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1.
Abstract Standardised fishing methods using gillnets (EN 14575), electric fishing (EN 14011) and hydroacoustics (WI 00230244 CEN enquiry) to estimate species composition, abundance, biomass and size distribution were compared in 14 alpine lakes >50 ha. More fish species were detected using benthic gillnets (mean = 72.7%) than electric fishing (mean = 59.5%) and pelagic gillnets (mean = 29.6%). For all but two lakes, additional information from a local fisheries manager was required to obtain a complete list of species. Biomass data generated by standardised gillnetting and hydroacoustic surveys were not fully comparable, but a positive correlation was found. Gill netting and hydroacoustics both indicated a nearly fishless habitat below 75 m, which confirmed the maximum required fishing depth according to the European Standard EN 14757. Size distributions obtained from gillnet and hydroacoustic surveys differed statistically for large fish (>40 cm). Each standardised method reflected typical shortcomings. The European standard (EN 14757) should be amended for pelagic fish habitat in deep alpine lakes to include sampling effort corresponding to water volume, and additional gillnets with larger mesh sizes (e.g. 70 mm). Furthermore, the electric fishing standard (EN 14011) should be extended to incorporate requirements of lake fish sampling. 相似文献
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Effects of eutrophication on fish and fisheries in Finnish lakes: a survey based on random sampling 总被引：6，自引：0，他引：6
J. Tammi A. Lappalainen J. Mannio M. Rask J. Vuorenmaa 《Fisheries Management and Ecology》1999,6(3):173-186
Abstract The effects of eutrophication on fish and fisheries in Finnish lakes were determined by an extensive lake survey conducted in 1995 and 1996. The study lakes (873) were chosen by stratified random sampling from all Finnish lakes with a surface area ≥ 0.04km2 (29,515 lakes in all). The chemical parameters of the lake water were determined for water samples taken in autumn 1995. Information on the fish stocks of the study lakes was collected by means of a postal questionnaire sent to local fishing authorities and lake owners. The results show that the fish community structure is cyprinid dominated, reflecting eutrophication in 2100 lakes (7% of all the target lakes). Strong fouling of the fishing gear, as well as a great abundance of unwanted species in the catch of passive gears, were considered to be a continuous problem in more than 10% of the lakes. Roach, Rutilus rutilus (L.), and bream, Abramis brama (L.), were the most common species to have increased in abundance in the study lakes, whereas burbot, Lota lota (L.), and vendace, Coregonus albula (L.), decreased, especially in highly eutrophic lakes. High total phosphorus and cyprinid dominance in lakes were found mainly in the most intensive agricultural regions in the western and southern parts of Finland. 相似文献
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Influences of gear type and analytical methodology on fish assemblage characterisations in temperate lakes 
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下载免费PDF全文 C. J. Sullivan D. P. Coulter Z. S. Feiner S. B. Donabauer T. O. Hk 《Fisheries Management and Ecology》2015,22(5):388-399
A variety of gears and analytical methods can be used to characterise lentic fish assemblages; however, the combined influence of gear type and analysis can affect conclusions about assemblage patterns. Fish assemblages sampled with night electric fishing, gillnets and trapnets from 153 lakes were evaluated using summary indices of species composition, pairwise community similarity comparisons and multivariate ordination. For a given amount of effort, electric fishing had the highest species richness, while gillnets had higher diversity and evenness. Pairwise comparisons between gears revealed that (1) richness was positively correlated among all gears, (2) diversity and evenness were generally not correlated across gears and (3) electric fishing and trapnets captured more similar species than all other pairwise comparisons. Gear‐specific multivariate correlation and ordination revealed that gillnet and electric fishing samples more similarly characterised variation in assemblages among lakes, while trapnets characterised assemblages along different gradients of species composition. These results indicate that either electric fishing or trapnetting can be used when assessing shallow‐water assemblages for diversity or evenness, gillnets and either electric fishing or trapnets should be used for whole‐lake assessments, and either gillnets or electric fishing should be used when evaluating regionwide variation in lake assemblages. 相似文献
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Carlos E.C. Freitas Flávia K. Siqueira‐Souza Alexandro C. Florentino Lawrence E. Hurd 《Ecology of Freshwater Fish》2014,23(3):470-477
