Editing Bycatch (section)

== Examples ==

===Recreational fishing===
Given the popularity of recreational fishing throughout the world, a small local study in the US in 2013 suggested that discards may be an important unmonitored source of fish mortality.<ref>{{Cite journal |doi = 10.7287/peerj.preprints.120v1|title = By-catch in a recreational fishery: An unmonitored source of mortality|last1 = McCallum|first1 = Malcolm L.|last2 = Worley|first2 = Gina M.|last3 = Safi|first3 = Barroq|last4 = Dickens|first4 = Kris|last5 = Jones|first5 = Jason|last6 = McCallum|first6 = Jamie L.|journal=PeerJ Preprints|doi-access = free}}</ref>

===Shrimp trawling===
[[File:Trawer Hauling Nets.jpg|thumb|right|Double-rigged shrimp [[fishing trawler|trawler]] hauling in [[Fishing net|nets]]|alt=Photo of boat moving forward at sea. On each side, the boat has one pole pointing away from boat with nets attached]] 
[[File:Shrimp bycatch.jpg|thumb|right|[[Shrimp]] bycatch|alt=Photo of hundreds of dead fish lying on ship deck]]

The highest rates of [[incidental catch]] of non-target species are associated with tropical [[shrimp]] [[trawling]]. In 1997, the [[FAO|Food and Agriculture Organization of the United Nations]] (FAO) documented the estimated bycatch and [[Discards|discard]] levels from shrimp fisheries around the world. They found discard rates (bycatch to catch ratios) as high as 20:1 with a world average of 5.7:1.<ref>{{cite book|last=Clucas |first=Ivor|year=1997|url=http://www.fao.org/docrep/W6602E/w6602E09.htm|title=Discards and bycatch in shrimp trawl fisheries
|publisher=[[FAO]] Fisheries Circular|issue= 928 FIIU/C928}}</ref>

Shrimp trawl fisheries catch two percent of the world total catch of all fish by weight, but produce more than one-third of the world total bycatch. US shrimp trawlers produce bycatch ratios between 3:1 (3 bycatch:1 shrimp) and 15:1 (15 bycatch:1 shrimp).<ref name=Hall>{{cite journal|last1=Hall |first1=M |last2=Alverson |first2=DL |last3=Metuzals |first3=KI|year=2000
|title=By-catch: problems and solutions|journal=Marine Pollution Bulletin|volume=41|issue=1–6|pages=204–219 |doi=10.1016/S0025-326X(00)00111-9|bibcode=2000MarPB..41..204H }}</ref>

[[Trawling|Trawl nets]] in general, and shrimp trawls in particular, have been identified as sources of mortality for [[cetacea]]n and [[finfish]] species.<ref name="SAFMC">SAFMC (2004){{Full citation needed|date=June 2021}}</ref> When bycatch is discarded (returned to the sea), it is often dead or dying.<ref>{{cite book|last1=Morgan |first1=LE |last2=Chuenpagdee |first2=R
|year=2003|title=Shifting Gears. Addressing the Collateral Impacts of Fishing Methods in U.S. Waters}}</ref>

Tropical shrimp trawlers often make trips of several months without coming to port. A typical haul may last four hours after which the net is pulled in. Just before it is pulled on board the net is washed by zigzagging at full speed. The contents are then dumped on deck and are sorted. An average of 5.7:1 means that for every [[kilogram]] of shrimp there are 5.7&nbsp;kg of bycatch. In tropical inshore waters the bycatch usually consists of small fish. The shrimps are frozen and stored on board; the bycatch is discarded.<ref>{{cite book|editor=Clucas, I. |editor2=Teutscher, F. |title=FAO/DFID Expert Consultation on Bycatch Utilization in Tropical Fisheries. Beijing (China), 21–28 September 1998|year=1999|publisher=University of Greenwich, NRI|isbn=978-0-85954-504-4|page=333}}</ref>

