Editing Rainbow trout (section)

===Invasive species and disease===
====Whirling disease====
{{see also|Salmonid susceptibility to whirling disease}}
{{nowrap|''[[Myxobolus cerebralis]]''}} is a [[myxosporea]]n [[parasite]] of [[Salmonidae|salmonids]] (salmon, trout, and their allies) that causes whirling disease in pen [[Aquaculture of salmonids|farmed salmon]] and trout and also in [[Wild fisheries|wild fish populations]].<ref name=whirlingdiseaseinitiative2009>{{cite web |url=http://whirlingdisease.montana.edu/pdfs/wdi_final_2009.pdf |title=Whirling Disease Initiative: Final Report |date=October 2009 |publisher=Montana Water Center, Montana State University |page=1 |access-date=2013-12-30 |url-status=dead |archive-url=https://web.archive.org/web/20120717065507/http://whirlingdisease.montana.edu/pdfs/wdi_final_2009.pdf |archive-date=2012-07-17 }}</ref> It was first described in rainbow trout introduced to Germany a century ago, but its range has spread and it has appeared in most of Europe, northern Asia, the U.S., South Africa<ref name="S-Afr-CIB">{{cite web | title=Trout impact on distributional patterns of native fish species | website=[[Centre for Invasion Biology]] | date=2021-09-20 | url=http://blogs.sun.ac.za/cib/trout-impact-on-distributional-patterns-of-native-fish-species/ | access-date=2021-09-25 | first=Lerato | last=Maimela}}</ref> and other countries.<ref name=TUWD2009>{{cite web |url=http://fwp.mt.gov/fwpDoc.html?id=40473 |title=Whirling Disease in the United States – A Summary of Progress in Research and Management 2009 |publisher=Whirling Disease Foundation, Trout Unlimited |access-date=2013-12-31 |author1=Elwell, Leah C. Steinbach |author2=Stromberg, Kajsa Eagle |author3=Ryce, Eileen K.N. |author4=Bartholomew, Jerri L. |archive-date=2013-08-28 |archive-url=https://web.archive.org/web/20130828195623/http://fwp.mt.gov/fwpDoc.html?id=40473 |url-status=dead }}</ref> In the 1980s, {{nowrap|''M. cerebralis''}} was found to require ''[[Tubifex tubifex]]'' (a kind of [[Annelid|segmented worm]]) to complete its [[Biological life cycle|life cycle]]. The parasite infects its hosts with its cells after piercing them with [[polar filament]]s ejected from [[cnidocyte|nematocyst]]-like capsules.<ref name=wddescription/>
[[File:Worldwide distribution of Mcerebralis.png|right|thumb|300px|alt=Map of worldwide distribution of Whirling Disease|''M. cerebralis'' has been reported in Germany (1893), Italy (1954), [[USSR]] (1955), including [[Sakhalin]] Island (1960), U.S. (1958), [[Bulgaria]] (1960), [[Socialist Federal Republic of Yugoslavia|Yugoslavia]] (1960), Sweden (1966), South Africa (1966), Scotland (1968), New Zealand (1971), [[Ecuador]] (1971), Norway (1971), [[Colombia]] (1972), [[Lebanon]] (1973), Ireland (1974), Spain (1981) and England (1981).]]
