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1.
The impact of spatial autocorrelation on CPUE standardization between two different fisheries 总被引：2，自引：0，他引：2
Catch per unit of eff ort(CPUE) data can display spatial autocorrelation. However, most of the CPUE standardization methods developed so far assumes independency of observations for the dependent variable, which is often invalid. In this study, we collected data of two fisheries, squid jigging fishery and mackerel trawl fishery. We used standard generalized linear model(GLM) and spatial GLMs to compare the impact of spatial autocorrelation on CPUE standardization for different fisheries. We found that spatialGLMs perform better than standard-GLM for both fisheries. The overestimation of precision of CPUE estimates was observed in both fisheries. Moran's I was used to quantify the level of autocorrelation for the two fisheries. The results show that autocorrelation in mackerel trawl fishery was much stronger than that in squid jigging fishery. According to the results of this paper, we highly recommend to account for spatial autocorrelation when using GLM to standardize CPUE data derived from commercial fisheries. 相似文献
2.
Standardization of CPUE for Chilean jack mackerel (Trachurus murphyi) from Chinese trawl fleets in the high seas of the Southeast Pacific Ocean 总被引：1，自引：0，他引：1
The generalized linear model (GLM) and generalized additive model (GAM) were applied to the standardization of catch per unit effort (CPUE) for Chilean jack mackerel from Chinese factory trawl fishing fleets in the Southeast Pacific Ocean from 2001 to 2010 by removing the operational, environmental, spatial and temporal impacts. A total of 9 factors were selected to build the GLM and GAM, i.e., Year, Month, Vessel, La Niña and El Niño events (ELE), Latitude, Longitude, Sea surface temperature (SST), SST anomaly (SSTA), Nino3.4 index and an interaction term between Longitude and Latitude. The first 5 factors were significant components in the GLM, which in combination explained 27.34% of the total variance in nominal CPUE. In the stepwise GAM, all factors explained 30.78% of the total variance, with Month, Year and Vessel as the main factors influencing CPUE. The higher CPUE occurred during the period April to July at a SST range of 12–15°C and a SSTA range of 0.2–1.0°C. The CPUE was significantly higher in normal years compared with that in La Niña and El Niño years. The abundance of Chilean jack mackerel declined during 2001 and 2010, with an increase in 2007. This work provided the relative abundance index of Chilean jack mackerel for stock assessment by standardizing catch and effort data of Chinese trawl fisheries and examined the influence of temporal, spatial, environmental and fisheries operational factors on Chilean jack mackerel CPUE. 相似文献
3.
In the Indian Ocean, bigeye tuna supports one of the most important fisheries in the world. This fishery mainly consists of two components: longline and purse seine fisheries. Evidence of overfishing and stock depletion of bigeye tuna calls for an evaluation of alternative management strategies. Using an age-structured operating model, parameterized with the results derived in a recent stock assessment, we evaluated the effectiveness of applying constant fishing mortality (CF) and quasi-constant fishing mortality (QCF) strategies to reduce fishing effort of purse seining with fish aggregating devices (FADs) at different rates. Three different levels of productivity accounted for the uncertainty in our understanding of stock productivity. The study shows that the results of CF and QCF are similar. Average SSB and catch during simulation years would be higher if fishing mortality of FAD-associated purse seining was reduced rapidly. The banning or rapid reduction of purse seining with FAD resulted in a mean catch, and catch in the last simulation year, higher than that of the base case in which no change was made to the purse seine fishery. This could be caused by growth overfishing by purse seine fisheries with FADs according to the per-recruit analysis. These differences would be more obvious when stock productivity was low. Transferring efforts of FAD-associated purse seining to longline fisheries is also not feasible. Our study suggests that changes are necessary to improve the performance of the current management strategy. 相似文献
4.
WANG Yingbin LIU Qun* and WANG Yanjun College of Fisheries Ocean University of China Qingdao P. R. China 《中国海洋大学学报(英文版)》2007,6(1):53-59
1 Introduction Natural mortality coefficient (M) is one of the key population parameters common to most analyses in fish stock assessment. Many mathematical models of fish stock dynamics include M directly or indirectly. However, until now M is the least known among the four factors affecting fish stock variation: recruitment, growth, natural death and fishing death (Quinn and Deriso, 1999). There is an extensive literature concerning the impact of errors in M on stock assessment (Mertz and… 相似文献
5.
