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: 

Central Mediterranean Sea

Target catch: 

swordfish

Effect on bycatch species: 

Circle hooks captured fewer (2) loggerheads compared to 2J hooks (9)

Effect on target catch: 

16/0 hooks resulted in a non-statistically significant decrease in catchability compared to size 2 J hooks, but statistically significant decrease compared to size 4 and 5 J hooks

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Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the wild

Location: 

Eastern Pacific Ocean

Target catch: 

Billfish and tuna

Effect on bycatch species: 

Significant differences were found between J4 and C15 and between J4 and C18.

Effect on target catch: 

Significant differences between catch rates were only found between the J-4 and C18 hooks. Large circle hooks (C18) had the lowest catch rates for tunas and small circle hooks (C15) had the lowest catch rates for billfish

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Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the wild

Location: 

Pacific Ocean

Target catch: 

Tuna

Effect on bycatch species: 

Blue and oceanic whitetip shark bycatch increased.

Effect on target catch: 

Tuna catches were significantly higher, but lengths for bigeye and skipjack were smaller; shortbill spearfish and striped marlin catch was lower; no difference in swordfish catch rates, but lengths were greater

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Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the wild

Location: 

California

Target catch: 

White seabass

Effect on bycatch species: 

None reported

Effect on target catch: 

Circle hooks penetrated the lip more frequently (73%) than the J-hook (41%). Hook location was correlated with immediate mortality; all mortalities involved hook damage to the visceral region. A 10% post-release mortality was seen with both hook types.

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Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the wild

Location: 

eastern Pacific Ocean

Target catch: 

Tuna

Effect on bycatch species: 

Significant differences between J and circle hook size 15 and between J and circle hook size 16 were found in the bycatch species group (all species grouped together). Chub mackerel bait caught the sharks.

Effect on target catch: 

No significant differences in catch rates of the target species were found between hook types. The highest catch rates for tunas were found on circle hooks size 15. Squid and jack mackerel bait had the highest catch rates for tunas.

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Bycatch species: 

Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the wild

Location: 

northwest Pacific Ocean

Target catch: 

Pelagic species

Effect on bycatch species: 

None reported

Effect on target catch: 

There were no significant differences in catch rates between hook types but squid bait caught significantly more blue and silky sharks and dolphinfish.

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Reduction technique: 

Fishing Gear: 

Study Type: 

Field study in the wild

Location: 

South-western Atlantic Ocean

Target catch: 

Tuna, blue sharks, swordfish

Effect on bycatch species: 

The incidental capture of loggerhead sea turtles was reduced by 55% and for leatherback sea turtles by 65% when circle hooks were used.

Effect on target catch: 

Catch rates of targeted species including bigeye and albacore tuna and blue sharks were increased with the use of circle hooks, while no difference was found for yellowfin tuna, shortfin mako or hammerhead sharks or for dolphinfish.

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