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1.
The catch and effort data analysis(CEDA) and ASPIC(a stock assessment production model incorporating covariates) computer software packages were used to estimate the maximum sustainable yield(MSY) from the catch and effort data of Greater lizardfish Saurida tumbil fishery of Pakistan from 1986 to 2009. In CEDA three surplus production models of Fox, Schaefer and Pella-Tomlinson were used. Here initial proportion(IP) of 0.5 was used because the starting catch was roughly 50% of the maximum catch. With IP = 0.5, the estimated MSY from Fox model were 20.59 mt and 38.16 mt for normal and log-normal error assumptions, while the MSY from Schaefer and Pella-Tomlinson were 60.40, 60.40 and 60.40 mt, for normal, log-normal and gamma error assumptions respectively. The MSY values from Schaefer and Pella-Tomlinson models of three error assumptions were the same. The R2 values from those three models were above 0.6. When IP = 0.5, the MSY values estimated from ASPIC from Fox were 132 mt, and from logistic model were 69.4 mt, with R2 value above 0.8. Therefore we suggest the MSY of S. tumbil fishery from Pakistan to be 60–70 mt, which is higher than the latest catch, thus we would recommend that the fishing efforts for this fishery may be kept at the current level.  相似文献   

2.
Most fisheries in China do not have maximum sustainable yield(MSY) estimates due to limited and poor data.Therefore, finding a common method to estimate MSY or total allowable catch(TAC) for fishery management is necessary. MSYs of three important fisheries in the East China Sea were evaluated through a catch-based model.Estimates for intrinsic rate of increase(r) and five levels of process error were considered. Results showed hairtail Trichiurus japonicas(Temminck and Schlegel) and small yellow croaker Larimichthys polyactis(Bleeker) fisheries experienced overfishing from the mid-1990 s to the early 2000 s, and the suggested TACs were 55.8×10~4 t and9.06×10~4 t, respectively. Decades of overfishing in wintering and spawning grounds of large yellow croaker Larimichthys crocea(Richardson) caused the fishery's collapse in the 1980 s, and it has not recovered until today.The Catch–MSY model generated similar estimated MSYs with other methods and may be a useful choice for the assessment of regional stocks in China.  相似文献   

3.
In this paper Cohort Analysis (VPA) with the data on catch in number by age and year is used to estimate independently fishing mortality, abundance and actual number of spawning stock of the Pacific herring in the Huanghai Sea. The results show that catch rate of the fishery is very high, and that the fishing mortality of the dominant age group aged 2-4 was 0.87-2.97 during the years 1971-1984. The size of year class has been decreased since 1982 although the variability for this species in the Huanghai Sea is frequent. This results in reducing the recruitment of the fishery, the abundance and the actual number of spawning stock. Therefore, an urgent management measure should be considered.The magnitude of several sources of errors in Cohort Analysis (VPA) are examined, and the precision of the estimates is mainly dependent on an accurate natural mortality.  相似文献   

4.
In recent years, the small pelagic fishery on the Pacific northwest coast of Mexico has significantly increased fishing pressure on thread herring Opisthonema spp. This fishery is regulated using a precautionary approach(acceptable biological catch(ABC) and minimum catch size). However, due to fishing dynamics, fish aggregation habits and increased fishing mortality, periodic biomass assessments are necessary to estimate ABC and assess the resource status. The Catch-MSY approach was used to analyze historical series of thread herring catches off the western Baja California Sur(BCS, 1981–2018) and the Gulf of California(GC, 1972–2018) to estimate exploitable biomass and target reference points in order to obtain catch quotas. According to the results, in GC,the maximum biomass reached in 1972(at the beginning of fishery) and minimum biomass reached in 2015; the estimated exploitable biomass for 2019 was 42.2×10~4 t; and the maximum sustainable yield(MSY) was 15.4×10~4 t.In the western BCS coast, the maximum biomass was reached in 1981(at the beginning of fishery) and minimum biomass was reached in 2017; the estimated exploitable biomass for 2019 was 3.2×10~4 t; and the MSY was 1.2×10~4 t.Both stocks showed a decrease in biomass over the past years and were currently near to point of full exploitation.The results suggest that the use of the Catch-MSY method is suitable to obtain annual biomass estimates, in order to establish an ABC, to know the current state of the resource, and to avoid overcoming the potential recovery of the stocks.  相似文献   