Using surplus production model packages of ASPIC(a stock-production model incorporating covariates) and CEDA(Catch effort data analysis),we analyzed the catch and effort data of Sillago sihama fishery in Pakistan.ASPIC estimates the pa-rameters of MSY(maximum sustainable yield),Fmsy(fishing mortality),q(catchability coefficient),K(carrying capacity or unexploited biomass) and B1/K(maximum sustainable yield over initial biomass).The estimated non-bootstrapped value of MSY based on logistic was 598 t and that based on the Fox model was 415 t,which showed that the Fox model estimation was more conservative than that with the logistic model.The R2 with the logistic model(0.702) is larger than that with the Fox model(0.541),which indicates a better fit.The coefficient of variation(cv) of the estimated MSY was about 0.3,except for a larger value 88.87 and a smaller value of 0.173.In contrast to the ASPIC results,the R2 with the Fox model(0.651-0.692) was larger than that with the Schaefer model(0.435-0.567),indicating a better fit.The key parameters of CEDA are:MSY,K,q,and r(intrinsic growth),and the three error assumptions in using the models are normal,log normal and gamma.Parameter estimates from the Schaefer and Pella-Tomlinson models were similar.The MSY estimations from the above two models were 398 t,549 t and 398 t for normal,log-normal and gamma error distributions,re-spectively.The MSY estimates from the Fox model were 381 t,366 t and 366 t for the above three error assumptions,respectively.The Fox model estimates were smaller than those for the Schaefer and the Pella-Tomlinson models.In the light of the MSY estimations of 415 t from ASPIC for the Fox model and 381 t from CEDA for the Fox model,MSY for S.sihama is about 400 t.As the catch in 2003 was 401 t,we would suggest the fishery should be kept at the current level.Production models used here depend on the assumption that CPUE(catch per unit effort) data used in the study can reliably quantify temporal variability in population abundance,hence the mod-eling results would be wrong if such an assumption is not met.Because the reliability of this CPUE data in indexing fish population abundance is unknown,we should be cautious with the interpretation and use of the derived population and management parameters. 相似文献
6.
The catch and effort data of Sillago sihama fishery in Pakistani waters were used to investigate the performance of two closely related stock assessment models: logistic and generalized surplus-production models. Compared with the generalized production model, the logistic model produced more reasonable estimates for parameters such as maximum sustainable yield. The Akaike’s Information Criterion values estimated at 4.265 and -51.152 respectively by the logistic and generalized models. Simulation analyses of the S. sihama fishery showed that the estimated and observed abundance indices for the logistic model were closer than those for the generalized production model. Standardized residuals were distributed closer for logistic model, but exhibited a slightly increasing trend for the generalized model. Statistical outliers were seen in 1989 and 1993 for the logistic model, and in 1981 and 1999 for the generalized model. Simulated results revealed that the logistic estimates were close to the true value for low CVs (coefficients of variation) but widely dispersed for high CVs. In contrast, the generalized model estimates were loose for all CV levels. The estimated production model curve parameter was not reasonable at all the tested levels of white noise. With the increase in white noise R2 for the catch per unit effort decreased. Therefore, we conclude that the logistic model performs more reasonably than the generalized production model. 相似文献
7.
针对病态最小二乘问题,提出基于Neumann级数的有偏估计方法。由该方法建立的有偏估计公式,包含现有的最小二乘估计、岭估计和广义岭估计公式,建立有偏估计和无偏估计的本质联系,并可以据此引申出一系列新的有偏估计形式。在这一系列的有偏估计中,存在着比岭估计或广义岭估计更接近于真值的解。以一个病态方程组为例对该方法进行验证表明,当观测向量中含有误差时,由最小二乘估计所得结果和真值误差较大,而各级有偏估计的结果和真值更加接近,且二级和三级有偏估计结果比相应的岭估计更接近于真值。 相似文献
8.
