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1.
The Queensland Great Barrier Reef line fishery in Australia is regulated via a range of input and output controls including minimum size limits, daily catch limits and commercial catch quotas. As a result of these measures a substantial proportion of the catch is released or discarded. The fate of these released fish is uncertain, but hook-related mortality can potentially be decreased by using hooks that reduce the rates of injury, bleeding and deep hooking. There is also the potential to reduce the capture of non-target species though gear selectivity. A total of 1053 individual fish representing five target species and three non-target species were caught using six hook types including three hook patterns (non-offset circle, J and offset circle), each in two sizes (small 4/0 or 5/0 and large 8/0). Catch rates for each of the hook patterns and sizes varied between species with no consistent results for target or non-target species. When data for all of the fish species were aggregated there was a trend for larger hooks, J hooks and offset circle hooks to cause a greater number of injuries. Using larger hooks was more likely to result in bleeding, although this trend was not statistically significant. Larger hooks were also more likely to foul-hook fish or hook fish in the eye. There was a reduction in the rates of injuries and bleeding for both target and non-target species when using the smaller hook sizes. For a number of species included in our study the incidence of deep hooking decreased when using non-offset circle hooks, however, these results were not consistent for all species. Our results highlight the variability in hook performance across a range of tropical demersal finfish species. The most obvious conservation benefits for both target and non-target species arise from using smaller sized hooks and non-offset circle hooks. Fishers should be encouraged to use these hook configurations to reduce the potential for post-release mortality of released fish.  相似文献   

2.
We conducted a meta‐analysis of literature reporting on the use of circle hooks and J‐hooks in pelagic longline fisheries. Our study included more data than previous meta‐analyses of the effects of hook type, due to both a larger number of relevant studies available in recent years and a more general modelling approach. Data from 42 empirical studies were analysed using a random effects model to compare the effects of circle hooks and J‐hooks on catch rate (43 species) and at‐vessel mortality (31 species) of target and bycatch species. Catch rates with circle hooks were greater for 11 species, including four tuna species, six shark species and one Istiophorid billfish. Catch rates on circle hooks were lower for seven species, including two Istiophorid billfishes and two species of sea turtle. At‐vessel mortality was significantly lower with circle hooks in 12 species, including three tuna species, three Istiophorid billfishes, swordfish (Xiphias gladius) and three shark species. No species had significantly greater at‐vessel mortality when captured with a circle hook rather than a J‐hook. While our general approach increased model variability compared to more detailed studies, results were consistent with trends identified in previous studies that compared the catch rates and at‐vessel mortality (between hook types) for a number of species. Our results suggest that circle hooks can be a promising tool to reduce mortality of some bycatch species in pelagic longline fisheries, although the effects depend on the species and the metric (catch rate or at‐vessel mortality), emphasizing the need for fishery‐specific data in conservation and management decisions.  相似文献   

3.
Catch composition, catch rates, hooking location, and status at release at haulback were monitored during 81 experimental sets (launches and hauling fishing per day) in a commercial pelagic longline fishery targeting tuna in the equatorial South Atlantic Ocean. Circle hooks (size 18/0, 0° offset) and J-style hooks (size 9/0, 10° offset) with squid baits were deployed in an alternating fashion. The catch composition was not significantly different for most species between the two types of hooks, except for bigeye tuna, which showed a significantly higher proportion of catches on the circle hook (p ? 0.001) and for sailfish, pelagic stingray, and leatherback sea turtle, which had higher catch rates on the J-style hook (p = 0.018, p ? 0.001, and p = 0.044, respectively). Bigeye and yellowfin tuna showed significantly higher rates of survival at the time of gear retrieval with circle hooks, and circle hooks hooked bigeye tuna, yellowfin tuna, swordfish, and sailfish significantly more often externally than internally. Our results suggest that the use of size 18/0, 0° offset circle hooks in the equatorial pelagic longline fishery may increase the survival of bycatch species at the time of gear retrieval with minimal effects on the catches of target species.  相似文献   

