Dead-bait trolling off Iztapa, Guatemala, showed conclusively that circle hooks produce more fish that are released without evidence of bleeding. Out of 461 sailfish bites, they hooked 360. Using an equal number of J hooks and circle hooks, 125 were caught and released on J hooks versus 235 on circle hooks. Out of those 235 releases, only 14 sailfish showed any signs of bleeding, six of which were deemed severe. Of the J-hook-caught fish, 71 had bleeding, 32 of which were deemed severe. The conclusion? Sailfish caught on J hooks are 21 times more likely to suffer hook-related bleeding — and possible death — than fish caught on circle hooks. Furthermore, circle hooks had a higher hookup percentage. Follow-up studies all came to the same conclusion: Significant conservation benefits can be realized in dead- and live-bait fisheries for billfish and tuna by simply changing the terminal tackle from J hooks to circle hooks.