Excluder devices

These can consist of a grid of metal bars or mesh placed usually within the neck of a trawl that has an opening for escape at either the top or bottom. Examples include “skylights” which consist of a mesh opening located at the top of the codend. ”Skylights” can be combined with guiding funnels that create visual and tactile stimuli to direct finfish towards the “skylight” escape sections. A different but similar type of design is the fisheye (including Gulf and yarrow fisheyes and bigeyes) which are openings typically forming a rigid frame constructed of aluminum or steel rods and placed along the top center portion of the codend (i.e. Catchpole and Revill 2007). Typically, large animals that strike the bar exit through the opening, while the smaller target species pass through the bars and are captured in the net or codend. Examples of excluder devices in trawls are the Nordmore grid, the Turtle Excluder Device (TED), and the Sea Lion Excluder Device (SLED). A sea turtle excluder chain mat is used in the Northwest Atlantic scallop dredge fishery. A new modification to pound nets may reduce sea turtle bycatch by replacing the upper two-thirds of the leader netting with vertical ropes spaced wide enough apart to let sea turtles swim through without becoming entangled (DeAlteris et al., 2005).

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Study Type: 

Field study in the wild

Location: 

New South Wales, 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

Article: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the 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.

Article: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the 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%

Article: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the 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: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the 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

Article: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the 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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Bycatch species: 

Reduction technique: 

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