4.
  1. This study evaluated the circle hook use as a tool for shark management in the pelagic longline fishery in the Gulf of Gabès.
  2. The usual J‐hook No. 2 with 10° offset, which has been traditionally used by the fishery, was compared to the 18/0 non‐offset circle hook in an alternating fashion along the main line. In total, 22 experimental longline sets were deployed through the shark fishing seasons of 2016 and 2017 to examine the effects of hook types on the catch composition, the catch rates, the hooking location, and the status at haulback.
  3. The catch composition differed significantly among hook types. Moreover, an overall increase in catch rates for the main species, the sandbar shark Carcharhinus plumbeus, and the shortfin mako shark Isurus oxyrinchus, was observed when using circle hooks.
  4. There was no size‐selective effect of circle hooks for the common species. The circle hooks were not effective at reducing at‐haulback mortality of sandbar shark. Conversely, shortfin mako and smooth‐hound shark Mustelus mustelus showed significantly lower relative mortality at haulback with circle hooks than with J‐hooks. Furthermore, circle hooks were more frequently hooked externally than the J‐hooks for the three shark species.
  5. Results demonstrated that the use of 18/0 non‐offset circle hooks in the pelagic shark longline fishery can reduce mortality at haulback for some species without any benefit for the dominant species, the sandbar shark.
  6. Overall, it is difficult to promote the adoption of the use of circle hooks as a management measure in this specialized fishery. Management measures focusing on fishing effort controls, fishing closures in critical habitats, and size limits could have significant benefits for the conservation of shark species and may help to improve the sustainability of the shark fishery in the Gulf of Gabès.
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5.
We performed a quantitative review to evaluate circle hook use in recreational and commercial hook-and-line fisheries that interact with billfishes (Family: Istiophoridae). Specifically, we scrutinized the findings of 11 recent empirical studies that reported, on a species-specific basis, side-by-side measures of circle vs. J-hook fishing performance: catch, mortality, deep-hooking and bleeding rates. Of the 30 total comparisons extracted from the literature that satisfied our inclusion criteria, 13 indicated significant differences between hook types for the specific metric compared. No study reported significant billfish catch rate differences between hook types. However, when significant differences between hook types were found, higher mortality rates and higher rates of deep-hooking and bleeding were associated with J-hooks relative to circle hooks. We conclude that empirical evidence is sufficient to promote circle hook use in almost all hook-and-line fishery sectors that typically interact with istiophorids. However, billfish conservation benefits will only be realized if fishers use unmodified circle hooks, commit to releasing live fish and take other appropriate measures which maximize post-release survival. While there may be fishing modes where circle hook effects are negative, for billfish conservation, we recommend managers grant exceptions to circle hook use only when experimental results support such a practice.  相似文献   

6.
The U.S. Atlantic coastal pelagic longline fishery that targets tunas and swordfish also interacts with a wide range of non-target species including billfishes and sea turtles. Preliminary studies indicate that a change in terminal gear from J-style hooks to circle hooks may reduce bycatch mortality, but the effects of this change on catch rates of target species are unclear. To evaluate this, we monitored catch composition, catch rates, hooking location, and number of fish alive at haulback during 85 sets in the fall and spring seasonal fisheries from a commercial vessel operating in the western North Atlantic. Circle (size 16/0, 0° offset) and J-style (size 9/0, 10° offset) hooks were deployed in an alternating fashion. Hook–time recorders were used to assess time at hooking and temperature–depth recorders to measure gear behavior. Catch rates for most species categories were not significantly different between hook types (P < 0.05), although circle hooks generally had higher tuna catch rates in the fall and lower swordfish catch rates in the spring. In the fall, both total catches and catches of pelagic rays were significantly higher on J-style hooks. Yellowfin tuna in the fall and dolphinfish in the spring caught on circle hooks were significantly larger than those caught on J-style hooks. In both seasonal fisheries, circle hooks caught fishes in the mouth more frequently than J-style hooks, which hooked more often in the throat or gut, although these differences between hook types were not statistically significant. Yellowfin tuna in the fall fishery were over four times more likely to be hooked in the mouth with circle hooks than with J-style hooks. Several target and bycatch species showed higher rates of survival at haulback with circle hooks, although only for dolphinfish in the fall fishery was this difference statistically significant. Our results suggest that the use of 0° offset circle hooks in the coastal pelagic longline fishery will increase the survival of bycatch species at haulback with minimal effects on the catches of target species.  相似文献   

