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1.
为持续利用皮氏叫姑鱼(Johnius belangerii)资源,采用单船底拖网调查方法,于2015年5月至2016年2月4个季度季度从厦门海域6个站点采集皮氏叫姑鱼样本,研究皮氏叫姑鱼的生长、死亡、性比、繁殖习性和摄食强度等生物学特性。结果表明:厦门海域皮氏叫姑鱼群体体长分布范围为9~201 mm,平均106 mm,优势体长为80~120 mm,体重分布范围为1.2~166.3 g,平均30.5 g,优势体重为0~35 g。体长与体重的关系式为W=1×10~(-5)L~(3.0791),体长生长方程为L_t=220.5[1-e~(-0.56(t+0.61))],体重生长方程为W_t=165.38[1-e~(-0.56(t+0.61))]~(3.0791)。皮氏叫姑鱼的总死亡系数、自然死亡系数和捕捞死亡系数分别为2.25、0.63、1.62,开发率为0.72。雌雄比为1.14∶1,性成熟以Ⅱ期为主,性成熟个体春季最多。摄食强度以1级和2级为主,冬季摄食强度最强。结果说明厦门海域皮氏叫姑鱼资源已处于过度开发状态,应控制捕捞力度,根据皮氏叫姑鱼的繁殖习性建议加强繁殖群体和幼鱼群体的保护。  相似文献   

2.
基于矢耳石形态的平鲉属鱼类鉴别及研究方法比较   总被引:1,自引:1,他引:0  
分析了青岛胶州湾铠平鲉(Sebastes hubbsi)、花斑平鲉(Sebastes nigricans)和许氏平鲉(Sebastes schlegelii) 3种平鲉属鱼类的矢耳石形态特征,探究基于矢耳石形态鉴别3种鱼类的可行性.以8个耳石形状指标和37个椭圆傅里叶系数进行的单因素方差分析结果基本一致,显示铠平鲉与许氏平鲉的耳石形态差异最大,铠平鲉与花斑平鲉间差异最小.利用耳石形状指标、椭圆傅里叶系数、耳石形状指标与椭圆傅里叶系数相结合的方法,对3种鱼类的综合判别率均可达95%以上,判别分析散点图可明显将3种鱼类区分开.耳石长介于4~7 mm的3种鱼类小规格组与2龄及以上成鱼组耳石样本的判别结果一致,表明针对不同发育阶段平鲉属鱼类,基于耳石形态的种类鉴别均是可行的;仅使用椭圆傅里叶系数鉴别3种鱼类时综合判别率虽高达100%,但难以快速定位3种鱼类耳石形态间,在统计上差异显著而实际上微小的形状差异所在;而使用耳石形状指标和椭圆傅里叶系数联合判别,综合判别率亦高达99%,且能快速找出3种鱼类耳石在矩形趋近率、形态因子、面密度等的形态差异.研究表明,耳石形状指标和椭圆傅里叶分析联合判别是平鲉属鱼类种类鉴别及耳石形态差异分析的有效手段.  相似文献   

3.
分析了青岛胶州湾铠平鲉(Sebastes hubbsi)、花斑平鲉(Sebastes nigricans)和许氏平鲉(Sebastes schlegelii)3种平鲉属鱼类的矢耳石形态特征,探究基于矢耳石形态鉴别3种鱼类的可行性。以8个耳石形状指标和37个椭圆傅里叶系数进行的单因素方差分析结果基本一致,显示铠平鲉与许氏平鲉的耳石形态差异最大,铠平鲉与花斑平鲉间差异最小。利用耳石形状指标、椭圆傅里叶系数、耳石形状指标与椭圆傅里叶系数相结合的方法,对3种鱼类的综合判别率均可达95%以上,判别分析散点图可明显将3种鱼类区分开。耳石长介于4~7mm的3种鱼类小规格组与2龄及以上成鱼组耳石样本的判别结果一致,表明针对不同发育阶段平鲉属鱼类,基于耳石形态的种类鉴别均是可行的;仅使用椭圆傅里叶系数鉴别3种鱼类时综合判别率虽高达100%,但难以快速定位3种鱼类耳石形态间,在统计上差异显著而实际上微小的形状差异所在;而使用耳石形状指标和椭圆傅里叶系数联合判别,综合判别率亦高达99%,且能快速找出3种鱼类耳石在矩形趋近率、形态因子、面密度等的形态差异。研究表明,耳石形状指标和椭圆傅里叶分析联合判别是平鲉属鱼类种类鉴别及耳石形态差异分析的有效手段。  相似文献   

