印度洋中南部水域金枪鱼延绳钓钓钩钩型对钓获对象的选择性

基于2008年9月至2009年4月在印度洋中南部水域金枪鱼延绳钓渔场收集的数据,研究分析和比较了3种钓钩钩型(传统金枪鱼钩、“J”形钩和圆形钩)的渔获效益及对钓捕对象的选择性。结果表明:(1) 从渔获种类上看,大眼金枪鱼和大青鲨金枪鱼钩钓获比例最高,“J”形钩和圆形钩的钓获比例相当;而长鳍金枪鱼则为金枪鱼钩钓获比例最高,其次为“J”形钩和圆形钩。(2) 大眼金枪鱼存活率以金枪鱼钩最高,“J”形钩最低;长鳍金枪鱼则为“J”形钩稍高于圆形钩,金枪鱼钩最低;大青鲨则以圆形钩最高,“J”形钩最低。(3) “J”形钩钓获的长鳍金枪鱼和鲨鱼平均叉长较金枪鱼钩和圆形钩稍大;而金枪鱼钩钓获的大眼金枪鱼平均叉长较圆形钩和“J”形钩稍大。(4) 3种钩型钓获的长鳍金枪鱼、大眼金枪鱼和大青鲨叉长分布均不存在显著性差异。     

印度洋公海温跃层与黄鳍金枪鱼和大眼金枪鱼渔获率的关系

2005年9月15日-12月12日,金枪鱼延绳钓渔船"华远渔18、19号"对印度洋公海进行了金枪鱼渔业调查.利用多功能水质仪(XR-620)、温盐深仪(CTD SBE37SM)和微型温度深度计(TDR-2050)等获取海洋环境数据,得出作业海域的温跃层深度和强度,结合每天作业时记录的渔获数据,分别计算黄鳍金枪鱼和大眼金枪鱼在温跃层内和深水层的渔获率,研究温跃层与黄鳍金枪鱼和大眼金枪鱼渔获率之间的关系.结果表明:(1)2艘船分别有60.9%和60.0%的作业天数中,温跃层内黄鳍金枪鱼渔获率较高,"华远渔18号"船在温跃层内和温跃层以下的平均渔获率分别为18.22尾每千钩和6.04尾每千钩,"华远渔19号"船温跃层内和温跃层以下平均渔获率分别为2.22尾每千钩和1.31尾每千钩.通过t-检验成对双样本均值分析,温跃层以内和温跃层以下黄鳍金枪鱼总平均渔获率有显著性差异(P=0.02<0.05),温跃层以内比温跃层以下的渔获率明显要高;(2)2艘船分别有69.6%和100%的作业天数中,温跃层以下水深大眼金枪鱼渔获率较高,"华远渔18号"温跃层以内和温跃层以下平均渔获率分别为4.18尾每千钩和4.88尾每千钩."华远渔19号"温跃层以内和温跃层以下平均渔获率分别为0.10尾每千钩和2.57尾每千钩.大眼金枪鱼渔获率在温跃层以下水深较高.通过t-检验成对双样本均值分析,温跃层以内和温跃层以下大眼金枪鱼总平均渔获率无显著性差异(P=0.070.05),但对"华远渔19号"船的渔获率数据经t-检验发现大眼金枪鱼在温跃层以内和温跃层以下的渔获率有显著性差异(P=0.00<0.05).     

金枪鱼延绳钓钓具的最适浸泡时间

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。     

磁珠富集法制备大口鲶的微卫星分子标记

2004年3月16日-6月8日，在广东广远渔业集团有限公司玻璃钢大滚筒冷海水金枪鱼延绳钓渔船“华远渔19”号，对印度洋马尔代夫海域进行金枪鱼渔业调查。所获数据资料包括：①CTD测定的温度、盐度和深度数据，TDR测定的实际钩深；②作业参数，包括每次作业的钩数、投绳位置、投绳时间、航向、航速、出绳速度、两浮子间的钩数、起绳位置、起绳时间等；③渔场环境数据，包括风速、风向、钓具对地漂移速度和方向；④渔获统计，包括大眼金枪鱼的渔获尾数以及部分大眼金枪鱼的钓获钩号；⑤生物学数据，包括起捕时已死的大眼金枪鱼的体温。分析计算的方法和步骤为：①由理论公式推算出每次作业时各钩号的理论深度；②应用逐步回归的方法，建立理论钩深与实测的平均钩深之间的数学关系模型；③根据实际平均钩深模型计算出每个钓钩的平均作业深度；④根据CTD测得的作业地点的温度、盐度的垂直分布（41次），获得分布曲线。由此，以计算的钩深，从曲线上查出该尾鱼捕获水深处的温、盐数据；⑤根据121尾大眼金枪鱼的取样数据，推算出各水层、水温段、盐度段的渔获率；⑥根据起捕时已死的34尾大眼金枪鱼（鱼体发硬）的体温、以死鱼体温为引数，在曲线上查出该尾鱼捕获水深和盐度；最后，对钓获的大眼金枪鱼的钓获水层、水温和盐度进行了总体分析。分析结果表明：在马尔代夫海域，捕获大眼金枪鱼的水层为50～210m、水温范围为13．0～29．9℃、盐度范围为35．00～35．79；渔获率最高的水层为70～90m、水温范围为27．0～27．9oC、盐度范围为35．70～35．79；捕获时已死鱼的捕获水层、水温和盐度推算数据为63～203m、14．0～27．0℃和34．94～35．42，主要集中在63～134m、16．0～27．0℃和35．30～35．42。     

