Effects of no‐take area size and age of marine protected areas on fisheries yields: a meta‐analytical approach     

Frederic Vandeperre  Ruth M. Higgins  Julio Sánchez‐Meca  Francesc Maynou  Raquel Goñi  Pablo Martín‐Sosa  Angel Pérez‐Ruzafa  Pedro Afonso  Iacopo Bertocci  Romain Crec’hriou  Giovanni D’Anna  Mark Dimech  Carmelo Dorta  Oscar Esparza  Jesús M. Falcón  Aitor Forcada  Ivan Guala  Laurence Le Direach  Concepción Marcos  Celia Ojeda‐Martínez  Carlo Pipitone  Patrick J. Schembri  Vanessa Stelzenmüller  Ben Stobart  Ricardo S. Santos 《Fish and Fisheries》2011,12(4):412-426

Marine protected areas (MPAs) are often promoted as tools for biodiversity conservation as well as for fisheries management. Despite increasing evidence of their usefulness, questions remain regarding the optimal design of MPAs, in particular concerning their function as fisheries management tools, for which empirical studies are still lacking. Using 28 data sets from seven MPAs in Southern Europe, we developed a meta‐analytical approach to investigate the effects of protection on adjacent fisheries and asking how these effects are influenced by MPA size and age. Southern European MPAs showed clear effects on the surrounding fisheries, on the ‘catch per unit effort’ (CPUE) of target species, but especially on the CPUE of the marketable catch. These effects depended on the time of protection and on the size of the no‐take area. CPUE of both target species and the marketable catch increased gradually by 2–4% per year over a long time period (at least 30 years). The influence of the size of the no‐take area appeared to be more complex. The catch rates of the entire fishery in and around the MPA were higher when the no‐take areas were smaller. Conversely, catch rates of selected fisheries that were expected to benefit most from protection increased when the no‐take area was larger. Our results emphasize the importance of MPA size on its export functions and suggest that an adequate, often extended, time frame be used for the management and the evaluation of effectiveness of MPAs.  相似文献   

Catch per unit effort standardization of the eastern Bering Sea walleye pollock (Theragra chalcogramma) fleet     

Brian C. Battaile  Terrance J. Quinn II   《Fisheries Research》2004,70(2-3):161-177

A general linear model (GLM) was used to standardize catch per unit effort (CPUE) data for Alaska walleye pollock (Theragra chalcogramma) from the Bering Sea fleet for the years 1995–1999. Data were stratified temporally by year and season and spatially by area using either Alaska Department of Fish and Game (ADF&G) or National Marine Fisheries Service (NMFS) reporting areas. Four factors were used: vessel identification (ID) number, vessel speed, percentage of pollock by weight in the haul (a measure of targeting), and whether most of the haul took place before or after sunset. At least 29 combinations of main effects, quadratic covariates, and interactions were tested for each year/area/season stratum. GLM models explained from 31 to 48% of the total sums of squares. Vessel identification number was included in all models and explained the most variability. Of the remaining factors, the square of the percentage of pollock in the haul was included in most models, following an F-test to determine parsimony. Analysis of the vessel identification number coefficients indicated that larger vessels tended to have higher CPUEs; and that this relationship differed between dedicated catcher vessels and offshore catcher processors. Coefficient estimates and response surfaces generally indicated increased CPUEs with the percentage of pollock in the haul and showed mixed results with vessel speed. The vessel identification number incorporated most vessel characteristics, leaving vessel speed primarily as a fitting variable with less biological meaning. The year/area/season stratification procedure was found to be necessary due to the unbalanced design, which otherwise would have factor levels with no data in a large combined model. In addition, the stratification procedure reduced the variability in CPUE substantially.  相似文献   

应用分层抽样技术估计北部湾底拖网渔业产量   总被引：1，自引：0，他引：1  

莫苑敏  龚超  冯波  卢伙胜 《现代渔业信息》2014,(3):211-214

传统的按行政单元逐级上报的渔业产量调查方法在数据获取过程中受人为因素的干扰,而全面普查的方法受限于时间和经费,相比而言,抽样调查是一种科学合理的方法。本研究于2007年8月对北部湾底拖网产量进行了调查,以全体底拖网渔船为抽样总体,按功率段划分了抽样层次,按比例分配了抽样单元数,分别以生产渔船总数和总功率数推算总产量,并比较了这两种方法的方差。结果表明,用每kW平均产量估计总产量的变异系数为1.13%,用单船平均产量估计总产量的变异系数为14.65%。同时由于渔业抽样调查的难点在于总体船数的掌握,建议统计推断时,采用单位渔捞努力量渔获量（CPUE）推算总体渔获量。  相似文献   

栉孔扇贝异精雌核发育四倍体早期胚胎发育的细胞学荧光显微观察     

迟长凤  杨爱国  王清印  刘志鸿  周丽青 《中国水产科学》2007,14(2):175-182

用1500μW/cm2的紫外线照射长牡蛎(Crassostrea gigas)精子60 s以进行灭活处理,并使之与栉孔扇贝(Chlamys farreri)卵子受精,在卵子受精后排出第一极体前用6-DMAP(50 mg/L)处理受精卵,持续处理35 min,抑制第一极体和第二极体的排放,诱导异精雌核发育四倍体。采用二脒基苯基吲哚(DAPI)荧光染色显微观察法,对灭活的长牡蛎精子诱导的栉孔扇贝雌核发育四倍体早期胚胎发育过程进行细胞学观察。结果表明:经紫外线灭活过的长牡蛎精子进入栉孔扇贝卵子后发生轻微膨胀;在第一次卵裂中期,精核形成一致密的染色质小体(DCB),位于两组分开的母本染色体之间,不参与核分裂;第一次卵裂结束时DCB滞留于两卵裂球的分裂沟上或进入其中一分裂球中;第二次卵裂过程中,DCB的去向与第一次卵裂时基本一致。6-DMAP处理有效地抑制了第一极体和第二极体的排出,从而使雌核四倍化。对担轮幼虫染色体倍性分析结果表明,通过本方法可以获得6.25%的四倍体幼虫。本研究还对灭活的异源长牡蛎精子诱导栉孔扇贝雌核发育四倍体过程中产生的复杂倍性、核物质分离紊乱及多精附卵现象进行了观察和分析。  相似文献   