4.
作者用无液界电池电动势法测定了25℃恒离子强度(I=0.1,0.3,0.5和0.7)条件下KCl+KNO_3水溶液中KCl的平均质量摩尔浓度标度的活度系数,发现其活度系数的对数与混合溶液中KNO_3的浓度服从下列公式的关系: Lgγ1±=Lgγ_(1±)~0-a_(12)m_2-β12m_2~2且用最小二乘法求得了各离子强度条件下相应的哈奈特系数。还用Pitzer公式计算了混合溶液中KCl的平均活度系数及超额自由能,计算的活度系数与实验值之间的标准偏差为±0.006。较高的超额自由能表明该体系有较大的混合效应,同时表明在低浓度下K~+-NO_3离子对也可能发生较强的相互作用。已用简单的循环逼近法求算了KNO_3~0的化学计量缔合常数,其结果可用下列经验公式表示: LnK~*=a+bI_e已求得在海水离子强度(I_c=0.68)下KNO_3~0之K~*=2.4,用外推法求得25℃时KNO_3~0的热力学缔合常数值K_a=0.40。  相似文献   

5.
根据1997—1999年与2011—2015年北部湾底拖网调查数据,对短尾大眼鲷Priacanthus macracanthus两个时期的体长组成、性比与性腺发育、摄食以及生长、死亡和性成熟参数进行了研究。结果表明:1)1997—1999年优势体长组为110~170mm,2011—2015年为90~150mm,两个时期的体长组成及均值有显著性差异(P0.05),1997—1999年个体明显大于2011—2015年个体。2)除秋季外,2011—2015年短尾大眼鲷的雌雄比都明显高于1997—1999年;雌雄比随体长变化,1997—1999年先减少后增加,2011—2015年则是先减少后增加再减少;2011—2015年初次性成熟体长(L50)比1997—1999年缩短了5mm。3)与1997—1999年相比,2011—2015年的平均摄食强度明显要高,分析认为,可能是因为过度开发使鱼类减少,捕食压力减小,饵料相对充足。4)电子体长频率分析法评估的2011—2015北部湾短尾大眼鲷渐近体长(L?)和生长参数(K)分别为291mm和0.70a?1,总死亡系数(Z)和自然死亡系数(F)分别为4.57和1.38,开发率(E)为0.70,略高于1997—1999年水平,表明该群体仍处于过度开发状态。  相似文献   

6.
根据2011年海州湾及邻近海域的底拖网调查资料,对大泷六线鱼(Hexagrammos otakii)的群体结构、体长-体重关系、生长、死亡和资源利用状况进行初步研究。结果表明:大泷六线鱼渔获群体体长范围为44~292mm,优势体长组为54~74mm,平均体长为88mm;体重范围为0.35~574.3g,优势体重组为10g,平均体重为17.94g;体长-体重关系为W=4.23×10-6 L3.31(R2=0.978 6,n=1 514)。应用FiSATⅡ软件中的ELEFANⅠ方法估算的von Bertalanffy生长方程参数L∞、K和t0分别为328mm、0.36a-1和-0.43a;应用FiSAT软件中变换体长渔获曲线法求得总死亡系数Z为2.06,自然死亡系数M和捕捞死亡系数F分别为0.62和1.44,开发率E为0.70。Beverton-Holt单位补充量渔获量模型分析表明,在现行捕捞死亡系数F=1.44、YW/R取最大值时对应的开捕年龄为1.83a。现阶段大泷六线鱼资源已处于过度开发状态,考虑拐点年龄、临界年龄、繁殖和经济效益等综合因素,建议将海州湾大泷六线鱼最适开捕规格定为体长191mm。  相似文献   