Application of CEDA and ASPIC computer packages to the hairtail (Trichiurus japonicus) fishery in the East China Sea 总被引：1，自引：0，他引：1
Surplus-production models are widely used in fish stock assessment and fisheries management due to their simplicity and lower data demands than age-structured models such as Virtual Population Analysis. The CEDA (catch-effort data analysis) and ASPIC (a surplus-production model incorporating covariates) computer packages are data-fitting or parameter estimation tools that have been developed to analyze catch-and-effort data using non-equilibrium surplus production models. We applied CEDA and ASPIC to the hairtail (Trichiurus japonicus) fishery in the East China Sea. Both packages produced robust results and yielded similar estimates. In CEDA, the Schaefer surplus production model with log-normal error assumption produced results close to those of ASPIC. CEDA is sensitive to the choice of initial proportion, while ASPIC is not. However, CEDA produced higher R 2 values than ASPIC. 相似文献
9.
The impact of climate change on sea level has received a great deal of attention by scientists worldwide.In this context,the problem of sea levels on global and regional scales have been analyzed in a number of studies based on tide gauges observations and satellite altimetry measurements.This study focuses on trend estimates from 18 high-quality tide gauge stations along the Mediterranean Sea coast.The seasonal Mann-Kendall test was run at a 5% significance level for each of the 18 stations for the period of 1993-2015(satellite altimetry era).The results of this test indicate that the trends for 17 stations were statistically significant and showed an increase(no significant trend was observed only at one station).The rates of sea level change for the 17 stations that exhibit significant trends,estimated using seasonal Sen's approach,range after correction for Vertical Land Motion(VLM)from 1.48 to 8.72 mm/a for the period1993-201 5.Furthermore,the magnitude of change at the location of each tide gauge station was estimated using the satellite altimetry measurements.Thus,the results obtained agree with those from the tide-gauge data analysis. 相似文献
10.
This study focused on the quantitative evaluation of the impact of the spatio-temporal scale used in data collection and grouping on the standardization of CPUE(catch per unit effort).We used the Chinese squid-jigging fishery in the northwestern Pacific Ocean as an example to evaluate 24 scenarios at different spatio-temporal scales,with a combination of four levels of temporal scale(weekly,biweekly,monthly,and bimonthly)and six levels of spatial scale(longitude×latitude:0.5°×0.5°,0.5°×1°,0.5°×2°,1°×0.5°,1°×1°,and 1°×2°).We applied generalized additive models and generalized linear models to analyze the24 scenarios for CPUE standardization,and then the differences in the standardized CPUE among these scenarios were quantified.This study shows that combinations of different spatial and temporal scales could have different impacts on the standardization of CPUE.However,at a fine temporal scale(weekly)different spatial scales yielded similar results for standardized CPUE.The choice of spatio-temporal scale used in data collection and analysis may create added uncertainty in fisheries stock assessment and management.To identify a cost-effective spatio-temporal scale for data collection,we recommend a similar study be undertaken to facilitate the design of effective monitoring programs. 相似文献
11.
We conducted acoustical surveys with a horizontal beam transducer to detect fish and with a vertical beam transducer to detect depth and macrophytes in two typical shallow lakes along the middle and lower reaches of the Changjiang(Yangtze) River in November 2013. Both lakes are subject to active fish management with annual stocking and removal of large fish. The purpose of the study was to compare hydroacoustic horizontal beam estimates with fish landings. The preliminary results show that the fish distribution patterns dif fered in the two lakes and were af fected by water depth and macrophyte coverage. The hydroacoustically estimated fish biomass matched the commercial catch very well in Niushan Lake, but it was two times higher in Kuilei Lake. However, acoustic estimates included all fish, whereas the catch included only fish 45 cm(smaller ones were released). We were unable to determine the proper regression between acoustic target strength and fish length for the dominant fish species in the two lakes. 相似文献
12.
