Study

A comparison of circle hook and J hook performance in a western equatorial Atlantic Ocean pelagic longline fishery

  • Published source details Pacheco J.C., Kerstetter D.W., Hazin F.H., Hazin H., Segundo R.S.S.L., Graves J.E., Carvalho F. & Travassos P.E. (2011) A comparison of circle hook and J hook performance in a western equatorial Atlantic Ocean pelagic longline fishery. Fisheries Research, 107, 39-45.

Actions

This study is summarised as evidence for the following.

Action Category

Use circle hooks instead of J-hooks

Action Link
Reptile Conservation

Use a different hook type

Action Link
Marine Fish Conservation
  1. Use circle hooks instead of J-hooks

    A replicated, paired, controlled study in 2006–2007 in pelagic waters in the western equatorial Atlantic Ocean off the coast of Brazil (Pacheo et al. 2011) found that using circle instead of J-hooks in a longline fishery did not reduce unwanted catch of leatherback turtles Dermochelys coriacea, green turtles Chelonia mydas or olive ridley turtles Lepidochelys olivacea. Numbers of sea turtles caught with circle hooks (leatherback: 1.4 turtles/1,000 hooks, green: 1.4, olive ridley: 2.5) was statistically similar to J-hooks (3.1, 1.7, 1.9). Catch rates of commercially-targeted bigeye tuna Thunnus obesus increased when circle hooks were used (23 fish/1,000 hooks) compared to J-hooks (17 fish/1,000 hooks). Catch rates of commercially-targeted sailfish Istiophorus platypterus reduced when circle hooks were used (0.6 fish/1,000 hooks) compared to J hooks (4.4 fish/1,000 hooks). Catch rates of all other commercially-targeted species were similar between hook types (see paper for details). On six fishing trips, three commercial pelagic longline fishing vessels (24.6–26.9 m long) using similar gear carried out 81 deployments targeting swordfish Xiphias gladius and bigeye tuna Thunnus obseus (11–15 deployments/trip) in August 2006–January 2007. Circle hooks (size 18/0, 0◦ offset) and traditional J-style hooks (size 9/0, 10◦ offset) were alternated along the mainline (50,170 hooks in total, divided equally between circle and J-hooks). Hooks were baited with squid Illex sp. and lit with battery-run light attractants. Lines were deployed overnight.

    (Summarised by: Katie Sainsbury)

  2. Use a different hook type

    A replicated, controlled study in 2006–2007 in an area of pelagic water in the Atlantic Ocean, off Brazil (Pacheco et al. 2011) found that circle hooks caught fewer unwanted rays Myliobatiformes and sailfish Istiophorus platypterus compared to J hooks, and overall similar amounts of other target and non-target fish groups. Overall, circle hooks caught fewer rays (two species, mainly pelagic stingray Pteroplatytrygon violacea) than J hooks (circle: 21, J hook: 161). Catches of unwanted sailfish were also lower on circle hooks (2) than J hooks (10). Overall catches of three other species groups (billfish Istiophoridae, other bony fish and sharks) and total catch composition were similar for each hook type (data reported as statistical model results). The occurrence of deep-hooking injuries (associated with higher post-release mortality) was lower on circle hooks than J hooks for all species groups (data reported as graphical analysis). In addition, target catches of tunas Thunnus spp. were higher on circle (29/1,000 hooks) than J hooks (23/1,000 hooks), but swordfish Xiphias gladius catches were similar. Data were collected during six pelagic longline trips using three vessels in August 2006 and January 2007. A total of 81 longline sets were fished (50,170 hooks) with circle hooks (size 18/0, 0° offset) alternated equally with J hooks (size 9/0, 10° offset) baited with squid Illex sp.

    (Summarised by: Leo Clarke)

Output references
What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 19

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.


Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape Programme Red List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Bern wood Supporting Conservation Leaders National Biodiversity Network Sustainability Dashboard Frog Life The international journey of Conservation - Oryx British trust for ornithology Cool Farm Alliance UNEP AWFA Butterfly Conservation People trust for endangered species Vincet Wildlife Trust