7.
台湾海峡及邻近海域4种头足类的食性和营养级研究   总被引:7,自引:0,他引:7  
黄美珍 《台湾海峡》2004,23(3):331-340
本文研究中国枪乌贼、杜氏枪乌贼、目乌贼和短蛸4种头足类的食性与营养级.结果表明,中国枪乌贼和杜氏枪乌贼整年摄食率都高,目乌贼在春、夏季高,短蛸则在秋季摄食率高.4种头足类胃饱满系数皆呈现明显的季节变化.中国枪乌贼属游泳生物食性类型,杜氏枪乌贼和目乌贼属游泳动物和底栖动物混合食性类型,短蛸属浮游动物和底栖生物食性类型.4种头足类混合饵料的营养级分别为2.62、2.85、2.88和2.04级,均处于第三营养层次.其食物的重叠指数均超过0.7,食物重叠明显,对该海域的鱼类、甲壳动物(长尾类和短尾类)、头足类、糠虾类、端足类、樱虾类、腹足类等饵料生物存在激烈的竞争.  相似文献   

8.
石岛湾四种常见鱼类的热耐受性比较研究   总被引:4,自引:2,他引:2       下载免费PDF全文
作者分别采用动态法和静态法两种实验方法,以石岛湾4种常见鱼类(许氏平鲉(Sebastes schlegeli)、大泷六线鱼(Hexagrammos otakii)、褐菖鲉(Sebastiscus marmoratus)和矛尾虎鱼(Chaeturichthys stigmatias))为研究对象,对比研究了在4个季节基础水温(5.0~26.0℃)和9个温升速率(0.5~15.0℃/h)下这些鱼类的热耐受性。结果表明,4种鱼类的CTM(最大临界温度)和24 h UILT_(50)(24 h高起始致死温度)均与基础水温呈显著正相关,温升速率对鱼类耐热性的影响因鱼种和季节基础温度而异;相同基础水温下4种实验鱼类的CTM值均高于24 h UILT_(50)。4种鱼类的24 h UILT50依次为:矛尾虎鱼许氏平鲉褐菖鲉大泷六线鱼。  相似文献   

9.
利用衰减模型评估柔鱼西部冬春生群体资源   总被引:4,自引:0,他引:4  
根据2001~2004年8~11月中国大陆鱿钓船在西北太平洋生产的柔鱼渔获及其平均个体等数据,利用衰减模型估算各年度西部冬春生群体8月上旬的初始资源量、旬自然死亡系数和逃逸率等参数。评估认为,各年度8月上旬初始资源量为134.89×106~182.80×106ind.,平均值为160.57±17.13×106ind.。各年度初始资源量大小有所差异,其中2001年和2004年较高。2001~2004年可捕系数分别为3.722×10-5、3.892×10-5、8.491×10-5和6.665×10-5。各年度8~11月自然死亡系数在0.0377~0.0609/旬,平均值为0.0493±0.0118/旬。总死亡系数为0.1720~0.1957/旬,平均值为0.1834±0.0097/旬。2001~2004年11月末柔鱼的逃逸率在14.81%~23.34%间,逃逸量为12824~24499 t。分析认为,柔鱼西部冬春生群体的资源处在充分利用状态,年可捕量在8×104~10×104t。  相似文献   

10.
世界范围内,海洋渔业资源广泛面临着过度捕捞的压力.鱼类的不同生活史特征可表征不同的生活史对策,其变化可揭示鱼类种群对渔业捕捞压力的响应.台湾海峡及其邻近海域的主要渔场30多年来面临着过度捕捞的压力,导致了鱼类群落结构发生改变.本研究分析了该海域51种主要经济鱼类的生态参数,系统研究了其生活史特征及其变化.采用主成分分析法可将51种鱼类分成5个不同的生活史对策组,分组结果表明超过60%的鱼类被归纳入第5组,即近r对策组,且多为中上层鱼类.在此基础上收集相关历史数据,对其中25种经济鱼类进行生活史变化分析,讨论不同鱼类种群对渔业开发的响应.分析结果表明,在长期的渔业开发活动下多数鱼类表现出小型化、低龄化、早熟和生长率加快等趋势.此外,本研究计算了每种鱼类的开发率以进一步研究渔业捕捞压力对鱼类种群的影响,发现其中4种底层和近底层鱼类的生活史特征变化显著,提示某些物种可能对捕捞压力更敏感.本研究可为渔业管理和保护提供重要的科学依据.  相似文献   

