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1.
Fishery-dependent catch per unit effort (CPUE) data have been used as an abundance index (AI) in fish stock assessments. However, fishery-dependent CPUE data are influenced not only by changes in fish abundance but also by other factors, such as the choice or restrictions of fishing grounds to operate. Accordingly, bias may arise in AIs due to a lack of data from unfished or rarely fished areas. To improve the accuracy of AI estimates, spatially arranged CPUE datasets from both trawl fisheries and research vessel surveys in the East China Sea were concurrently analyzed in the present study using a multivariate autoregressive state-space (MARSS) model. Survey datasets complemented information on stock status in the fishing areas where fishery-dependent datasets were limited. As a result, the combined use of datasets from both sources effectively improved the accuracy of estimates of AIs and the spatial distribution of the population density of each fish species. 相似文献
2.
《水生生物资源》2000,13(2):77-90
Fish stocks found on lagoon bottoms and near reefs are characterized by a high diversity and heterogeneous habitat which make stock estimation difficult. In particular, it is necessary to combine several methods in order to evaluate the major components of these stocks. The present study aimed at estimating reef fish stocks in the Northern Province of New Caledonia, a region where they represent a major target for the local fishermen. These estimates were based on experimental fishing with handlines and bottom longlines. Handlines were used to assess the stocks near reefs, and longlines for those in areas away from reefs and on lagoon soft bottoms. Handline stations (363) were sampled in three different regions (west, north and east lagoons) and three biotopes (nearshore, middle lagoon and barrier reef). A total of 104 species were caught, the major families being Lethrinidae, Lutjanidae and Serranidae. Species composition and catch per unit of effort (CPUE) varied among regions and biotopes. In particular, the north zone showed characteristics of an unexploited area with very high yields. An increase in CPUE and fish size from the coast towards the barrier reef and with increasing depth was observed in all regions. Correlations between CPUE from handlines and the numerical density and biomass estimates from underwater visual censuses (UVC) performed on nearby reefs were significant. A total of 206 longline stations were sampled in the west and east regions. A total of 80 species were caught, the major families being the same as those caught in stations with handlines with the addition of Carangidae. The CPUE of longlines was significantly correlated with numerical density and biomass estimates made by UVC along the longlines. Stock estimates based on the correlations between CPUE from handlines or longlines and UVC estimates indicate that 90 % of the lagoon stock were found on soft bottoms and near reefs. Reefs, despite biomasses that were five times larger than soft-bottom and near-reef areas, made only a small contribution to total stock. The ratio between density and CPUE was highest for the lowest densities, thus indicating that fishing efficiency increased with density. Comparison of handline catch performed around reefs and UVC data from nearby reefs suggests that there were strong relationships between the fish assemblages of these two biotopes. 相似文献
3.
Density‐ and species‐dependent errors in single‐pass timed electrofishing assessment of riverine salmonids 
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下载免费PDF全文 Hannele M. Honkanen Jennifer A. Dodd Jessica R. Fordyce Patrick Boylan Colin E. Adams 《Ecology of Freshwater Fish》2018,27(1):98-102
Electrofishing techniques are widely used for the estimation of the size of stream‐dwelling fish populations for both fishery management and scientific study. In contrast to multiple pass, population depletion methods, single‐pass catch‐per‐unit‐effort (CPUE) methods are less time‐consuming and labour‐intensive. A possible issue with the commonly used fixed total time CPUE protocol is that it does not differentiate between the time spent actively fishing and the time incurred while not actively fishing (e.g. removing fish from nets and navigating the site). This issue is likely related to fish density. This study compared two methods of CPUE electrofishing and tested the hypothesis that time spent handling fish and navigating a site can be a source of error in the commonly used fixed total time electrofishing method. Seventy‐one sites were sampled across three subcatchments in the Foyle catchment in Northern Ireland. We found a difference in the catch per unit time between the two methods and that this difference increased with fish density. The fixed‐time CPUE method also failed to detect a species presence in low‐density sites. 相似文献
4.