大西洋中部金枪鱼延绳钓性能评估初步研究

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。     

东太平洋长鳍金枪鱼个体大小与钓获深度的关系

长鳍金枪鱼(Thunnus alalunga)具有重要的经济价值,其个体大小与钓获深度有一定的关联。本研究利用2013年东太平洋渔业观察员的数据,将渔获物分为76~85 cm、86~95 cm、96~105 cm、106~115 cm和116~125 cm 5个叉长组,运用悬链线公式得到钓获深度,统计各叉长组渔获个体钩位差异和各钩位渔获个体大小差异,分析个体大小与钓获深度的关系,得到结果如下:渔获物钓获深度范围为61.3~236.1 m。各叉长组主要渔获钩位随叉长增大而增大。各钩位主要渔获个体随序号增大而增大。76~85 cm叉长组的渔获物主要分布在61.3~121.8 m水层,平均钓获深度为(110.6±11.7)m;86~95 cm叉长组的在102.3~174.4 m,平均钓获深度为(144.1±4.5)m;96~105 cm叉长组的在189.4~202.8 m,平均钓获深度为(184.9±1.6)m;106~115 cm叉长组的在214.3~223.6 m,平均钓获深度为(193.8±3.8)m;116~125 cm叉长组的在230.5~236.1 m,平均钓获深度为(219.3±7.2)m。研究结果表明:东太平洋长鳍金枪鱼随叉长增大,栖息深度也加深,二者有相关关系。生产时调整钓具深度可有效保护资源可持续发展。     

中西太平洋金枪鱼围网黄鳍金枪鱼产量的时空分布及与表温的关系

黄鳍金枪鱼是中西太平洋金枪鱼围网渔业中的重要捕捞种类之一。本文根据2003年中西太平洋金枪鱼围网生产统计及其表温数据,利用频次统计分析和地理信息软件Marine Explorer 4.0对黄鳍金枪鱼产量和单位日产量(CPUE)的时空分布进行分析,探讨其与海水表温的关系。结果显示,产量和CPUE最高的是2月份,其次是9月份,5月份为最低。高产量的范围为140~160°E、0°~5°S;CPUE高值区分布在130°E、0°~15°S,140°~160°E、0°~15°S和175°W、0°~15°S;产量经纬度重心分别为150°30′E和3°48′S。产量主要分布在海表温为28~31℃的海域,产量比重高达95.45%,其中29~30℃产量为最高,占69.54%。     

中东太平洋金枪鱼延绳钓渔获量及其分布

根据2000年9月至2002年8月两年的中东太平洋金枪鱼延绳钓探捕调查结果,对延绳钓渔获量及其分布特征进行了初步分析。结果显示,延绳钓渔获物以金枪鱼为主,大眼金枪鱼(Thun-nusobesus)等3种金枪鱼的渔获量占总渔获量75·9%。“海欣”船延绳钓作业的平均日产量为(994·8±19·9)kg/d,上钩率为(12·5±0·3)ind/103钩。主要目标鱼种大眼金枪鱼和黄鳍金枪鱼(Thunnusalbacares)的平均日产量分别为(466·9±13·9)kg/d和(190·6±7·2)kg/d。探捕期间日产量的月间差异显著(P<0·001),6~8月为渔发汛期,日产量较高;2~5月为相对淡季,日产量较低。探捕区南部的平均日产量最高,与中、北部比较差异显著(P<0·001);东部平均日产量与西部比较差异不显著(P>0·05)。     

