Gillnets

Gillnets are single, double, or triple layers of net suspended vertically in the water column. The top of the net is connected to floats (headrope), while the bottom is weighted (footrope). Adjustment of the floats and weights allows gillnets to be positioned at varying depth, depending on the target species. Gillnets are generally deployed in large numbers and trap fish either by entangling the gills or by entangling all or part of the fish body. Variation in net mesh size allows fishermen to control the size of their catch.
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<i>Set nets</i> are stationary gillnets set near the bottom or at a particular depth. A subset of set gillnets, <i> fixed nets </i> are stretched between stakes driven into the bottom in intertidal areas. In contrast, <i>drift nets</i> are unanchored and float with the current. Drift nets are mostly used near the sea surface. <i>Trammel nets</i> are multi-layered gillnets usually set near the ocean bottom. FIsh are ensnared in the middle layer, which has the finest mesh size. <i>Encircling gillnets</i> are set in a circle in shallow water. Fishers create a disturbance in the water that drives fish into the nets. Several gillnet types may be used in conjunction; combined gill-trammel nets are particularly popular.
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For more detailed information, please visit the FAO Fisheries and Aquarculture Department <a href="http://www.fao.org/fishery/geartype/107/en" target="_blank"> gillnets </a> web page.

Experimental testing of acoustic alarms (pingers) to reduce bycatch of harbor porpoise, Phocoena phocoena, in the state of Washington

Study Type: 

wild

Location: 

Washington State

Target catch: 

Salmon & sturgeon

Effect on bycatch species: 

Reduced harbor porpoise bycatch

Effect on target catch: 

Did not affect target catch

Article: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

A field experiment using acoustic alarms (pingers) to reduce harbour porpoise by-catch in bottom-set gillnets

Study Type: 

wild

Location: 

Sweden

Target catch: 

Cod and pollock

Effect on bycatch species: 

No bycatch in nets with or without pingers

Effect on target catch: 

Did not affect target catch

Article: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

Analysis and mitigation of cetacean bycatch in UK fisheries

Study Type: 

wild

Location: 

Scotland

Target catch: 

Trout

Effect on bycatch species: 

Increased bycatch

Article: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

Analysis and mitigation of cetacean bycatch in UK fisheries

Study Type: 

wild

Location: 

Scotland

Target catch: 

Trout

Effect on bycatch species: 

Reduced bycatch

Article: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

Analysis and mitigation of cetacean bycatch in UK fisheries

Study Type: 

wild

Location: 

Scotland

Target catch: 

Trout

Effect on bycatch species: 

Did not reduce bycatch

Article: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

Target strength of a nylon monofilament and an acoustically enhanced gillnet: predictions of biosonar detection ranges

Study Type: 

wild

Location: 

Captivity

Target catch: 

Trout

Effect on bycatch species: 

Increased detectability

Article: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

Nylon barium sulphate gillnet reduces porpoise and seabird mortality

Study Type: 

wild

Location: 

Canada

Target catch: 

Multiple species

Effect on bycatch species: 

Reduced harbor porpoise bycatch

Effect on target catch: 

No difference in catch

Article: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

Field Study 155

Study Type: 

wild

Location: 

Gulf of Maine

Target catch: 

n/a

Effect on bycatch species: 

Gillnets with pingers caught fewer porpoise

Effect on target catch: 

n/a

Article: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

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