This parasite was originally a mild pathogen of brown trout in central Europe and other salmonids in northeast Asia, and the spread of the rainbow trout has greatly increased its impact. Having no innate [[Immunity (medicine)|immunity]] to {{nowrap|''M. cerebralis''}}, rainbow trout are particularly susceptible, and can release so many spores that even more resistant species in the same area, such as {{nowrap|''Salmo trutta''}}, can become overloaded with parasites and incur mortalities of 80 to 90&nbsp;percent. Where {{nowrap|''M. cerebralis''}} has become well-established, it has caused a decline or even elimination of whole [[Taxonomic rank#All ranks|cohorts]] of fish.<ref>Nehring, R. B. "Whirling Disease in Feral Trout Populations in Colorado". In Bergersen, E. P., and Knopf, B. A. (1996). ''Proceedings, Whirling Disease Workshop, Denver, Colorado, February 6–8, 1996: Where Do We Go from Here?'' Fort Collins, Colorado: Colorado Cooperative Fish and Wildlife Research Unit, pp. 126–144. {{OCLC|37379539}}</ref><ref>Vincent, E. R. "Whirling Disease – the Montana Experience, Madison River". In Bergersen, E. P., and Knopf, B. A. (1996). ''Proceedings, Whirling Disease Workshop, Denver, Colorado, February 6–8, 1996: Where Do We Go from Here?'' Fort Collins, Colorado: Colorado Cooperative Fish and Wildlife Research Unit, p. 159. {{OCLC| 37379539}}</ref>

The parasite {{nowrap|''M. cerebralis''}} was first recorded in North America in 1956 in Pennsylvania,<ref name=wddescription>{{cite web |url=http://www.ncrac.org/NR/rdonlyres/3CBECF1E-2AE0-4661-9C08-29A0A15DE403/26267/Whirling2.pdf |title=What Is Whirling Disease? |publisher=North Central Regional Aquaculture Center and Michigan State University Extension |date=December 2004 |access-date=2013-12-31 |author1=Faisal, Mohamed |author2=Garling, Donald |url-status=dead |archive-url=https://web.archive.org/web/20140101073322/http://www.ncrac.org/NR/rdonlyres/3CBECF1E-2AE0-4661-9C08-29A0A15DE403/26267/Whirling2.pdf |archive-date=2014-01-01 }}</ref> but until the 1990s, whirling disease was considered a manageable problem affecting only rainbow trout in hatcheries. It eventually became established in the natural waters of the Rocky Mountain states ([[Colorado]], Wyoming, [[Utah]], [[Montana]], [[Idaho]], [[New Mexico]]), where it is damaging several sport fishing rivers. Some streams in the western U.S. lost 90&nbsp;percent of their trout.<ref>{{cite web |date=January 13, 1997 |title=Scientific Breakthrough Helps Combat Trout Disease |publisher=U.S. Fish and Wildlife Service Whirling Disease Foundation News Release| url=http://www.fws.gov/mountain-prairie/pressrel/97-01.HTM |author1=Tennyson, J. |author2=Anacker, T. |author3=Higgins, S. |access-date=2014-01-05}}</ref> Whirling disease threatens recreational fishing, which is important for the tourism industry, a key component of the economies of some U.S. western states. For example, in 2005 anglers in Montana spent approximately $196,000,000 in activities directly related to trout fishing in the state.<ref>{{cite web |url=http://www.montanatrout.org/native.html |title=Montana's Wild Trout |publisher=The Trout Conservancy |archive-url=https://web.archive.org/web/20140101135600/http://www.montanatrout.org/native.html |archive-date=2014-01-01}}</ref> Some of the salmonids that {{nowrap|''M. cerebralis''}} infects ([[bull trout]], [[cutthroat trout]], and anadromous forms of rainbow trout—steelhead) are already threatened or endangered, and the parasite could worsen their population decline.<ref name="Gilbert">{{cite journal |last1=Gilbert |first1=M. A. |last2=Granath |first2=W. O. Jr. |year=2003 |title=Whirling Disease and Salmonid Fish: Life Cycle, Biology, and Disease |journal=Journal of Parasitology |volume=89 |issue=4 |pages=658–667 |doi= 10.1645/GE-82R|jstor=3285855 |pmid=14533670 |s2cid=8950955 }}</ref>

