Editing Blue cod (section)

== Predators, parasites, and diseases ==
=== Predators ===
''[[Homo sapiens]]'' (humans) fish 2000 to 2500 tons of ''P. colias'' annually.<ref name="MPI2014" >{{cite web |url= http://fs.fish.govt.nz/Doc/23548/08_BCO%202014%20FINAL.pdf.ashx
 |title=Fisheries Assessment Plenary May 2014: Stock Assessments and Stock Status. Blue Cod (BCO)|author= Ministry for Primary Industries |date=2014 |access-date=2018-04-15}}</ref> Natural predators include: 
*[[Great white shark]]<ref name="NHNZ" />
*[[Benthic zone|Benthic]] feeders, such as:
**[[Yellow-eyed penguin]]s<ref name="Chilvers2014">{{cite journal | last1=Chilvers| first1=B.L. | last2=Dobbins| first2=M.L. | last3=Edmonds| first3=H.K.| year=2014| title= Diving behaviour of yellow-eyed penguins, Port Pegasus/Pikihatiti, Stewart Island/Rakiura, New Zealand. | journal=New Zealand Journal of Zoology |volume=41 |issue=3 |pages=161–170| doi=10.1080/03014223.2014.908931 | s2cid=87018205 }}</ref><ref name="Moore">{{cite journal | last1=Moore| first1=P.J. | last2=Wakelin| first2=M.D. | year=1997| title=Diet of the yellow-eyed penguin ''Megadyptes antipodes'', South Island, New Zealand, 1991-1993. | journal=Marine Ornithology |volume=25 |pages=17–29| doi=10.5038/2074-1235.25.1.377 }}</ref><ref name="Van">{{cite journal|last1=Van Heezik|first1=Y.|author-link=Yolanda van Heezik|year=1990|title=Diets of yellow-eyed, Fiordland crested, and little blue penguins breeding sympatrically on Codfish Island, New Zealand.|journal=New Zealand Journal of Zoology|volume=17|issue=4|pages=543–548|doi=10.1080/03014223.1990.10422952|doi-access=free}}</ref>
**[[Dolphins]]<ref name="Federal">{{cite journal | last1=Federal Register| year=2015| title=Endangered and Threatened Wildlife and Plants; Notice of 12-Month Finding on a Petition To List Bottlenose Dolphins in Fiordland, New Zealand as Threatened or Endangered Under the Endangered Species Act. | journal=Federal Government of United States |url=https://www.federalregister.gov/documents/2015/06/19/2015-15087/endangered-and-threatened-wildlife-and-plants-notice-of-12-month-finding-on-a-petition-to-list}}</ref> 
*[[Sea birds]], such as [[mollymawk]]s<ref name="Govier">{{cite thesis |last1=Govier |first1=D. |year=2001 |title=Growth and movement of Blue Cod (''Parapercis colias'') in Paterson Inlet, Stewart Island, New Zealand |type=M.Sc. thesis |publisher=University of Otago |hdl=10523/2967 |url=http://hdl.handle.net/10523/2967}}</ref>

As many marine predators are [[generalist and specialist species|generalists]]<ref name="Murdoch" /> there are many other potential predators not listed. ''P. colias'' are known to predate upon juveniles of their own species.<ref name="Young" />

=== Parasites ===
Hewitt and Hine<ref name="HewittHine">{{cite journal | last1=Hewitt| first1=G.C. | last2=Hine| first2=P.M. | year=1972| title= Checklist of parasites of New Zealand fishes and of their hosts. | journal=New Zealand Journal of Marine and Freshwater Research |volume=6 |issue=1–2 |pages=69–114| doi=10.1080/00288330.1977.9515410| doi-access=free | bibcode=1972NZJMF...6...69H }}</ref> summarised the parasites found on blue cod including species in five main groups:

{| class="wikitable" style="text-align: left;"
|-
! style="width:20em;" |Group
! style="width:20em;" |Species
! style="width:20em;" |Location on host
|-
|[[Protozoa]]
|
*''[[Trypanosoma]] parapercis''
|
*[[Blood]]
|-
|[[Digenea]]
|
*''[[Apocreadiidae|Pancreadium]] otagoensis''
*''[[Opecoelidae|Plagioporus]]([[Caudotestis]]) pachysomus''
*''[[List of diseases and parasites in cod|Steringotrema]] rotundum''
*''Lecitocladium excisum''
*''[[List of diseases and parasites in cod|Gonocerca]] phyddis''
|
*[[Gastrointestinal tract|Intestine]]
*[[Gastrointestinal tract|Intestine]]
*[[Gallbladder|Gall bladder]] and [[stomach]]
*[[Stomach]]
*[[Stomach]]
|-
|[[Monogenea]]
|
*''[[Microcotyle]] constricta''
|
*[[Gill]]s
|-
|[[Nematode|Nematoda]]
|
*''[[Anisakis]]'' sp. larva
*Contracaecum ''(Thynnascaris)'' sp. larva
|
*[[Viscera]], [[Mesentery (zoology)|mesenteries]] and under [[peritoneum]]
*[[Stomach]], [[Gastrointestinal tract|intestine]] and body cavity
|-
|[[Copepod]]a
|
*''Aethon percis''
*''[[Caligus]] buechlerae''
|
*[[Gill]]s
*[[Skin]]
|}

Blood sucking [[sea louse|sea lice]] are also known to parasitise ''P. colias''.<ref name="NHNZ" />

=== Disease and Injuries ===
No specific [[disease]] is found on ''P. colias'', but some [[Injury|injuries]] have been recorded.  Hooking injuries could cause tissue damage and possibly lead to [[Death|mortality]].<ref name="Carbines1999" >{{cite journal | last1=Carbines |first1=G. | year=1999 | title=Large hooks reduce catch-and-release mortality of blue cod ''Parapercis colias'' in the Marlborough Sounds of New Zealand | journal=North American Journal of Fisheries Management | volume=19 |issue=4 |pages=992–998|doi=10.1577/1548-8675(1999)019<0992:LHRCAR>2.0.CO;2|bibcode=1999NAJFM..19..992C }}</ref> Despite having greater risk for [[Parasitism|parasitic]], [[bacteria]]l, or [[Fungus|fungal]] infections, mortality after having a hook injury is often caused by blood loss rather than disease.<ref name="Meka" >{{cite journal |last1=Meka |first1=J.M. |year=2004| title=The Influence of Hook Type, Angler Experience, and Fish Size on Injury Rates and the Duration of Capture in an Alaskan Catch-and-Release Rainbow Trout Fishery |journal=North American Journal of Fisheries Management | volume=24 |issue=4 |pages=1309–1321 |doi=10.1577/M03-108.1|bibcode=2004NAJFM..24.1309M }}</ref>  An article suggests that small hooks cause more blood loss problems than big hooks to ''P. colias''.<ref name="Carbines1999" />

Compared to other [[Osteichthyes|bony fish]], [[swim bladder|swimming bladder]] in ''P. colias'' is absent,<ref name="Blackwell" >{{cite web |last1=Blackwell |first1=R.G. |year=2014 |title=Abundance, size and age composition, and yield-per-recruit of blue cod in the Marlborough Sounds, September 1996.| publisher=NIWA |url=http://fs.fish.govt.nz/Doc/22460/BCO2003-01%20Blue%20Cod%20Marlborough%20Sounds%20Tasman%20Bay%20abundance%20size%20Objective%201%202%203%20final.pdf.ashx}}</ref> this means that they do not suffer from [[barotrauma]] – an injury due expansion or eruption of the [[swim bladder|swimming bladder]] in fish, it is often caused by rapid water pressure change when rising from deep water to water surface.<ref name="Thorncraft">{{cite journal| last1=Thorncraft |first1=G. |last2=Baumgartner |first2=L.J. |last3=Boys |first3=C.A. |last4=Brown |first4=R.S. |year=2013 | title=Merging hydraulics with biology |journal=International Water Power & Dam Construction | volume=65 |issue=1 |pages=42–43}}</ref>