Generalized linear models (GLM) and generalized additive models (GAM) were used to standardize catch per unit fishing effort
(CPUE) of Ommastrephes bartramii for Chinese squid-jigging fishery in Northwest Pacific Ocean. Three groups of variables were considered in the standardization:
spatial variables (longitude and latitude), temporal variables (year and month) and environmental variables, including sea
surface temperature (SST), sea surface salinity (SSS) and sea level height (SLH). CPUE was treated as the dependent variable
and its error distribution was assumed to be log-normal in each model. The model selections of GLM and GAM were based on the
finite sample-corrected Akaike information criterion (AICC) and pseudo-coefficient (Pcf) combined P-value, respectively. Both GAM and GLM analysis showed that the month was the most important variable affecting CPUE and could
explain 21.3% of variability in CPUE while other variables only explained 8.66%. The interaction of spatial and temporal variables
weakly influenced the CPUE. Moreover, spatio-temporal factors may be more important in influencing the CPUE of this squid
than environmental variables. The standardized and nominal CPUEs were similar and had the same trends in spatio-temporal distribution,
but the standardized CPUE values tended to be smaller than the nominal CPUE. The CPUE tended to have much higher monthly variation
than annual variations and their values increased with month. The CPUE became higher with increasing latitude-high CPUE usually
occurred in 145°E–148°E and 149°E–162°E. The CPUE was higher when SST was 14–21°C and the SLH from −22 cm to −18 cm. In this
study, GAM tended to be more suitable than GLM in analysis of CPUE. 相似文献
13.
利用国际上常用的8个冰川均衡调整（GIA）模型分别对利用卫星重力(GRACE)数据解算的2005~2014年全球质量变化趋势进行GIA改正。在对南极地区进行改正时发现,ICE-6G_C、ICE-6G_D和IJ05这3种模型的改正值相近;在对全球海水质量变化趋势进行改正时发现,不同改正模型对全球海水质量变化影响的均值都小于-2.0 mm/a;对比陆地水及冰盖对海水质量变化趋势的贡献,同时联合卫星测高和Argo温盐数据集进一步验证发现,Paulson07、GW13和ICE-6G_D模型对全球海水质量改正效果较好。综合整个陆地和海洋的分析结果来看,ICE-6G_D模型更适用于全球质量变化趋势的调整。 相似文献
14.
本文对近20年来中国地表气温变化估算方法进行了全面的总结,并对不同研究者所采用的资料、时间尺度及研究结果进行了对比分析。结合当前国际上应用较多的几种升温估算方法,本文以1970-2007年的气温数据为基础,分别应用直接算术平均法、逐站计算法、区域面积加权法、一级差分法和空间插值法,对中国大陆近40年的升温幅度分别进行了估算,从结果的对比分析中揭示中国地表气温变化估算中存在的不确定性:中国大陆地区近40年来的增温趋势在0.30~0.43℃/10a之间,升温幅度在1.16~1.56℃之间;冬季升温最为显著,夏季升温最少;整体上北方升温幅度高于南方。不同计算方法计算得到的增温速率在绝对值上有着一定差异,但整体趋势是相同的。 相似文献
15.
Impacts of distorted fishery statistical data on assessments of three surplus production models 总被引：1，自引：0，他引：1
We evaluated the effect of various error sources in fishery harvest/effort data on the maximum sustainable yield(MSY) and corresponding fishing effort(EMSY) using Monte Carlo simulation analyses.A high coefficient of variation(CV) of the catch and effort values biased the estimates of MSY and EMSY.Thus,the state of the fisheries resource and its exploitation was overestimated.We compared the effect using three surplus production models,Hilborn-Waters(H-W),Schnute,and Prager models.The estimates generated us... 相似文献
16.
������ 《中国海洋湖沼学报》2012,30(4):535-546
Fish traps were investigated to understand the effects of season, bait type, trap size, and trap soak time on catch rates, catch composition, and trap loss rates from March 2004 to September 2005, to improve the performance and management of Kuwait’s gargoor (cage style fish trap) fishery, which used to be the nation’s most important one in terms of value and landings volume. Catch rates were the highest in April/May (5-8 kg/trap haul) and again in December (7 kg/trap haul). Bait type and trap size also affected catch rates and species composition. Of the seven baits tested, the best catch rates, >5 kg/trap haul, occurred with cuttlefish (Sepia pharaonis), but wolf-herring (Chirocentrus dorab) and mullet (Liza klunzingeri) also produced good results (4-5 kg/trap haul). Within the five tested sizes, the two largest-sized traps captured more fish and larger size fish. Analysis of variance (ANOVA) showed significant differences of catch rate among traps with different baits as well as among traps of different sizes. Duncan test further revealed these differences between two specific baits and sizes. Cluster Analysis of species composition showed more differences among different baits than among different trap sizes. Longer soak times did not result in larger catch rates, but increased trap loss. About 10-day soak time resulted in trap loss 7%, while 40-day soak time could result in a loss of around 20%. Consequently, it is recommended that the gargoor be checked every 10 or fewer days. The average overall catch rate during the study period was lower than that of 1980s (4.5 vs. 5.8 kg/trap haul), indicating a possible decline of fish abundance in Kuwait’s waters. It is recommended that the number of gargoor fishing boats and gargoors from each boat should be limited to allow stock rehabilitation. 相似文献
17.