Abstract Electric fishing depletion systematically underestimates fish abundance in streams. Electric fishing mark-recapture estimates are unbiased, but only when performed over several days to allow marked fish to recover from electric fishing. A mark-recapture procedure that can be performed in 1 day and produces unbiased population estimates is described. It involves minnow trapping, marking and releasing juvenile salmonids in a stop-netted reach, followed by electric fishing the reach 1 h after release of marked fish. Recapture of marked fish during electric fishing can form the basis of a dual-gear mark-recapture population estimate, or an unbiased estimate of electric fishing capture efficiency. The marking technique did not affect short-term catchability of the target species ( P = 0.823), and provided unbiased estimates of capture efficiency (0.38–0.40) that were similar to those documented by other researchers. However, local validation to confirm equal catchability of marked and unmarked fish, as described in this study, is recommended. 相似文献
5.
Relationships between catch and effort in Fijian multispecies reef fisheries subject to different levels of exploitation 总被引：2，自引：0，他引：2
Abstract The catch-per-unit-effort (CPUE) and value-of-catch-per-unit-effort (VPUE) of reef-associated fish species from six Fijian native fishing grounds ( qoliqoli ) subject to different fishing intensities were determined using records of fishing activity from a voluntary logbook scheme. Line and spear fishing techniques were used for more than half the total fishing time (h person-1 d-1 ) in all qoliqoli , and yet the favoured technique in a given qoliqoli was frequently less efficient (lower CPUE) than other techniques. The popularity of relatively ineffective fishing methods implies that fishermen did not always attempt to maximize their catch rates. To compare fishing effort in different qoliqoli , all effort was rescaled on the basis of its recorded efficiency (measured as multispecies CPUE) and expressed as hours equivalent to boat-based spear fishing over coral by day to catch fish for sale. Total fishing intensity in the six qoliqoli ranged from 72 to 4310 h km-2 reef year-1 . The relationship between catch and effort was linear at all fishing intensities, suggesting that the qoliqoli were all fished on a sustainable basis. Furthermore, whilst there was a significant difference in CPUE and VPUE between the one or two qoliqoli with lowest fishing intensity and all the others, there were no significant differences between these other qoliqoli in terms of the VPUE of the saleable multispecies boat catch or the CPUE of species from piscivorous and carnivorous genera ( Epinephelus, Lethrinus and Plectropomus ) which the fishermen prefer to catch. 相似文献
6.
ABSTRACT: The recruitment abundance index of Pacific bluefin tuna Thunnus orientalis was estimated from 1980 to 2003 fishing year by using the troll fishery data in Nagasaki Prefecture, western Japan. It has been shown that the troll fishery in Nagasaki Prefecture operates with good time–area coverage of the species habitat, and that the fishing power slightly changed during the period analyzed, based on fisheries statistics, published information, and interviews with the fishers. Average catch per unit effort (CPUEs) were standardized by a generalized linear model (GLM) considering the effects of fishing year, season and landing area. Standardized CPUE of age-0 bluefin tuna showed larger fluctuations year by year than the nominal CPUE combined for all ages. High CPUEs in fishing years of 1981, 1994, 1996 and 1999 were observed. Data from these years agreed with the higher recruitments estimated by virtual population analysis (VPA) or higher catch of age-0 fish reported for the Pacific side. The age-specific standardized CPUE of age-0 bluefin tuna in this study was judged to be a useful indicator of recruitment. 相似文献
7.
T. Vehanen T. Sutela P. Jounela A. Huusko A. Mäki‐Petäys 《Fisheries Management and Ecology》2013,20(1):10-20
The EU Water Framework Directive (WFD) obligates authorities to assess the ecological status of rivers. The sampling of the fish assemblage must be based on a reliable and cost‐effective monitoring programme, and it should be optimised to measure the ecological quality cost‐effectively. The efficiency of single‐pass versus three‐pass backpack electric fishing was measured to assess ecological status. The data included 295 electric fishing samplings from 137 rivers in Finland and a 5‐year data series from six small forest streams in mid‐eastern Finland. Compared with three‐pass electric fishing, single‐pass electric fishing in the same area increased the risk of missing rare fish species and species with low catchability. The concordance of the calculated fish metrics (e.g. proportion of tolerant and intolerant species) between one‐ and three‐pass measurements was, however, high, suggesting that single‐pass electric fishing was a suitable sampling procedure to evaluate ecological status. Increasing the area sampled by single‐pass removals stabilised the variances in the fish metrics and similarity indexes. It was concluded that in small streams electric fishing an area 24–27 times the stream width and in general a minimum of 300 m2, but preferably more than 450 m2, was adequate to estimate fish assemblage attributes reliably in boreal streams. 相似文献
8.
