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基于灰色系统理论的舟山海洋渔业劳动力结构及产量动态预测分析 总被引：1，自引：0，他引：1
运用灰色系统理论中的关联分析方法,对浙江省舟山市海洋渔业劳动力的组成结构和捕捞产量的发展动态进行了关联分析,在此基础上对2014~2018年舟山市海洋渔业劳动力和捕捞产量进行了趋势预测。关联分析结果显示,与舟山市海洋渔业劳动力结构的综合关联度大小依次为:海洋捕捞劳动力＞海洋其他劳动力＞水产品加工劳动力＞海水养殖劳动力,说明舟山市的海洋渔业仍以海洋捕捞为主,海水养殖业的规模相对还较小。模型预测结果显示,2014~2018年舟山海洋渔业劳动力人数为6.34×104~7.23×104人,海洋渔业劳动力数量呈下降趋势;海洋捕捞产量在102.65×104~105.23×104 t,产量年下降率约为0.6 %。文章通过对实证结果进行评析,建议加快调整舟山市海洋渔业产业结构,合理配置海洋渔业人力资源结构,积极引导海洋渔业劳动力转产转业,从而实现海洋渔业健康持续发展。 相似文献
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在“六五”计划期间,我国沿海各地积极贯彻“养捕并举”的方针,大力发展海水养殖业。使养殖产量在水产品总产量中的比例明显提高,增长幅度大大超过海洋捕捞产量的增加。1984年,全国海水养殖水产品的产量比1980年增加近20万吨,增长幅度为43.7%,而在此期间,海洋捕捞产量仅增长17.5%。据不完全统计,去年已有11个海洋渔业重点县的各类海水养殖产品的产值超过了海洋捕捞产品的产值。其中有福建省的福清等7个县,辽宁省的金县及大连旅顺口区,还有山东省的福山县和烟台市的芝罘区。现将以上各县按不变价计算的1984年海水养殖及海洋捕捞产值列表如下。 相似文献
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当前南海区海洋捕捞业面临的主要矛盾及其对策 总被引：2，自引：0，他引：2
一、当前海洋捕捞业的主要矛盾 南海区的海洋渔业从1981年起经历了二十年的持续高速发展,粤、桂、琼三省(区)海捕产量从52.8万t上升到1999年的334万t,机动渔船由1.4万余艘增至7万多艘(不含港澳渔船)。由于不断地增加捕捞量,目前近海资源已被充分利用,沿岸浅海资源被过度利用,单位产量下降,渔获组成低龄化,个体越来越小,过半渔船亏本。捕捞强度超过资源再生能力成为当今海洋渔业的主要矛盾已是不争的事实。 相似文献
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山东省三面临海，自然条件优越，海洋生物资源丰富，是我国渔业生产最发达的省份之一，水产品总年产量居全国第三位，1983年为67万吨(包括烟台海洋渔业公司)。近年来，由于捕捞力量发展超过了生物资源的再生能力，主要经济鱼类资源遭受破坏，海洋捕捞产量比1978年显著降低，海水养殖虽有发展，但产量仍低于1978年的水平。 相似文献
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2007年世界的天然捕捞和养殖的鲑鳟鱼合计总产量为280．6万t（换算为原条鱼的产量），比2006年的240．3万t增加17％，其中天然捕捞产量为97．3万t（占35％），比2006年的74．7万t增加30％；养殖产量为183．6万t（占65％），比2006年的165．6万t增加11％。表明世界的养殖鲑鳟鱼产量已占绝对的优势。 相似文献
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根据2008—2020年渔港渔业生产抽样调查数据,开展了南海北部鲔(Euthynnus affinis)资源的评估,统计发现,南海北部的鲔被围网、罩网、刺网和拖网捕捞,分别占其总产量的69.01%、10.98%、17.77%和2.23%。采用剩余产量模型对12个单位捕捞努力量渔获量数据进行了分析。平衡Schaefer模型计算的最大可持续产量为56 493.19 t,平衡Fox模型计算的最大可持续产量为49 888.98 t,非平衡产量模型计算的最大可持续产量为50 012.00 t。罩网201～300 kW、围网50～100 kW和刺网151～200 kW 3种作业方式与功率段在2020年被判断为捕捞努力量水平投入过度,即捕捞型过度捕捞,但这3种作业方式与功率段的产量只占总产量的13.73%,因此,当前鲔资源的利用状况整体上较为乐观。综合推断南海北部鲔资源总可捕捞量可设定在4.9×104 t。 相似文献
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为探明广东省海洋渔业资源现状及其对实现渔业可持续发展的重要意义,基于广东省1961—2018年海洋渔业统计产量数据,利用一种包含协变量的剩余产量模型(a surplus-production model incorporating covariates, ASPIC)和Catch-MSY模型对广东海洋渔业资源总可捕量、5个重要经济类群的最大可持续产量(maximum sustainable yield, MSY)以及可捕量进行了评估。结果显示,ASPIC与Catch-MSY模型的评估结果相近,广东海洋渔业资源MSY约为164×10~4 t, 1996—2006年处于过度捕捞状态,当前产量低于MSY。Schaefer与Fox模型评估的MSY相差不大,且B/B_(MSY)与F/F_(MSY)的历史变化趋势较为一致,但是评估的渔业现状差异较大,Schaefer模型评估结果表明当前渔业状态较差(B/B_(MSY)1且F/F_(MSY)1),而Fox模型表明当前渔业状态良好(B/B_(MSY)1且F/F_(MSY)1)。综合两个模型结果显示,带鱼类MSY为14.62×10~4～15.08×10~4 t,日本鲭(Scomber japonicus)MSY为3.82×10~4～6.78×10~4 t,鲳类MSY为5.77×10~4～6.21×10~4 t,鲷类MSY为4.16×10~4～4.54×10~4 t,蓝圆鲹(Decapterus maruadsi)MSY为17.68×10~4～19.84×10~4 t。5个经济类群中日本鲭和蓝圆鲹处于过度捕捞后的衰退状态,而带鱼类、鲳类和鲷类在近年来遭受过度捕捞。研究结果可为广东海洋渔业限额捕捞提供理论依据。 相似文献