11.
Commercial exploitation of lobsters from the Indian seas began in the 1950s. Annual landings have been declining from a peak of 4075 t in 1985 to 1364 t in 2002. Major fisheries were located on the north‐west, south‐west, and south‐east coasts. Among the 12 species recorded, only four species of spiny lobsters (three littoral and one deep sea) and one species of slipper lobster are commercially important. At Kayalpattinam and Tharuvaikulam, on the south‐east coast, lobster landings sharply declined for the gill‐net fishery. Of the two species that contributed to the fishery, Panulirus ornatus and Panulirus homarus, the latter has been more affected owing to high vulnerability to fishing activities. Catch composition analysis of the trammel‐net fishery showed that 35% of the landings consisted of P. homarus in the size range of 23–50 mm carapace length. On the north‐west coast, the spiny lobster Panulirus polyphagus and the slipper lobster Thenus orientalis are incidentally caught in trawl nets. However, the fishery for T. orientalis in the waters off Mumbai lasted only up to 1994. Large‐scale exploitation of spawning females, which formed 60% of the total catch, might have been detrimental to the recruitment process resulting in rapid decline and total collapse of the fishery. Abundance of P. polyphagus reached its maximum during September, constituting 23% of the average annual landing during 1988–2002. A high exploitation ratio (>0.7) indicated over‐fishing of the stock. Repeated spawning and high annual egg production are probably responsible for sustaining the stock, despite over‐exploitation. Major problems confronting the resource management of the multi‐gear and multi‐species lobster fisheries in India are discussed. An operational project, involving fisher community, has been taken up for creating awareness of the need for sustainable exploitation of the resource. Regulatory measures, such as closure of the fishery during the peak of the breeding season, ban on trammel‐net, mandatory release of egg‐bearing lobsters, and establishment of lobster sanctuaries are suggested to the State Governments for implementation.  相似文献   

12.
Individuals with high discount rates are likely not partial to conservation because they are unwilling to sacrifice short term benefits for potentially higher gains in the future. Many reef fisheries worldwide are open access, and fishers under open access systems are theorized to discount the future at an infinite rate. In contrast, fishers in a customary managed fishery can be expected to be more long term oriented, and thus possibly have lower discount rates. The present study tests this hypothesis by eliciting the discount rates of fishers in an open access small-scale reef fishery, and compares these rates to those of fishers in a customary managed reef fishery. Results indicate that fishers in both open access and traditionally managed reef fisheries have high annual discount rates that are on average over 200%. Contrary to expectations, fishers under an open access system are not associated with higher discount rates compared to customary management. It also appears that a larger proportion of open access fishers are more long-term oriented than those in the customary managed fishery, which is encouraging for the future conservation and sustainability of open access fisheries resources.  相似文献   

13.
The life spans of demersal species of fishes occurring in deep-waters are much longer and their potential growth rates much lower than those of related shallow water species. As a result, deep-sea demersal fish species are more vulnerable to exploitation. This is because low growth rates relative to the available market discount rate for capital makes it desirable for fishing firms to mine, rather than sustainably exploit, these resources even in the absence of fisheries subsidies. However, it is common knowledge that governments around the world do provide subsidies to their fishing industries. The objective of this contribution is to estimate the global amount of subsidies paid to bottom trawl fleets operating in the high seas, i.e., outside of the Exclusive Economic Zones of maritime countries. Our study suggests that fisheries subsidies to these fleets stand at about US$152 million per year, which constitutes 25% of the total landed value of the fleet. Economic data for bottom trawlers suggest that the profit achieved by this vessel group is normally not more than 10% of landed value. The implication of this finding is that without subsidies, the bulk of the world's bottom trawl fleet operating in the high seas will be operating at a loss, and unable to fish, thereby reducing the current threat to deep-sea and high seas fish stocks.  相似文献   