Recent sampling in the South Atlantic [[Sicyonia brevirostris|rock shrimp]] fishery found 166 species of finfish, 37 [[crustacean]] species, and 29 other species of [[invertebrate]] among the bycatch in the trawls.<ref name="SAFMC"/> Another sampling of the same fishery over a two-year period found that rock shrimp amounted to only 10% of total catch weight. Iridescent swimming crab, dusky flounder, inshore [[lizardfish]], spot, [[Crangon crangon|brown shrimp]], longspine swimming crabs, and other bycatch made up the rest.<ref name="SAFMC"/>

Despite the use of [[bycatch reduction device]]s, the shrimp fishery in the Gulf of Mexico removes about 25–45 million [[Lutjanus|red snapper]] annually as bycatch, nearly one-half the amount taken in recreational and commercial snapper fisheries.<ref name="GMFMC (2006)"/><ref>{{cite book|publisher=Southeast Data, Assessment, and Review (SEDAR) Stock Assessment Report of SEDAR
|issue=7|year=2005|url=http://www.sefsc.noaa.gov/sedar/download/S7SAR_FINALreduce.pdf?id=DOCUMENT|title=Gulf of Mexico Red Snapper: Assessment Summary Report}}</ref>

===Cetacean===
{{main|Cetacean bycatch}}
[[File:Fraser s group.jpg.jpeg|thumb|left|Group of [[Cetacean bycatch#Spinner and Fraser's dolphins|Fraser's dolphins]]]]
[[Cetacean]]s, such as [[dolphin]]s, [[porpoise]]s, and [[whale]]s, can be seriously affected by entanglement in [[fishing net]]s and [[fishing line|lines]], or direct capture by [[Fish hook|hooks]] or in [[Trawling|trawl nets]]. Cetacean bycatch is increasing in intensity and frequency.<ref name="Demaster (2001)">{{cite journal
|last1=Demaster |first1=DJ |last2=Fowler |first2=CW |last3=Perry |first3=SL |first4=ME |last4=Richlen 
|year=2001
|title=Predation and competition: the impact of fisheries on marine mammal populations over the next one hundred years
|journal=Journal of Mammalogy
|volume=82
|issue=3
|pages=641–651 |doi=10.1644/1545-1542(2001)082<0641:PACTIO>2.0.CO;2
|doi-access=free }}</ref> In some fisheries, cetaceans are captured as bycatch but then retained because of their value as [[Whale meat|food]] or [[Bait fish|bait]].<ref name="Read (2006)">{{cite journal |vauthors=Read AJ, Drinker P, Northridge S |year=2006 |title=Bycatch of marine mammals in the U.S. and global fisheries |journal=[[Conservation Biology (journal)|Conservation Biology]] |volume=20 |issue=1 |pages=163–169 |pmid=16909669 |doi=10.1111/j.1523-1739.2006.00338.x|bibcode=2006ConBi..20..163R |s2cid=157350 }}</ref> In this fashion, cetaceans can become a target of fisheries.