5.
The majority of fishery stocks in the world are data limited, which limits formal stock assessments. Identifying the impacts of input data on stock assessment is critical for improving stock assessment and developing precautionary management strategies. We compare catch advice obtained from applications of various datalimited methods(DLMs) with forecasted catch advice from existing data-rich stock assessment models for the Indian Ocean bigeye tuna(Thunnus obesus). Our goal was to evaluate the co...  相似文献   

6.
-On the basis of the data obtained from the surveys in the Bohai Sea during 1982-1983, this paper analysed and discussed the distribution and seasonal variation of primary productivity in the Bohai Sea, and the correlations between the primary productivity and environmental factors. The organic carbon production and prospect of fishery production in the waters of this sea are estimated. It is shown that, there exists production patential in the Bohai Sea, the primary production is 112 gC/ (m2 ?a)the production of organic carbon being 10 million ton per year, the fishery yields 1 million ton and the maximum catch of sea products 0. 5 million ton. The results of the investigation can serve as the basic data for the exploitation, utilization and management of the fishery resources in the Bohai Sea.  相似文献   

7.
The pelagic species is closely related to the marine environmental factors, and establishment of forecasting model of fishing ground with high accuracy is an important content for pelagic fishery. The chub mackerel(Scomber japonicus) in the Yellow Sea and East China Sea is an important fishing target for Chinese lighting purse seine fishery. Based on the fishery data from China's mainland large-type lighting purse seine fishery for chub mackerel during the period of 2003 to 2010 and the environmental data including sea surface temperature(SST), gradient of the sea surface temperature(GSST), sea surface height(SSH) and geostrophic velocity(GV), we attempt to establish one new forecasting model of fishing ground based on boosted regression trees. In this study, the fishing areas with fishing effort is considered as one fishing ground, and the areas with no fishing ground are randomly selected from a background field, in which the fishing areas have no records in the logbooks. The performance of the forecasting model of fishing ground is evaluated with the testing data from the actual fishing data in 2011. The results show that the forecasting model of fishing ground has a high prediction performance, and the area under receiver operating curve(AUC) attains 0.897. The predicted fishing grounds are coincided with the actual fishing locations in 2011, and the movement route is also the same as the shift of fishing vessels, which indicates that this forecasting model based on the boosted regression trees can be used to effectively forecast the fishing ground of chub mackerel in the Yellow Sea and East China Sea.  相似文献   

8.
Many fish stocks in the world are depleted as a result of overexploitation, which reduces stock productivity and results in loss of potential yields. In this study we analyzed the catch trends and approximate thresholds of sustainable fishing for fished stocks to estimate the potential loss of catch and revenue of global fisheries as a result of overexploitation during the period of 1950–2010 in 14 FAO fishing areas. About 35% of stocks in the global marine ocean have or had suffered from overexploitation at present. The global catch losses amounted to 332.8 million tonnes over 1950–2010, resulting in a direct economic loss of US$298.9 billion(constant 2005 US$).Unsustainable fishing caused substantial potential losses worldwide, especially in the northern hemisphere.Estimated potential losses due to overfishing for different groups of resources showed that the low-value but abundant small-medium pelagics made the largest contribution to the global catch loss, with a weight of 265.0 million tonnes. The geographic expansion of overfishing not only showed serial depletion of world's fishery resources, but also reflected how recent trends towards sustainability can stabilize or reverse catch losses.Reduction of global fishing capacity and changes in fishery management systems are necessary if the long-term sustainability of marine fisheries in the world is to be achieved.  相似文献   