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Abstract Escapement goals for Chinook salmon, Oncorhynchus tshawytscha (Walbaum), populations tend to be highly uncertain due to variability in, and in some cases complete absence of, spawner-recruit data. A previous study of 25 populations from Oregon to Alaska demonstrated that watershed size is a good predictor of unfished equilibrium population size. Here this relationship is further developed by evaluating a series of Bayesian hierarchical models of increasing complexity. The model that performed best included a temporal random walk to account for patterns in the spawner-recruit residuals and life history-specific distributions for the productivity parameter. 相似文献
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为进一步提高我国广大池塘养鱼的产品质量、经济效益和改善其生态环境。本试验在武汉新洲973项目实验基地9个陆基鱼池中进行了三种不同混养模式鱼类生长和效益的比较研究,每种模式设3个重复。模式Ⅰ中放养草鱼、鲢、鳙和高背鲫;模式Ⅱ中放养草鱼、鲢、鳙、匙吻鲟和高背鲫;模式Ⅲ中放养草鱼、鲢和高背鲫。
结果表明：通过122d的养殖试验,模式Ⅱ中草鱼的生长不仅显著高于模式Ⅰ和模式Ⅲ（P<0.05）,而且其经济效益模式Ⅱ同样高于模式Ⅰ和模式Ⅲ。 相似文献
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池塘鱼鸭混养高产技术试验 总被引：1，自引：0，他引：1
研究了鱼鸭混养技术措施，初步探索出鱼鸭混养的最佳养殖模式；放养大规模鱼种，滤食性鱼占４５％，杂食性鱼占５％，底层鱼占５０％，每亩水面配养鸭１２０只，每亩纯收入９２１６．７４元，比单纯养鱼提高３００％，专家验收认为：技术和综合效益均达国内领先水平。 相似文献
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Stock assessment of the blue jack mackerel,Trachurus picturatus,in the North‐eastern Atlantic 
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下载免费PDF全文 Joana Vasconcelos Ricardo Sousa Rodrigo Riera João Delgado Graça Faria Leonel Serrano Gordo 《Fisheries Management and Ecology》2018,25(4):233-239
A total of 49,151 blue jack mackerel, Trachurus picturatus, (Bowdich) was collected in Madeira Island (North‐eastern Atlantic) between 2002 and 2016 to evaluate possible influence of fishing on landings and reproductive parameters. A decreasing trend in the length composition was observed over the study period and length at first maturity decreased by 2.78 cm TL. Maximum yield per recruit decreased from 2002 to 2016 but the corresponding fishing mortality was constant (Fmax = 0.4/year). Considering the fishing mortality level in 2016, it is evident that the stock may be exploited beyond its sustainability limit. Amendments of the purse‐seine fishing regulations and implementation of measures to reduce fishing effort are suggested. 相似文献
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Evaluation of the advantage of marine protected areas over the reduction of the fishing mortality coefficient 总被引：1，自引：0，他引：1
ABSTRACT: In the present study, we compared the advantage of marine protected areas (MPA) to the reduction of the fishing mortality coefficient ( F ). We accomplished this by comparing the yield per recruitment (YPR) and spawner biomass per recruitment (SPR) under two controls. This was accomplished using a mathematical model. We used the following five measures as comparisons: (i) the condition of the fishery where the increase in YPR is possible; (ii) the increase in YPR or SPR obtained by allocating half the fishing ground as an MPA and by reducing F by half; (iii) the maximum YPR obtainable when the fishing mortality coefficient or the proportion of MPA in the fishing ground is completely controlled; (iv) the proportion of the MPA and