东太平洋南北部海域大眼金枪鱼生物学特性对比研究

明确大眼金枪鱼(Thunnus obesus)的生物学特征是进行种群资源评估并依此制定和实施养护管理措施的重要前提。为掌握广泛的时间和空间范围内东太平洋大眼金枪鱼种群特征, 本研究利用 2013—2019 年执行东太平洋金枪鱼延绳钓资源探捕调查期间采集的大眼金枪鱼渔获数据, 对东太平洋南、北部海域大眼金枪鱼的叉长、净重、摄食等级、性腺成熟期等生物学特性进行了分析, 结果显示: (1)北部海域大眼金枪鱼的叉长范围为 72~229 cm, 优势叉长为 80~160 cm, 平均叉长(121.53±29.11) cm, 雌雄比为 0.91∶1, 优势性腺成熟期为 III、Ⅳ期; (2)南部海域大眼金枪鱼的叉长范围为 63~209 cm, 平均叉长为(134.87±25.73) cm, 优势叉长组 110~150 cm, 雌雄性比为 0.62∶1, 优势性腺成熟期为 III、Ⅴ期; (3)南北海域大眼金枪鱼的优势摄食等级分别为 1 级和 2 级, 空胃率分别为 46.98%和 3.22%, 总体上摄食强度随叉长的增大而增加; (4) ANCOVA 结果显示, 南部和北部海域叉长与净重的关系存在较明显的差异(P<0.05); (5) ANOVA 结果显示, 大眼金枪鱼雌雄个体性腺成熟差异不显著(P>0.05); (6)钓获后处于存活状态的个体占比较高, 死亡状态仅占 8.52%。研究表明, 东太平洋南北部海域大眼金枪鱼的叉长、性比和摄食强度等生物学特性具有一定的空间异质性。     

中西太平洋金枪鱼围网黄鳍金枪鱼渔获时空分析

中西太平洋的金枪鱼围网渔业目前的年产量约在1×106t左右,其中黄鳍金枪鱼占有很重要的地位。本文通过对围网捕获的黄鳍金枪鱼渔获数据进行时间序列以及空间位置变化等时空分析,试图找出其变化规律以及趋势。结果表明,20世纪70年代以来,随着渔船数的增加,中西太平洋围网捕获的黄鳍金枪鱼渔获量分布,从太平洋岛屿近海逐渐向太平洋热带中部海域扩展。渔获量经度重心随着中西太平洋金枪鱼围网渔业的发展有向东移动的趋势,70年代在128°E附近,到80年代在145°E左右,90年代在152°E左右,近年在155°E左右。而黄鳍金枪鱼渔获量纬度重心位于赤道区域,70年代在3°30′N附近,80年代在0°30′N左右,90年代在0°40′S左右,近年在1°20′S左右。经纬度5°×5°小区范围内10年内的最高总产量则从70年代的8×104t,增加到90年代超过20×104t。渔获量空间分布除了随着渔业发展向外海扩展以外,还受到被称为南方涛动的ENSO现象的明显影响,一般来说渔获量经度中心在厄尔尼诺年比较偏东,在拉尼娜年比较偏西,渔获量纬度重心在厄尔尼诺年或次年比较偏南,在拉尼娜次年比较偏北。此外,黄鳍金枪鱼渔获量经度重心在厄尔尼诺年变化比较大,渔获量纬度重心在厄尔尼诺年或次年变化比较大。     

Effects of circle versus J-style hooks on target and non-target species in a pelagic longline fishery

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.     

A comparison of circle hook and J hook performance in a western equatorial Atlantic Ocean pelagic longline fishery

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.     

Comparing the effects of offset and non‐offset circle hooks on catch rates of fish and sea turtles in a shallow longline fishery

• 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.

     

Potential bycatch of seabirds and turtles in hook-and-line fisheries of the Itaipava Fleet, Brazil

The decline of populations of certain seabirds and sea turtles around the world is partly related to their incidental capture in large-scale fisheries. However, the impacts of small-scale fisheries on endangered seabirds and sea turtles, being carried out in many places around the world, have been largely neglected by scientists and governments. We monitored 178 fishing days and described a range of poorly known hook-and-line commercial fisheries carried out by the Itaipava fleet, southeastern Brazil, composed by 497 vessels and deploying hooks from 18°S to 35°S. Seven fisheries were defined: fast trolling for tuna and tuna-like species, slow trolling for Bigeye tuna, handlining, surface longline for Dolphinfish, pelagic longline for Swordfish, bottom dropline, and pole-and-line with live bait. We observed bycatch of 47 seabirds of six species and 45 turtles of four species. Capture rates were higher for the surface longline for Dolphinfish (0.15 birds/1000 hooks and 1.08 turtles/1000 hooks), slow trolling for Bigeye tuna (0.41 birds/day) and handlining targeting Yellowfin tuna (0.61 birds/day). Endangered Spectacled petrel (Procellaria conspicillata), Atlantic Yellow-nosed (Thalassarche chlororhynchos), and Black-browed (T. melanophris) albatrosses were the main seabirds caught. Immature Loggerhead turtles (Caretta caretta) and immature or adult Leatherback turtles (Dermochelys coriacea) were the main sea turtles affected by the surface longline for Dolphinfish. Monitoring the fleet and bycatch levels, development of mitigation measures, establishment of educational programs, government control over the fleet, and enforcement, are urgently required for the hook-and-line fisheries described in the present study.     

