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.

Field Study 586

Study Type: 

wild

Location: 

Mid Atlantic Bight

Target catch: 

Longfin squid

Effect on bycatch species: 

The square-mesh escape panel significantly reduced the average catches of scup and black sea bass. The panel also reduced catches of sublegal-size scup and black sea bass.

Effect on target catch: 

Longfin squid catch was reduced by 88% and 84% in numbers and weight respectively.

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Field Study 560

Study Type: 

wild

Location: 

Northern Australia

Target catch: 

Prawns

Effect on bycatch species: 

Upward facing TED's reduced sea turtle bycatch by 99%

Effect on target catch: 

Reduced the proportion of soft and damaged prawns by 35.8% and reduced catches of tiger prawns by 6.3%

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Field Study 555

Study Type: 

wild

Location: 

Northern Australia

Target catch: 

Prawns

Effect on bycatch species: 

Reduced the number of sharks and rays by 35% when the Popeye Fishbox was placed 70 meshes from the codend draw strings and by 27% when it was placed 100 meshes from the codend draw strings

Effect on target catch: 

Did not significantly reduce the catch of prawns

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Field Study 554

Study Type: 

wild

Location: 

Western Australia

Target catch: 

Red emperor, scarlet perch, spangled emperor, Rankin cod, blue spot emperor, rosy threadfin brea, flagfish, frypan snapper, red snapper and goldband snapper

Effect on bycatch species: 

No rays larger than 120 cm were caught when the grid was used

Effect on target catch: 

None reported

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Field Study 538

Study Type: 

wild

Location: 

Florida

Target catch: 

Shrimp

Effect on bycatch species: 

Florida fisheye bycatch reduction device (BRD) did not significantly reduce finfish bycatch. The large-mesh extended-mesh funnel BRD significantly reduced bycatch. The simulator cone (used with both BRD's) significantly reduced bycatch.

Effect on target catch: 

Florida fisheye BRD retained shrimp. The large-mesh extended-mesh funnel BRD had low shrimp loss at Tarpon Springs but at Biscayne Bay shrimp loss was significant. The simulator cone (used with both BRD's) resulted in significant shrimp loss.

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Field Study 357

Study Type: 

wild

Location: 

Northern Australia

Target catch: 

Prawns

Effect on bycatch species: 

JT 2 design reduced finfish bycatch by 5%

Effect on target catch: 

Caught 5.2% more tiger prawns and 6.9% more endeavour prawns than standard net

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Field Study 356

Study Type: 

wild

Location: 

Northern Australia

Target catch: 

Prawns

Effect on bycatch species: 

JT 2 design did not prevent capture of large sharks and rays

Effect on target catch: 

Caught 5.2% more tiger prawns and 6.9% more endeavour prawns than standard net

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