14.
中国近海渔业资源结构特点及演替的研究   总被引:1,自引:0,他引:1  
渔业资源是一种不断变化和更新的生物资源,如能合理地开发和利用可望取得良好的经济、社会和生态效益及永续利用的目的。然而由于人类的过度的开发和利用,加之生态环境的日趋恶化,使得许多渔业资源遭到破坏而严重衰退。近十多年来我国渔业与世界渔业发展的总趋势相似,随着捕捞强度的盲目增加,使得许多传统渔业资源遭到不同程度的破坏,主要捕捞对象替代频繁,其结构发生了显著的变化,总趋势是:经济价值高的、个体大的、年龄结构复杂的和在生态系统中营养层次高的类群逐渐被经济价值低的、个体小的、年龄结构简单的和营养层次低的类群所替代;底层鱼类所占比例日益减少,中、上层鱼类及虾、蟹类比例逐年增加。 对渔业资源结构特点和演替规律的研究一直受到国内外学者的重视,许多国家为了保护其近海渔业资源和本国的渔业权益,纷纷宣布建立渔业保护区和专属经济区,并采取了一系列的保护措施,因此近年特别着重研究建立保护区后的渔业资源结构的变化( Gunnar,1989; Megrey and Wespestaa,1990; Pinhorn and Halliday,1990)。我国学者也有许多渔业资源方面的研究报告(中国海洋渔业资源编写组,1990;邓景耀等,1991;孙宗烨等,1987;宋海棠等,1990;罗秉征等,1992;1993)。本文探讨了近40年来我国近海渔业资源结构的特点及其演变规律及趋势,并对我国不同海区渔业资源的演变进行了比较,进而分析了我国海洋渔业资源变化的原因,旨在为更加合理地利用我国的海洋渔业资源,并为其持续发展提供科学依据。  相似文献   

15.
根据2006年5月~2007年5月逐月采集青岛沙子口近海作业的定置网具渔获物的分析与测定,记述了该海区出现的98种渔业生物,并进行了定置网渔获物组成的分析,分析了种类组成特点及生物多样性的季节变化情况.结果表明,本调查区域渔获物以小型低值鱼类、经济无脊椎动物和经济幼鱼为主,渔获个体偏小.据此提出了保护近海生物多样性与合理利用近海渔业资源的一些建议.  相似文献   

16.
基于2006~2007年福建沿岸海域4个航次的底拖网调查,分析了福建沿岸海域石首鱼科鱼类的资源现状.结果表明:4个航次共捕获石首鱼类16种,其中春季捕获石首鱼类10种,夏季和冬季均捕获14种,秋季捕获12种.不同航次捕获的石首鱼类占所有鱼类总渔获量的比例为10.43%~23.23%,平均15.71%.平均资源密度和平均个体密度分别为81.49 kg/km2和3 663.06 ind./km2.平均资源密度和平均个体密度均以秋季最高,分别为130.02 kg/km2和5 702.64 ind./km2.闽东沿岸海域、闽江口及其附近海域、闽中沿岸海域和厦门沿岸海域石首鱼类的全年平均资源密度分别为70.75、96.23、22.54和84.57 kg/km2.在各种石首鱼类中,叫姑鱼(Johnius belengerii)的资源密度和个体密度最大,其次是丁氏(Wak tingi).叫姑鱼的相对重要性指数最高,为871.01,仅叫姑鱼为优势种.与近20 a前的调查资料相比较,石首鱼类的渔获量占鱼类总渔获量的比例升高,但资源密度显著下降,必须采取措施,避免开发强度的继续增加,以利于其资源的可持续利用.  相似文献   