Variation in characteristics among gizzard shad populations: The role of impoundment size and productivity 下载免费PDF全文
下载免费PDF全文 P. H. Michaletz 《Fisheries Management and Ecology》2017,24(5):361-371
Population characteristics of gizzard shad, Dorosoma cepedianum (Lesueur), an ecologically important fish species in Midwestern and southern USA impoundments, vary widely among water bodies. Impoundment productivity is known to influence population variables (e.g., recruitment, growth, mortality, size and age composition), but the role of impoundment morphometry (e.g., surface area, depth) is unknown. Differences in population characteristics of gizzard shad were compared between large and small impoundments across an impoundment–productivity gradient (indexed by total phosphorus [TP] concentration). Populations shifted from those comprised mostly of low abundances (indexed by catch per unit effort [CPUE], fish/hr of electric fishing) of long‐lived, large adults to those comprised of high abundances of short‐lived, small adults as TP increased. However, the trends in population variables across the TP gradient were less apparent in small impoundments than in large impoundments owing to considerable variation at a given TP level. Further analysis revealed that CPUE of gizzard shad was lowest in the smallest impoundments (<33 ha surface area) regardless of TP concentrations, probably because of more frequent winter kills. Overall, population characteristics were influenced by both density‐dependent effects and impoundment characteristics. Characteristics of gizzard shad were highly variable among populations, which have important consequences for ecosystem structure and function. 相似文献
9.
基于空间相关性的西北太平洋柔鱼CPUE标准化研究 总被引：5，自引：1，他引：5
CPUE标准化方法通常都假设名义CPUE之间是相互独立且没有相关性,然而鱼类集群分布通常存在着空间相关性,为此本研究以西北太平洋柔鱼的CPUE标准化为例,采用1999-2012年6-11月中国鱿钓生产数据以及对应的海表面温度和叶绿素浓度的环境数据,将空间相关性加入广义线性模型(general linear model,GLM)中.在空间GLM模型中运用4个距离模型(指数模型、球面模型、线性模型和高斯模型),进行标准GLM模型和4种空间GLM模型的CPUE标准化结果比较.结果发现,4种空间GLM模型均比标准GLM模型的最小信息准则(akaike information criterion,AIC)更小,标准化结果更准确.同时,在4个距离模型中,指数模型的AIC值最小,其CPUE标准化结果最佳.研究表明,在CPUE标准化中,鉴于鱼类集群与分布特性,应该充分考虑空间相关性这一因素. 相似文献
10.
M. JANKOVSKÝ D. S. BOUKAL K. PIVNIČKA J. KUBEČKA 《Fisheries Management and Ecology》2011,18(4):297-306
Abstract Recreational fisheries statistics can provide valuable information on the dynamics of fish stocks and their exploitation. For some reservoirs in the Czech Republic, there are conspicuous synchronous fluctuations in catches of different species that might be caused by fishing skills and strategies. This study describes a method that could detect signatures of such phenomena in individual logbooks. It classifies anglers by species reported during 1 year and compares the resulting angler groups by group size, fishing effort, catch per unit effort (CPUE) and annual catch. The method is illustrated by data from one reservoir, showing that the number of generalist anglers who caught several species was higher than expected. Generalists also had higher catches and effort but lower CPUE than specialists who caught only one of the species. The results indicate that generalist anglers with a low degree of specialisation and high effort could contribute to long‐term correlations in species catches. 相似文献
11.
