Editing Fish farming (section)

=== Parasites and disease ===
[[Sea lice]], particularly ''Lepeophtheirus salmonis'' and various ''Caligus'' species, including ''C. clemensi'' and ''C. rogercresseyi'', can cause deadly infestations of both farm-grown and wild salmon.<ref>[https://web.archive.org/web/20101214173552/http://farmedanddangerous.org/uploads/File/Reports/SeaLice_FullReport.pdf Sea Lice and Salmon: Elevating the dialogue on the farmed-wild salmon story] ''Watershed Watch Salmon Society'', 2004.<!--accessed January 15, 2010--></ref><ref>{{cite journal | last1 = Bravo | first1 = S | year = 2003 | title = Sea lice in Chilean salmon farms | journal = Bull. Eur. Assoc. Fish Pathol | volume = 23 | pages = 197–200 }}</ref> Sea lice are [[ectoparasite]]s which feed on mucus, blood, and skin, and migrate and latch onto the skin of wild salmon during free-swimming, planktonic ''nauplii'' and ''copepodid'' larval stages, which can persist for several days.<ref>{{cite journal | last1 = Morton | first1 = A. | last2 = Routledge | first2 = R. | last3 = Peet | first3 = C. | last4 = Ladwig | first4 = A. | year = 2004 | title = Sea lice (Lepeophtheirus salmonis) infection rates on juvenile pink (Oncorhynchus gorbuscha) and chum (Oncorhynchus keta) salmon in the nearshore marine environment of British Columbia, Canada | journal = Canadian Journal of Fisheries and Aquatic Sciences | volume = 61 | issue = 2| pages = 147–157 | doi=10.1139/f04-016}}</ref><ref>Peet, C. R. 2007. Interactions between sea lice (''Lepeophtheirus salmonis'' and ''Caligus clemensi'') and juvenile chum (''Oncorhynchus keta'') and pink salmon (''Oncorhynchus gorbuscha'') in British Columbia. M. Sc. Thesis, University of Victoria.</ref><ref>{{cite journal | last1 = Krkošek | first1 = M. | last2 = Gottesfeld | first2 = A. | last3 = Proctor | first3 = B. | last4 = Rolston | first4 = D. | last5 = Carr-Harris | first5 = C. | last6 = Lewis | first6 = M.A. | year = 2007 | title = Effects of host migration, diversity, and aquaculture on disease threats to wild fish populations | journal = Proceedings of the Royal Society of London, Series B | volume = 274 | issue = 1629| pages = 3141–3149 | doi=10.1098/rspb.2007.1122 | pmid=17939989 | pmc=2293942}}</ref> Large numbers of highly populated, open-net salmon farms can create exceptionally large concentrations of sea lice; when exposed in river estuaries containing large numbers of open-net farms, many young wild salmon are infected, and do not survive as a result.<ref>{{cite journal | last1 = Morton | first1 = A. | last2 = Routledge | first2 = R. | last3 = Krkošek | first3 = M. | year = 2008 | title = Sea louse infestation in wild juvenile salmon and Pacific herring associated with fish farms off the east-central coast of Vancouver Island, British Columbia | journal = North American Journal of Fisheries Management | volume = 28 | issue = 2| pages = 523–532 | doi=10.1577/m07-042.1| bibcode = 2008NAJFM..28..523M }}</ref><ref>{{cite journal | last1 = Krkošek | first1 = M. | last2 = Lewis | first2 = M.A. | last3 = Morton | first3 = A. | last4 = Frazer | first4 = L.N. | last5 = Volpe | first5 = J.P. | year = 2006 | title = Epizootics of wild fish induced by farm fish | journal = Proceedings of the National Academy of Sciences | volume = 103 | issue = 42| pages = 15506–15510 | doi=10.1073/pnas.0603525103 | pmid=17021017 | pmc=1591297| bibcode = 2006PNAS..10315506K | doi-access = free }}</ref> Adult salmon may survive otherwise critical numbers of sea lice, but small, thin-skinned juvenile salmon migrating to sea are highly vulnerable. On the [[Pacific coast of Canada]], the louse-induced mortality of pink salmon in some regions is commonly over 80%.<ref>{{cite journal | last1 = Krkošek | first1 = Martin | display-authors = etal | year = 2007 | title = Report: "Declining Wild Salmon Populations in Relation to Parasites from Farm Salmon | journal = Science | volume = 318 | issue = 5857| pages = 1772–1775 | doi=10.1126/science.1148744 | pmid=18079401| bibcode = 2007Sci...318.1772K | s2cid = 86544687 }}</ref> In Scotland, official figures show that more than nine million fish were lost to disease, parasites, botched treatment attempts and other problems on fish farms between 2016 and 2019.<ref name="The Ferret">{{Citation |last=Edwards |first=Rob |date=2019-04-14 |title=Mass deaths: nine million fish killed by diseases at Scottish salmon farms |journal=[[The Ferret (website)|The Ferret]] |url=https://theferret.scot/salmon-deaths-farms-nine-million/ |access-date=2019-06-15 |postscript=.}}</ref> One of the treatments for parasite infestations involved bathing fish in hydrogen peroxide,<ref>{{Cite web|title=Use of Hydrogen Peroxide in Finfish Aquaculture|url=https://thefishsite.com/articles/use-of-hydrogen-peroxide-in-finfish-aquaculture|access-date=2021-11-14|website=thefishsite.com|date=13 February 2009 |language=en}}</ref> which can harm or kill farmed fish if they are in a weak condition or if the chemical concentration is too strong.

