山东半岛南部三疣梭子蟹增殖放流群体贡献率

根据2010—2016年每年5—8月在山东半岛南部海域对三疣梭子蟹增殖放流前后进行的3个航次的跟踪调查结果,定量分析三疣梭子蟹自然群体和增殖放流群体的数量,并根据三疣梭子蟹放流苗种数量和放流后捕捞产量以及增殖放流群体的贡献率和回捕率,对三疣梭子蟹近年的增殖放流结果进行分析。研究结果表明,2010—2016年的5月,山东半岛南部三疣梭子蟹增殖放流前自然群体资源量较少,相对资源密度为0.20~17.17尾/(站·h),平均资源密度为3.46尾/(站·h);放流苗种数量逐年增加,平均放流苗种数量为14 367.78万尾,放流后约10d的跟踪调查结果表明,三疣梭子蟹的资源量有了较大提高,相对资源密度为6.7~53尾/(站·h),平均资源密度为16.65尾/(站·h),放流群体贡献率的均值为85.82%;8月进行的相对资源量调查,其相对资源密度为0.75~6.72尾/(站·h),均值为1.76尾/(站·h);秋汛期间的回捕产量为2332.91~10 410.77t,平均产量为5308.66t,根据各年秋汛期间调查获得的三疣梭子蟹的平均体质量,得出的放流群体回捕率为5.76%~21.18%,平均回捕率为12.16%。总体上,放流群体在山东半岛南部海域三疣梭子蟹的资源群体中起到了很重要的补充作用,放流群体贡献率较稳定,且相对处于较高水平。     

辽东湾三疣梭子蟹增殖放流效果评估

根据2018年6—8月在辽东湾对三疣梭子蟹增殖放流前后进行的4个航次的对比调查结果,定量分析了辽东湾三疣梭子蟹自然群体和增殖放流群体的数量,并根据三疣梭子蟹放流苗种数量和放流后捕捞产量调查数据,对辽东湾三疣梭子蟹增殖放流效果开展评价。结果显示,2018年6月上中旬辽东湾海域三疣梭子蟹增殖放流前,自然群体资源量较低,相对资源密度为2.80只/h;在6月下旬共放流苗种3 678.94万只,7月上中旬、8月上中旬和8月下旬三疣梭子蟹相对资源密度分别为16.60、2.20和13.33只/h。通过6月上中旬放流前本底调查和8月下旬放流后跟踪调查分析增殖放流前后三疣梭子蟹资源量的变化,通过内禀增长率来计算自然群体在放流前后的种群扩繁能力,计算出2018年辽东湾三疣梭子蟹放流后,放流群体所占比例为30.10%;同时采用世代分析法,分析出2018年三疣梭子蟹当年补充群体占比为94.54%。统计2018年秋汛期间三疣梭子蟹捕捞产量为1 890 t,增殖放流回捕产量538 t,回捕率9.36%,投入产出比为1∶12.02。通过扫海面积法估算三疣梭子蟹的资源量为2 056 t,接近于回捕调查的实际产量。建议可以适当加大辽东湾三疣梭子蟹的放流量,促进辽东湾三疣梭子蟹资源修复和渔民增收。     

放流三疣梭子蟹月间回捕率及繁殖贡献率研究

2015年6月,将约500万只人工繁育的三疣梭子蟹C2期稚蟹放流到辽宁盘锦沿岸海域。当年7月28日—10月3日在盘锦沿岸以地笼网回捕1671只三疣梭子蟹样本,剪其螯足,剥离肌肉,提取DNA,利用微卫星DNA分子标记进行亲子鉴定,开展个体识别。试验结果显示,120只为当年放流蟹,放流后苗种短期月间放流蟹占当月回捕蟹群体的比例为2.61%~16.43%。在所检测的样本中,有22只雌性繁殖亲蟹在1671只回捕蟹群体中鉴定到其所产子代,占所检测的雌性繁殖亲蟹总样本的44%。有87只回捕到的放流蟹均来自3只雌性繁殖亲蟹,其他参与繁殖的雌性亲蟹对放流苗种的贡献率仅为0.83%~4.17%。遗传分析发现,本次增殖放流所使用的雌性繁殖亲蟹遗传多样性较高,种质质量有一定保证。上述研究成果将深化对三疣梭子蟹增殖放流的认知,为科学增殖放流提供参考。     