The Amazon River Basin has the highest fish species diversity of any region in the world, but is under threat from anthropogenic perturbations including overharvesting, alien species and drought. We asked whether species diversity in this region is more a function of within‐lake species richness (i.e., α diversity) or differences among lakes (β diversity). Although many studies have reported on species richness and diversity in single habitats, the importance of measuring diversity at different spatial scales is not yet well established. We collected fish in 10 floodplain lakes along the Solimões River (Brazil), divided evenly between two lake types: those on islands in the river channel (island lakes) and those on the margins of the river (coastal lakes) during 2006. We partitioned fish diversity into three spatial scales: α = within each lake; β1 = among lakes of the same type (coastal or island) and β2 = between the two types of lakes, and compared their relative contributions to regional (γ) diversity. β1 + β2 contributed as much or more to γ diversity than did α. Although many of the 116 fish species were shared between lake types (S = 72), 32 species were found exclusively in coastal lakes and 12 species were found exclusively in island lakes. Coastal lakes, which were deeper and cooler than island lakes, consistently had higher fish species richness than island lakes. We suggest that it will be necessary to set areas large enough to contain multiple lakes of both types to preserve regional fish diversity. 相似文献
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Goutam Kumar Kundu Md. Monirul Islam Md. Foijul Hasan Samapti Saha Gouri Mondal Bijoya Paul Md. Ghulam Mustafa 《Ecology of Freshwater Fish》2020,29(2):364-376
Understanding biodiversity and community composition is a prerequisite to sustainable exploitation and conservation of fisheries. We assessed the spatial and seasonal patterns of fish community composition and biodiversity in seasonal no-take riverine sanctuaries in Bangladesh, which aim to conserve the anadromous hilsa shad (Tenualosa spp. and Hilsa keele). Fish samples were collected during monsoon, as well as pre- and postmonsoon, from five sites within two sanctuaries and one site in an open fishing area. Although total abundance was similar along the rivers, species richness was significantly higher at the open fishing site due to its connectivity to nearby habitats. The diversity apparently decreased in a downstream direction. Fish communities at two upstream sites were separated from other sites in multivariate space largely due to higher abundance of hilsa at downstream sites and presence of floodplain-oriented species at the two upstream sites. Short body length and high trophic level at all sites indicated that fish communities were overexploited. Our results also indicated that riverine hilsa sanctuaries in Bangladesh are rich in fish species diversity and support several threatened species designated by the International Union for Conservation of Nature (IUCN). Our study also suggested that since hilsa abundance shapes community patterns, it can therefore impact riverine ecosystem functioning in the sanctuary areas. The findings of this study can serve as an important baseline for future biodiversity assessment, conservation and impact assessment of conservation in rivers, and therefore help to establish multispecies ecosystem-based management of riverine fisheries around the world. 相似文献
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Abstract Data from Lake Ontario tributaries were used to evaluate the efficacy of single-pass backpack electric fishing for stream fish monitoring by: testing the relationship between single-pass catch-per-unit-effort (CPUE) and multiple-pass-based population estimates; comparing species richness estimates derived from single-pass and multiple-pass data and assessing the concordance of fish assemblage patterns described using single-pass and multiple-pass data. Significant correlations were calculated between single-pass CPUE and removal-based population estimates for total catch, 15 species, six taxonomic families, five feeding and four reproductive guilds and tolerant/intolerant species. Strong correlations were more commonly associated with the abundance of individual species than other metrics. Capture probability was not affected by stream size or habitat complexity for most measures. Species accumulation curves and significant correlations ( r 2 = 0.9) between single-pass and multiple-pass electric fishing indicate that single-pass surveys provide a representative index of species diversity. In addition, within and among-site variation in fish community composition based on single-pass and multiple-pass data were similar. 相似文献
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Jeremy Collie Jan Geert Hiddink Tobias van Kooten Adriaan D Rijnsdorp Michel J Kaiser Simon Jennings Ray Hilborn 《Fish and Fisheries》2017,18(4):619-637