the reduction ratio of F required for attaining 30% SPR; and (v) the YPR obtainable while maintaining 30% SPR. Our results show that the MPA has a minor disadvantage in terms of the first measure. The MPA is advantageous in increasing SPR in the second measure, with a low migration rate of fish. The MPA is also advantageous in increasing YPR in the second measure, with some intermediate migration. The MPA is disadvantageous in the third measure. The MPA is advantageous in the fourth measure, with a low migration rate. The MPA is disadvantageous in the fifth measure. 相似文献
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3种饵料模式对中间球海胆生长、性腺产量和性腺品质的影响 总被引：3，自引：1，他引：2
研究了3种饵料模式对中间球海胆整个生长周期的生长速度及商品规格性腺产量和品质的影响。选取6月龄中间球海胆,以3种饵料模式海带(E1)、海带+贻贝(E2)、玉米+贻贝(E3)养殖至商品规格,期间每隔2个月对海胆的壳径和体质量进行测量,实验结束时,对海胆的性腺湿重、性腺水分和性腺颜色等进行测量和分析。结果显示:在海胆的各生长阶段,饵料模式对其壳径和体质量均具有极显著影响,3种模式下海胆的壳径和体质量均为E2>E1>E3。饵料模式对海胆大部分生长阶段壳径和体质量的特定生长率具有极显著影响,3种模式下海胆壳径和体质量的特定生长率均为E2≥E1>E3。饵料模式对商品规格海胆性腺产量和性腺品质具有显著或极显著影响,对于性腺湿重,E2模式[雌性:(7.58±1.21)g,雄性:(7.74±1.95)g]表现最优,其次是E1模式[雌性:(4.50±1.20)g,雄性:(4.87±1.02)g],最后为E3模式[雌性:(2.66±1.02)g,雄性:(2.32±0.75)g];对于性腺指数,E2模式(雌性:15.07%±1.84%,雄性:15.83%±3.01%)表现最优,其次为E1模式(雌性:10.49%±2.71%,雄性:11.27%±2.45%)和E3模式(雌性:12.48%±4.33%,雄性:12.78%±3.73%);对于性腺水分和性腺颜色,E2和E1模式表现最优,E3模式表现较差。饵料模式对不同性别海胆的影响差别较小。实验结果表明,单一投喂海带,中间球海胆即可获得较好的壳生长,而添加动物性蛋白可以明显的提高其体质量和性腺产量,海带+贻贝这一模式可应用于提高海胆养殖效率,而玉米对促进海胆的体生长和性腺产量和品质均无有益效果,即使添加动物性蛋白,玉米+贻贝这一模式也很难替代海带有效地养殖中间球海胆。 相似文献
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A 74‐day experiment was conducted to evaluate the production performance and water quality variation in three types of farming system for largemouth bass Micropterus salmoides. The tested aquaculture models included monoculture of largemouth bass (MC), polyculture of largemouth bass, gibel carp Carassius auratus gibelio and silver carp Hypophthalmichthys molitrix (PC), and integrated culture of largemouth bass, gibel carp, silver carp and freshwater pearl mussel Hyriopsis cumingii (IC). The ratio of largemouth bass, gibel carp and silver carp was 30:2:1 in the PC model, and the ratio of largemouth bass, gibel carp, silver carp and mussel was 30:2:1:5 in the IC model. The largemouth bass were fed with formulated feed twice daily. No significant differences were found in weight gain and yield of largemouth bass, total fish yield, nitrogen (N) and phosphorus (P) utilization efficiencies, N and P wastes, pH, nitrite, nitrate, reactive phosphate, total nitrogen, total phosphorus, total organic carbon, chemical oxygen demand, 5‐day biochemical oxygen demand, chlorophyll a, primary productivity among the MC, PC and IC models. The ammonia was lower, while the dissolved oxygen was higher in the PC tanks than in the MC tanks. These results suggest that the environment situation was better in the PC tanks relative to that in the MC tanks. The present study reveals that the PC model should be a way to optimize the aquaculture model for commercial largemouth bass farming. 相似文献