Sampling fish communities in shallow lowland lakes: point-sample electric fishing vs electric fishing within stop-nets 总被引：1，自引：0，他引：1
M.R. PERROW A.J.D. JOWITT & L. ZAMBRANO GONZÁLEZ 《Fisheries Management and Ecology》1996,3(4):303-313
Fractional or point-abundance sample (PAS) electric fishing was compared with conventional electric fishing within stop-nets in several shallow, structurally complex, lowland lakes. The two methods tended to sample the fish community in different ways. PAS provided significantly higher total population estimates, partly as a result of the higher estimates for the dominant small fish (e.g. 0 + perch, Perca fluviatilis L.). Fish hidden by cover (macrophytes, branches, etc.) or substrate, such as eels Anguilla anguilla (L.) and ruffe Gymnocephalus cernuus (L.), were also sampled at a higher rate and for eel, this led to considerable variation in biomass estimates between the two methods. It is argued that PAS, rather than electric fishing within stop-nets, provided more accurate estimates of fish population parameters and that PAS had several distinct advantages when used for qualitative and quantitative stock assessment, particularly in shallow lakes dominated by emergent and submerged vegetation. 相似文献
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M. Prchalová J. Kube&#;ka M. &#;ech J. Frouzová V. Dra&#;tík E. Hohausová T. J&#;za M. Kratochvíl J. Mat&#;na J. Peterka M. &#;íha M. Tu&#;er M. Va&#;ek 《Ecology of Freshwater Fish》2009,18(2):247-260
Abstract – Spatial distribution of the fish community in the deep canyon-shaped Římov Reservoir, Czech Republic, was studied using overnight gillnetting fishing in 1999–2007. Effects of depth, distance from the dam to the tributary and habitat type (benthic and pelagic) on fish community structure, catch per unit of effort (CPUE), biomass per unit of effort (BPUE) and average weight were tested. Fish were recorded in all sampled depths and parts of the reservoir. Redundancy analysis revealed that effects of three environmental variables were significant and most variability was explained by depth, then by distance from the dam and habitat type. CPUE and BPUE of all species decreased with depth and responses of individual species to depth were similar for juvenile and adult fish. Number of species, CPUE and BPUE of all species except perch increased heading towards the tributary and peaked close to or at the tributary part of the reservoir. Responses of juvenile fish to distance from the dam differed from that of adult fish. Structure of fish community differed in benthic and pelagic habitats with species preferably occupying epipelagic (bleak, asp, rudd and juvenile bleak, roach and bream) or littoral waters (perch, pikeperch, ruffe, roach, bream and juvenile percids). This study showed that fish distribution in the reservoir followed distinct patterns, which were probably shaped by a combination of physiological constraints plus trade-off between food resources and competition. 相似文献
14.
ABSTRACT: The stock size of sandfish in the northern Sea of Japan was estimated by a virtual population analysis (VPA) and sensitivity analyses were attempted on the VPA estimate. The stock size estimates were approximately 600–900 million until 1975, but since 1976 they have rapidly decreased. In the sensitivity analyses, the estimates of absolute stock size were not sensitive against the changes in the fishing mortality coefficient for terminal age and the measurement error in catch-at-age. This suggested that the relative stock size remains almost unaffected by the error in the data used in the VPA, if the degree of catch-at-age error and the natural mortality coefficient is correct. The relationships between the biomass estimated by the VPA and the density index from Danish seine fisheries, and between the biomass and the catch per unit effort (CPUE) from the experimental survey using Danish seine nets, were also examined. The density index and the CPUE indicated significant relations with the biomass. Consequently, the CPUE is useful to monitor the relative stock size in a timely manner, and the VPA estimate and the CPUE should be utilized for adjusting the total allowable catch in the multiseasons. 相似文献
15.
Abstract Removal sampling by electric fishing is widely used for assessing fish population size. As it is manpower consuming, less-demanding techniques have been proposed to increase the number of sites covered with the same human resources. These techniques essentially provide relative abundance measures. To be used for absolute abundance estimation, they need to be inter-calibrated with another method such as removal sampling. Here, hierarchical Bayesian modelling framework is used for this inter-calibration because it allows an estimate of absolute abundance from abundance index data alone while accounting for the main sources of uncertainty. It is applied to a 0+ juvenile Atlantic salmon, Salmo salar L. data set from 21 sites on the River Faughan, Northern Ireland. A positive relationship was found between the abundance index (number of fish caught in 5 min of actual electric fishing) and the density. The estimates from the index of abundance alone are fairly imprecise, but still allow differentiation of contrasting levels of fish density. 相似文献
16.