A 2008 meta-analysis of available data shows that salmon farming reduces the survival of associated wild salmon populations. This relationship has been shown to hold for Atlantic, steelhead, pink, chum, and coho salmon. The decrease in survival or abundance often exceeds 50%.<ref>{{cite journal | last1 = Ford | first1 = JS | last2 = Myers | first2 = RA | year = 2008 | title = A Global Assessment of Salmon Aquaculture Impacts on Wild Salmonids| journal = PLOS Biol | volume = 6 | issue = 2| page = e33 | doi=10.1371/journal.pbio.0060033 | pmid=18271629 | pmc=2235905 | doi-access = free }}</ref>

[[Fish diseases and parasites|Diseases and parasites]] are the most commonly cited reasons for such decreases. Some species of sea lice have been noted to target farmed coho and Atlantic salmon.<ref>{{cite web|url=http://www.umaine.edu/livestock/Publications/sea_lice_bullets.htm|archive-url=https://web.archive.org/web/20100521115210/http://www.umaine.edu/livestock/Publications/sea_lice_bullets.htm|url-status=dead|archive-date=2010-05-21|title=Sea Lice Information Bullets}}</ref> Such parasites have been shown to have an effect on nearby wild fish. One place that has garnered international media attention is British Columbia's [[Broughton Archipelago]]. There, juvenile wild salmon must "run a gauntlet" of large fish farms located off-shore near river outlets before making their way to sea. The farms allegedly cause such severe sea lice infestations that one study predicted in 2007 a 99% collapse in the wild salmon population by 2011.<ref>{{cite web|title=Fish Farms Drive Wild Salmon Populations Toward Extinction|url=https://www.sciencedaily.com/releases/2007/12/071213152606.htm|website=ScienceDaily|access-date=2018-01-06|date=16 December 2007}}</ref> This claim, however, has been criticized by numerous scientists who question the correlation between increased fish farming and increases in sea lice infestation among wild salmon.<ref>{{cite web|url=http://www.newsdata.com/fishletter/242/4story.html|title=Northwest Fishletter|access-date=30 January 2016}}</ref>