三疣梭子蟹摄食来源与食物竞争的研究方法

三疣梭子蟹(Portunus trituberculatus)是山东沿海的重要经济种类,在过度捕捞和环境变化影响下,资源已大幅衰退。为恢复三疣梭子蟹资源量,山东省自2005年开始实施大规模增殖放流工作。截止2019年,累计放流37亿尾,回捕产量超过16万t,取得了良好的经济效益、社会效益。三疣梭子蟹和日本鲟(Charybdis japonica)均属十足目、梭子蟹科,两者食性相近,在黄渤海均有分布。了解三疣梭子蟹的食物来源和食物竞争状况,是科学确定放流最佳数量的重要基础,是增殖放流迫切需要解决的关键问题之一.     

基于线粒体控制区序列的三疣梭子蟹增殖放流亲蟹遗传多样性研究

为研究山东沿海三疣梭子蟹增殖放流亲蟹群体的遗传多样性状况,实验采用536 bp的线粒体DNA控制区片段作为分子标记,对4个亲蟹群体的遗传多样性和遗传结构进行了分析。结果显示,301个三疣梭子蟹个体共检测到155个单倍型,4个群体的单倍型多样度为0.972 3~0.993 0,核苷酸多样度为0.021 2~0.023 6,表现出丰富的遗传多样性。AMOVA分析和Fst分析结果均显示,4个三疣梭子蟹亲蟹群体间遗传分化微弱,未形成明显的遗传结构,NJ系统树中未出现与各群体相对应的的谱系分支。研究表明,4个增殖放流亲蟹群体的遗传多样性丰富,且其遗传结构与放流海域的野生群体间没有明显分化,种质资源质量较好。此外,群体历史动态分析显示,渤海南部和黄海北部的三疣梭子蟹历史上曾经历过群体扩张事件。     

天津海域三疣梭子蟹生物学及资源量分析

根据2012年四个航次渔业资源调查数据,对三疣梭子蟹的群体结构,资源密度等分析研究。结果表明,天津海域三疣梭子蟹平均头胸甲长为49.32mm,平均头胸甲宽为104.12mm,平均体重为65.24g,三疣梭子蟹的平均生物密度为11.39尾/(网.h),平均生物量为0.526kg/(网.h)。通过调查发现,三疣梭子蟹呈现小型化趋势,生长速度加快,繁殖群体减少。     

三疣梭子蟹稚蟹标志方法的探讨

前言经济价值较大的甲壳类之一——三疣梭子蟹,近年来由于过度捕捞的影响,资源量大幅度下降,开展梭子蟹的人工育苗及放流增殖的研究,是很有必要的。1986年～1988年,日本海外渔业协力财团与营口增殖实验站合作,在前人试验的基础上,在我国首次取得了三疣梭子蟹工厂化人工     

长江口、杭州湾海域渔业资源增殖放流与效果评估

通过长江口、杭州湾海域2004—2006年渔业资源增殖放流前后调查、分析与评估结果表明,增殖放流种类对放流海域总资源补充量的增加有显著作用,放流种类的资源密度指数呈上升趋势,放流种类的资源补充量逐年增加;三疣梭子蟹、海蜇等放流种类在增殖放流区附近形成了区域性渔场,说明资源增殖、修复的效果非常明显;增殖放流整体的经济效益明显,3年总的苗种放流资金与捕捞经济效益的投入产出比平均达到1∶5,连续放流3年以上时增殖的累积效应得以逐渐体现;增殖放流使渔民的收入明显增加,促进了渔区社会稳定。     

