Editing Trawling (section)

==Bottom vs. midwater trawling==
[[File:Trawling Drawing.jpg|thumb|left|Bottom trawling]]{{More citations needed section|date=December 2021}}
Trawling can be divided into [[bottom trawling]] and [[midwater trawling]], depending on how high the trawl (net) is in the [[water column]]. Bottom trawling is towing the trawl along (benthic trawling) or close to (demersal trawling) the sea floor. Bottom trawling is an industrial fishing method in which a large net with heavy weights is dragged across the seafloor, scooping up everything in its path. Bottom trawling can be disadvantageous because it can stir up significant amounts of  sediments that lie on the sea bed <ref>{{Cite journal |last=Oberle |first=Ferdinand K.J. |last2=Storlazzi |first2=Curt D. |last3=Hanebuth |first3=Till J.J. |date=July 2016 |title=What a drag: Quantifying the global impact of chronic bottom trawling on continental shelf sediment |url=https://linkinghub.elsevier.com/retrieve/pii/S0924796315002328 |journal=Journal of Marine Systems |language=en |volume=159 |pages=109–119 |doi=10.1016/j.jmarsys.2015.12.007|url-access=subscription }}</ref> and can harm some marine species.<ref>{{Cite journal |last=Watling |first=Les |date=September 2013 |title=Deep-sea trawling must be banned |url=https://www.nature.com/articles/501007a |journal=Nature |language=en |volume=501 |issue=7465 |pages=7–7 |doi=10.1038/501007a |issn=0028-0836}}</ref> It also causes water pollutants to mix with some plankton, which in turn will move into the food chain, which will then create harmful algae blooms leading to insufficient oxygen. A 2021 study estimated that [[greenhouse gas emissions]] from bottom trawling were as much as aviation.<ref>{{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=2021-12-08|website=the Guardian|language=en}}</ref> However, the estimation methods in the original article  published in the journal Nature,<ref> Sala, E., Mayorga, J., Bradley, D. et al. Protecting the global ocean for biodiversity, food and climate. Nature 592, 397–402 (2021). https://doi-org.mime.uit.no/10.1038/s41586-021-03371-z</ref> have been criticized by other scientists, claiming that the green house gas emission estimates are uncertain.<ref>Hiddink, J. G. et al. Quantifying the carbon benefits of ending bottom trawling. Nature https://doi-org.mime.uit.no/10.1038/s41586-023-06014-7 (2023)</ref> Pr 2024 there is an intense scientific debate going on about this and no final conclusion can yet be drawn. Newer, trial methods employing bottom trawling gear that do not touch the seabed could potentially have lower environmental impact than livestock or fed aquaculture if employed.<ref>{{Cite journal |last=Hilborn |first=R |last2=Amoroso |first2=R |last3=Collie |first3=J |last4=Hiddink |first4=J G |last5=Kaiser |first5=M J |last6=Mazor |first6=T |last7=McConnaughey |first7=R A |last8=Parma |first8=A M |last9=Pitcher |first9=C R |last10=Sciberras |first10=M |last11=Suuronen |first11=P |date=2023-08-11 |editor-last=Raicevich |editor-first=Saša |title=Evaluating the sustainability and environmental impacts of trawling compared to other food production systems |url=https://academic.oup.com/icesjms/article/80/6/1567/7226311 |journal=ICES Journal of Marine Science |language=en |volume=80 |issue=6 |pages=1567–1579 |doi=10.1093/icesjms/fsad115 |issn=1054-3139|doi-access=free }}</ref>
Midway trawling or pelagic trawling target fishes that are living in the upper water column of the ocean. The funnel shaped trawl nets are hauled by one or two boats. This method is generally used to catch fishes of a single species. Unlike bottom trawling, this type of trawl does not come into contact with the sea bed and hence is not involved in damage of marine habitat. Some species caught with this trawling method are mackerel, herring, and hoki. However there may be some disadvantages in using this method as in the process of catching the targeted species of fish, one may end up capturing non targeted fish accidentally and thus discarding of juvenile commercial species of fish may impact on the population. Still, bycatch level is typically lower.

Midwater trawling is also known as [[Pelagic zone|pelagic]] trawling. Midwater trawling catches [[pelagic fish]], whereas bottom trawling targets both bottom-living fish ([[groundfish]]) and semi-pelagic fish.

The gear itself can vary a great deal. Pelagic trawls are typically much larger than bottom trawls, with very large mesh openings in the net, little or no ground gear, and little or no chaffing gear. Additionally, pelagic trawl doors have different shapes than bottom trawl doors, although doors that can be used with both nets do exist.