====New Zealand mud snail====
[[File:Potamopyrgus antipodarum map.png|thumb|alt=Map of U.S. distribution of New Zealand mud snail|Distribution of New Zealand mud snail within the U.S. in 2009]]
The [[New Zealand mud snail]] {{nowrap|(''Potamopyrgus antipodarum'')}}, once [[endemism|endemic]] to New Zealand, has spread widely and has become [[Naturalisation (biology)|naturalised]] and an invasive species in many areas including Australia,<ref>{{cite journal |url=https://www.cabi.org/isc/datasheet/43672 |title=Datasheet: Potamopyrgus antipodarum (New Zealand mudsnail) |author=<!--Not stated--> |website=Invasive Species Compendium |date=2013 |publisher=[[Centre for Agriculture and Bioscience International]] |doi=10.1079/cabicompendium.43672 |access-date=2012-12-04|doi-access=free }}</ref> Asia (Japan,<ref name="Davidson"/> in the Garmat Ali River in Iraq since 2008<ref>{{cite journal  |year=2009 |url=http://www.aquaticinvasions.net/2009/AI_2009_4_2_Naser_Son.pdf |title=First Record of the New Zealand Mud Snail ''Potamopyrgus antipodarum'' (Gray 1843) from Iraq: the Start of Expansion to Western Asia? |journal=Aquatic Invasions |volume=4 |pages=369–372 |author1=Naser, Murtada D. |author2=Son, Mikhail O. |issue=2 |doi=10.3391/ai.2009.4.2.11|doi-access=free }}</ref>), Europe (since 1859 in England), and North America (U.S. and Canada: [[Thunder Bay (Ontario landform)|Thunder Bay]] in Ontario since 2001, British Columbia since July 2007<ref name="Davidson">{{cite journal |url=https://www.researchgate.net/publication/236342603 |title=Northern Range Expansion and Coastal Occurrences of the New Zealand Mud Snail ''Potamopyrgus antipodarum'' (Gray, 1843) in the Northeast Pacific |journal=Aquatic Invasions |year=2008 |volume=3 |pages=349–353 |author1=Davidson, Timothy M. |author2=Brenneis, Valance E. F. |author3=de Rivera, Catherine |author4=Draheim, Robyn |author5=Gillespie, Graham E. |issue=3 |format=PDF |doi=10.3391/ai.2008.3.3.12|doi-access=free }}</ref>), most likely inadvertently during human activity.<ref name=usgs/> It can reach concentrations greater than {{convert|500000|/m2|/sqft}}, endangering the [[food chain]] by outcompeting native snails and water insects for food, leading to sharp declines in native populations.<ref>{{cite web| author=Benson, Amy| year=2006| title=New Zealand Mudsnail: Potamopyrgus antipodarum| work=Florida Integrated Science Center| url=http://cars.er.usgs.gov/Nonindigenous_Species/New_Zealand_Mudsnail/new_zealand_mudsnail.html| access-date=2006-05-04| url-status=dead| archive-url=https://web.archive.org/web/20060219142324/http://cars.er.usgs.gov/Nonindigenous_Species/New_Zealand_Mudsnail/new_zealand_mudsnail.html| archive-date=2006-02-19}}</ref> There is evidence North American fishes are unable to digest the tiny but hard shells of the mud snail, and that their presence may result in poor growth outcomes for rainbow trout.<ref>{{cite journal |last1=Vinson |first1=M. R. |last2=Baker |first2=M. A. |date=2008 |title=Poor growth of rainbow trout fed New Zealand mud snails ''Potamopyrgus antipodarum'' |journal=North American Journal of Fisheries Management |volume=28 |issue=3 |pages=701–709 |doi=10.1577/M06-039.1|bibcode=2008NAJFM..28..701V }}</ref>