7.
The issue of deep hooking is of concern in white sturgeon, Acipenser transmontanus Richardson, fisheries because nearly all anglers use bait with a stationary presentation on the river bottom to catch them, and bait fishing is often associated with higher instances of deep hooking and hooking mortality. Deep hooking rates, landing success and catch rates were investigated for anglers bait fishing for white sturgeon using circle and J hooks with inline and offset alignments fished with both active and passive hook‐setting methods. Anglers hooked 578 white sturgeon and landed 508 fish, ranging in size from 60 to 316 cm total length (mean = 137 cm). Deep hooking rates averaged 0.6% and did not differ between hook types, hook alignments or hook‐setting methods. Landing success (the proportion of hooked sturgeon that were successfully landed) and catch rates were also equivalent between hook types, hook alignments and hook‐setting methods; landing success averaged 88% and catch rates averaged 0.27 fish/hr. Results of this study indicate that deep hooking is rare when angling for white sturgeon using standard bait‐fishing gear regardless of hook‐setting method or whether circle or J hooks were used; regulations restricting hook type in sturgeon bait fisheries are therefore unwarranted.  相似文献   

8.
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9.
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10.
  • 1. This study compared the catch rates of targeted dolphinfish or mahimahi (Coryphaena hippurus), and sea turtles and other fish bycatch in a shallow‐set Costa Rican longline fishery using 14/0 circle hooks with and without a 10° offset. The effect of hook offset on hooking location and injury in captured sea turtles, specifically if the hooking was external, in the mouth, or in the esophagus was also evaluated.
  • 2. Results were compared from six trips totalling 33 876 hooks with squid (Dosidicus gigas) used as bait. In total, mahimahi catch‐per‐unit‐effort (CPUE, expressed as number caught per 1000 hooks) was similar between hook types (CPUE～52).
  • 3. Olive ridley sea turtles (Lepidochelys olivacea) were caught on all 42 sets. In total, 640 olive ridley turtles were caught and released alive. There were no significant differences in the number of sea turtles caught between hooks with and without an offset (CPUE～19) nor between hook type and anatomical hooking location, suggesting similar levels of injury for turtles caught on each hook type.
  • 4. These data suggest that a 10° offset on 14/0 circle hooks does not confer any selective advantages over hooks with no offset with respect to capture rates of mahimahi, sea turtles, sharks, or pelagic stingrays in a shallow set pelagic longline fishery. Copyright © 2010 John Wiley & Sons, Ltd.
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11.
  • 1. Circle hooks have rapidly become popular among recreational anglers, based largely on the assumption that their use aids in the conservation of fisheries resources by reducing gut hooking, and hence mortality. In addition, circle hooks are intended to facilitate jaw hooking. Unfortunately, these assumptions have been perpetuated by anecdotal reports with very little rigorous scientific information to support these assertions.
  • 2. A number of recently published, forthcoming, and grey literature reports provide an opportunity to review briefly and synthesize research conducted on circle hooks. We surveyed literature databases and also used questionnaires to solicit information from unpublished or in‐progress circle hook research.
  • 3. Although among studies the results have been quite disparate, overall the mortality rates were consistently lower for circle hooks than J‐style hooks. In addition, circle hooks were more frequently hooked in the jaw, and less frequently hooked in the gut than conventional hook types. There is no doubt that in some marine fisheries, such as tuna, billfish, and striped bass, capture efficiency remains high and injury and mortality rates are drastically reduced. However, in other species (e.g. bluegill), injury can actually be more severe from circle hooks relative to some other hook types. In other species, such as largemouth bass, circle hooks have minimal conservation benefit, but have reduced capture efficiency relative to conventional hook designs.
  • 4. Factors such as hook size, fishing style, fish feeding mode, and mouth morphology all appear to affect the effectiveness of circle hooks. For these reasons, it is difficult to promote the adoption of the use of circle hooks as a panacea for all fish and fisheries. Instead, we recommend that management agencies focus on recommending circle hooks only for instances for which appropriate scientific data exist.
  • 5. The recent interest in circle hooks has been beneficial for stimulating interest and research on the role of hook designs in reducing hooking‐related injury and mortality. We encourage tackle manufacturers to continue to develop new hook designs that have the potential to provide conservation benefit to caught and released fish. This paper provides direction to management agencies and outdoor media for disseminating responsible information to anglers regarding the application of circle hooks for conserving fisheries resources.
Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