Because of parasite problems, some aquaculture operators frequently use strong antibiotic drugs to keep the fish alive, but many fish still die prematurely at rates up to 30%.<ref>Lymbery, P. CIWF Trust report, "[http://www.eurocbc.org/fz_lymbery.pdf In Too Deep – The Welfare of Intensively Farmed Fish]" (2002)</ref> Additionally, other common drugs used in salmonid fish farms in North America and Europe include anesthetic, chemotherapeutic, and anthelmintic agents.<ref>{{Cite journal|last1=Burka|first1=J. F.|last2=Hammell|first2=K. L.|last3=Horsberg|first3=T. E.|last4=Johnson|first4=G. R.|last5=Rainnie|first5=D. J.|last6=Speare|first6=D. J.|date=October 1997|title=Drugs in salmonid aquaculture – A review|journal=Journal of Veterinary Pharmacology and Therapeutics|volume=20|issue=5|pages=333–349|doi=10.1046/j.1365-2885.1997.00094.x|pmid=9350253|issn=0140-7783}}</ref> In some cases, these drugs have entered the environment.<ref>{{Cite journal|last1=Cabello|first1=Felipe C.|last2=Godfrey|first2=Henry P.|last3=Tomova|first3=Alexandra|last4=Ivanova|first4=Larisa|last5=Dölz|first5=Humberto|last6=Millanao|first6=Ana|last7=Buschmann|first7=Alejandro H.|date=2013-05-26|title=Antimicrobial use in aquaculture re-examined: its relevance to antimicrobial resistance and to animal and human health|journal=Environmental Microbiology|volume=15|issue=7|pages=1917–1942|doi=10.1111/1462-2920.12134|pmid=23711078|issn=1462-2912|doi-access=free|bibcode=2013EnvMi..15.1917C }}</ref> Additionally, the residual presence of these drugs in human food products has become controversial. Use of antibiotics in food production is thought to increase the prevalence of [[antibiotic resistance]] in human diseases.<ref>{{cite web|url=https://www.fda.gov/oc/opacom/hottopics/antiresist_facts.html|title=Public Health Focus|website=[[Food and Drug Administration]]}}</ref> At some facilities, the use of antibiotic drugs in aquaculture has decreased considerably due to vaccinations and other techniques.<ref>{{cite web|url=http://www.ooa.unh.edu/environment/environment_care.html|archive-url=https://web.archive.org/web/20090810082202/http://www.ooa.unh.edu/environment/environment_care.html|url-status=dead|archive-date=2009-08-10|date=2007 |title=Fish care|author=Atlantic Marine Aquaculture Center|publisher=University of New Hampshire}}</ref> However, most fish-farming operations still use antibiotics, many of which escape into the surrounding environment.<ref>{{cite news|url=https://www.nytimes.com/2009/07/27/world/americas/27salmon.html| title=Chile's Antibiotics Use on Salmon Farms Dwarfs That of a Top Rival's |date=July 26, 2009|access-date=2009-08-28 | work=The New York Times | first=Alexei | last=Barrionuevo}}</ref>

The lice and pathogen problems of the 1990s facilitated the development of current treatment methods for sea lice and pathogens, which reduced the stress from parasite/pathogen problems. However, being in an ocean environment, the transfer of disease organisms from the wild fish to the aquaculture fish is an ever-present risk.<ref>{{cite journal | year = 2002 | title =Trends in therapy and prophylaxis 1991–2001 | url =https://eafp.org/download/2002-Volume22/Issue%202/22_117.pdf | journal = Bulletin of the European Association of Fish Pathologists | volume = 22 | issue = 2| pages = 117–125 }}</ref>
[[File:Criadero de peces en el Lago Titicaca cerca de Copacabana Bolivia.jpg|thumb|A [[Lake trout|North American lake trout]] fishing farm on [[Lake Titicaca]] near [[Copacabana, Bolivia|Copacabana]], [[Bolivia]]. Since their introduction in the 1930s, trout have been an [[invasive species]] endangering the local fish population.<ref>{{Cite web |last1=Magazine |first1=Smithsonian |last2=Bloudoff-Indelicato |first2=Mollie |title=What Are North American Trout Doing in Lake Titicaca? |url=https://www.smithsonianmag.com/science-nature/what-are-north-american-trout-doing-lake-titicaca-180957472/ |access-date=2023-07-24 |website=Smithsonian Magazine |language=en}}</ref>]]