The mud snail was first detected in the U.S. in Idaho's Snake River in 1987. Since then, the snail has spread to the [[Madison River]], Firehole River, and other watercourses around Yellowstone National Park, and has been discovered throughout the western U.S.<ref name=usgs>{{cite web | url = https://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=1008 | title = ''Potamopyrgus antipodarum'' | access-date = 2013-05-25 |author1=Benson, A. J. |author2=Kipp, R. M. |author3=Larson, J. |author4=Fusaro, A. | year = 2013 | work = USGS Nonindigenous Aquatic Species Database | publisher = U.S. Geological Survey}}</ref> The exact means of transmission is unknown, but it is likely that it was introduced in water transferred with live [[game fish]] and has been spread by [[ship ballast]] or contaminated recreational equipment such as [[Waders (footwear)|wading gear]].<ref name="Montana">{{cite web| title=Aquatic Nuisance Project Fact Sheet: New Zealand Mudsnail (''Potamopyrgus antipodarum'')| publisher=Aquatic Nuisance Species Project| url=http://www.aquaticnuisance.org/fact-sheets/new-zealand-mudsnail| access-date=2014-01-03| archive-date=2013-12-12| archive-url=https://web.archive.org/web/20131212164937/http://www.aquaticnuisance.org/fact-sheets/new-zealand-mudsnail| url-status=dead}}</ref>

====Didymo====
{{nowrap|''[[Didymosphenia geminata]]''}}, commonly known as didymo or rock snot, is a species of [[diatom]] that produces nuisance growths in freshwater rivers and streams with consistently cold water temperatures.<ref name=dpiw-tassie>{{cite web | url=http://dpipwe.tas.gov.au/biosecurity/aquatic-pests-and-diseases/aquatic-biosecurity-threats/didymo-%28rock-snot%29 | title=DPIPWE - Didymo (Rock Snot) | publisher=Tasmania Department of Primary Industries, Parks, Water and Environment | access-date=2014-08-12 | url-status=dead | archive-url=https://web.archive.org/web/20150308142725/http://dpipwe.tas.gov.au/biosecurity/aquatic-pests-and-diseases/aquatic-biosecurity-threats/didymo-(rock-snot) | archive-date=2015-03-08 }}</ref> In New Zealand, invasive didymo can form large mats on the bottom of rivers and streams in late winter. It is not considered a significant human health risk, but it can affect stream habitats and sources of food for fish, including rainbow trout, and make recreational activities unpleasant.<ref name="biosec-nz">{{cite web |url=http://www.biosecurity.govt.nz/faq/term/907/didymo-11.htm |title=Is Didymo an Exotic Species? |access-date=2013-12-01 |last=Biosecurity New Zealand |date=August 2007 |publisher=Biosecurity New Zealand |archive-url=https://web.archive.org/web/20131203005603/http://www.biosecurity.govt.nz/faq/term/907/didymo-11.htm |archive-date=2013-12-03 |url-status=dead }}</ref> Even though it is native in North America, it is considered a nuisance organism or invasive species.<ref>{{cite web |url=https://www.invasivespeciesinfo.gov/profile/didymo |title=Invasive Aquatic Species-Didymo |publisher=U.S. Department of Agriculture |access-date=2013-12-16}}</ref>

====Redmouth disease====
Enteric redmouth disease is a [[bacterial infection]] of freshwater and marine fish caused by the pathogen {{nowrap|''[[Yersinia ruckeri]]''}}. It is primarily found in rainbow trout and other cultured [[salmonids]]. The disease is characterized by [[Subcutaneous tissue|subcutaneous]] hemorrhaging of the mouth, fins, and eyes. It is most commonly seen in fish farms with poor water quality. Redmouth disease was first discovered in Idaho rainbow trout in the 1950s.<ref>{{cite journal |last=Busch |first=R. A. |url=http://spo.nmfs.noaa.gov/mfr403/mfr40311.pdf |title=MFR Paper 1296 Enteric Redmouth Disease (Haggerman Strain) |journal=Marine Fisheries Review |volume=40 |date=March 1978 |issue=3 |access-date=2014-01-05 |archive-date=2017-05-25 |archive-url=https://web.archive.org/web/20170525110624/http://spo.nmfs.noaa.gov/mfr403/mfr40311.pdf |url-status=dead }}</ref>