12.
Abstract  Experiments were carried out to test the dependence of anatomical hooking location on terminal rig configuration, and identify strategies by which hook ingestion can be minimised to reduce post-release mortality of angled yellowfin bream, Acanthopagrus australis (Günther). Eighty-five anglers targeted yellowfin bream using different designs and sizes of circle and J hooks and recorded technical, environmental and biological data for each landed fish. Considerably fewer fish (16.6 and 8.5%, respectively) ingested hooks than those hooked in the mouth (82.1 and 88.6%), and a greater percentage of J hooks were ingested than circle hooks or a J hook modified with a 15-mm horizontal bar. Irrespective of hook type, the rate of ingestion also declined with increasing hook weight and decreasing fish size. In cage experiments, significantly more hooks baited with natural soft baits (e.g. intestines and cephalopods) were ingested than those baited with artificial baits, crustaceans or teleosts, while in the field fewer hooks were ingested using artificial bait (e.g. bread and pellets) than terrestrial animals, teleosts, crustaceans, teleost or terrestrial animal intestines, cephalopods or polychaetes. Similarly, rigs with floats, short traces or a sinker only on the hook, along with angling in environments with at least some current reduced ingestion. Based on this study, anglers targeting yellowfin bream should be encouraged to use circle or modified J hooks and, regardless of the hook design, the largest hook size possible attached to short traces or a sinker only and hard baits.  相似文献   

13.
金枪鱼延绳钓环形钩和圆形钩钓获率比较   总被引：3，自引：0，他引：3  
根据"华远渔18号"和"华远渔19号"两艘冰鲜金枪鱼延绳钓渔船2005年9月15日~12月12日在印度洋热带公海水域(0°47′~10°16′N,61°40′~70°40′E)作业期间收集的数据,以每千钩钓获尾数和平均净重,对环型钩与圆型钩对大眼金枪鱼和黄鳍金枪鱼的选择性、钓获率差异等进行了比较研究。结果表明:不同钓具漂移速度下环型钩与圆型钩各自对大眼金枪鱼和黄鳍金枪鱼的选择性无显著差异;不同钓具漂移速度下环型钩与圆型钩之间对大眼金枪鱼和黄鳍金枪鱼的钓获率无显著差异;环型钩与圆型钩之间对大眼金枪鱼和黄鳍金枪鱼渔获物净重无显著差异。  相似文献   

14.
基于有限元分析的金枪鱼延绳钓钓钩力学性能研究   总被引：2，自引：1，他引：1  
马骏驰  袁军亭  宋利明 《水产学报》2015,39(11):1742-1751
掌握金枪鱼延绳钓钓钩的应力、变形等力学性能有利于改进钓钩设计和正确选用材料。实验针对生产实际中常用的2种钓钩(环形钩和圆形钩)进行三维实体建模,利用ANSYS软件对其进行有限元分析,获得钓钩的等效应力、变形的分布模式和可能的破坏条件及形式;由同尺寸和同结构钓钩的拉伸实验结果验证了数值分析得到的最大应力和变形结果,并根据数值分析的结果对钓钩进行了结构优化分析。结果显示:(1)同规格环形钩的抗拉强度优于圆形钩15.80%~29.40%,环形钩X、Y轴最大变形率比圆形钩分别小3.00%和0.21%;(2)钓钩的主要受力区域在后弯处(承受83.00%~86.00%的应力),轴头孔下端存在应力集中;(3)对后弯、前弯表面进行压扁处理(压下率为15.00%),适当增加钓钩后弯的圆弧曲率(曲率半径由14 mm增至16 mm)、钩轴采用圆弧过渡等措施,可提升钓钩强度4.60%~10.80%。研究表明,圆形钩是良好的生态保护型钓钩,强度满足使用要求,可在延绳钓渔业中使用。  相似文献   