印度洋中西部黄鳍金枪鱼生物学特性的初步研究

根据2003~2004年1~6月我国农业部印度洋金枪鱼延绳钓观察员项目所收集的有关数据,对印度洋中西部黄鳍金枪鱼的基本生物学特征进行了研究。结果表明,2003年和2004年渔获物中黄鳍金枪鱼加工后体重范围分别为7~81kg和20~78kg,优势组分别为20~50kg和30~60kg。叉长范围分别为70~180 cm和110~170 cm。2003年渔获物雌雄性比的平均值为0.71,月间性比组成差异较小;而2004年渔获雌雄性比的平均值为1.00,月间性比组成差异较大。2003年各月的摄食等级以1~2级为主,月间差异较小;而2004年摄食等级以1级为主,并且月间各等级组成差异大。体长与体重关系为W=2.1890×10-5L2.9269。     

Circle hook effectiveness for the mitigation of sea turtle bycatch and capture of target species in a Brazilian pelagic longline fishery

• 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.

     

Circle hooks, 'J' hooks and drop-back time: a hook performance study of the south Florida recreational live-bait fishery for sailfish, Istiophorus platypterus

Abstract  This study evaluates the performance of two types of non-offset circle hooks (traditional and non-traditional) and a similar-sized 'J' hook commonly used in the south Florida recreational live-bait fishery for Atlantic sailfish, Istiophorus platypterus (Shaw). A total of 766 sailfish were caught off south Florida (Jupiter to Key West, FL, USA) to assess hook performance and drop-back time, which is the interval between the fish's initial strike and exertion of pressure by the fisher to engage the hook. Four drop-back intervals were examined (0–5, 6–10, 11–15 and >15 s), and hook performance was assessed in terms of proportions of successful catch, undesirable hook locations, bleeding events and undesirable release condition associated with physical hook damage and trauma. In terms of hook performance, the traditionally-shaped circle hook had the greatest conservation benefit for survival after release. In addition, this was the only hook type tested that performed well during each drop-back interval for all performance metrics. Conversely, 'J' hooks resulted in higher proportions of undesirable hook locations (as much as twofold), bleeding and fish released in undesirable condition, particularly during long drop-back intervals. Non-traditional circle hooks had performance results intermediate to the other hook types, but also had the worst performance relative to undesirable release condition during the first two drop-back intervals. Choice of hook type and drop-back interval can significantly change hook wounding, and different models of non-offset circle hooks should not be assumed to perform equivalently.     

马绍尔群岛海域和吉尔伯特群岛海域黄鳍金枪鱼生物学特性比较

利用2006年10月至次年1月在马绍尔群岛海域与2009年10～12月和2010年11月至次年1月在吉尔伯特群岛海域延绳钓探捕所取得的黄鳍金枪鱼(Thunnus albacares)的生物学数据,应用统计学方法对两个海域的黄鳍金枪鱼生物学特性进行分析、比较。结果表明:(1)马绍尔群岛海域和吉尔伯特群岛海域黄鳍金枪鱼的优势叉长分别为120～140 cm和100～140 cm,平均叉长分别为(129±1.08)cm和(119±0.78)cm,差异性显著;(2)性别比例(雄性∶雌性)分别约为1.07∶1和1.40∶1,无显著性差异;(3)马绍尔群岛海域黄鳍金枪鱼的性腺成熟度高于吉尔伯特群岛北部海域,吉尔伯特群岛北部海域黄鳍金枪鱼的性腺成熟度高于南部;(4)摄食等级均以0和1级为主,其中马绍尔群岛海域分别占48.31%和35.96%,吉尔伯特群岛海域分别占27.91%和40.70%,无显著性差异;(5)两海域原条鱼重与叉长的关系无显著性差异;(6)马绍尔群岛海域的黄鳍金枪鱼可能是从吉尔伯特群岛海域洄游过去的。     

Effects of 17/0 circle hooks and bait on sea turtles bycatch in a Southern Atlantic swordfish longline fishery

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