The Difference Between Circle and “J” Hooks
Although circle hooks have only recently begun to be used in some of the inshore recreational fisheries, they have been used in the commercial longline industry since the 1970s. However, in many cases, the "hooks" used by Native Americans most resembled the circle hook configuration rather than the "J" style hook. The use of circle hooks is currently being touted as a more conservative gear because they are believed to be less injurious and more effective in hooking and catching the targeted quarry. Conservation groups believe that replacing "J" hooks with circle hooks will significantly reduce release mortality and therefore positively impact exploited fish stocks.
A literature search documented a limited number of research reports that addressed the comparative effects of circle and "J" hooks. More than half of the studies found significant positive advantages to using circle hooks while the rest found no significant differences between the two hook types, however, four of these studies dealt with flat fishes, summer flounder, and halibut. The remaining study looked only at using circle hooks of different sizes. If we consider the effects and advantages of using circle hooks in the fisheries that target fishes of the Order Perciformes, (the typical torpedo shaped, dorso-ventrally oriented fishes) then all of the pertinent studies found positive significant improvements when using circle hooks.
Studies that compared the effects of the two hook types in the commercial longline and recreational fisheries for tunas found higher rates of "hook and hold," higher frequency of hooking locations in the jaw, less physical damage and consequential lower release mortality, and an overall significant increase in CPUE (catch-per-unit-effort). Similar studies conducted in the billfish fisheries reported that circle hooks achieved the following advantages over "J" hooks: there were about twice as many hook ups, 85% of the hook ups occurred in the jaw, fish caught on "J" hooks were 21 times more likely to bleed, and that circle hooks minimized deep hooking, foul hooking and injury. Researchers found that circle hooks used in the salmon fisheries reduced release mortality by hooking the fish in the mouth. A study conducted on striped bass found that circle hooks reduced deep hooking fourfold and that the mean lengths of fishes caught on either type hook was not significantly different. In studies conducted on summer flounder, there were no differences in the numbers of fishes caught on either of the hook types. Hook type was not found to be a significant predictor of mortality nor were there statistical differences for both hookset location and release condition. Additionally, offsetting the points of circle hooks greater than 150 resulted in increased gut hooking.
A single study on salmon found that circle hooks caught fewer sub-legal chinook and adult coho salmon but resulted in decreased incidental mortality.
Overall, past research supports the hypothesis that release mortality can be reduced by replacing "J" hooks with circle hooks and that this may result in positive impacts on the exploited fish stocks in Florida.