15.
Fishing with circle hooks along with prescribed hook-setting methods can reduce deep-hooking rates in some fisheries, but baited circle hooks have not been evaluated in stillwater trout fisheries. Deep-hooking rates and catch probabilities were compared for cutthroat trout Oncorhynchus clarkii​ (Richardson), rainbow trout Oncorhyncus mykiss (Walbaum), cutthroat × rainbow trout hybrids, and brook trout Salvelinus fontinalis (MItchill) caught using three types of baited hooks (circle, intermediate circle and traditional J) and two hook-setting methods (active and passive) in several lakes containing naturally reared trout. Hook type had a negligible effect on deep-hooking rates, which averaged 20%. Actively setting the hook and fishing with a bobber both reduced deep-hooking rates, regardless of hook type. Larger fish were deeply hooked more frequently regardless of hook type. Catch probabilities were higher when active rather than passive hook-setting was used, particularly in combination with intermediate circle hooks. The present results, which indicate that circle hook use did not reduce deep hooking in lentic settings, contrast earlier studies done in lotic waters. Therefore, before proposing hook-type regulations intended to reduce deep hooking, fisheries managers should consider waterbody type in addition to fishing methods, fish size and species.  相似文献   

16.
Bonefish (Albula spp.) support a circum-tropical sport fishery in which anglers predominantly release angled fish. The influence of hook location, size, and type on hook retention, post-release feeding ability and survival were evaluated. Overall, 46% of bonefish held in large holding tanks expelled hooks within a 14-day observation period. Hooks located in the lip were expelled 2.6 times more frequently than hooks located in the gut. Barbless hooks were expelled 3.9 times faster when located deep in the oral cavity compared to barbed hooks, but there was no difference in expulsion rates among barbed and barbless hooks in shallow-hooked fish. For the two hook sizes studied, hook size had no impact on hook expulsion rates or duration of hook retention regardless of hook location or type. The presence of a hook had no significant effect on weight change, indicating the presence of a hook did not impede feeding ability. No post-release mortality was observed for bonefish during the short duration of this study. Leaving a difficult to remove hook in a bonefish is recommended to increase the likelihood of post-release survival, especially in cases where the threat of bonefish predators is high.  相似文献   

