Check out this video for a great introduction to circle hooks: Survival 911: Circle Hooks
The circle hook, though existing in various forms for hundreds of years, has only recently been recognized for its conservation benefits, especially its ability to reduce sea turtle by-catch. Circle hooks demonstrate how a minor change in fishing gear can have powerful benefits in terms of sea turtle conservation and sustainability, and for that reason a circle hook is the logo for the International Smart Gear competition. The major difference between the traditionally used J hooks and circle hooks is simply the direction in which the point of the hook faces. In a J hook, the point of the hook runs parallel to the shank, while in a circle hook, this point is perpendicular to the shank. As the name implies, a circle hook is rounded, and comes in many different sizes and various degrees of offset. Circle hooks are often larger than J hooks, making them less likely to be swallowed by non-targeted species such as sea turtles and makes their removal easier and less likely to cause harmful injuries.
Global examples of the use of circle hooks
Circle hooks have been implemented and tested in many fisheries around the world. We found a number of studies reviewing and assessing the efficacy of switching from traditional J hooks to circle hooks of varying size. The three examples we chose come from Sicily, Italy; Hawaii, USA and Ecuador’s Pacific coast. Though the locations, target species and vessel sizes differ, all are longline fisheries that assessed the effectiveness of circle hooks at reducing by-catch without adversely affecting target catch. The simplified results from the three studies can be seen in Table 1 below.
Table 1. Combined results of experiments testing circle hooks in various fisheries.
The results indicate the use of circle hooks, in all fisheries assessed, decreases sea turtle by-catch. In contrary, however, the effectiveness of circle hooks varies with target catch and must be considered fishery by fishery. Circle hooks, as demonstrated above, have the potential to reduce sea turtle mortality; but to make their implementation effective and successful, target catch per unit effort must not be reduced. Common to all three studies is the recommendation of rigorous experimentation and assessment of the use of circle hooks within each fishery. We support this recommendation in hopes to conserve the ocean’s turtle populations.
References:
Cooke, S.J. & Suski, C.D. (2004) Are circle hooks an effective tool for conserving marine and freshwater recreational catch-and-release fisheries? Aquatic Conservation: Marine and Freshwater Ecosystems, 14, 299-326. DOI: 10.1002/aqc.614
Gilman, E., Zollett, E., Beverly, S., Nakano, H., Davis, K., Shiode, D., Dalzell, P., & Kinan, I. (2006) Reducing sea turtle by-catch in pelagic longline fisheries. Fish and Fisheries, 7, 2–23.
Montrey, N. (1999) Circle hooks ready to boom: Design pierces fish through jaw, promotes conservation. American Sportfishing, 2(1), 6–7.
Piovano, S., Basciano, G., Swimmer, Y., & Giacoma, C. (2012) Evaluation of a bycatch reduction technology by fishermen: A case study from Sicily. Marine Policy, 36, 272-277.
Read, A. (2007) Do circle hooks reduce the mortality of sea turtles in pelagic longlines? A review of recent experiments. Biological Conservation, 135, 155-169.
