共查询到19条相似文献，搜索用时 234 毫秒
1.
《渔业现代化》2021,(3)
海龟是金枪鱼延绳钓误捕的主要物种之一,如何减少其误捕是国际社会关切的热点。海龟栖息水层和环境不同于金枪鱼,钓钩和饵料等也影响海龟的误捕。文章从钓钩深度、钓钩的选择性、饵料的选择性、环境因子以及声学因素等方面综述了国内外金枪鱼延绳钓渔业中缓解海龟误捕方法的研究进展。控制延绳钓钓钩深度是缓解海龟误捕的有效途径;较大尺寸的圆型钩可以有效缓解海龟误捕;蓝色染色饵料或许能缓解海龟误捕;避开海龟偏好的海表面温度进行作业对缓解海龟误捕有效;应用声学干扰可缓解海龟误捕。建议金枪鱼延绳钓渔业中缓解海龟误捕研究应做到:确定钓钩最佳沉降深度;探索减少海龟误捕和保证金枪鱼渔获率的钓钩最佳尺寸和钩型;研究染色饵料或拟饵等对海龟选择性的影响;考虑诱饵、钓钩类型、钓钩尺寸和钓具浸泡时长对海龟误捕和海龟释放后存活率的潜在协同效应;继续开展利用声学区分海龟和金枪鱼及缓解海龟误捕方法的研究。 相似文献
2.
利用2009～2010年我国大西洋中部金枪鱼延绳钓调查数据,对金枪鱼延绳钓钓具性能进行评估。结果表明:金枪鱼延绳钓具有较好的种类选择性,大眼金枪鱼渔获量和尾数分别占总渔获量的73.67%和76.00%;大眼金枪鱼(Thunnus obesus)、黄鳍金枪鱼(Thunnus albacares)和剑鱼(Xiphias gladius)未达到性成熟的渔获尾数比例分别为13.00%、25.97%和48.93%;1～6号钓钩,大眼金枪鱼上钩率随钓钩深度增加呈递增趋势,6～8号钓钩上钩率呈递减趋势,6号钓钩上钩率最大为9.46尾/千钩;3号至8号钓钩上钩率均大于7尾/千钩,表明1号和2号钓钩利用率偏低;根据钓钩理论深度,推测大眼金枪鱼主要分布水层为220m～350m。通过调节缩短率和浮子绳长度对钓具进行优化,使得钓钩分布水层与大眼金枪鱼分布水层更为接近,提高钓钩利用率。 相似文献
3.
根据中国金枪鱼延绳钓渔业观察员于2018年9-12月在北太平洋公海(150°W-164°W,30°N-37°N)采集的金枪鱼延绳钓渔获数据,分析了钓钩的垂直分布及浸泡时间与渔获物之间的关系。结果表明,11种主要渔获物钓获深度差异很大,鲣(Katsuwonus pelamis)的平均钓获深度最浅,大青鲨(Prionace glauca)最深;除大青鲨和帆蜥鱼(Alepisaurus ferox)外,其他兼捕鱼类的钓钩深度分布与大眼金枪鱼(Thunnus obesus,目标鱼种)之间差异显著;随着浸泡时间的增加,总渔获率呈先增加后下降的趋势,10~14 h内渔获率较高,且在第10小时达到峰值[1.44尾·(千钩·h)-1];浸泡时间在10~16 h内大眼金枪鱼的渔获率较高,且在第11小时达到峰值[0.45尾·(千钩·h)-1]。研究结果可为渔业生产和CPUE的标椎化提供参考,为制定有效减少兼捕鱼种的管理措施提供科学依据。 相似文献
4.
2015年3-4月及2017年1月在南海外海进行了两次罩网渔船兼作金枪鱼延绳钓的捕捞试验,基于试验数据分析延绳钓钓钩深度及渔获水层分布,以期优化改进试验钓具,有效提高南海金枪鱼延绳钓捕捞效益。研究发现:1)经济渔获以剑鱼(Xiphias gladius)与黄鳍金枪鱼(Thunnus albacares)为主,剑鱼的单位捕捞努力量渔获量(CPUE,kg·千钩-1)为所有渔获中最高; 2)钓钩深度(D)与钩位(n)、风速(SW)、风流合压角(γ)成正相关,与漂移速度(SD)、投绳船速(SV)呈负相关,回归方程为:D=10. 259n-37. 247SD-29. 878SV+6. 940SW+23. 493γ+35. 633; 3)模型的预测结果与实测数据间无显著性差异,相对权重表明各影响因子中钩位具有最大的相对重要性; 4)试验中拟合钩深分布范围为35. 08～110. 80 m,剑鱼上钩率与CPUE最高的水层为60～80 m,黄鳍金枪鱼上钩率与CPUE最高的水层为80～100 m; 5) 60～80 m水层主要经济渔获CPUE最大且钓钩数目最多,认为钓钩水层分布较合理。 相似文献
5.
