Use non-ringed hooks

Overall effectiveness category Awaiting assessment
Number of studies: 1
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not assessed
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Background information and definitions

Ringed hooks are made of two parts: the hook itself which is connected to a separate ring that attaches to the line. Non-ringed hooks are in one piece that attaches directly to the line. Ringed hooks tend to be more mobile when underwater and this added mobility may increase the likelihood of sea turtles being caught.

Studies in this action specifically test whether non-ringed hooks are more or less likely to catch sea turtles than ringed hooks. For studies that compare using different types of circle hooks to different types of J-hooks, see: Use circle hooks instead of J-hooks.

See also Use non-offset hooks and Use larger hooks for studies that specifically test these variations in hook design. See also Modify number of hooks between floats on longlines.

Study locations

Key messages

One study evaluated the effects of using non-ringed hooks on reptile populations. This study was in the Mediterranean.

COMMUNITY RESPONSE (0 STUDIES)

POPULATION RESPONSE (0 STUDIES)

BEHAVIOUR (0 STUDIES)

OTHER (1 STUDY)

Unwanted catch (1 study): One replicated, paired study in the Mediterranean found that when non-ringed circle hooks were used in a swordfish longline fishery fewer loggerhead turtles were caught compared to when ringed hooks were used.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

A replicated, paired study in 2009–2013 in pelagic waters in the Strait of Sicily and South Tyrrhenian Sea, central Mediterranean Sea (Piovano & Swimmer 2017) found that fewer loggerhead turtles Caretta caretta were incidentally caught on non-ringed circle hooks than ringed circle hooks in a longline fishery targeting swordfish Xiphias gladius. No loggerhead turtles were caught on non-ringed hooks, compared to six turtles caught on ringed hooks (statistical analyses not carried out due to small sample size). Catch rates of target swordfish were lower on non-ringed hooks (7 fish/1,000 hooks) compared to ringed hooks (9 fish/1,000 hooks). Ringed and non-ringed circle hooks (size: 16/0) with a 10° offset were alternately set along a mainline in an even ratio from six longline vessels (600–1,100 hooks/vessel). Data were collected during 65 longline deployments (using 25,400 of each hook type) in July-September in 2009–2010 and 2012–2013.
Study and other actions tested
Referenced paper
Piovano S. & Swimmer Y. (2017) Effects of a hook ring on catch and bycatch in a Mediterranean swordfish longline fishery: small addition with potentially large consequences. Aquatic Conservation: Marine and Freshwater Ecosystems, 27, 372-380.

Please cite as:

Sainsbury K.A., Morgan W.H., Watson M., Rotem G., Bouskila A., Smith R.K. & Sutherland W.J. (2021) Reptile Conservation: Global Evidence for the Effects of Interventions for reptiles. Conservation Evidence Series Synopsis. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

This Action forms part of the Action Synopsis:

Reptile Conservation

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