渔业资源增殖放流效果评估方法的研究

依据渔业资源评估原理,结合渔业资源增殖放流的特点,提出一套计算群体生物统计量进而评估渔业资源增殖放流效果的方法。选用渔业资源评估模型,估算未建立生长方程的增殖放流种类的生长参数及其自然死亡系数,以及增殖放流种类的合理放流数量。提出确认渔获物中来自放流种苗数量的方法。推导了计算捕捞死亡系数和按时间序列计算放流群体残存量、回捕量、回捕率和回捕效益等的公式。     

崂山湾中国对虾(Fenneropenaeus chinensis)增殖放流的效果评价

为了评价崂山湾中国对虾的增殖效果，2012年5月在崂山湾分两批次放流中国对虾15673万尾。2012年7–9月开展了中国对虾跟踪与回捕调查，进行了中国对虾放流苗种存活生长状况、洄游分布及回捕情况的研究，并应用“Bhattacharya”法区分了中国对虾的自然群体与放流群体。结果显示，8月中旬中国对虾放流苗种主要生活在崂山湾中部海域，第1、2批放流苗种的平均体长分别达到144.9、130.5 mm，随着水温的降低，作季节性短距离的由浅水向深水区移动，放流种群和自然种群分别占总群体的92%和8%；由于受到竞争生物及栖息地环境因素的影响，中国对虾放流群体的回捕率仅为0.58%。虽然相比其他海域中国对虾的回捕率较低，但是崂山湾中国对虾增殖放流仍然取得了一定的生态、经济和社会效益。     

Movement of adult male snow crab, Chionoecetes opilio, in the southern Gulf of St. Lawrence and eastern Nova Scotia, Canada

A total of 12,755 adult male snow crabs (Chionoecetes opilio) were tagged with spaghetti–Carlin tags in 33 sites throughout the southern Gulf of St. Lawrence (sGSL) and eastern Nova Scotia (eNS) between 1993 and 2003. Of the 1971 tag returns obtained between 1994 and 2004, 1703 had accurate geographical recapture positions. The average distance travelled was 16.7 km for sGSL (maximum 165 km) and 61.5 km for eNS (maximum 368 km). The release site and the number of days at liberty before recapture were significant factors affecting the distance travelled by the crabs. Size had no significant effect on the distance travelled or the direction of movement. The present observations support the sedentary nature previously reported for the sGSL snow crab stock, but not the eNS stock, where the movement of snow crab was more dynamic. In both regions, there were movements between management areas, which indicates that managing the fisheries in discrete units is not warranted.     

A review of seed production and stock enhancement for commercially important portunid crabs in Japan

We reviewed the present status of seed production for stock enhancement and evaluated the impact of stocking on commercial catches in Japan, of portunid crabs particularly Portunus trituberculatus and Scylla paramamosain. The mean survival rate from hatching to first-stage crabs was around 10%, and 20–30% of the larval culture trials conducted in recent years could not harvest juveniles during seed production. To achieve reliable mass seed production technologies, measures for controlling disease and the nutritional condition of larvae in seed production tanks are required to be developed. The main spawning season extends from April/May to July. Reflecting their life cycle characteristics such as high growth rates, crabs recruit to the fishery after September and largely contribute to the commercial landings until December in the hatching year. The main release season of juveniles is from June to July. Consequently, released juveniles are expected to contribute to commercial landings in the release year. Analyses of catch and release statistics in two small bays estimated the yield from released individuals (YPR, yield per release) at 2.4 g for P. trituberculatus and 3.3–7.7 g for S. paramamosain, which were similar to values reported from tagging surveys. On a major regional basis, catch and release histories of P. trituberculatus highlighted the impact of hatchery releases on commercial landings as 33.6 g YPR in the Seto Inland Sea, where catches and releases have been greatest. Although the YPR estimates were different between small bays and major regional seas, Japanese stock enhancement programmes should have had an impact on portunid crab production, dependent on the magnitude of the releases.     

