Editing Salmon (section)

===Parasites===
{{main|Diseases and parasites in salmon}}
According to Canadian biologist Dorothy Kieser, the [[myxozoa]]n parasite ''[[Henneguya salminicola]]'' is commonly found in the flesh of salmonids. It has been recorded in the field samples of salmon returning to the [[Haida Gwaii Islands]]. The fish responds by walling off the parasitic infection into a number of cysts that contain milky fluid. This fluid is an accumulation of a large number of parasites.
[[File:Henneguya salminicola in flesh of coho salmon, BC, Canada.JPG|thumb|left|''[[Henneguya salminicola]]'', a [[myxozoa]]n parasite commonly found in the flesh of salmonids on the West Coast of Canada, in coho salmon]]

''Henneguya'' and other parasites in the [[myxosporean]] group have complex life cycles, where the salmon is one of two hosts. The fish releases the spores after spawning. In the ''Henneguya'' case, the spores enter a second host, most likely an invertebrate, in the spawning stream. When juvenile salmon migrate to the Pacific Ocean, the second host releases a stage infective to salmon. The parasite is then carried in the salmon until the next spawning cycle. The myxosporean parasite that causes [[whirling disease]] in trout has a similar life cycle.<ref>{{cite web | url = http://el.erdc.usace.army.mil/ansrp/myxobolus_cerebralis.pdf | title = Whirling Disease&nbsp;- ''Myxobolus cerebralis'' | access-date = 13 December 2007 | first1 = Danielle M. | last1 = Crosier | first2 = Daniel P. | last2 = Molloy | first3 = Jerri | last3 = Bartholomew | url-status = dead | archive-url = https://web.archive.org/web/20080216100913/http://el.erdc.usace.army.mil/ansrp/myxobolus_cerebralis.pdf | archive-date = 16 February 2008 }}</ref> However, as opposed to whirling disease, the ''Henneguya'' infestation does not appear to cause disease in the host salmon—even heavily infected fish tend to return to spawn successfully.

According to Dr. Kieser, a lot of work on ''Henneguya salminicola'' was done by scientists at the Pacific Biological Station in Nanaimo in the mid-1980s, in particular, an overview report<ref>{{cite journal | url = http://publications.gc.ca/collections/collection_2013/mpo-dfo/Fs97-6-1405-eng.pdf | title = Investigation of the Distribution, Detection, and Biology of Henneguya salminicola (Protozoa, Myxozoa), a Parasite of the Flesh of Pacific Salmon | last1 = Boyce | first1 = N.P. | last2 = Kabata | first2 = Z. | last3 = Margolis | first3 = L. | year = 1985 | journal = Canadian Technical Report of Fisheries and Aquatic Sciences | issue = 1450 | page = 55 | archive-url = https://web.archive.org/web/20141112112222/http://publications.gc.ca/collections/collection_2013/mpo-dfo/Fs97-6-1405-eng.pdf | archive-date = 12 November 2014 | url-status = live}}</ref> which states, "the fish that have the longest fresh water residence time as juveniles have the most noticeable infections. Hence in order of [[prevalence]], coho are most infected followed by sockeye, chinook, chum and pink. As well, the report says, at the time the studies were conducted, stocks from the middle and upper reaches of large river systems in British Columbia such as [[Fraser River|Fraser]], [[Skeena River|Skeena]], [[Nass River|Nass]] and from mainland coastal streams in the southern half of B.C., "are more likely to have a low prevalence of infection." The report also states, "It should be stressed that ''Henneguya'', economically deleterious though it is, is harmless from the view of [[public health]]. It is strictly a [[fish parasite]] that cannot live in or affect [[warm blooded]] animals, including man".

According to Klaus Schallie, Molluscan Shellfish Program Specialist with the [[Canadian Food Inspection Agency]], "''Henneguya salminicola'' is found in southern B.C. also and in all species of salmon. I have previously examined smoked chum salmon sides that were riddled with cysts and some sockeye runs in [[Barkley Sound]] (southern B.C., west coast of [[Vancouver Island]]) are noted for their high incidence of infestation."{{Citation needed | date = May 2019 | reason = This paragraph appears to be sentences that are copied from website to website with unclear origin; would improve reliability if primary source is specified.}}