基于GAM模型分析水温垂直结构对热带大西洋大眼金枪鱼渔获率的影响 总被引：2，自引：2，他引：0
通过模型分析环境变量对延绳钓大眼金枪鱼渔获率的影响,评估适宜垂直活动空间对大西洋大眼金枪鱼延绳钓渔获率的作用。首先采用回归分析检验环境变量对延绳钓渔获率(由单位捕捞努力渔获量(catch per unit fishing effort,CPUE)表示)的影响显著性,结合时空变量,采用GAM(generalized additive model)模型分析各变量对大眼金枪鱼CPUE非线性作用。模型结果表明,环境因子和时空变量对热带大西洋延绳钓大眼金枪鱼渔获率空间分布影响明显。大西洋大眼金枪鱼延绳钓的高渔获率月份出现在夏季和冬季,空间上在赤道以北和30?~50?W。12℃等温线深度对大眼金枪鱼延绳钓渔获率的影响表现为抛物线形状,高渔获率出现在深度较浅的250 m水层,随着12℃等温线深度的增加,大眼金枪鱼延绳钓渔获率降低。温跃层下界深度和深度差对大眼金枪鱼延绳钓渔获率的影响都是穹顶状。随着温跃层下界深度值和深度差由小变大至200 m,延绳钓渔获率递增;温跃层下界深度和深度差超过200 m后,延绳钓渔获率变小。温跃层下界深度和深度差对大眼金枪鱼延绳钓渔获率影响显著的水层分别是200 m和50 m。研究结果显示,12℃等温线深度和温跃层对热带大西洋延绳钓大眼金枪鱼渔获率影响是交叉的,在大眼金枪鱼适宜垂直活动水层受限到和延绳钓作业深度相同时,延绳钓渔获率最高;在适宜垂直活动空间过深或者过浅时,延绳钓渔获率都变小,但可以通过改变作业方式提高渔获率。采用延绳钓CPUE进行渔场和资源评估要考虑金枪鱼适宜垂直活动空间。 相似文献
6.
五、金枪鱼延绳钓具装配中应注意的问题金枪鱼延绳钓的主绳长度和支绳间距决定于最佳的放钓钩数,浮子绳和支绳长度控制钓钩的所在水层,而最佳的钓沟数是取决于钓船的放钓能力和作业环境。因此,在考虑钓具的松放深度时,要求适应金枪鱼类的栖息水层,从而提高鱼类的上钓率。 (一)主绳的长度、粗度和捻向: 相似文献
7.
为了减少沙氏刺鲅(Acanthocybium solandri)的兼捕率,文章利用2012年9月~2012年11月在南太平洋库克群岛海域延绳钓渔业调查数据(包括钓钩深度数据,温度、盐度和叶绿素a质量浓度垂直剖面数据,作业参数和渔获统计数据),采用逐步回归的方法建立钓钩预测深度计算模型,利用统计和聚类分析的方法分析沙氏刺鲅的兼捕率与水层和温度的关系,并根据沙氏刺鲅兼捕率最高的水层推断得出其兼捕率最高的盐度和叶绿素a质量浓度范围。结果表明,库克群岛附近海域沙氏刺鲅兼捕率最高的水层和温度分别为40.0~80.0 m和26.0~28.0℃,推断得出沙氏刺鲅兼捕率最高的盐度段为36.30~36.90,叶绿素a质量浓度为0.070~0.243μg·L~(-1)。建议把钓钩深度设置到80 m以深、水温低于26℃、盐度高于36.90、叶绿素a质量浓度高于0.243μg·L~(-1)以减少延绳钓渔业中沙氏刺鲅的兼捕率。 相似文献
8.