9.
Estimation of Wind Wave Frequency Spectra by Use of the Arcsine Law   总被引:1,自引:0,他引:1  
In the present study,the surface elevation of wind waves oberved in laboratory and in the Bohai Sea are adopted for the estimation of the wind wave frequency spectrum by use of the method of the arcsine law(MAL).The traditional method uses the surface elevation to calculate the correlation and then estimate the frequency spectrum while the MAL,presented by Yu and Lan(1979),uses the time sequence of zero-crossing points of surface elevation rather than directly the surface elevation to calculate the correlation.66 sets of wind wave data obtained in laboratory and 420 sets of data observed in the Bohai Sea are adopted for the examination of the method introduced by Yu and Lan.Results show that the MAL can give reliable estimation of wind wave spectra.Correlation and form of spectra estimated by the MAL are similar to those estimated by the traditional method.The peak frequency and the spectral density in peak frequency by the MAL are close to those obtained by the traditional method.  相似文献   

10.
The southern Patagonian stock(SPS) of Argentinian shortfin squid, Illex argentinus, is an economically important squid fishery in the Southwest Atlantic. Environmental conditions in the region play an important role in regulating the population dynamics of the I. argentinus population. This study develops an environmentally dependent surplus production(EDSP) model to evaluate the stock abundance of I. argentines during the period of 2000 to 2010. The environmental factors(favorable spawning habitat areas with sea surface temperature of 16–18°C) were assumed to be closely associated with carrying capacity(K) in the EDSP model. Deviance Information Criterion(DIC) values suggest that the estimated EDSP model with environmental factors fits the data better than a Schaefer surplus model without environmental factors under uniform and normal scenarios.The EDSP model estimated a maximum sustainable yield(MSY) from 351 600 t to 685 100 t and a biomass from 1 322 400 t to1 803 000 t. The fishing mortality coefficient of I. argentinus from 2000 to 2010 was smaller than the values of F_(0.1) and F_(MSY). Furthermore, the time series biomass plot of I. argentinus from 2000 to 2010 shows that the biomass of I.argentinus and this fishery were in a good state and not presently experiencing overfishing. This study suggests that the environmental conditions of the habitat should be considered within squid stock assessment and management.  相似文献   

11.
杨春蕙  刘琦  王迎宾 《海洋与湖沼》2022,53(5):1219-1224
当渔业资源出现衰退时,加强资源增殖放流以养护渔业资源、提高渔业产量对于渔业资源可持续利用具有重要意义;与此同时,增殖放流的实施会对基于资源开发与管理的评估的结果产生影响。基于2001~2015年间东海北部海域三疣梭子蟹(Portunus trituberculatus)渔业数据,采用增殖剩余产量模型,对东海北部海域三疣梭子蟹的最大可持续产量(MSY)及取得MSY时所需捕捞努力量(EMSY)和原存生物量(BMSY)进行了评估,并与传统Schaefer模型评估结果进行了比较。结果表明,当年增殖放流量约在3×106~95×106尾之间时,三疣梭子蟹年产量逐渐增加, MSY在14.2×104 t和14.6×104 t之间, EMSY基本在15×104吨位左右。增殖放流量增加,其对应的MSY也越高,能承受的EMSY也越高(从15×104~15.4×104吨位之间),相反BMSY则减小(从188.4×104 t降至186.6×104 t)。与传统的Schaefer模型评估结果相比,增殖剩余产量模型由于考虑了增殖放流生物量的因素,得到了MSY和EMSY有所增加,而BMSY有所下降的结论。研究结果有望为该研究海域三疣梭子蟹可持续地捕捞、放流与管理提供科学依据。  相似文献   

