Editing Bottom trawling (section)

{{Short description|Fishing method by towing a net along the seafloor}}
[[File:RV Celtic Explorer, Galway Bay, Ireland.jpg | thumb | The ''[[RV Celtic Explorer|Celtic Explorer]]'', a [[research vessel]] engaged in bottom trawling]]
'''Bottom trawling''' is [[trawling]] (towing a '''trawl''', which is a [[fishing net]]) along the seafloor. It is also referred to as "dragging". The scientific community divides bottom trawling into benthic trawling and [[Demersal zone|demersal]] trawling. Benthic trawling is towing a net at the very bottom of the ocean and demersal trawling is towing a net just above the [[benthic zone]]. Bottom trawling can be contrasted with [[midwater trawling]] (also known as [[Pelagic zone|pelagic]] trawling), where a net is towed higher in the [[water column]]. Midwater trawling catches [[pelagic fish]] such as [[anchovies]] and [[mackerel]], whereas bottom trawling targets both bottom-living fish ([[groundfish]]) and [[semi-pelagic]] species such as [[cod]], [[squid]], [[shrimp]], and [[Sebastes|rockfish]].

Trawling is done by a [[Fishing trawler|trawler]], which can be a small open boat with only {{convert|30|hp|abbr=on}} or a large factory trawler with {{convert|10000|hp|abbr=on}}. Bottom trawling can be carried out by one trawler or by two trawlers fishing cooperatively ([[pair trawling]]).

Global catch from bottom trawling has been estimated at over 30 million tonnes per year, an amount larger than any other fishing method.<ref>{{Cite journal|last1=Watson|first1=Reg A.|last2=Tidd|first2=A.|date=2018-07-01|title=Mapping nearly a century and a half of global marine fishing: 1869–2015|journal= [[Marine Policy]] |language=en|volume=93|pages=171–177|doi=10.1016/j.marpol.2018.04.023|bibcode=2018MarPo..93..171W |s2cid=158305071 |issn=0308-597X|url=http://osf.io/mcvp5/|url-access=subscription}}</ref> Concerns about the environmental impacts of bottom trawling have led to changes in gear design, such as the addition of [[turtle excluder device]]s to reduce [[bycatch]], and limitations on locations where bottom trawling is allowed, such as [[marine protected area]]s.<ref>{{Cite web|url=http://www.seafoodwatch.org/ocean-issues/fishing-and-farming-methods|title=Fishing and Farming Methods from the Seafood Watch Program at the Monterey Bay Aquarium|website=www.seafoodwatch.org|language=en|access-date=2018-08-23}}</ref> A 2021 paper estimated that bottom trawling contributed between 600 and 1500 million tons of carbon dioxide a year by disturbing carbon dioxide in the sea floor&nbsp;– emissions approximately equivalent to [[Climate change in Germany|those of Germany]], or [[Environmental impact of aviation|the aviation industry]].<ref>{{Cite journal|last1=Sala|first1=Enric|last2=Mayorga|first2=Juan|last3=Bradley|first3=Darcy|last4=Cabral|first4=Reniel B.|last5=Atwood|first5=Trisha B.|last6=Auber|first6=Arnaud|last7=Cheung|first7=William|last8=Costello|first8=Christopher|last9=Ferretti|first9=Francesco|last10=Friedlander|first10=Alan M.|last11=Gaines|first11=Steven D.|date=2021-03-17|title=Protecting the global ocean for biodiversity, food and climate|url=https://www.nature.com/articles/s41586-021-03371-z|journal=Nature|volume=592|issue=7854|language=en|pages=397–402|doi=10.1038/s41586-021-03371-z|pmid=33731930|bibcode=2021Natur.592..397S|s2cid=232301777 |issn=1476-4687}}</ref><ref>{{Cite news|last=Einhorn|first=Catrin|date=2021-03-17|title=Trawling for Fish May Unleash as Much Carbon as Air Travel, Study Says|language=en-US|work=The New York Times|url=https://www.nytimes.com/2021/03/17/climate/climate-change-oceans.html|access-date=2021-03-18|issn=0362-4331}}</ref><ref name=":0">{{Cite web|date=2021-03-17|title=Bottom trawling releases as much carbon as air travel, landmark study finds|url=http://www.theguardian.com/environment/2021/mar/17/trawling-for-fish-releases-as-much-carbon-as-air-travel-report-finds-climate-crisis|access-date=2021-03-20|website=The Guardian|language=en}}</ref> However, these values are highly uncertain and have been criticized as overestimates.<ref>{{Cite journal |last1=Hiddink |first1=Jan Geert |last2=van de Velde |first2=Sebastiaan J. |last3=McConnaughey |first3=Robert A. |last4=De Borger |first4=Emil |last5=Tiano |first5=Justin |last6=Kaiser |first6=Michel J. |last7=Sweetman |first7=Andrew K. |last8=Sciberras |first8=Marija |date=2023 |title=Quantifying the carbon benefits of ending bottom trawling |url=https://www.nature.com/articles/s41586-023-06014-7 |journal=Nature |language=en |volume=617 |issue=7960 |pages=E1–E2 |doi=10.1038/s41586-023-06014-7 |pmid=37165247 |bibcode=2023Natur.617E...1H |issn=1476-4687}}</ref><ref>{{Cite journal |last1=Hilborn |first1=Ray |last2=Kaiser |first2=Michel J. |date=2022 |title=A path forward for analysing the impacts of marine protected areas |url=https://www.nature.com/articles/s41586-022-04775-1 |journal=Nature |language=en |volume=607 |issue=7917 |pages=E1–E2 |doi=10.1038/s41586-022-04775-1 |pmid=35794262 |bibcode=2022Natur.607E...1H |issn=1476-4687|url-access=subscription }}</ref> International attempts to limit bottom trawling have been ineffective.