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Hook Choice Does Matter - Sailfish
Effects of Circle Hook Models on Postrelease Survival of Sailfish
A major target species for offshore recreational anglers, the Atlantic Sailfish, in the vast majority of cases are taken in the U.S. fishery on natural baits and subsequently released.
A recent study by the National Marine Fisheries Service, Miami, Florida, reported that hook choice does matter in the postrelease survival of Sailfish. The study demonstrates that the use of circle hooks with natural baits resulted in a highly significant increase in Sailfish postrelease survival relative to the use of straight-shank (J-type) hooks with natural baits.
Terminal gear performances were assessed in terms of fishing success, hook location and bleeding associated with physical hook damage and trauma.
· 360 Pacific sails were caught in Guatemala to assess terminal gear performance: 235 sail were on circle hooks and 125 were on "J" hooks. Circle hooks used on sailfish had hooking percentages that were 1.83 times higher compared to "J" hooks.
· Significantly more sailfish were hooked in the corner of the mount using circle hooks (85%vs27%) whereas significantly more sailfish were deep hooked in the throat and stomach using "J" hooks (46%vs 2'%).
· Only one sailfish was foul hooked using circle hooks while 11 sailfish caught on "J" hooks were foul hooked.
· Sailfish caught on "J" hooks are about 21 times more likely to suffer hook related bleeding than those caught on circle hooks.
The study of the Atlantic Sailfish was primarily and compared the use of variations of offset circle hooks while live baiting for sailfish in S. Florida.
· 75 Atlantic sailfish were used in this study. No differences in catch percentage or bleeding was found between circle hooks with no offset, minor offset (about 4 degrees), or severe offset points (about 15 degrees).
· The percentage of deep hooking in the throat and stomach for circle hooks with severe offset (44%) was comparable to the deep hooking percentage for "J" hooks (46%)
· In general, use of circle hooks resulted in measures of fishing success that were comparable to or higher than "J" hooks.
· Circle hooks minimized deep hooking, foul hooking, and bleeding.
· Thus, the use of circle hooks has considerable potential for promoting the live release of billfish in recreational fisheries.
MORTALITY
· Stocks of Atlantic Sailfish, blue marlin and white marlin have been identified by ICCAT as either over-exploited or fully exploited for more than two decades.
· The most current summaries of stock status for Atlantic sailfish and marlin note the historically high rates of fishing mortality observed in recent years.
· Recent reports indicate that circle hooks used in rod & reel recreational fisheries for striped bass, Chinook salmon and Atlantic bluefin tuna have been shown to significantly reduce deep hooking and thus promote the live release of these species.
RESULTS OF STUDIES
· Circle hooks showed significantly higher hooking percentages compared to "J" hooks.
· Odds ratio tests indicated that on average, circle hooks are 1.83 times more likely to hook a sailfish than a "J" hook.
· Circle hooks are closely associated with hooks in in the corner of the mouth while "J" hooks were closely associated with deep hooking and foul hooking.
· Seventy on of the 125 sailfish caught on "J" hooks were observed bleeding, as compared to 14 of 235 sailfish caught on circle hooks. This difference was highly significant and the Odds ratio test indicated that a sailfish caught on a "J" hook was 20.75 times more likely to bleed compared to one caught on a circle hook.
· Correspondence analysis showed that "J" hooks were highly associated with minor/moderate/severe bleeding, while circle hooks were associated with no bleeding.
· Seventy-five sailfish were caught on circle hooks using live bait in the recreational fishery off South Florida. Conclusion showed that severe offset circle hooks were associated with deep hooking, while minor and no offset hooks were associated with jaw and corner of mouth hook locations.
FISHING SUCCESS
· One of the first concerns in attempting to change the terminal gear in any recreational fishery is that such a change will negatively impact fishing success. This study showed that catch percentages were unaffected by a change in hook type using the different terminal gears during the fishing in Guatemala.
· Sailfish catch percentages were also high for circle hooks fished with live bait off Florida. However, it should be noted that catch percentages and catch rates for circle hooks depended on the novel forehead hook placement used to rig the dead natural baits, as well as a certain amount of training to implement a more passive approach to setting circle hooks.