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We examine the claim in Christensen that Maximum Economic Yield (MEY) is equal to Maximum Sustainable Yield (MSY). The basis for this claim is that MEY considers only the ‘catching’ of fish and that when the full value‐chain is considered; it is the MSY level that maximizes economic value. We argue that to maximize society’s benefit from a given sector of an economy, resources need to be allocated across all sectors such that additional net benefits from employing one more unit of society’s resources are equalized across all sectors of the economy. In this way, the opportunity cost of employing society’s resources across all economic sectors is minimized. In an economy where all resources are fully utilized, further value added in the value chain for fish is an additional cost and has the effect of reducing fishing effort and optimum yield rather than the opposite. In a less developed economy or a developed one in recession where all resources are not fully used, the multiplier effect could be important, and if it is high for fisheries it would be an argument to maximize sustainable yield and effort. We show, using current input‐output data, that this is not the case. Furthermore, from a simple principle of optimization, we know that to optimize a sector that consists of many segments through time, one has to optimize every portion of the chain through time. 相似文献
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Robert A. McConnaughey Jan G. Hiddink Simon Jennings C. Roland Pitcher Michel J. Kaiser Petri Suuronen Marija Sciberras Adriaan D. Rijnsdorp Jeremy S. Collie Tessa Mazor Ricardo O Amoroso Ana M. Parma Ray Hilborn 《Fish and Fisheries》2020,21(2):319-337
Bottom trawling accounts for almost one quarter of global fish landings but may also have significant and unwanted impacts on seabed habitats and biota. Management measures and voluntary industry actions can reduce these impacts, helping to meet sustainability objectives for fisheries, conservation and environmental management. These include changes in gear design and operation of trawls, spatial controls, impact quotas and effort controls. We review nine different measures and actions and use published studies and a simple conceptual model to evaluate and compare their performance. The risks and benefits of these management measures depend on the extent to which the fishery is already achieving management objectives for target stocks and the characteristics of the management system that is already in place. We offer guidance on identifying best practices for trawl‐fisheries management and show that best practices and their likelihood of reducing trawling impacts depend on local, national and regional management objectives and priorities, societal values and resources for implementation. There is no universal best practice, and multiple management measures and industry actions are required to meet sustainability objectives and improve trade‐offs between food production and environmental protection. 相似文献