17.
福建近海主要底层经济鱼类的种群动态   总被引:15,自引:1,他引:14  
本文研究了1994年福建近海底拖网渔船主要捕捞对象-带鱼,白姑鱼,二长棘鲷,短尾大眼鲷和条尾绯鲤5种底层和近底层鱼类的种群结构,生长和死亡参数及其开发比率,与1976年比较,带鱼渔获的最大年龄由1976年7龄降至1994年的4齿,白姑鱼,二长棘鲷和短尾大眼鲷由1976年或1982年的5龄降至1994年的3龄,条尾绯鲤由1976年的5龄降至1994年的4龄,带鱼的捕捞死亡系数由1976年的0.491上升到1994年的0.956。二长棘鲷由0.340上升到1.273,短尾大眼鲷由0.505上升到0.868。条尾绯鲤由0.576上升到0.924,白姑鱼由1982年的0.235上升到1994年的0.789,开发比率均比1976年或1982年有较大提高,分别在0.495,0.706,呈现充分开发或过度利用,并讨论了种群变动原因,捕捞结构和底拖网捕捞力量调整及5种鱼类的最小可捕标准问题。  相似文献   

18.
Studies that categorise species according to their conservation status often fall short in their implementation by not having taken into account the impacts on, or the response from, those that either benefit from, or exploit, the resource under consideration. This is especially true in multispecies fisheries where personnel and funding limitations often create the dilemma over which species should be the first to receive management and research attention. This study uses a multicriteria decision analysis approach to prioritise 176 South African linefish species on the basis of a number of criteria indicating conservation and socio-economic, including fishery sector, importance. For each species, conservation criteria were: abundance trend, level of knowledge, vulnerability, range, and relative exploitation throughout that range. Sectoral criteria were: total catch, degree of targeting, the number of participants and the economic value of each species. The scores given to each species on the basis of each of these criteria were summed to allow an examination of each fish's importance from the points of view of (i) conservation, (ii) each fishery sector separately and combined, and (iii) the overall combined conservation and sectoral importance. Different weight sets were used in the weighted summation of the scores, and results were examined for sensitivity. The results were reasonably insensitive to these changes in weights. Relative scores within each of the fishery sectors were dominated by two or three species. Consequently, the scores separating the remaining species from each other were small. This meant that, in many cases, even when the rank of species changed by a number of places with a different weight set, the differences in score were slight. On the whole, the top fish included the most important species in each sector and biogeographical region and in terms of conservation. The separate and overall rankings should assist in the development of broadly acceptable management strategies for different fish species.  相似文献   

19.
为了解舟山市小干岛附近海域渔业资源状况,并为其可持续开发利用提供科学依据,文章于2016年5月(春季)在该海域设置15个站位,进行渔业资源定点拖网调查;采用相对重要性指数以及Shannon-Weaver指数、均匀度指数和丰富度指数,分析该海域的生物种类和生物多样性。研究结果表明:研究区生物种类有47种,为12目31科40属,优势种包括六丝钝尾虾虎鱼等3种,常见种包括日本鼓虾等9种;鱼类在质量和尾数方面都占绝对优势,虾类和蟹类也较多,渔业资源个体较小、经济价值较低;各调查站位的生物量和尾数分布有所不同;与其他海域渔业资源相比,研究区的生物多样性处于中等水平,应加强保护和恢复。  相似文献   

20.
Based on the fishing net surveying data about anguillid elver of the Yangtze estuary collected in 2006 and historical data from previous research of the region, this study was focused on analyzing the fishing effort and catch variations of the elver, revealing the effects on fishery resources caused by elver fishing activities. It was found that the elver fishing activities took place in the tidal area of the Yangtze estuary from January to April. The yearly elver catch in 2000–2006 was 3 times greater than that in the 1970s–1980s. The catch per unit effort (CPUE) (ind./net/day) of the elver had some characteristics of temporal variation. It was higher in spring tide periods than that in neap tide periods, and the CPUE in February and March was 3–4 times greater than that in January. Twenty-eight fish species, 6 shrimp species, 2 crab species and 8 other invertebrates were found in the by-catch of the eel nets. Among the fishes, shrimps and crabs, the individual proportion of fishes is the highest, and they are mostly juveniles or small-size fishes, while the shrimps and crabs also make up a certain proportion. Most of the individuals in the by-catch were juveniles and were dead when they were harvested. It was proven that the activity of elver fishing has a great negative effect on regional fishery resources, though it has brought great commercial benefit. Relevant management and conversation should be reinforced.  相似文献   

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