· Circle hooks fished in the manner described were found to have a higher hooking percentage for sailfish compared to "J" hooks and this result was corroborated with field observations. For example, it was observed that "J" hooks often de-hooked during the fight when sailfish jumped out of water and this was less likely to occur with a circle hook. The curved point of the circle hook appeared to reduce de-hooking under these circumstances.
· Overall, catch percentages, hooking percentages, and catch rates reported in this study were generally comparable to or higher for circle hooks compared to those for "J" hooks. These results are likely to encourage recreational billfishing constituents, who might not otherwise be receptive to changes in their fishing tackle, to consider the use of circle hooks as a terminal gear alternative to "J" hooks.
PHYSICAL INJURIES DUE TO HOOKING
· Hooks found in the jaw hinge or mouth, or fish bleeding from these locations, were not considered life threatening. Conversely, hooks found in the upper palate, throat, pharynx, esophagus, or in the stomach and fish showing lacerations or bleeding from these areas were considered potentially lethal.
· The results of this study clearly indicated that the use of circle hooks can minimize deep hooking and foul hooking in the recreational trolling/pitch bait fisheries for sailfish.
· Several instances were documented where "J" hooks were foul hooked in the eye. If eye injuries result in blindness, then this injury could potentially affect survival because billfish are highly dependent on daytime sight feeding in the upper portions of the water column. Blindness in one eye would negatively impact peripheral vision and could seriously inhibit the ability of these species to feed. Numerous instances were also documented where "J" hook injuries that were not caused by foul hooking could have caused eye damage. In some cases, "J" hooks caused deep lacerations to the upper palate, which, on occasion, affected the occipital orbit and resulted in hemorrhaging in the eye. These injuries are deceptive and are difficult to see in the fish at boat side. In addition, upper palate injuries can also affect the integrity of the cranial cavity by making this area susceptible to possible infection. However, these injuries are not immediately evident upon capture.
· The evaluation of bleeding indicated that significantly more sailfish caught on "J" hooks bled compared to circle hooks. This result may be the single most compelling finding in this study, as sailfish caught on "J" hooks were about 21 times more likely to bleed compared to those caught on circle hooks.
· Bleeding from the gills was found in 10% of the sailfish caught on "J" hooks and 1% of the sailfish caught on circle hooks. However, circle hooks were not found embedded in gill arches or filaments, whereas numerous "J" hooks were found lodged in these structures. After closer observation, it was determined that monofilament frequently became caught behind the gill plates during the fight, regardless of the type of terminal gear. Monofilament coming into contact with the gill structure appeared to irritate the gill filaments and resulted in mostly moderate or minor bleeding. This was non-hook related bleeding.
CONCLUSION
"The current high rate of fishing mortality and depressed stock status of most Atlantic billfish justify development of alternative approaches for reducing hook induced mortality for these species. One such approach would be the modification of terminal gear in order to reduce hook related injuries and trauma experienced during catch and release fishing. This study compared circle hook and similar size "J" hook performance while trolling/pitching dead bait or drifting live bait for billfish-methods often used by anglers targeting these species. Rates of fishing success and hooking percentage were comparable or higher for circle hooks compared to "J" hooks. In addition, use of circle hooks resulted in lower rates of deep hooking, foul hooking, and bleeding compared to "J" hooks. During live bait experiments, severe offset circle hooks (>15 degrees) were associated with increased deep hooking percentages (44%) that were similar to percentages observed for "J" hooks using dead bait (46%). Given the multiple benefits of minimized hook related injury and comparable or improved fishing success and hooking percentages using circle hooks in dead or live bait recreational fisheries for billfish, this terminal gear appears to have potential as a means to promote the live release of these species.
Current U.S. domestic management measures requiring the use of non-offset circle hooks with natural baits during registered tournaments for Atlantic billfishes (Istiophoridae) will provide some relief for sailfish; however, the use of circle hooks in recreational fisheries targeting this species throughout the Atlantic Ocean could substantially reduce fishing mortality on this overfished resource. Many Florida anglers independently choose circle hooks for a perceived benefit that circle hooks generally lodge in the corner of the jaw, avoiding internal injuries sometimes associated with deeply embedded J hooks.
