Editing Salmon (section)

==Ecology==
[[File:Cub with trophy.jpg|thumb|left|Bear cub with salmon]]
{{see also|Salmon run}}
In the [[Pacific Northwest]] and [[Alaska]], salmon are [[keystone species]].<ref name=Willson/> The migration of salmon represent a massive retrograde [[nutrient]] transfer, rich in [[nitrogen]], [[sulfur]], [[carbon]] and [[phosphorus]], from the ocean to the inland [[freshwater ecosystem]]s. Predation by [[piscivorous]] land animals (such as [[osprey]]s, [[bear]]s and [[otter]]s) along the journey serve to transfer the nutrients from the water to land, and [[decomposition]] of salmon carcass benefits the [[forest ecosystem]].

In the case of [[Pacific salmon]], most (if not all) of the salmon that survive to reach the [[headwater]] spawning grounds will [[semelparity|die after laying eggs]] and their dead bodies sink to cover the gravel beds, with the nutrients released from the [[biodegradation]] of their corpses providing a significant boost to these otherwise [[biomass (ecology)|biomass]]-poor shallow streams.

===Bears===
[[Grizzly bear]]s function as [[ecosystem engineer]]s, capturing salmon and carrying them into adjacent dry land to eat the fish. There they deposit nutrient-rich urine and feces and partially eaten carcasses. Bears preparing for [[hibernation]] tend to preferentially consume the more nutrient- and [[food energy|energy]]-rich [[salmon roe]]s and [[brain]] over the actual [[flesh]],<ref>{{cite journal|title=Consumption choice by bears feeding on salmon|url=https://link.springer.com/article/10.1007/s004420000590|last1=Gende |first1=S.M.|last2=Quinn|first2=T.P.|last3=Willson|first3=M.F.|date=2001-05-01|journal=[[Oecologia]]|volume=127|issue=3|pages=372–382|doi=10.1007/s004420000590|pmid=28547108 |bibcode=2001Oecol.127..372G |s2cid=41395058 |accessdate=2023-09-14}}</ref> and are estimated to discard up to half the salmon they've harvested uneaten on the forest floor,<ref name=Reimchen2001/><ref name=Quinn2009/> in densities that can reach {{cvt|4000|kg}} per hectare,<ref name=Reimchen2002/> providing as much as 24% of the total nitrogen available to the [[riparian]] [[woodland]]s. The foliage of [[Picea glauca|spruce trees]] up to {{cvt|500|m}} from a stream where grizzlies fish salmon have been found to contain nitrogen originating from the fished salmon.<ref name=Helfield2006>{{Cite journal | last1 = Helfield | first1 = J. | name-list-style = amp | last2 = Naiman | first2 = R. | year = 2006 | title = Keystone Interactions: Salmon and Bear in Riparian Forests of Alaska | url = http://myweb.wwu.edu/~helfiej/publications_pdfs/Helfield_Naiman_2006.pdf | journal = Ecosystems | volume = 9 | issue = 2 | pages = 167–180 | doi = 10.1007/s10021-004-0063-5 | bibcode = 2006Ecosy...9..167H | s2cid = 28989920 | archive-url = https://web.archive.org/web/20120426080102/http://myweb.wwu.edu/~helfiej/publications_pdfs/Helfield_Naiman_2006.pdf | archive-date = 26 April 2012 | url-status = live}}</ref>

===Beavers===
[[File:Sockeye salmon jumping over beaver dam Lake Aleknagik, AK Kristina Ramstad 1997.jpg|thumb|upright|Sockeye salmon jumping over beaver dam]]

[[Beaver]]s also function as ecosystem engineers; in the process of tree-cutting and [[beaver dam|dam]]ming, beavers alter the local ecosystems extensively. Beaver ponds can provide critical habitat for [[juvenile salmon]].