Aatu Turunen Andrés Salgado-Ismodes Hannu Huuskonen Kimmo K. Kahilainen Mikko Olin Jukka Ruuhijärvi Anssi Vainikka 《Fisheries Management and Ecology》2023,30(1):99-108
Management of inland recreational fisheries would benefit from stock abundance and size structure data. Feasibly standardised angling methods such as ice fishing could produce representative catch-per-unit-effort (CPUE) information on the abundance of different-sized fish in small lakes. Here, we first used standard Nordic multimesh gillnets to obtain number-per-unit-effort (NPUE), biomass-per-unit-effort (BPUE) and size structure data on Eurasian perch (Perca fluviatilis) stocks in 11 small boreal lakes in summer. Second, the same lakes were ice-fished by voluntary anglers using a pre-defined, loosely standardised protocol to obtain angling-based NPUE, BPUE, and length frequency distributions. Effects of environmental variables such as water oxygen concentration and light penetration on angling catch rates were controlled statistically. Neither perch Nordic gillnet NPUE nor BPUE corresponded to ice-fishing CPUEs. However, the length distribution of the catch did not differ between methods. Our results imply that traditional ice fishing applying natural baits is relatively unselective for fish size and could produce valid length-based indicators for management purposes while angling CPUE was poorly related to Nordic gillnet CPUE. 相似文献
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Chao Hsiung Cheng Tsuyoshi Kawasaki Kuo Ping Chiang Chuan Hung Ho 《Fisheries Science》2001,67(1):3-13
SUMMARY: The distribution and movement of the hairtail Trichiurus lepturus stock in the Aru Sea were investigated using logbook data from four Taiwanese commercial otter trawlers. Fluctuations in population size, population density index and the distribution of catch per unit effort (CPUE) and fishing effort are discussed. The CPUE data were standardized by using the generalized linear model (GLM) in which fishing month, fishing area and size category of the hairtail were taken into account. The fishing season could be divided into three episodes: aggregation between March and April, dispersion between May and June, and aggregation again between July and December. A seasonal two-peak distribution of the population size of hairtail reflects the aggregation–dispersion pattern. The first peak in May–June can be explained in terms of the hairtails' overwintering migration. The second peak in October–December is likely to be the result of spawning aggregation. 相似文献
19.
本研究是在阐明传统CPUE(Catch Per Unit Effort)单位表述多样性的基础上,分析传统CPUE存在的不确定性、单位不统一性以及解析与意义不完整等问题。对24个CPUE单位,首先通过通用性标准,筛选出各种捕捞方式均能适用的8个CPUE单位;再通过相似性标准,对CPUE单位聚类分成2组,并在每组中筛选出最佳单位为kg/(kW·d)和kg/d;最后通过稳定性筛选标准对其标准差与变异系数值计算,最终得到CPUE的标准单位:kg/(kW·d),并确定CPUE的表达形式。本研究还基于CPUE单位标准化进行了实证分析,对2016年4个季度南海三省区的9种主要作业类型渔船的生产调查数据进行了分析比较,捕捞能力大小依次为:围网双拖刺网罩网张网单拖拖虾笼壶钓具。CPUE经单位标准化后已具备进行捕捞产量统计、评估渔船捕捞能力、衡量资源相对丰度指数、评估渔业资源利用水平等功能。 相似文献
20.
Catch per unit of effort (CPUE) needs to be standardized to remove the effects of factors such as fishing time and location, before it can be used as an index of abundance in fish stock assessments. One of the most substantial effects arises from a change of target species. This is particularly important for the Taiwanese distant-water longline fishery, which has a long history of fishery data from two fleets that target various tuna species across three oceans. We review the development of the Taiwanese distant-water longline fishery and compare five designs for standardizing the catch rate of yellowfin tuna (Thunnus albacares) in the western and central Pacific Ocean, using generalized linear models with lognormal and delta-lognormal error assumptions. Two approaches to address targeting effects were tested: separating fishing fleet data based on observer records, and including four target indicators calculated from catch data. Four statistical regions (relating to major fishing grounds) were treated as a single factor in the first three cases and were treated separately for the last two (one independent run for each region). The last case, which involved independent analyses for each fishing fleet for each region, and using the delta-lognormal approach, was considered to provide the most informative standardized CPUE trends for yellowfin tuna. 相似文献