基于线粒体COⅠ基因和形态学方法的3种梭子蟹科溞状幼体物种鉴定

为调查黄海蟹类资源情况,并识别梭子蟹科溞状幼体各阶段形态,利用2018年5月下旬至8月上旬在黄海海州湾及邻近水域的鱼类浮游生物大面综合调查获得的海洋蟹类幼体样品,基于线粒体COⅠ基因和形态学方法对梭子蟹科溞状幼体种类进行了鉴定。结果显示,春夏季调查水域共出现3种梭子蟹科幼体:三疣梭子蟹(Portunus trituberculatus)、日本蟳(Charybdis japonica)和双斑蟳(Charybdis bimaculata);线粒体COⅠ基因测序可准确识别3个物种。对3种梭子蟹溞状幼体的形态学观察结果表明,背棘与额棘形态、尾叉外缘小刺的有无可作为区分上述3种梭子蟹溞状幼体的主要形态学指标。根据3个物种幼体形态特征建立了梭子蟹科溞状幼体分类检索表,基于检索表对幼体进行分类鉴定,并选择8月上旬航次形态学鉴定的80个三疣梭子蟹溞状幼体、24个日本蟳溞状幼体、70个双斑蟳溞状幼体样品进行分子测序验证。结果表明,上述3种蟹类溞状幼体的形态学鉴定准确率分别达到93.75%、100%和97.14%,误判皆发生于溞状幼体Ⅰ期梭子蟹科3个物种之间。研究初步建立了黄海中部梭子蟹科溞状幼体形态鉴定...     

Effects of net height of crab entangling nets on the capture of targeted economically important portunid species and non-target species

The aim of this study was to determine the effects of net height on the capture performance of crab entangling nets. Fishing trials were conducted using nets at varying net heights (1) 12 meshes down (MD), (2) 24 MD and (3) 50 MD. A total of 1290 individuals comprising 87 species belonging to 53 families were caught. One-way analysis of variance showed that net height significantly affected the various catch parameters, including catch per unit effort (CPUE) of the total and target catch, amount of non-target catch, size of catch and species richness. The use of appropriate net height is a potential technical measure for a selective but still efficient crab entangling net fishery. Lower net height significantly reduced non-target catch by up to 70%. Lower net height also decreased the CPUE of target catch such as Portunus pelagicus and Charybdis feriatus by up to 65% at 12 MD, but catch at 24 MD was not significantly different than that at 50 MD. The use of a net height of 24 MD also resulted in the capture of larger-sized P. pelagicus. The richness of the catch species decreased by up to 58% in lower nets. These results are useful to fishery managers and government institutions when developing and/or improving existing regulations towards a sustainable crab fishery, particularly blue swimming crabs.     

The enhancement of abalone stocks: lessons from Japanese case studies

The dramatic declines in abalone Haliotis spp. fishery production have been documented all over the world. Release of hatchery‐reared juveniles into natural habitats has been considered as one measure to sustain and/or augment the current fishery production of abalone, as well as to restore collapsed abalone stocks. However, attempts at abalone release programmes have only been undertaken at experimental scales, except for Japan, where large‐scale stock enhancement programmes for abalone have been undertaken since late 1960s. To evaluate the potential of stock enhancement for abalone, we analysed the release surveys of 13 case studies in Japan in terms of the overall recapture rate (number of recaptures through a lifetime/number of juveniles released), yield per release (YPR, yields from released individuals), the economic efficiency of releases (ratio of income from recaptured abalone to release cost) for each release year, and the contribution of hatchery releases to total catches for each fishing year. The average estimates for overall recapture rates (0.014–0.238) and YPR (3.1–60.3 g/individual) varied between locations and release years. The economic efficiency was estimated at 0.4–6.2. The released abalone contributed 6.9–83.5% to total catches. Hatchery releases could augment total production at some locations, but the success of release programmes would be limited by the carrying capacity at release areas, because density‐dependent mortality occurred following releases in some cases. Throughout Japan, the annual catch of abalone has continuously declined from ～6500 t in 1970 to ～2000 t in the mid‐1990s, despite the increase in the number of hatchery releases. Based on the estimates for YPR, the magnitude of the abalone releases on a national scale has not been sufficiently large to sustain the total production of Japanese abalone, which has primarily fluctuated according to the abundances of wild populations. Our results suggest that releases should be targeted at local populations in regions where stock enhancement is predicted to have the greatest chance of success, and the magnitude of releases should be considered carefully and determined for each region by taking the local carrying capacity into account. We also address the future prospects of abalone stock enhancement.     