[[File:Entangled porpoise.jpg|right|thumb|A [[Dall's porpoise]] caught in a fishing net]]
One example of bycatch is dolphins caught in [[tuna]] nets. As dolphins are [[mammal]]s and do not have [[gill]]s, they may drown while stuck in nets underwater. This bycatch issue has been one of the reasons of the growing [[ecolabel]]ling industry, where fish producers mark their packagings with disclaimers such as "dolphin friendly" to reassure buyers. However, "dolphin friendly" does not mean that dolphins were not killed in the production of a particular tin of tuna, but that the fleet which caught the tuna did not ''specifically'' target a feeding [[Dolphin#Social behavior|pod]] of dolphins, but relied on other methods to spot tuna schools.{{citation needed|date=April 2009}}
The bycatch of the [[Caspian seal]] may be recognized as one of the biggest entanglements of pinnipeds as bycatch in the world <ref>{{cite journal |doi=10.1371/journal.pone.0067074|pmid=23840590|pmc=3694144|title=Assessment of Caspian Seal By-Catch in an Illegal Fishery Using an Interview-Based Approach|journal=PLOS ONE|volume=8|issue=6|pages=e67074|year=2013|last1=Dmitrieva|first1=Lilia|last2=Kondakov|first2=Andrey A.|last3=Oleynikov|first3=Eugeny|last4=Kydyrmanov|first4=Aidyn|last5=Karamendin|first5=Kobey|last6=Kasimbekov|first6=Yesbol|last7=Baimukanov|first7=Mirgaliy|last8=Wilson|first8=Susan|last9=Goodman|first9=Simon J.|bibcode=2013PLoSO...867074D|doi-access=free}}</ref><ref>{{cite journal |doi=10.1016/j.marpol.2017.09.022|title=Assessment of the sturgeon catches and seal bycatches in an IUU fishery in the Caspian Sea|journal=Marine Policy|volume=87|pages=284–290|year=2018|last1=Ermolin|first1=Ilya|last2=Svolkinas|first2=Linas|url=http://eprints.whiterose.ac.uk/124584/5/Assessment%20of%20IUU%20catches%20after%20revision.pdf}}</ref>

===Albatross===
{{see also|Longline fishing}}
[[File:Albatross hook.jpg|thumb|left|[[Black-browed albatross]] hooked on a long-line|alt=Photo of bird struggling to fly away]]

Of the 22 [[albatross]] species recognised by IUCN on their [[IUCN Red List|Red List]], 15 are [[Threatened species|threatened with extinction]], six species are considered as [[Near-threatened species|Near Threatened]], and only one of [[Least-concern species|Least Concern]].<ref name=":1">{{Cite web |title=BirdLife Data Zone |url=http://datazone.birdlife.org/species/results?cmn=albatross&cty=0&fam=0&gen=0&kw=&reg=0&spc=&thrlev1=&thrlev2=&so=rl |access-date=2022-12-28 |website=datazone.birdlife.org}}</ref> Two species, the [[Tristan albatross]] and the [[waved albatross]], are considered as [[Critically Endangered]].<ref name=":1" /> One of the main threats is commercial [[longline fishing]],<ref>{{cite journal |author=Brothers NP |year=1991 |title=Albatross mortality and associated bait loss in the Japanese longline fishery in the southern ocean |journal=Biological Conservation |volume=55 |issue=3 |pages=255–268 |doi=10.1016/0006-3207(91)90031-4|bibcode=1991BCons..55..255B }}</ref> because albatrosses and other [[seabird]]s which readily feed on [[offal]] are attracted to the set bait, after which they become hooked on the lines and drown. An estimated 100,000 albatross per year are killed in this fashion. Unregulated [[Illegal, unreported and unregulated fishing|pirate fisheries]] exacerbate the problem.

