Electromagnetic deterrents

Electromagnetic fields created in the vicinity of a fishing activity to deter interaction of non-target species with fishing gear, bait, or target species. For example, rare earth metals, such as cerium or lanthanide, are attached or imbedded into hooks (longline, hook and line etc.) in an effort to deter the incidental bycatch of sharks and rays (Tallack et al. 2009). The main prize of the 2006 Smart Gear competition run by the World Wildlife Fund was for a magnetic shark deterrent to be tested on pelagic longlines. Polet et al (2005) describe evaluations of an "electro-trawl" in which electric charges stimulated shrimp into moving upward from the sea floor into the path of the trawl mouth. In this approach, the space between the groundrope and the benthos might be increased without reducing target catch levels but decreasing the contact the trawl might have with some non-target benthic invertebrates and groundfish.

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Study Type: 

Field study in the wild

Location: 

Northeast Atlantic Ocean

Target catch: 

Tuna

Effect on bycatch species: 

Magnets did not deter blue sharks and may have had an attractive effect.

Effect on target catch: 

Not tested

Article: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Study in the lab

Target catch: 

Shrimp tended to do a tail flip in response to some electric pulses and ragworm showed a squirming response independent of the frequency.

Effect on bycatch species: 

N/A

Effect on target catch: 

N/A

Article: 

Bycatch species: 

Reduction technique: 

Study Type: 

Field study in the wild

Location: 

NE Atlantic

Target catch: 

Tuna and blue sharks

Effect on bycatch species: 

Magnets increased and did not decrease blue shark catch rates. Larger magnets had a stronger effect.

Effect on target catch: 

None reported

Article: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the wild

Location: 

Alaska

Target catch: 

Pacific halibut

Effect on bycatch species: 

Experimental hooks resulted in greater reduction on catch of longnose skate

Effect on target catch: 

Did not affect catches

Article: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Summary study

Location: 

North Sea

Target catch: 

Flatfish

Effect on bycatch species: 

30-50% reduction in fish and 48-73% reduction in benthic discards

Effect on target catch: 

Catches were 65-69% lower compared to conventional trawls

Article: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

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