Trawls

Trawls are cone-shaped nets with two, four, or more panels, ending in a bag. They are towed at midwater or near the bottom, and held open horizontally by heavy doors (<i>otter trawls</i>), by beams, or by the tension created by lines connecting the net to two separate vessels (<i>pair trawls</i>). The net opening is sustained vertically by floats and weights. Fish size and species is controlled by mesh size; pelagic, demersal, and benthic fish can be targeted. The recent development of trawls with large wheels (<i>rockhoppers</i>) prevents damage and tangling of nets, and has eliminated the disincentive to trawling along rugged seafloors.
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For more detailed information, please visit the FAO Fisheries and Aquaculture Department <a href="http://www.fao.org/fishery/geartype/103/en" target="_blank">trawl nets</a> web page.

Displaying 1 - 10 of 112

Study Type: 

Field study in the wild

Location: 

North Coast, Australia

Target catch: 

Prawns: White Banana (Fenneropenaeus merguiensis), Red-legged Banana (F. indicus), Brown Tiger (Penaeus esculentus), Grooved Tiger (P. semisulcatus), Blue Endeavour (Metapenaeus endeavouri), and Red Endeavour (M. ensis)

Effect on bycatch species: 

Reduced bycatch if small individuals by 37.6%

Effect on target catch: 

Increased by .05%

Article: 

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Study Type: 

Field study in the wild

Location: 

Skagerrak, Norway

Target catch: 

Norway lobster (Nephrops norvegicus)

Effect on bycatch species: 

Bycatch of roundfish and flatfish was low

Effect on target catch: 

Optimal catch size of large Nephrops was too low for commercial use

Article: 

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Study Type: 

Field study in the wild

Location: 

Skagerrak, Norway

Target catch: 

Norway lobster (Nephrops norvegicus)

Effect on bycatch species: 

The majority of fish were separated successfully into the upper compartment

Effect on target catch: 

Not tested

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Study Type: 

Field study in the wild

Location: 

Skagerrak, Norway

Target catch: 

Northern shrimp (Pandalus borealis)

Effect on bycatch species: 

Bycatch of Norway pout was slightly reduced in the shorter trawl.

Effect on target catch: 

The trawls fished shrimp above 19 mm carapace length equally, while catch rates of shrimp below 15.5–16 mm carapace length in the shorter trawl were more than halved.

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Study Type: 

Field study in the wild

Location: 

Bay of Biscay

Target catch: 

hake (Merluccius merluccius), megrim (Lepidorhombus, spp.), and anglerfish (Lophius spp.)

Effect on bycatch species: 

Increasing panel size increased escapes of blue whiting

Effect on target catch: 

Placing the square mesh panel lower in. the trawl net panel increased escape of undersized hake

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Bycatch species: 

Reduction technique: 

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Study Type: 

Field study in the wild

Location: 

Oregon, USA

Target catch: 

Ocean shrimp (Pandalus jordani)

Effect on bycatch species: 

Illumination reduced bycatch of eulachon (Thaleichthys pacificus) and yellowtail rockfish (Sebastes flavidus), but did not result in significant changes in the bycatch of other rockfish (Sebastes spp.) and flatfish

Effect on target catch: 

No change in average catch efficiency or length-dependent catch efficiency.

Article: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the wild

Target catch: 

Demersal fish

Effect on bycatch species: 

60% of all fish escaped through the white panel

Effect on target catch: 

Not tested

Article: 

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Reduction technique: 

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Study Type: 

Field study in the wild

Location: 

Northern Australia

Target catch: 

Tiger prawn (Penaeus semisulcatus and P. esculentus) and endeavor prawn (Metapenaus endeavouri and M. ensus)

Effect on bycatch species: 

TEDs facilitated the escape of large elasmobranchs, with bar spacing and TED orientation acting as important design factors affecting escape.

Effect on target catch: 

Not tested

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Study Type: 

Field study in the wild

Location: 

Guyana

Target catch: 

Seabob shrimp (Xiphopenaeus kroyeri)

Effect on bycatch species: 

40% decline in elasmobranch catch rate; mean size of elasmobranch captured reduced by 6.3%

Effect on target catch: 

Not tested

Article: 

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Reduction technique: 

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Study Type: 

Field study in the wild

Location: 

Newport, Oregon, USA

Target catch: 

Pacific hake (Merluccius productus)

Effect on bycatch species: 

Artificial illumination can influence where Chinook salmon exit out of a bycatch reduction device, and can be used to enhance overall escapement.

Effect on target catch: 

Not tested

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