One quarter of marine fish production is caught with bottom trawls and dredges on continental shelves around the world. Towed bottom‐fishing gears typically kill 20–50 per cent of the benthic invertebrates in their path, depending on gear type, substrate and vulnerability of particular taxa. Particularly vulnerable are epifaunal species, which stabilize the sediment and provide habitat for benthic invertebrates. To identify the habitats, fisheries or target species most likely to be affected, we review evidence of the indirect effects of bottom fishing on fish production. Recent studies have found differences in the diets of certain species in relation to bottom fishing intensity, thereby linking demersal fish to their benthic habitats at spatial scales of ~10 km. Bottom fishing affects diet composition and prey quality rather than the amount of prey consumed; scavenging of discarded by‐catch makes only a small contribution to yearly food intake. Flatfish may benefit from light trawling levels on sandy seabeds, while higher‐intensity trawling on more vulnerable habitats has a negative effect. Models suggest that reduction in the carrying capacity of habitats by bottom fishing could lead to lower equilibrium yield and a lower level of fishing mortality to obtain maximum yield. Trawling effort is patchily distributed – small fractions of fishing grounds are heavily fished, while large fractions are lightly fished or unfished. This patchiness, coupled with the foraging behaviour of demersal fish, may mitigate the indirect effects of bottom fishing on fish productivity. Current research attempts to scale up these localized effects to the population level. 相似文献
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A multigear sampling method to quantify fish richness and abundance in Amazonian Terra firme streams was assessed. This method is based on the four‐pass removal method using the combined application of different nets. The efficiency of the method was explored over 10 replicated sites along three streams over day, night and seasons. Use of four successive passes allowed both abundant and rare species to be collected and the abundance of common species to be estimated. On average, a high proportion (41%) of rare species was collected per sample (only one or two individuals) after four fishing passes. The efficiency of the sampling method to detect species richness per sample between successive passes was estimated using an autosimilarity approach. Although species richness and abundance increased with successive passes, no major differences were obtained between the third and fourth pass. A single pass considerably underestimated the richness and abundance of species in these type of streams, and night sampling also increased beta‐diversity by at least 20%. Abundance estimates demonstrated high efficiency with an overall sampling error of only 8 and 11% for samples and single species, respectively. Capture efficiency differed among fish species exhibiting different ecological traits and showed significant differences among seasons for total samples. Results supported the robustness of the method and its suitability to quantify fish richness and abundance in small, wadeable Amazonian Terra firme streams inhabited by highly diverse fish assemblages. 相似文献
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Alan M. Friedlander 《Aquarium Sciences and Conservation》2001,3(1-3):135-150
Extensive and unregulated harvest of marine ornamental fishes can lead to localized depletion of target species and habitat degradation from inappropriate collecting techniques. One potential solution to these problems is the creation of marine reserves where fishing is prohibited. Marine reserves have been shown to increase fish abundance and protect ecosystems from habitat destruction associated with fishing. If protective areas are to be effective, they must include the diversity of habitats necessary to accommodate the wide range of fish species that are of interest to the marine ornamental fish trade.Fish assemblages with high diversity and abundance are often associated with habitats of high structural complexity. A relationship between fish size and reef complexity suggests the importance of shelter as a refuge for certain fishes in avoiding predation. Many species tend to aggregate to spawn in structurally complex habitats to reduce their risk of predation. Closing of spawning areas during aggregation periods has been shown to be a highly effective management strategy for these species. The limited home ranges and high degree of habitat specificity associated with many marine ornamental fishes should make marine reserves a highly effective strategy for managing these resources. 相似文献
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Selectivity matters: Rules of thumb for management of plate‐sized,sex‐changing fish in the live reef food fish trade 下载免费PDF全文
下载免费PDF全文 Holly K Kindsvater John D Reynolds Yvonne Sadovy de Mitcheson Marc Mangel 《Fish and Fisheries》2017,18(5):821-836
Effective management of fisheries depends on the selectivity of different fishing methods, control of fishing effort and the life history and mating system of the target species. For sex‐changing species, it is unclear how the truncation of age‐structure or selection of specific size or age classes (by fishing for specific markets) affects population dynamics. We specifically address the consequences of plate‐sized selectivity, whereby submature, “plate‐sized” fish are preferred in the live reef food fish trade. We use an age‐structured model to investigate the decline and recovery of populations fished with three different selectivity scenarios (asymptotic, dome‐shaped and plate‐sized) applied to two sexual systems (female‐first hermaphroditism and gonochorism). We parameterized our model with life‐history data from Brown‐marbled grouper (Epinephelus fuscoguttatus) and Napoleon fish (Cheilinus undulatus). “Plate‐sized” selectivity had the greatest negative