17.
  • 1. Incidental catches by the pelagic longline fishery is a major global threat for loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) sea turtles.
  • 2. The reduction of incidental capture and post‐release mortality of sea turtles in the Brazilian pelagic longline fishery, operating in the south‐western Atlantic Ocean, was investigated by comparing the performance of 18/0 circle hooks with 9/0 J‐type (control) hooks. Hook selectivity experiments were performed between 2004 and 2008, in a total of 26 trips, 229 sets and 145 828 hooks. The experimental design included alternating control and experimental hooks along sections of the mainline.
  • 3. An overall decrease in capture rates for loggerhead turtles of 55% and for leatherbacks of 65% were observed when using circle hooks. In addition, deep‐hooking in loggerheads decreased significantly from 25% using J‐hooks to 5.8% with circle hooks, potentially increasing post‐release survival.
  • 4. Circle hooks increased catch rates of most of the main target species, including tunas (bigeye Thunnus obesus and albacore T. alalunga), and sharks (blue Prionace glauca and requiem sharks of the genus Carcharinus), with no difference in the capture rates of yellowfin tuna (T. albacares), shortfin mako shark (Isurus oxyrinchus), hammerhead sharks (Sphyrna lewini and S. zygaena), and dolphinfish or mahi mahi (Coryphaena hippurus). On the other hand, a significant decrease in the capture rate of swordfish (Xiphias gladius) was detected when using circle hooks.
  • 5. Overall, results support the effectiveness of using circle hooks for the conservation of loggerhead and leatherback sea turtles, with positive effects on capture of most target species of the south‐western Atlantic longline fishery. Copyright © 2010 John Wiley & Sons, Ltd.
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18.
Elasmobranch mortality in pelagic longline fisheries poses a risk to some populations, alters the distribution of abundance between sympatric competitors, changing ecosystem structure, processes and stability. Individual and synergistic effects on elasmobranch catch and survival from pelagic longline gear factors, including methods prescribed to mitigate bycatch of other vulnerable taxa, were determined. Overall relative risk of higher circle vs. J‐shaped hook shark catch rates conditioned on potentially informative moderators, from 30 studies, was estimated using an inverse‐precision weighted mixed‐effects meta‐regression modelling approach. Sharks had a 1.20 times (95% CI: 1.03–1.39) significantly higher pooled relative risk of capture on circle hooks, with two significant moderators. The pooled relative risk estimate of ray circle hook catch from 15 studies was not significant (RR = 1.22, 95% CI: 0.89–1.66) with no significant moderators. From a literature review, wire leaders had higher shark catch and haulback mortality than monofilament. Interacting effects of hook, bait and leader affect shark catch rates: hook shape and width and bait type determine hooking position and ability to sever monofilament leaders. Circle hooks increased elasmobranch catch, but reduced haulback mortality and deep hooking relative to J‐shaped hooks of the same or narrower width. Using fish vs. squid for bait increased shark catch and deep hooking. Pelagic stingray (Pteroplatytrygon violacea) catch and mortality were lower on wider hooks. Using circle instead of J‐shaped hooks and fish instead of squid for bait, while benefitting sea turtles, odontocetes and possibly seabirds, exacerbates elasmobranch catch and injury, therefore warranting fishery‐specific assessments to determine relative risks.  相似文献   

19.
We evaluated the post-release mortality (PRM) following catch-and-release in Trachynotus ovatus, one of the main target species of north-western Mediterranean recreational fisheries. In this study, we observed the line-caught fish for 10 d in a holding tank in order to investigate the independence and impact on mortality of several explanatory variables, including fish size, surface temperature, anatomical hooking location, bleeding, hook type, and line cutting. We observed a total PRM of 24.1% and the most important mortality factor by far was the anatomical position of the hook. Anatomically deeper hooking events were highly correlated with fish size and the presence of blood during hooking injuries. The PRM obtained in this study was higher than values reported in previous studies of this species, mainly because we considered the effects of passive angling techniques. Passive angling increased the incidence of deep hooking and consequently increased mortality compared to active angling. This technique also led to an increase in deep hooking by circle hooks. Therefore, we recommend that active angling techniques be encouraged and we emphasize the need for education on the correct use of circle hooks. This study provides guidelines to managers, scientists, and anglers that will promote sustainable development of the recreational fisheries of the Mediterranean.  相似文献   

20.
Abstract  The factors affecting mortality in Diplodus annularis (L.) and Lithognathus mormyrus (L.) caught and released in a recreational fishery in the Balearic Islands (NW Mediterranean) were examined. A total of 194 and 214 specimens of each species, respectively, were caught and individually monitored in containment tanks for 10 days. The circumstances of the catch, such as capture depth, water temperature, fish size, hook type, hook location, bleeding, unhooking time and cutting the hook line were tested with a logistic regression model. Diplodus annularis experienced moderate rates of mortality (15%), and only deep-hooking was a significant predictor of death. The incidence of undersized fish for this species was 48%. By contrast, L. mormyrus exhibited higher mortality rates (33%) with over 90% of the catch under the minimum legal size. Deep-hooking was the strongest predictor of mortality. When circle hooks were used, or if the line was cut when the fish were deep-hooked, mortality was considerably reduced. Strategies, such as promoting the use of more selective gears that reduce the capture of undersized fish and implementing gentler release techniques, should be considered in managing these species.  相似文献   

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