Visual deterrents

These devices can vary. For example, they could consist of battery-operated lights set at different flicker rates intended to attract fish but not sea turtles (Wang et al. 2007). Other examples include the illumination of gillnets with a light source such as LED lights or chemical lightsticks (Wang et al. 2013). Deploying the shape of a major predator, such as sharks, near fishing gear. Some studies have indicated that shark shapes trigger an escape response in loggerhead sea turtles (Higgins, 2006). Rope consisting of polypropylene blended with a phosphor that glows a bright yellow-green underwater in wavelengths large cetaceans can see is another example. It glows for 48 hours after activation at an intensity a human can see readily at 20 yards (18 m). The design is based on the premise that with increased visibility cetaceans and perhaps turtles would be more likely to avoid rope entanglements at night or at depth. Current research is looking at how to maintain the glowing properties under the rigors of mechanized hauling (CWBR 2006). Opaque mesh netting can be inserted into the upper portion of a gillnet. This material is highly visible to birds and therefore deters them from becoming entangled in the net. This material is also more visible to marine mammals (Melvin and Conquest 1996).

Displaying 1 - 10 of 17

Study Type: 

Study in the lab

Location: 

Melbourne Zoo, Australia

Target catch: 

N/A

Effect on bycatch species: 

Orange colored monofilament resulted in lower collision rates with a gillnet mimic versus green and clear monofilament

Effect on target catch: 

Not tested

Article: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the wild

Location: 

Bay of Biscay

Target catch: 

hake (Merluccius merluccius), megrim (Lepidorhombus, spp.), and anglerfish (Lophius spp.)

Effect on bycatch species: 

Increasing panel size increased escapes of blue whiting

Effect on target catch: 

Placing the square mesh panel lower in. the trawl net panel increased escape of undersized hake

Article: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the wild

Location: 

San Jose, Salaverry, Ancon, Peru

Target catch: 

Elasmobranchs, tuna, dolphinfish

Effect on bycatch species: 

Bycatch probability per set was reduced by up to 74.4% for sea turtles and 70.8 for small cetaceans in comparison to non-illuminated nets. For seabirds, nominal BPUE decreased by 84% in the presence of LEDs.

Effect on target catch: 

No effect

Article: 

Study Type: 

Field study in the wild

Location: 

Oregon, USA

Target catch: 

Ocean shrimp (Pandalus jordani)

Effect on bycatch species: 

Illumination reduced bycatch of eulachon (Thaleichthys pacificus) and yellowtail rockfish (Sebastes flavidus), but did not result in significant changes in the bycatch of other rockfish (Sebastes spp.) and flatfish

Effect on target catch: 

No change in average catch efficiency or length-dependent catch efficiency.

Article: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the wild

Location: 

Newport, Oregon, USA

Target catch: 

Pacific hake (Merluccius productus)

Effect on bycatch species: 

Artificial illumination can influence where Chinook salmon exit out of a bycatch reduction device, and can be used to enhance overall escapement.

Effect on target catch: 

Not tested

Article: 

Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the wild

Location: 

Finnmark (northern Norway)

Target catch: 

Demersal fish

Effect on bycatch species: 

Escape behavior of haddock can be triggered by mechanical stimulation and were slightly affected by light. Cod did not react significantly to the presence of mechanical stimulation or LED light stimulation.

Effect on target catch: 

Not tested

Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the wild

Location: 

Oregon

Target catch: 

Pacific hake

Effect on bycatch species: 

Chinook were able to escape out of the escape window; Rockfish bycatch was reduced by 32.4%

Effect on target catch: 

Pacific hake continued to swim into the codend

Bycatch species: 

Reduction technique: 

Fishing Gear: 

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