A research study examined the impact of illegal [[longline fishing]] vessels on albatrosses, by using [[environmental criminology]] as a guiding theoretical framework.<ref name=":2">{{Cite journal |last1=Petrossian |first1=Gohar A. |last2=Pires |first2=Stephen F. |last3=Sosnowski |first3=Monique |last4=Venu |first4=Prabha |last5=Olah |first5=George |date=2022 |title=Threats of Longline Fishing to Global Albatross Diversity |journal=Animals |language=en |volume=12 |issue=7 |page=887 |doi=10.3390/ani12070887 |pmid=35405876 |pmc=8997039 |issn=2076-2615|doi-access=free }} {{Creative Commons text attribution notice|cc=by4|from this source=yes}}</ref> The results indicated that potentially illegal longline fishing activities are highly concentrated in areas of illegally-caught fish species, and the risk to bycatch albatrosses is significantly higher in areas where these illegal longline fishing vessels operate.<ref name=":2" /> These findings provide strong grounding that illegal longline fishing poses a particularly serious threat to the survival of [[seabird]]s.
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===Sea turtles===
[[File:Loggerhead Sea Turtle.jpg|thumb|left|[[Loggerhead sea turtle]]|alt=Sea turtle swimming near a diverse group of fish.]]
[[Sea turtle]]s, already critically endangered, have been killed in large numbers in shrimp trawl nets. Estimates indicate that thousands of [[Kemp's ridley sea turtle|Kemp's ridley]], [[loggerhead sea turtle|loggerhead]], [[Green sea turtle|green]], and [[leatherback sea turtle]]s are caught in shrimp trawl fisheries in the [[Gulf of Mexico]] and the US [[Atlantic]] annually<ref name="Epperly">{{Cite journal |last1=Epperly |first1=S |last2=Avens |first2=L |last3=Garrison |first3=L |last4=Henwood |first4=T |last5=Hoggard |first5=W |last6=Mitchell |first6=J |last7=Nance |first7=J |last8=Poffenberger |first8=J |last9=Sasso |first9=C |last10=Scott-Denton |first10=E and |last11=Young |first11=C |year=2002 |access-date=20 December 2009 |url=http://www.sefsc.noaa.gov/PDFdocs/TM_490_Epperly_etal.pdf |title=Analysis of Sea Turtle Bycatch in the Commercial Shrimp Fisheries of Southeast US Waters and the Gulf of Mexico |journal=NOAA Technical Memorandum NMFS-SEFSC-490 |archive-url=https://web.archive.org/web/20090509022328/http://www.sefsc.noaa.gov/PDFdocs/TM_490_Epperly_etal.pdf |archive-date=2009-05-09 }}</ref> The speed and length of the trawl method is significant because, "for a tow duration of less than 10 minutes, the mortality rate for sea turtles is less than one percent, whereas for tows greater than sixty minutes the mortality rate rapidly increases to fifty to one hundred percent".<ref>{{cite journal |doi=10.1017/S0030605310001286 | volume=45 | title=Sea turtle bycatch and consumption in Egypt threatens Mediterranean turtle populations | year=2011 | journal=Oryx | pages=143–149 | last1 = Nada | first1 = Mohamed | last2 = Casale | first2 = Paolo| doi-access=free }}</ref>

Sea turtles can sometimes escape from the trawls. In the Gulf of Mexico, the Kemp's ridley turtles recorded most interactions, followed in order by loggerhead, green, and leatherback sea turtles. In the US Atlantic, the interactions were greatest for loggerheads, followed in order by Kemp's ridley, leatherback, and green sea turtles.<ref name="Epperly"/>
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===Fishing gear===
Bycatch is inevitable wherever there is fishing. The incidental catch is not limited to only fish species: dolphins, sea turtles, and seabirds are also victims of bycatch. Longlines, trawls and [[Seine fishing|purse seine]] nets are driving factors in the endangerment of no fewer than fifteen shark species. Bycatch may also affect reproduction of populations as juveniles are also victims of bycatch. Bycatch happens most commonly with the use of [[gillnetting]], [[longline fishing|longlines]], or [[bottom trawling]]. Longlines with bait hook attachments can potentially reach lengths of dozens of kilometres, and, along with gill nets in the water and bottom trawls sweeping the sea floor, can catch essentially everything in their path.<ref name="seafoodwatch.org">{{cite web|url=https://www.seafoodwatch.org/ocean-issues/wild-seafood/bycatch|title=Effects of Bycatch from Fishing for Wild Seafood from the Seafood Watch Program at the Monterey Bay Aquarium|website=www.seafoodwatch.org}}</ref> There are thousands of kilometres of nets and lines cast into the world's oceans daily. This modern fish gear is robust and invisible to the eye, making it efficient at catching fish and bycatching everything that happens to be in the way.<ref>{{cite web|url=https://www.worldwildlife.org/threats/bycatch|title=Bycatch - Threats|website=World Wildlife Fund}}</ref> Hook-and-line fishing could limit bycatch to a certain extent as the non-target animals can be released back to the ocean fairly quickly.<ref name="seafoodwatch.org"/>