effect on population trajectories, assuming accumulated fishing effort across ages was equal, while the relative effect of fishing on biomass was greatest with low natural mortality. Fishing such sex‐changing species before maturation decreased egg production (and the spawning potential ratio) in two ways: average individual size decreased and, assuming plasticity, females became males at a smaller size. Somatic growth rate affected biomass if selectivity was based on size at age because in slow growers, a smaller proportion of total biomass was vulnerable to fishing. We recommend fisheries avoid taking individuals near their maturation age, regardless of mating system, unless catch is tightly controlled. We also discuss the implications of fishing post‐settlement individuals on population dynamics and offer practical management recommendations. 相似文献
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Andreas Luek George E. Morgan Bjoern Wissel John M. Gunn Charles W. Ramcharan 《Ecology of Freshwater Fish》2013,22(3):348-360
Fish communities may increase in biomass and productivity due to energy subsidies from the littoral invertebrate community. In lakes recovering from acidification and metal contamination, such as those in Sudbury, Ontario, Canada, impaired benthic invertebrate communities (i.e., low diversity with higher abundance of small‐bodied taxa) allowed a critical test of the role of these littoral pathways on fish diet. We compared fish abundance, diversity, diet and biomass in eight recovering and eight reference lakes and related availability of the main littoral and pelagic invertebrate groups to fish diet regime using stable isotope analysis. A Bayesian mixing model (MixSIR) was used to estimate diet likelihood, and convex hull analysis was used to estimate trophic niche space of fish communities. Fish biomass did not differ between impaired and reference lakes despite substantial differences in potential diet. Fish depended strongly on littoral benthos in the reference lakes but consumed more pelagic food in the impaired lakes. The trophic niche of the focal, most common fish species (i.e., yellow perch, smallmouth bass, pumpkinseed and brown bullhead) was larger in the impaired lakes. We attributed these differences to low diversity at the highest trophic levels of fish communities in the impaired lakes as well as to depauperate benthic invertebrate communities. In contrast to the food webs of most temperate lakes, fish in impaired lakes preyed less on littoral invertebrates yet still managed to maintain a reference lake level of biomass standing crop by relying more on pelagic resources – macro zooplankton such as Chaoborus. 相似文献
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R. Eckmann 《Ecology of Freshwater Fish》1995,4(2):62-69
Fish species richness was assessed by electrofishing and gillnetting in 16 lakes of the northeastern lowland in Germany (the Schorfheide biosphere reserve). The lakes range from 0.03 to 10.55 km2 and support between 5 and 14 fish species. Species richness is significantly correlated with lake area in an exponential and a power model. Richness is also correlated with shoreline development and total dissolved solids. This supports the hypothesis that larger areas contain more species within a taxonomic group due to increased habitat diversity. The slope of the species-area curve is low compared with most other studies of fish species richness in lakes, and the intercept value is high. This is interpreted as the result of high habitat and food diversity, lack of stress from abiotic factors, and the small regional species pool from which these lakes can be colonized. Two species inventories, one from the beginning of this century and one from the 1950s, are available for comparison. Average species richness did not change during the last decades. Species turnover rates were not related to the degree of anthropogenic eutrophication or to the intensity of fishery exploitation in these lakes. On the species level, however, one effect of accelerated eutrophication is apparent, the disappearance of 4 bottom-living species from one to 6 of the study lakes. 相似文献
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Arely Ramírez-García Omar Domínguez-Domínguez Eugenia López-López Rodrigo Moncayo-Estrada José De La Cruz-Agüero 《Ecology of Freshwater Fish》2023,32(1):53-63
In spring lakes, which have homogeneous environmental characteristics, it is expected that there will be no significant changes in the composition and structure of communities over time, and fluctuations will generally be related to the ecological attributes of the species. We studied the fish community in a small subtropical spring lake, Lake Zacapu, for two different decades to analyse its structural characteristics. Sampling was performed every 3 months at four sites from January to October 1995 and from May 2019 to May 2020. We determined the temporal variation (seasonal and decadal) in the fish community structure with respect to composition, abundance, diversity and dominance. We evaluated the association between species and water quality. Our results showed spatial homogeneity in most physicochemical variables that remained in the same range across decades, although some nutrients (NO3) recently increased. All species identified in the early samples were present in the recent surveys (eleven native and two nonnative species), indicating that the fish community composition had significant qualitative stability. However, the dominant littoral cyprinid in 1995 was replaced by the more limnetic atherinopsid in 2019–2020, and the diversity and abundance of sensitive fish decreased in recent samplings. Consequently, the current status of critically endangered species is supported for some restricted and microendemic fish. The changes in the community structure attributes, which show a tendency for reduction in native species, emphasise the need to implement efforts to conserve freshwater fish diversity in small spring lakes. 相似文献