12.
应用Catch-MSY模型评估印度洋蓝枪鱼资源   总被引:2,自引:1,他引:1  
Catch-MSY模型可仅依靠渔获量数据进行渔业资源评估,在数据缺乏状况下能暂时替代标准资源评估模型。本研究以印度洋蓝枪鱼(Makaira nigricans)为例,根据有、无信息的内禀增长率r和环境容纳量K的先验分布,设立15组情景进行模型灵敏度分析、资源评估和预测。结果表明,参数r和K呈强烈的负相关,而最大可持续产量(Maximum Sustainable Yield,MSY)与参数r呈正相关;数据时间序列长度对评估结果影响有限,而模型对起止年渔获量较为敏感。资源状况评估表明,印度洋蓝枪鱼资源生物量状况良好,即B2015/BMSY大于1;而开发状况除其中两种情景外,均为过度捕捞,即F2015/FMSY大于1。资源预测表明,为使未来10年内B/BMSY>1的概率超过50%,需将渔获量缩减至当前渔获量的90%(13.86 kt);考虑到该模型在数据缺乏状况下会更加保守,若将当前渔获量的100%~110%(15.40~16.94 kt)设为管理目标,则未来5年内B/BMSY >1的概率超过50%。  相似文献   

13.
There is global interest in providing scientific advice on optimal harvesting of all commercially exploited fish stocks. Nevertheless, many commercially important stocks lack analytical assessments. Therefore, we evaluate a data-moderate stock assessment method: the stochastic surplus production model in continuous time (SPiCT). The method was applied to two Namibian stocks: (i) the data-rich Cape monkfish Lophius vomerinus, where results are compared to a new data-rich assessment using a state–space assessment model (SAM); and (ii) the data-moderate west coast sole Austroglossus microlepis, which is an important bycatch species in the Cape monkfish fishery, but currently unassessed. The information available to the data-moderate assessment is total commercial catch, commercial catch per unit effort (CPUE), and survey CPUE. SPiCT and SAM gave largely consistent estimates of relative fishing mortality (F/FMSY) and relative exploitable biomass (B/BMSY) for the Cape monkfish stock, although with some discrepancies. Differences in the biomass estimates between the two assessments suggest that further investigation is required to understand the cause, and that some caution is necessary when considering the biomass of the stock. SPiCT shows that the west coast sole may be overexploited, although the confidence bounds were too wide for a firm conclusion. Similarity in the estimates of F/FMSY for Cape monkfish in recent years, using SPiCT relative to SAM, likewise indicates the suitability of SPiCT for managing west coast sole.  相似文献   

14.
The Subei Shoal is a special coastal area with complex physical oceanographic properties in the Yellow Sea. In the present study, the distribution of phytoplankton and its correlation with environmental factors were studied during spring and summer of 2012 in the Subei Shoal of the Yellow Sea. Phytoplankton species composition and abundance data were accomplished by Uterm?hl method. Diatoms represented the greatest cellular abundance during the study period. In spring, the phytoplankton cell abundance ranged from 1.59×10~3 to 269.78×10~3 cell/L with an average of 41.80×10~3 cell/L, and Skeletonema sp. and Paralia sulcata was the most dominant species. In summer, the average phytoplankton cell abundance was 72.59×10~3 cell/L with the range of 1.78×10~3 to 574.96×10~3 cell/L, and the main dominant species was Pseudo-nitzschia pungens, Skeletonema sp., Dactyliosolen fragilissima and Chaetoceros curvisetus. The results of a redundancy analysis(RDA) showed that turbidity,temperature, salinity, pH, dissolved oxygen(DO), the ratio of dissolved inorganic nitrogen to silicate and SiO_4-Si(DIN/SiO_4-Si) were the most important environmental factors controlling phytoplankton assemblages in spring or summer in the Subei Shoal of the Yellow Sea.  相似文献   