金枪鱼延绳钓钓具的最适浸泡时间 总被引：2，自引：1，他引：1
根据2010年10月—2011年1月金枪鱼延绳钓海上调查数据,分两种起绳方式,建立每次作业每一根支绳的浸泡时间计算模型。将钓具的浸泡时间以1 h为间隔分别统计每个区间的支绳数量及大眼金枪鱼(Thunnus obesus)、黄鳍金枪鱼(Thunnus albacores)的渔获尾数,并计算其钓获率(CPUE)。结果表明:1)大眼金枪鱼和黄鳍金枪鱼的CPUE都随浸泡时间的增加呈现先增后减的趋势,这是由于饵料的诱引效果变化及渔获的丢失引起的;2)二次曲线可拟合浸泡时间与大眼金枪鱼和黄鳍金枪鱼CPUE的关系;3)大眼金枪鱼和黄鳍金枪鱼CPUE最高的浸泡时间分别为9.9 h和10.1 h。建议:1)今后在金枪鱼延绳钓作业中,保证每一根支绳在水中的浸泡时间为9.5~10.5 h,以提高捕捞效率并减少副渔获物;2)可把延绳钓钓具的浸泡时间作为有效捕捞努力量,并用于CPUE的标准化。研究结果可用于提高捕捞效率并减少副渔获物的技术方案制订,并为渔业生产和CPUE的标准化提供科学参考。 相似文献
9.
金枪鱼延绳钓业是钓渔业中最重要的一类,是远洋渔业中比较国际性的产业之一。渔法是使用钓线、钓钩并利用鱼饵诱使鱼类上钩而捕获的作业方法。国内的金枪鱼钓船基本上都在沿用台湾产的起钓机（或日产的功能相似的起钓机）。然而,一种操作简单省力且实用的中水层金枪鱼延绳钓船的钓机设备在南太平洋的个别岛国却很流行,这种由滚筒和射钓机配套使用的钓机设备最优越的特点就是它可简单的随意调整钓钩水层范围,特别是较深水层。可根据不同鱼类栖息的水层范围来调整放钓的深度,从而提高了渔获的比例,能够适应钓捕不同水层的鱼类和有效地钓… 相似文献
10.
为了探索南海金枪鱼延绳钓合适作业参数,根据2010年6月至2013年2月8个航次的南海金枪鱼延绳钓探捕调查数据,估算了大眼金枪鱼和黄鳍金枪鱼在不同水层的渔获率,以浮子绳长度hf、两浮子间钩数n和短缩率k这3个作业参数的调整为研究对象,采用最小二乘法度量不同水层上钓钩分布频率与金枪鱼渔获分布频率的匹配程度。当两者之间的频差平方和达到最小值时,即认为找到延绳钓最合适作业结构。结果显示:hf=34 m、n=25、k=0.68°对捕捞大眼金枪鱼最合适;hf=10 m、n=14、k=0.71°对捕捞黄鳍金枪鱼最合适;两种兼顾时,hf=8 m、n=27、k=0.69°更合适。 相似文献
11.
Reducing sea turtle by-catch in pelagic longline fisheries 总被引：6，自引：0，他引：6
Eric Gilman Erika Zollett Stephen Beverly Hideki Nakano Kimberly Davis Daisuke Shiode Paul Dalzell & Irene Kinan 《Fish and Fisheries》2006,7(1):2-23
Reducing by‐catch of sea turtles in pelagic longline fisheries, in concert with activities to reduce other anthropogenic sources of mortality, may contribute to the recovery of marine turtle populations. Here, we review research on strategies to reduce sea turtle by‐catch. Due to the state of management regimes in most longline fisheries, strategies to reduce turtle interactions must not only be effective but also must be commercially viable. Because most research has been initiated only recently, many results are not yet peer‐reviewed, published or readily accessible. Moreover, most experiments have small sample sizes and have been conducted over only a few seasons in a small number of fisheries; many study designs preclude drawing conclusions about the independent effect of single factors on turtle by‐catch and target catch rates; and few studies consider effects on other by‐catch species. In the US North Atlantic longline swordfish fishery, 4.9‐cm wide circle hooks with fish bait significantly reduced sea turtle by‐catch rates and the proportion of hard‐shell turtles that swallowed hooks vs. being hooked in the mouth compared to 4.0‐cm wide J hooks with squid bait without compromising commercial viability for some target species. But these large circle hooks might not be effective or economically viable in other longline fisheries. The effectiveness and commercial viability of a turtle avoidance strategy may be fishery‐specific, depending on the size and species of turtles and target fish and other differences between fleets. Testing of turtle avoidance methods in individual fleets may therefore be necessary. It is a priority to conduct trials in longline fleets that set gear shallow, those overlapping the most threatened turtle populations and fleets overlapping high densities of turtles such as those fishing near breeding colonies. In addition to trials using large 4.9‐cm wide circle hooks in place of smaller J and Japan tuna hooks, other fishing strategies are under assessment. These include: (i) using small circle hooks (≤ 4.6‐cm narrowest width) in place of smaller J and Japan tuna hooks; (ii) setting gear below turtle‐abundant depths; (iii) single hooking fish bait vs. multiple hook threading; (iv) reducing gear soak time and retrieval during daytime; and (v) avoiding by‐catch hotspots through fleet communication programmes and area and seasonal closures. 相似文献
12.