An example of this was seen in the years following 1818 in the [[Columbia River]] Basin. In 1818, the British government made an agreement with the U.S. government to allow U.S. citizens access to the Columbia catchment (see [[Treaty of 1818]]). At the time, the [[Hudson's Bay Company]] sent word to [[fur trapping|trappers]] to extirpate all furbearers from the area in an effort to make the area less attractive to U.S. fur traders. In response to the elimination of beavers from large parts of the river system, [[salmon run]]s plummeted, even in the absence of many of the factors usually associated with the demise of salmon runs. Salmon recruitment can be affected by beavers' dams because dams can:<ref>{{cite web | url = http://www.nwcouncil.org/history/Extinction.asp | title = Extinction | publisher = Northwest Power and Conservation Council | access-date = 21 December 2007 | archive-url = https://web.archive.org/web/20180101173222/https://www.nwcouncil.org/history/Extinction | archive-date = 1 January 2018 | url-status = live}}</ref><ref>{{cite journal | title=Sockeye salmon (''Oncorhynchus nerka'') nursery lake fertilization: Review and summary of results |journal=Environmental Reviews|volume=12|issue=3|pages=133–162|doi=10.1139/a04-008|year=2004|last1=Hyatt|first1=K D|last2=McQueen|first2=D J|last3=Shortreed|first3=K S|last4=Rankin|first4=D P|bibcode=2004EnvRv..12..133H |s2cid=12930576| url=http://pdfs.semanticscholar.org/0cfb/39999bce91178a1091a58a6f8f9d090570cb.pdf | archive-url=https://web.archive.org/web/20200807012439/http://pdfs.semanticscholar.org/0cfb/39999bce91178a1091a58a6f8f9d090570cb.pdf | url-status=dead | archive-date=7 August 2020 }}</ref><ref>{{cite web | url = http://rocky.ess.washington.edu/grg/publications/pdfs/Pollock.pdf | title = The Importance of Beaver Ponds to Coho Salmon Production in the Stillaguamish River Basin, Washington, USA | last1 = Pollock | first1 = M. M. | last2 = Pess | first2 = G. R. | last3 = Beechie | first3 = T. J. | access-date = 21 December 2007 | archive-url = https://web.archive.org/web/20060901185801/http://rocky.ess.washington.edu/grg/publications/pdfs/Pollock.pdf | archive-date = 1 September 2006 | url-status = live}}</ref>
*Slow the rate at which nutrients are flushed from the water system; nutrients provided by adult salmon dying throughout the fall and winter remain available in the spring to newly hatched juveniles
*Provide deeper [[salmon pool]]s where young salmon can avoid avian predators
*Increase productivity through [[algal]] [[photosynthesis]] and by enhancing the conversion efficiency of the [[cellulose]]-powered [[detritus cycle]]{{Clarify | date = May 2019 | reason = Not directly clear how it's related to Salmon; also, only one of the references seem to posit a question that the photosynthesis increase due to fertilizers related to Salmon may help juvenile salmons. }}
*Create slow-water environments where juvenile salmon put the food they ingest into growth rather than into fighting currents
*Increase structural complexity with many physical niches where salmon can avoid predators

Beaver dams are able to nurture salmon juveniles in estuarine [[tidal marsh]]es where the salinity is less than 10&nbsp;ppm. Beavers build small dams of generally less than {{convert|2|ft|cm|sigfig=1|abbr=on|order=flip}} high in channels in the [[myrtle zone]]{{Clarify | date = May 2019 | reason = What's a 'myrtle zone'}}. These dams can be overtopped at high tide and hold water at low tide. This provides refuges for juvenile salmon so they do not have to swim into large channels where they are subject to predation by larger fish.<ref>{{cite web | last1 = Hood | first1 = W Gregory  | title = AN OVERLOOKED ECOLOGICAL WEB | url = http://www.skagitwatershed.org/rpapers_overlooked.html | archive-url = https://web.archive.org/web/20080724000846/http://www.skagitwatershed.org/rpapers_overlooked.html | archive-date = 24 July 2008 | url-status = dead }}</ref>