[[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>
{{cite web | date = 2004 | title = Sea Lice and Salmon: Elevating the dialogue on the farmed-wild salmon story | url = http://www.farmedanddangerous.org/wp-content/uploads/2011/01/SeaLice_FullReport-April-2004.pdf | url-status = dead | publisher = Watershed Watch Salmon Society | archive-url = https://web.archive.org/web/20120713061313/http://www.farmedanddangerous.org/wp-content/uploads/2011/01/SeaLice_FullReport-April-2004.pdf | archive-date = 13 July 2012 }}</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 | url = https://www.researchgate.net/publication/279887581}}</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. | first2 = R | last2 = Routledge | first3 = C | last3 = Peet | first4 = A | last4 = Ladwig | 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 | year = 2004| bibcode = 2004CJFAS..61..147M }}</ref><ref>
{{cite thesis | last = Peet | first = C. R. | date = 2007 | title = Interactions between sea lice (''Lepeophtheirus salmonis'' and ''Caligus clemensii''), juvenile salmon (''Oncorhynchus keta'' and ''Oncorhynchus gorbuscha'') and salmon farms in British Columbia | type = MSc | publisher = University of Victoria | location = Victoria, British Columbia, Canada | url = http://www.raincoast.org/files/publications/papers/Peet-2007-Master-thesis.pdf | archive-url = https://web.archive.org/web/20161026164902/http://www.raincoast.org/files/publications/papers/Peet-2007-Master-thesis.pdf | archive-date = 26 October 2016 | url-status = live}}</ref><ref>
{{cite journal | last1 = Krkošek | first1 = M | first2 = A | last2 = Gottesfeld | first3 = B | last3 = Proctor | first4 = D | last4 = Rolston | first5 = C | last5 = Carr-Harris | first6 = M.A. | last6 = Lewis | title = Effects of host migration, diversity and aquaculture on sea lice threats to Pacific salmon populations | journal = Proceedings of the Royal Society B: Biological Sciences | volume = 274 | issue = 1629 | pages = 3141–9 | pmid = 17939989 | pmc = 2293942 | year = 2007 | doi = 10.1098/rspb.2007.1122}}</ref>

Large numbers of highly populated, open-net salmon farms<!--*** footnote begins ***-->{{Efn-ua |
Open-net fish farms are large anchored floating net cages often located in bays and relatively sheltered areas.  Each farm may have over a million fish.<ref>{{cite web | last1 = Morton | first1 = Alexandra | title = SALMON CONFIDENTIAL: The ugly truth about Canada's open-net salmon farms | url = http://www.alexandramorton.ca/salmon-confidential-booklet/ | at = WHAT IS A FISH FARM? | access-date = 10 May 2019 | archive-url = https://web.archive.org/web/20151005203923/http://www.alexandramorton.ca/salmon-confidential-booklet/ | archive-date = 5 October 2015 | url-status = live }}</ref>
}}<!--*** footnote ends ***-->
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 name="MortonRoutledge2008">{{cite journal | last1 = Morton | first1 = Alexandra | last2 = Routledge | first2 = Rick | last3 = Krkosek | first3 = Martin | 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 | year = 2008 | pages = 523–532 | issn = 0275-5947 | doi = 10.1577/M07-042.1 | bibcode = 2008NAJFM..28..523M | url = http://labs.eeb.utoronto.ca/krkosek/Publications_files/AM_NAJFM_2008.pdf | archive-url = https://web.archive.org/web/20130829060206/http://labs.eeb.utoronto.ca/krkosek/Publications_files/AM_NAJFM_2008.pdf | archive-date = 29 August 2013 | url-status = dead }}</ref><ref name="KrkosekLewis2006">{{cite journal | last1 = Krkosek | first1 = M. | last2 = Lewis | first2 = M. A. | last3 = Morton | first3 = A. | last4 = Frazer | first4 = L. N. | last5 = Volpe | first5 = J. P. | title = Epizootics of wild fish induced by farm fish | journal = Proceedings of the National Academy of Sciences | volume = 103 | issue = 42 | year = 2006 | pages = 15506–15510 | issn = 0027-8424 | 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 | last = Krkošek | first = Martin | title = Declining Wild Salmon Populations in Relation to Parasites from Farm Salmon | journal = Science | volume = 318 | issue = 5857 | pages = 1772–5 | doi = 10.1126/science.1148744 | pmid = 18079401 | year = 2007 | bibcode = 2007Sci...318.1772K | s2cid = 86544687 }}</ref>