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 295

Study Type: 

wild

Location: 

Northern Australia

Target catch: 

Prawns

Effect on bycatch species: 

Reduced the number of sea snakes caught by 87% when the Popeye Fishbox was placed 70 meshes from codend (no analysis was done when the device was placed 100 meshes from codend draw strings)

Effect on target catch: 

Did not significantly reduce the catch of prawns

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Field Study 291

Study Type: 

wild

Location: 

New South Wales, Australia

Target catch: 

Prawns

Effect on bycatch species: 

Reduced the overall weight of bycatch by 38% when mesh panels were oriented horizontally

Effect on target catch: 

Did not significantly reduce the catch of prawns

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Field Study 284

Study Type: 

wild

Location: 

New South Whales, Australia

Target catch: 

Prawns

Effect on bycatch species: 

Reduced the overall weight of bycatch by 46% when mesh panels were oriented vertically

Effect on target catch: 

Did not significantly reduce the catch of prawns

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Field Study 280

Study Type: 

wild

Location: 

Florida

Target catch: 

Shrimp

Effect on bycatch species: 

Reduced the biomass and number of finfish and the catch per unit effort

Effect on target catch: 

The number and biomass was not reduced in the 17 m or 20 m nets and the catch per unit effort varied by season and net size. Less shrimp was caught in the winter using the 14m nets.

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Field Study 275

Study Type: 

wild

Location: 

Northern Australia

Target catch: 

Prawns

Effect on bycatch species: 

Reduced sea turtle catches by 100%

Effect on target catch: 

Reduced the proportion of soft and damaged prawns by 41.6% and reduced catches of tiger prawns by 6.5%

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Field Study 274

Study Type: 

wild

Location: 

Northern Australia

Target catch: 

Prawns

Effect on bycatch species: 

Reduced large sponge catches by 85.3%

Effect on target catch: 

Reduced the proportion of soft and damaged prawns by 41.6% and reduced catches of tiger prawns by 6.5%

Article: 

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Reduction technique: 

Fishing Gear: 

ant

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: 

Reduced dolphin bycatch by almost 50% and reduced bycatch of sea turtles, large sharks and large rays

Effect on target catch: 

Not reported

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Reduction technique: 

Fishing Gear: 

ant

Study Type: 

wild

Location: 

Australia

Target catch: 

Tiger prawn

Effect on bycatch species: 

reduced mean weight of small bycatch and mean number of seasnakes caught

Effect on target catch: 

no loss of tiger prawns

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Reduction technique: 

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Study Type: 

wild

Location: 

Australia

Target catch: 

winter blue grenadier

Effect on bycatch species: 

Expelled caught seals and limited access to codend

Effect on target catch: 

Not available

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