===Lampreys===
It has been discovered that rivers which have seen a decline or disappearance of anadromous [[lamprey]]s, loss of the lampreys also affects the salmon in a negative way. Like salmon, anadromous lampreys stop feeding and die after spawning, and their decomposing bodies release nutrients into the stream. Also, along with species like [[rainbow trout]] and [[Sacramento sucker]], lampreys clean the gravel in the rivers during spawning.<ref>{{cite web | date = 19 January 2010 | title = Yuba River Steelhead Redd Surveys (preliminary draft) | url = http://www.yubaaccordrmt.com/Study%20Protocols/Steelhead%20Redd%202010%20Study%20Plan%201-19-10%20(deepwater%20strikeout).pdf | archive-url = https://web.archive.org/web/20180429222315/http://www.yubaaccordrmt.com/Study%20Protocols/Steelhead%20Redd%202010%20Study%20Plan%201-19-10%20(deepwater%20strikeout).pdf | archive-date = 29 April 2018 | url-status = live | publisher =  Yuba River Management Team (RMT) Web Site, Yuba County Water Agency }}</ref> Their larvae, called ammocoetes, are [[filter feeder]]s which contribute to the health of the waters. They are also a food source for the young salmon, and being fattier and oilier, it is assumed predators prefer them over salmon offspring, taking off some of the predation pressure on smolts.<ref>{{cite news | title = Elder's devotion to ugly fish lives on after his tragic death | date = 20 August 2014 | url = http://america.aljazeera.com/articles/2014/8/20/save-the-lampreyelmercrow.html | work = Al Jazeera America | archive-url = https://web.archive.org/web/20181116074100/http://america.aljazeera.com/articles/2014/8/20/save-the-lampreyelmercrow.html | archive-date = 16 November 2018 | url-status = live}}</ref>{{Unreliable source? | date = May 2019}} Adult lampreys are also the preferred prey of seals and sea lions, which can eat 30 lampreys to every salmon, allowing more adult salmon to enter the rivers to spawn without being eaten by the marine mammals.<ref>
{{cite news | title = Pacific Lamprey's Big Year | date = 18 June 2017 | url = http://kymkemp.com/2017/06/18/pacific-lampreys-big-year/ | work = Redheaded Blackbelt | archive-url = https://web.archive.org/web/20181116062430/http://kymkemp.com/2017/06/18/pacific-lampreys-big-year/ | archive-date = 16 November 2018 | url-status = live}}</ref><ref>
{{cite web | year = 2014 | title = A Primeval Marvel | url = http://terra.oregonstate.edu/files/2014/01/Terra-all-pages-single.pdf | work = terra | publisher = Oregon State University | volume = 9 | number = 2 | archive-url = https://web.archive.org/web/20180503042128/http://terra.oregonstate.edu/files/2014/01/Terra-all-pages-single.pdf | archive-date = 3 May 2018 | url-status = live}}</ref>

===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>

===Effect of pile driving===
The risk of injury caused by [[Pile driver#Environmental effects .28offshore pile driving.29|underwater pile driving]] has been studied by Dr. Halvorsen and her co-workers.<ref name="BrowmanHalvorsen2012">{{cite journal | last1 = Browman | first1 = Howard | last2 = Halvorsen | first2 = Michele B. | last3 = Casper | first3 = Brandon M. | last4 = Woodley | first4 = Christa M. | last5 = Carlson | first5 = Thomas J. | last6 = Popper | first6 = Arthur N. | title = Threshold for Onset of Injury in Chinook Salmon from Exposure to Impulsive Pile Driving Sounds | journal = PLOS ONE | volume = 7 | issue = 6 | year = 2012 | pages = e38968 | issn = 1932-6203 | doi = 10.1371/journal.pone.0038968 | pmid = 22745695 | pmc = 3380060 | bibcode = 2012PLoSO...738968H | doi-access = free }}</ref> The study concluded that the fish are at risk of injury if the cumulative [[sound exposure level]] exceeds 210 [[decibel|dB]] relative to 1 μPa<sup>2</sup> s.{{Clarify | date = May 2019 | reason = The cumulative SEL number is most likely meaningless to a layperson; probably needs examples to what this number is equivalent.}}