ABSTRACT: The underwater shape and hook depth of tuna longline gear are important factors determining fishing performance. In this study, how the shape of tuna longline gear changes in response to sea conditions and gear rigging is explained. Physical models of underwater gear shape were made to simulate fishing gear and analyzed according to the direction and velocity of currents. Then experiments with small-scale models were conducted in a flume tank to confirm the accuracy of the simulation analysis. Finally, the simulation was examined relative to actual longline fishing gear. This approach provided an improvement over previous analytical methods that did not consider fishing gear shape in response to different sea conditions. A useful result is an improved understanding of the relationship between ocean currents and the configuration of longline gear (the shortening ratio, and number of hooks per basket). These factors affect hook depth which, in turn, affects selectivity. Application of these results could lead to more effective and efficient fishing under different sea conditions. 相似文献
13.
Habitat models are used to correct estimates of fish abundance derived from pelagic longline fishing gear. They combine information on hook depth with the species’ preferences for ambient environmental conditions to adjust the gear's catchability. We compare depth distributions of bigeye tuna (Thunnus obesus) catch predicted by a habitat model with distributions derived from data collected by observers on longliners in the tropical Pacific Ocean. Our analyses show that the habitat model does not accurately predict the depth distribution of bigeye tuna; its predictions are worse than those from models that assume no effect of depth on catches. Statistical models provided superior fits to the observed depth distribution. The poor performance of the habitat model is probably due to (1) problems in estimating hook depth, (2) fine‐scale variations in environmental conditions, (3) incomplete knowledge of habitat preferences and (4) differences between the distribution of bigeye tuna and their vulnerability to longline gear. 相似文献
14.
15.
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
16.
J.C. Pacheco D.W. Kerstetter F.H. Hazin Humberto Hazin R.S.S.L. Segundo J.E. Graves F. Carvalho P.E. Travassos 《Fisheries Research》2011,107(1-3):39-45
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
17.
18.
吉尔伯特群岛海域延绳钓渔场大眼金枪鱼的环境偏好 总被引：2，自引：0，他引：2
为了掌握基里巴斯吉尔伯特群岛附近海域大眼金枪鱼的环境偏好,2009年9月至12月,金枪鱼延绳钓船"深联成719"在该海域进行了调查。利用仪器获取海洋环境数据,结合每天渔获数据,应用逐步回归方法,建立钓钩深度预测模型,计算大眼金枪鱼在各水层、温度、盐度、叶绿素、含氧量、水平海流和垂直海流范围内的渔获率,渔获率最大的各环境因子范围为大眼金枪鱼偏好的环境。结果表明:(1)大眼金枪鱼偏好的水层、水温、盐度、叶绿素、含氧量、水平海流和垂直海流范围分别为200.0~240.0 m、14.0~15.0℃、35.00~35.10、0.24~0.26μg/L、3.0~4.0 mg/L、0.00~0.20 m/s和0.03~0.04 m/s;(2)一般情况下,接近成熟的大眼金枪鱼偏好的水温为14.0~17.0℃;(3)大眼金枪鱼的适盐性较广;(4)溶解氧高于门限值(0.8 mg/L)时,大眼金枪鱼的分布由其它环境因子决定。 相似文献
19.
中东太平洋公海金枪鱼延绳钓误捕海龟的观察和分析 总被引：4，自引：1，他引：3
根据2006年2－11月科学观察员对热带东太平洋公海海域(05°N～10°S,134° W~173°W)金枪鱼延绳钓渔业的调查,期间共投钩223次(天),误捕到绿海龟、蠵龟、丽龟、玳瑁和棱皮龟5种共22尾,死亡海龟13尾。从海龟误捕率看,平均每次尾数为0.098 65。平均每千钩尾数0.037 40。从海龟的钩获部位看,喙(嘴)上钩占41.0%,躯干部位上钩占13.6%,喉部上钩占13.6%,前肢上钩占18.2%,主绳缠绕被捕获占13.6%。海龟的误捕区域位于04°S以北海域,几乎可全年捕获。此外分析了不同钩位误捕海龟的数量,探讨了影响误捕率和死亡率的因素,提出保护对策。 相似文献