Age,growth,and mortality rate of the yellow goosefish Lophius litulon(Jordan,1902) in the Yellow Sea
《中国海洋湖沼学报》2021,(2)
With the decline in the most fisheries resources in the Yellow Sea,the yellow goosefish Lophius litulon has increased in commercial and ecological importance in recent years.We studied the length distribution,length-weight relationship,age composition,growth pattern,mortality,and exploitation rates of the yellow goosefish in the Yellow Sea.Total length(TL) of females and males ranged from 173 to582 mm and 178 to 500 mm,respectively.The length-weight relationships were also estimated for females and males.Age classes from 2 to 4 years predominated in the samples.The von Bertalanffy growth function(VB GF),estimated based on non-linear least-squares methodology,showed significant differences between sexes.Females attained a greater estimated asymptotic total length(765 mm TL) compared to males(579 mm TL).The VBGF did not differ significantly between stocks of the northern Yellow Sea and the southern Yellow Sea.Estimated natural instantaneous mortality rate(M) ranged from 0.25/a to 0.33/abased on four age-and length-based methods.Total instantaneous mortality rate(Z) of total samples calculated by the age-based catch curve method was 0.591/a and the average fishing mortality(F) was 0.30/a.Estimated exploitation rate(E) was approximately 0.5,indicating that the population of L.litulon in the Yellow Sea may be sustainable.These results provide a reference for the present status of L.litulon and information for the management. 相似文献
18.
ZHOU De-min XU Jian-chun GONG Hui-li 《中国地理科学(英文版)》2006,16(1):70-78
1INTRODUCTIONOakland,locatedat37°47′43″N, 122°13′41″W, isa cityon the east side of San Francisco Bay in Northern Cali-fornia in the United States. As of 2000, the city had anarea of 202.4km2with a total population of 399 484,making it the third largest city in the San Francisco BayArea after San Jose and San Francisco. The city of Oak-land stretches from San Francisco Bay up into the EastBay Hills (from the "flatlands" West Oakland, NorthOakland up into the foothill distr… 相似文献
19.
2004年北太平洋柔鱼钓产量分析及作业渔场与表温的关系 总被引：1，自引：0，他引：1
根据2004年5~11月我国鱿钓船在北太平洋生产数据,结合表温资料,按经纬度1°×1°的格式,利用Marineexplorer 4.0软件作图进行柔鱼钓产量及渔场与表温的关系分析。结果表明,5~7月在160°E以东海域作业,产量较低;8~10月在150°~160°E海域作业,为生产作业的产量高峰期,占总产量的62.5%;11月在150°E以西海域作业,产量也较低。在150°E以西海域CPUE最高,150°~160°E中部海域次之,160°E以东海域最低。作业渔场的适宜表温呈现出季节性变化。各月适宜表温分别为:5月12~14℃;6月15~16℃;7月14~16℃;8月18~19℃;9月16~17℃;10月15~16℃;11月12~13℃。 相似文献
20.
M. S. HEYDARNEJAD 《中国海洋湖沼学报》2009,27(1):61-62
The aim of this study is to report the length-weight relationship parameters (a and b) for some economically important fish species from Iranian freshwaters. The length-weight relationships (LWR) are calculated for six freshwater fish species collected during 2006 and 2007 in Iran. The values of the exponent b in the LWR (W=aLb) vary between 2.985 and 3.543. The LWR with high correlation coefficient (r2) is significant for all the species. These parameters are of great importance to evaluate the relative condition of populations, biology, species management and their fisheries and stock assessment. The application of the length-weight relationships presented here should be limited to the observed length ranges. 相似文献