Circle hooks

A circular hook design in which the point of the hook is perpendicular to the hook shank. Circle hooks are used widely in many recreational and commercial fisheries and recently have been shown to reduce both the hooking rate and the mortality of turtles that are hooked on pelagic longline gear. As a result of several successful field trials (Bolten and Bjorndal 2005)(Watson et al. 2005), these hooks are becoming increasingly used in longline fisheries.

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Study Type: 

Field study in the wild

Location: 

Hawaii

Target catch: 

Bigeye tuna

Effect on bycatch species: 

Catch rates on circle hooks were significantly lower than on Japanese style and "J" hooks for 16 and 8 species respectively. Fish length was significantly shorter for four species on Japanese style hooks and for three species on "J" hooks. Survival was

Effect on target catch: 

There were no significant differences in catch, catch rate or mean length for bigeye tunas. Survival was significantly higher for bigeye tuna caught on circle vs. Japanese style hooks.

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Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the wild

Location: 

Brazil

Target catch: 

tuna (pelagic) and sharks (bottom)

Effect on bycatch species: 

CPUE was significantly higher for night, blue, silky, and oceanic whitetip sharks on circle hooks.

Effect on target catch: 

None reported for pelagic longlines. On bottom longlines, CPUE was higher for blacknose and nurse sharks and southern stingrays; no CPUE difference between hook type; more tiger and blacknose sharks were alive at haulback with circle hooks

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Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the wild

Location: 

Bay of Bengal

Target catch: 

Tunas and billfish

Effect on bycatch species: 

J-hooks caught a higer percentage (74.5%) of bycatch compared to target (25.5%) species, while circle hooks caught a similar percentage of each (53.3% and 46.7% respectively). Bycatch catch rates were higher on J-hooks (5.6 individuals/1,000 hooks) than

Effect on target catch: 

Target species catch rates were higher on circle hooks (2.2 individuals/1,000 hooks) compared to J-hooks (1.9 individuals/1,000 hooks). Swordfish caught by J-hooks were slightly larger than those caught on circle hooks.

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Reduction technique: 

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Study Type: 

Field study in the wild

Location: 

US Atlantic

Target catch: 

Tuna and swordfish

Effect on bycatch species: 

Pelagic stingrays had higher catch rates on J-style hooks and survival rates of dolphinfish and escolar were higher when circle hooks were used (fall and spring respectively)

Effect on target catch: 

Catch rates of yellowfin tuna caught in the fall were higher on circle hooks. Yellowfin tuna were caught four times as often in the mouth when circle hooks were used in the fall.

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Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the wild

Location: 

Strait of Sicily

Target catch: 

Swordfish

Effect on bycatch species: 

Circle hooks reduced the incidental capture of immature sea turtles

Effect on target catch: 

Circle hooks did not affect catch rates or the size of the targeted catch

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Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the wild

Location: 

off Hawaii

Target catch: 

Swordfish

Effect on bycatch species: 

Leatherback turtle capture rates declined by 83% and loggerhead capture rates declined by 90%

Effect on target catch: 

Swordfish catch increased by 16%, tuna catch decreased by 50%, and mahi-mahi, opah, and wahoo catch decreased by 34%

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Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the wild

Location: 

off Hawaii

Target catch: 

Swordfish

Effect on bycatch species: 

Highly significant reduction in the proportion of turtles that swallowed hooks

Effect on target catch: 

Swordfish catch increased by 16%, tuna catch decreased by 50%, and mahi-mahi, opah, and wahoo catch decreased by 34%

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Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the wild

Location: 

Azores

Target catch: 

Swordfish and blue shark

Effect on bycatch species: 

Non-offset 16/0 and 18/0 circle hooks caught fewer turtles than Japanese tuna hook. Non-offset 18/0 circle hooks caught fewer turtles than non-offset 16/0

Effect on target catch: 

There was no significant difference in the number of blue sharks caught on non-offset 16/0 and 18/0 circle hooks .

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