The concept of a circle hook is almost as old as fishing itself. Archeologists have found ancient circle-style hooks made of reindeer horn in Japan, and similar designs of shell from Polynesia. In North America, Native Americans from the West Coast carved bone hooks that resemble some of today's designs. Circle hooks are, however, one of the hot items in today's fishing industry.

Demand has steadily grown from a base in marine commercial fisheries, particularly longlining, where baited hooks are set to fish passively. In addition to setting without rod action, circle hooks are favored in commercial fisheries because they hook and retain fish, even on slack lines. They also tend to hook fish in the jaw, causing less mortality than standard J-hooks.

Inland, trotliners and limbliners first tried circle hooks. Today, more anglers are experimenting with circle hooks for various species, based on their perceived benefits: Jaw hooking, which should make removal easier; reduced gut-hooking, resulting in less mortality; and easy setting of the hook, which would be ideal for inexperienced anglers and in deep water situations. Other possible advantages include fewer lost fish, fewer snags, and safer handling. Recently, fishery management agencies have recommended circle hooks for their conservation benefits. In a few situations, regulations even require circle hooks.

But what is a circle hook? This term has been applied to a range of designs, from models with a point that mildly turns toward the shank, to a true circle that snags nothing at all if placed in your pocket. In-Fisherman editors have used certain designs extensively in a variety of situations. We'll continue to report our findings as we move forward. Overall, variation in design, along with lack of standardization of sizes among manufacturers, have led to conflicting results and confusion. We receive questions and reports about different designs and sizes for various species and sizes of fish, without resolution of any specific questions.

There's been a similar rise in scientific studies of these tools, particularly their anatomical hooking position, degree of wounding, hooking success rate, and mortality. Dr. Steve Cooke and Cory Suski of the University of British Columbia recently published a major review of scientific findings on this topic.* They charted the increase in studies from 1996, when there were none, to 2004 when 15 were completed or in progress. They then reviewed the results of 43 separate evaluations of circle hooks.

Most have addressed marine fisheries, with striped bass the most common subject. That's due to the huge striper fishery on the East Coast, where annual catch-and-release angling mortality has been estimated at 1.3 million fish, more than the number taken in the commercial fishery that year. Generally, the species most studied are those commonly captured on live or dead baits and those that have substantial hooking mortality with conventional hooks.

Cooke's and Suski's analysis resulted in some conclusions about circle hooks, along with many exceptions, further questions, and new areas for research.

Hooking Mortality: From a management standpoint, hooking mortality is critical when regulations require release of fish of a certain size range. And, of course, fish that are voluntarily released should be in viable condition. Delayed mortality can be important, but it's far more challenging to measure. When results of all studies were lumped, circle hooks resulted in lower mortality than other types, mostly J-hooks and octopus styles. Mortality estimates for circle hooks ranged from 0 to 34 percent, compared to 0 to 46 percent for J-hooks.

*Cooke, S. J., and C. D. Suski. 2004. Are circle hooks an effective tool for conserving marine and freshwater recreational catch-and-release fisheries? Aquat. Conserv.: Mar. Freshwat. Ecosyst. 14:299-326.