15.
大多数渔业种类由于数据缺乏,无法使用传统的渔业资源评估方法开展评估和管理。越来越多的研究采用CMSY等基于有限数据的评估方法,但CMSY方法在渔获量数据时间序列长度有限、存在误差等情况下的评估可靠性尚有待验证。本研究运用CMSY方法对黄海3种产量较高的经济鱼类开展资源评估,探索渔获量数据时间序列长度、不同渔业发展阶段,以及观测误差水平对评估结果的影响。结果表明,鲐、带鱼和银鲳在2000年后均出现产量高于最大可持续产量(MSY)的情况,资源处于过度利用状况(B/BMSY<1、 F/FMSY>1),近10年来开发强度降低,但生物量仍处于较低水平(B/BMSY<1)。评估模型的回溯性分析结果差异较小,表明评估结果稳定。从数据长度上看,使用遍历产量上升和下降过程的长时间序列数据,其评估结果更为稳定。在观测误差大于20%的情况下,模型对MSY和BMSY出现高估,但结果仍较为稳健。在CMSY方法的应用中应注意选取长时间序列的产量数据,在评估结果不确定性高的情况下应采取相对保守的渔业管理措施。  相似文献   

16.
南海5类重要经济鱼类资源声学评估   总被引:11,自引:0,他引:11  
1997年12月至1999年6月,利用“北斗”号调查船配置的Simrad EK500回声探测-积分系统在南海北部海域进行了渔业资源声学调查,调查分春(4~6月)、夏(7~9月)、秋(10~12月)、冬(12~2月)4个季节进行.根据调查资料,运用渔业资源声学评估方法对该海域的带鱼科、蓝圆鲹、竹荚鱼、金线鱼科以及大眼鲷科等5类23种经济鱼类进行了评估与分析.结果表明,这些种类在南海北部海域仍具有一定的资源储量,其资源量分别为5.04×105,1.63×105,1.04×105,9.8×104和9.2×104t;分析了其资源量的区域分布和季节变化.  相似文献   

17.
西南大西洋阿根廷滑柔鱼,Illex argentinus,巴塔哥尼亚南部群体是重要的经济种类。海洋环境因子在柔鱼资源分布中起着重要的作用。本研究利用基于环境因子的动态产量模型评估2000-2010年的滑柔鱼的资源量。假设海洋环境因子(滑柔鱼产卵场最适宜海表温度占比)影响动态产量模型的参数K,DIC值表明在正态分布和均匀分布下均是基于环境因子的评估模型优于基本的动态产量模型。阿根廷滑柔鱼的最大可持续产量(MSY)在351600吨到685 100吨之间,资源生物量在1322400吨到1 803 000吨之间,其捕捞死亡系数均小于F0.1FMSY,资源处在良好状态,没有遭受过度捕捞。本研究为应用环境因子在柔鱼类的资源评估与管理提中供了科学的参考方法。  相似文献   

18.
基于Schaefer模型的东南太平洋茎柔鱼资源评估和管理   总被引:2,自引:0,他引:2  
东南太平洋茎柔鱼(Dosidicus gigas)是世界范围内最重要的经济头足类之一,也是我国鱿钓渔船的重要捕捞对象。本文根据2003—2012年中国大陆的渔业数据和FAO统计的东南太平洋茎柔鱼产量数据,利用Schaefer模型,基于贝叶斯统计方法,分基准方案和敏感性分析方案对东南太平洋茎柔鱼资源进行评估,并对其管理策略做了风险分析。结果表明,年渔获量和CPUE数据为贝叶斯资源评估模型提供了足够多的信息。2003—2012年捕捞死亡率低于目标参考点F0.1,渔获量小于最大可持续产量,资源量大于目标参考点Bmsy,资源状况良好,未遭受过度捕捞。在基准方案下,最大可持续产量为142.9万吨,维持最大可持续产量的资源量为214.7万吨,此时的捕捞死亡率为0.682;在敏感性分析方案下,最大的可持续产量为152.5万吨,维持最大可持续产量的资源量为229.6万吨,此时的捕捞死亡率为0.691。决策分析和风险分析表明,当捕获率设定为0.3以下时,资源能够得到较好的养护,资源崩溃的可能性很低。将捕获率设定在0.3左右是最适的管理策略,此时的持续产量为99万吨左右。  相似文献   

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