基于张网渔获的蟹笼渔具对三疣梭子蟹的相对选择性

蟹笼渔具是东海近海重要的作业方式,安装释放装置是改善蟹笼渔具选择性的重要技术手段。作者通过海上试验,对比释放口宽度分别为25 mm和30 mm的试验蟹笼、对照蟹笼和张网的三疣梭子蟹(Portunus trituberculatus)渔获,结合渔获方程和SELECT模型分析蟹笼的接触选择性和对张网的相对选择性。试验结果显示,张网渔具所捕获的群体较对照蟹笼更小;对比对照蟹笼渔获分布,分析试验蟹笼的接触选择性,结果显示,50%选择甲宽(l50)和蟹笼的捕捞能力随着释放口宽度的增大而增大,但选择范围(SR)基本不变。对比张网的渔获分布,获得蟹笼对三疣梭子蟹的相对选择性,结合张网和蟹笼的作业特点,将对照蟹笼的相对选择性视为蟹笼渔具的可捕率,结果显示,较大的个体更容易接触并进入蟹笼,50%概率接触并进入蟹笼的个体甲宽为98.7 mm;释放口宽度30 mm的试验蟹笼的相对选择性的l50(118.4 mm)和SR(10.5 mm)与接触选择性的l50(117.4 mm)和SR(9.5 mm)几无差异;对于释放口宽度25 mm的试验蟹笼,接触和相对选择性l50没有差异,但相对选择范围SR(5.6 mm)明显小于接触选择范围(11.3 mm),因此只考虑蟹笼的接触选择性而忽略其可捕率所得的结果可能会产生偏差。根据试验结果,本文对蟹笼渔具的可捕率的描述方式以及与蟹笼作业能力的区别进行了探讨。     

闽南渔场桁杆虾拖网作业渔获种类组成

2010年1～5月和8～11月在闽南海区桁杆虾拖网作业渔船上每月采样一次，分析样品9批，样品数量15833个，累计重量79．66kg。对渔获物进行种类鉴定、组成分析，结果表明：闽南渔场桁杆虾拖网作业渔获种类共有62种，其中鱼类35种、虾类17种、蟹类4种、头足类4种、口足类2种；渔获物以虾类为主，占总渔获重量的69．8...     

Use of escape vents to improve size and species selectivity of collapsible pot for blue swimming crab <Emphasis Type="Italic">Portunus pelagicus</Emphasis> in Thailand

Laboratory experiments were firstly conducted to determine the possibility of modification of the collapsible pot for blue swimming crab Portunus pelagicus by designing appropriate escape vents in terms of shape, position, and size to improve size selectivity by reducing the catch of immature crabs. In laboratory observations, nearly square-shaped vents of 35 mm height and 45 mm length, located at the lower part of the side panel, showed the best performance to allow the escape of immature-size crabs by side-crawling escape behavior through the vents, with L _50% selection carapace length (CL) of 39.1, 44.4, and 48.7 mm CL for 40, 45, and 50 mm vent length, respectively. Comparative fishing trials between conventional and vented pots with vents of 35 × 45 mm size were conducted to examine the crab size and species selectivity. Use of the vented pots was found to reduce the number of immature crabs in the catch from 70.5% to 11.0% on average, while not affecting the catch efficiency of mature-size crabs. The vented pots also had a selective effect for reducing the catch of bycatch species in comparative fishing trials.     

闽南渔场蟹笼作业渔获组成和主要种类

2010年1-12月(休渔除外)在闽南海区蟹笼作业渔船上每月采样一次,分析样品10批,累计重量111.37 kg.对该渔获进行种类鉴定、组成分析,结果表明:渔获物中共出现72个种,其中鱼类40种、蟹类23种、口足类3种、头足类3种、螺类2种、虾类1种；重量比例为蟹类占45.80％、鱼类占44.46％、口足类占6.47％...