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胶州湾及其邻近海域鱼类群落结构及与环境因子的关系 总被引：9，自引：4，他引：5
为了进一步研究胶州湾及其邻近水域鱼类群落结构及与环境因子的关系, 本文根据2011年冬季(2月)、春季(5月)、夏季(8月)和秋季(11月)在胶州湾及其邻近海域进行的渔业资源和环境调查数据, 应用相对重要性指数、生态多样性指数和多元分析方法等研究了胶州湾鱼类群落结构及其季节变化, 并分析了胶州湾鱼类群落结构与主要环境因子的关系。结果表明: 本次调查共捕获鱼类57种, 隶属于2纲10目31科46属, 种类组成以暖温性和暖水性鱼类为主。主要优势种有方氏云鳚(Pholis fangi)和六丝钝尾虾虎鱼(Amblychaeturichthys hexanema)等。胶州湾鱼类群落物种丰富度指数D的季节变化范围为1.02~1.65, 多样性指数H’变化范围为1.36~1.73, 均匀度指数J′变化范围为0.61~0.76。方差分析表明, 丰富度指数的季节变化显著, 而均匀度指数J′和多样性指数H′无显著性季节变化。单因子相似性(ANOSIM)分析表明, 胶州湾鱼类群落结构和种类组成存在明显的季节更替现象。相似性百分比分析(SIMPER)表明, 方氏云鳚、六丝钝尾虾虎鱼、细纹狮子鱼、斑、赤鼻棱鳀和皮氏叫姑鱼等是造成群落结构季节变化的主要分歧种。典范对应分析表明, 影响胶州湾及其邻近海域鱼类群落结构的主要环境因子为水温、盐度和pH, 其次是底质类型, 条件效应分别为0.310、0.084、0.176和0.256。本研究旨在通过分析胶州湾鱼类群落结构和多样性特征及其与环境因子的关系, 为胶州湾渔业资源的保护和可持续利用提供科学依据。
相似文献18.
Lucas Martínez-Ramírez C. Robert Priester Inês Sousa Karim Erzini David Abecasis 《水产资源保护:海洋与淡水生态系统》2021,31(7):1584-1595
- The implementation of marine protected areas (MPAs) has been widely used as a tool to manage and conserve marine resources and services. Yet, to date, the reserve effect is still weakly evaluated, particularly for soft-sediment habitats.
- The Arrábida MPA, considered as a biodiversity hotspot, was fully established in 2009 on the west coast of Portugal and is characterized by large expanses of soft-sediment habitats. This MPA was established to protect biodiversity and to ensure the livelihood of the local small-scale fisheries community.
- Beyond before–after-control–impact (BACI) analyses were carried out on catch data (abundance and biomass) of 351 trammel net sets from experimental fishing campaigns (2007–2019) to study the reserve effect on demersal fish populations.
- The results show a declining trend in abundance inside and outside the protected area, with significant positive effects only found for undersize commercial species and Solea senegalensis, and a general increase in fish species total length. Despite the lack of any obvious reserve effect, the increase in fish length can be considered as a first sign.
- Anthropogenic pressures are generalized around the area, and transgressions of the restrictions are frequently observed inside the no-take zone. These can, among other aspects, delay or prevent the expected reserve effects. Therefore, enforcement and/or modification of the spatial plan must be incentivized to achieve the goals of the MPA.
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Léa Daupagne Marlène Rolan-Meynard Maxime Logez Christine Argillier 《Fisheries Management and Ecology》2021,28(4):317-327
Fish stocking and regulation of fishing activities are widely implemented by freshwater fisheries authorities who have to protect aquatic communities. The effects of fish management on fish communities have not received sufficient attention. As a result of two datasets, one from EU Water Framework Directive (WFD) monitoring surveys, and one from a French survey targeting angler's associations, this study investigated the impacts of both fishing intensity and fish stocking on fish communities in French lakes. Both co-inertia analysis and community size spectra analysis, showed that: (i) stocking does not contribute to the standing stocks for five of the six most stocked fish species in France; and (ii) neither fishing intensity nor fish stocking lead to a change in the proportion of large and small fish. The results support alternative methods being promoted to enhance native fish populations. 相似文献
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Abstract The efficiencies of three different techniques for 0+ fish point abundance sampling by electric fishing were tested on a sandy beach of the Morava River, Czech Republic. During direct electric fishing (DE), the operator immerses an anode fastened on an extension pole. During thrown anode electric fishing (TE), the anode is thrown at a distance from the bank. During remote electric fishing (RE), a pre-positioned anode is activated after allowing sufficient time for fish to recolonise the area. The DE technique was found to disturb fish and that fish tend to escape, thereby reducing its efficiency (30% of efficiency of RE). There was no significant difference in relative abundance estimates or size structure of assemblages between DE and RE, but TE seemed to be a species selective technique on sandy river beaches, significantly overestimating relative abundance of bleak. Of the three techniques tested, RE was the most efficient and if time required for deployment could be reduced, it would be also the most suitable for monitoring 0+ fish assemblages on sandy river beaches. 相似文献