Hooked on Circle Hooks?

Commercial fishing uses circles hooks

What is a circle hook? Why are many governments enforcing their use in commercial and recreational fisheries? And most importantly, ARE they beneficial? As is often the case in marine science, the answer is… sort of. Read below to find out more!

© OCEANA / Mar MasBycatch is a Problem…a big Problem!

In many fisheries, both commercial and recreational, fish and other marine life are caught using a baited hook. But in many cases the species caught is not the one being targeted. For example, you may go out fishing for Northern Pike but end up hooking into a Smallmouth Bass; or, in a marine setting you may be fishing for Mahi Mahi and catch a Wahoo. Fisheries scientists call this unwanted catch “bycatch in commercial fisheries and “non-target catch” in recreational fisheries. Bycatch is a big deal – cetaceans, sea turtles, sharks, and sea birds are often caught as bycatch. These species typically die after being caught on a long-line hook.

In a perfect world there would be no bycatch because all fishing gear would be designed to catch only the species of interest, which is almost impossible and very unlikely to occur. In the next best scenario all of the bycatch would be released alive and without injury. Releasing bycatch would be similar to recreational anglers who practice catch-and-release. Captured fish are released either because the fish is too small, too big, or the wrong species and so it is put back, alive and well, into the water.

A Solution to Bycatch?


Being caught on a hook can be stressful and can injure a fish. So, in order for catch-and-release to be effective the fish must not die due to its injuries after it has been released.  This is where circle hooks come in. Circle hooks are a kind of hook that are baited and used on long-lines or in recreational fishing. The traditional hook used by many commercial and recreational fishers is called a “J” hook, because it looks like the letter J. By simply changing how round the hook is, we create a circle hook.

Circle hooks have become popular because some research has shown that these hooks reduce bycatch, and bycatch mortality. That is, the percentage of fish that die due to their injuries after being hooked with a circle hook is lower when compared to J hooks.

Higher Chance of Survival for Sea Turtles

For example, a sea turtle caught on a circle hook has a higher chance of survival than one caught on a J hook. Research suggests that circle hooks are effective at reducing mortality because they hook fish and other marine life by the lip or cheek more often than J hooks. While J hooks are known to become lodged in the throat and digestive system (gut) of fish or marine life; when a fish is hooked in the gut its chance of dying is much higher.

In addition to reducing mortality, research suggests that circle hooks are more effective than J hooks for catching some species of fish. That is, you catch more fish if you use circle hooks! In New Zealand it was found that circle hooks caught nearly double the amount of snapper than traditional J hooks in a long-line sea trial that examined the difference between the two types of hooks. Similar results were observed in an Australian study of circle hooks where catch rates for targeted marine species were appreciably higher when compared to J hooks. However, in this study the circle hooks did not reduce mortality of fish caught.

What about recreational fishing?

There is some evidence that suggests some species are HARDER to catch when using a circle hook with a rod and reel. That means for some species circle hooks have lower capture efficiency.  For example, the circle hook was 30-40% less effective at catching Mahi Mahi, yellowfin tuna and wahoo. The fish struck the bait just as often but the hook wouldn’t hold. However, this may be related to angler experience with circle hooks because the process to “set” the hook is a little different compared to traditional J hooks.

Circle Hooks Efficiency Depends on the Fish

Cooke and Suski (2004) summarized their assessment of circle hooks in this way: “Factors such as hook size, fishing style, fish feeding mode, and [fish] mouth morphology all appear to affect the effectiveness of circle hooks.” In their study they also found that capture efficiency is better when using circle hooks on marine species such as tuna, billfish, and striped bass, and that mortality is reduced. However, they found that there is little benefit to using circle hooks when fishing for some freshwater species such as bluegill or largemouth bass. In fact, for largemouth bass circle hooks reduced capture efficiency and didn’t appreciably lower capture mortality. That is, with a circle hook you may catch less bass, and if you catch one it still might die after you release it. Similar to largemouth bass, anglers seeking Musky may not see added capture efficiency or decreased mortality rate using circle hooks.

Given the mixed results as to whether or not circle hooks reduce mortality and prevent bycatch, why are they so popular as a conservation tool?

Commercial fishing uses circles hooks

One reason is that circle hooks are a cheap management tool and easily integrated into existing fishing practices. Also, circle hooks are very effective at reducing sea turtle mortality. Many long-line fisheries in the US are now required to use them (US Fed Reg 2011*). Also, circle hooks reduce shark mortality compared to J hooks; however, the circle hooks do not reduce the catch rates (or capture efficiency) of sharks. In other words, the same number of sharks will still be caught when compared to J hooks, but fewer sharks will die due to their injuries if caught on a circle hook.

So, how does this help you? Hopefully this article will encourage you to support the adoption of circle hooks in fisheries that may catch sea turtles, sharks, sea birds or cetaceans, and use circle hooks in your recreational fishing – as long as you’re not after largemouth bass!

*US fed reg. 2011. Fisheries of the Caribbean, Gulf, and South Atlantic. 50 c.f.r.§ 622. (last updated December 5, 2011)

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