access-date=2009-09-29 |archive-url=https://web.archive.org/web/20120531091225/http://news.bbc.co.uk/earth/hi/earth_news/newsid_8269000/8269414.stm |archive-date=2012-05-31}}</ref>

During a search conducted in the Yangtze basin from 2006 to 2008, a research team from the [[Chinese Academy of Fisheries Science]] in [[Jingzhou]] failed to catch any paddlefish,<ref name="bbc20090929"/> but two possible specimens were recorded with [[Hydroacoustics|hydroacoustic]] signals.<ref>Zhang; Wei1, Q.W.; Du, H.; Shen, L.; Li, Y.H.; and Zhao, Y. (2009). ''Is there evidence that the Chinese paddlefish (Psephurus gladius) still survives in the upper Yangtze River? Concerns inferred from hydroacoustic and capture surveys, 2006–2008.'' Journal of Applied Ichthyology 25(s2): 95-99. [[doi:10.1111/j.1439-0426.2009.01268.x|DOI: 10.1111/j.1439-0426.2009.01268.x]].</ref> A comprehensive study published in 2019, including scientists from the [[Chinese Academy of Fishery Sciences|Yangtze River Fisheries Research Institute]], found that the species was certainly extinct, based on its absence from extensive capture surveys of the Yangtze between 2017 and 2018. The paper estimated that the species went extinct between 2005 and 2010, but became [[Functional extinction|functionally extinct]] by 1993.<ref name="Zhang Jarić Roberts He 2020 p=136242" /><ref name="Yirka 2020">{{Cite web |last=Yirka |first=Bob |date=2020-01-08 |title=Chinese paddlefish declared extinct |url=https://phys.org/news/2020-01-chinese-paddlefish-declared-extinct.html |access-date=2020-01-09 |website=Phys.org |archive-date=8 January 2020 |archive-url=https://web.archive.org/web/20200108181752/https://phys.org/news/2020-01-chinese-paddlefish-declared-extinct.html |url-status=live }}</ref><ref name="Cheung 2020">{{Cite web |last=Cheung |first=Eric |date=2020-01-07 |title=Up to 23 feet long, the Chinese paddlefish was the giant of the Yangtze. And we killed it |url=https://www.cnn.com/2020/01/07/asia/chinese-paddlefish-extinct-study-intl-hnk-scli/index.html |access-date=2020-01-09 |website=CNN |archive-date=9 January 2020 |archive-url=https://web.archive.org/web/20200109010819/https://www.cnn.com/2020/01/07/asia/chinese-paddlefish-extinct-study-intl-hnk-scli/index.html |url-status=live }}</ref><ref name="nationalgeographic.com">{{Cite web |date=2020-01-08 |title=Chinese paddlefish, one of world's largest fish, declared extinct |url=https://www.nationalgeographic.com/animals/2020/01/chinese-paddlefish-one-of-largest-fish-extinct/ |access-date=2020-01-09 |website=Animals |language=en |archive-date=8 January 2020 |archive-url=https://web.archive.org/web/20200108130420/https://www.nationalgeographic.com/animals/2020/01/chinese-paddlefish-one-of-largest-fish-extinct/ |url-status=dead }}</ref> The primary cause of its extinction was overfishing and the construction of dams along the Yangtze. The paddlefish was heavily overfished in all stages of growth from [[Juvenile fish|fry]] (which were easily captured by traditional fishing methods) to adult, which combined with the long generation time due to its slow maturation led to reduced sustainability of viable populations. Dam construction, notably the [[Gezhouba Dam]], which became operational in 1981, and the [[Three Gorges Dam]] landlocked and divided populations and prevented the spawning migration.<ref name="iucn" /> The paper thus recommended the reclassification of the species as [[Extinction|Extinct]] by the IUCN.<ref name=":0" /> A similar recommendation was also made by the Species Survival Commission Sturgeon Specialist Group of the IUCN in September 2019.<ref name=IUCN2019/>

The official IUCN status of the species was formally updated to "extinct" in July 2022.<ref name=Master2022/><ref name="iucn"/>

==See also==
{{Portal|Fish|China}}
* [[Baiji]] – a critically endangered, probably extinct species of [[river dolphin]] also native to the Yangtze, whose decline was driven by the same factors that drove the Chinese paddlefish to extinction
* [[List of endangered and protected species of China]]

==References==
{{Reflist}}

==External links==
* [https://baijiahao.baidu.com/s?id=1654956520439607556&wfr=spider&for=pc Article on the extinction in Qilu Yidian, which contains numerous rare images of the fish alive or recently dead]
* [https://www.youtube.com/watch?v=UHLis_vv7WA Chinese documentary on the species, which features footage of the fish alive]

{{Chondrostei|state=collapsed}}
{{Acipenseriformes}}
{{Taxonbar|from1=Q477223|from2=Q18521053}}
{{Authority control}}

[[Category:Brackish water organisms]]
[[Category:Endemic fauna of China]]
[[Category:Fish described in 1862]]
[[Category:Fish extinctions since 1500]]
[[Category:Freshwater fish of China]]
[[Category:Extinct animals of China]]
[[Category:Polyodontidae]]
[[Category:Yangtze River]]
[[Category:Three Gorges Dam]]