瘤背石磺的生态习性观察   总被引：24，自引：3，他引：24  

黄金田  沈伯平  王资生 《海洋渔业》2004,26(2):103-109

2003年4～7月,作者对江苏射阳河口滩涂的瘤背石磺作了生态调查,并在室内进行温箱试养,观察其运动、呼吸、消化、生殖及对刺激物的反应等。结果表明,瘤背石磺栖息在潮上带滩涂,其每千克土壤中含N 0．325g、P 0．020g、K 0．521g、Cl 0．084g、有机质7．68g,土壤pH值9．43,含盐量1．615;在温度20～28℃,湿度接近100％时瘤背石磺才出来活动和摄食;在人工饲养下,瘤背石磺喜食螺旋藻。从解剖上看,它用呼吸腔呼吸,外套膜切片中有钙质颗粒,说明该物种是腹足纲动物由水生向陆生过渡的类型,体现了肺螺亚纲的特征。  相似文献   

棉花皱缩花叶病的初步研究     

章松柏  张长青  吴祖建  谢联辉 《河南农业科学》2010,(3)

2007年湖北荆州地区一些棉田棉花叶片上发生一种新的棉花病害,暂定名为棉花皱缩花叶病。通过症状描述、电镜观察和生物学接种对其进行了初步分析。结果显示:该病害症状疑似病毒病,但与已经报道的棉花病毒病症状都不相同。电镜观察显示,病株叶片汁液中存在4种杆状病毒颗粒,大小分别约是18nm×300nm、18nm×500nm、18nm×800nm、18nm×1100nm。生物学接种结果表明,该病不能经种子、棉蚜、烟粉虱、汁液摩擦4种方式传播。  相似文献   

甜菜花叶病毒病研究之二——感病细胞超微结构观察     

元平  裘维蕃 《植物病理学报》1994,24(3):223-226

 对不同时期感染甜菜花叶病毒(BtMV)的叶片,进行病理变化系列观察。早期侵染(7天前)的细胞质、细胞器均无变化,随着症状发展,风轮状内含体、束状内含体、细胞核卫星体,细胞质泡囊化旁类似病毒的束状结构,20天达到了高峰,风轮状及束状内含体一直持续两个月还存在。田间样品也观察到了典型的风轮状及束状内含体。细胞核卫星体出现很少。侵染后期,细胞质减少,叶绿体比相应健株提前出现淀粉粒,噬锇颗粒等,基粒片层也提前消解,表现细胞提前衰老的特征。此外细胞内还有许多健株没有的泡状结构。一种为旁壁体,可能与细胞壁加厚有关;一种为多重泡体的叠加,可能是液泡的吞噬作用加强与外源物质(BtMV)侵入有关;另外还有一种可能是过氧化物酶体或线粒体在病毒诱导下泡囊化,其作用不清楚。  相似文献   

陕北黄土高原多沙粗沙区乡村聚落土壤水蚀定位观测研究     

岳大鹏  甘枝茂  甘锐  查小春 《干旱区资源与环境》2005,19(6):142-146

为研究乡村聚落的土壤侵蚀,在陕北榆林、绥德、延安建立观测站,于2003年对乡村聚落中的户间道路、户间空地、院落在降雨时的次径流泥沙含量、平均含沙量、次侵蚀强度及观测期降雨形成的总侵蚀强度,进行了观测与分析。其观测结果,均说明户间道路、户间空地径流平均含沙量较大,榆林为29.37g/L、29.96g/L,缓德为21.06g/L、17.53g/L、延安为54.6g/L2、9.18g/L,而院落平均径流含沙量较小,榆林、绥德、延安分别为9.47g/L、8.64g/L、14.87g/L。观测期降雨侵蚀总强度,三个观测站均以户间道路最大,分别为1142t/km2、2156.6t/km26、285.7t/km2;户间空地次之,分别为744.5t/km2、1192.6t/km2、1953.2t/km2;院落较小,分别为161.1t/km23、78.7t/km2、1274.3t/km2。说明乡村聚落土壤侵蚀不可忽视,应加强防治。  相似文献   

核盘菌在亚麻上侵染致病的微观过程     

杨谦 Fox  RTV 《植物病理学报》1996,26(4):325-329

 第1次利用电子显微镜对核盘菌在亚麻叶片上侵染致病的微观过程进行深入细致的观察。结果表明,该菌在侵入叶表面之前可能产生某些酶类物质来软化溶解亚麻叶表面角质层,以帮助该菌对叶表面的侵入。本文还对菌丝和子囊孢子侵染过程的异同进行了比较。  相似文献   

沉降观测数据处理及绘图一体化程序开发与应用     

吴庆芳  裴良臣  徐辉  程正逢 《绿色科技》2013,(6):318-321

指出了随着测绘科学与技术的发展,电子水准仪应用到越来越多的高层建筑和地下工程等项目建设的沉降观测工作中,一套比较完整的沉降观测数据处理及绘图一体化程序可以改变传统的外业作业及内业人工数据处理和绘图方法。因此,开发沉降观测数据处理及绘图一体化程序具有重大的现实意义。  相似文献