Assessing the health of European rivers using functional ecological guilds of fish communities: standardising species classification and approaches to metric selection

Abstract  The functional ecological guild approach is the cornerstone for the development of Indices of Biotic Integrity and multi-metric indices to assess the ecological status of aquatic systems. These indices combine metrics (unit-specific measures of a functional component of the fish community known to respond to degradation) into a single measure of ecological assessment. The guild approach provides an operational unit linking individual species characteristics with the community as a whole. Species are grouped into guilds based on some degree of overlap in their ecological niches, regardless of taxonomic relationships. Despite European fish species having been classified into ecological guilds, classification has not been standardised Europe-wide or within the context of classifying species into guilds from which metrics can be developed for ecological assessment purposes. This paper examines the approach used by the EU project FAME to classify European fish species into consistent ecological guilds and to identify suitable metrics as basic tools for the development of a standardised ecological assessment method for European rivers to meet the requirements of the Water Framework Directive.     

The importance of stream interstitial conditions for the early‐life‐stage development of the European nase (Chondrostoma nasus L.)

Rheophilic cyprinid populations are in decline in many European rivers and have become target species of conservation and river restoration. This is especially true for the European nase (Chondrostoma nasus), a lithophilic species for which the early life stages pose the first bottlenecks in successful population development. In this study, egg dispersal at the substrate surface as well as within the stream interstitial was evaluated and the development of nase eggs was tested at three spawning grounds in the German Alpine Foreland. New incubation systems for cyprinid eggs as well as reference incubation boxes were developed. A significantly higher number of nase eggs (95.5%) were deposited within the stream interstitial compared to eggs sticking to the substrate surface (4.5%). Most eggs successfully developed within the stream interstitial, and hatched larvae moved deeper into the stream substrate. Higher fine sediment accumulation rates in incubation systems had a negative impact on hatching rates. Our results suggest that a permeable, well‐oxygenated stream interstitial at spawning grounds can greatly enhance hatching rates and successful development of nase, as previously found for other taxa such as salmonids. Furthermore, movements of hatched larvae into deeper layers of the stream interstitial underline its importance not only for egg development, but also as shelter for early life stages. Future conservation and restoration efforts should thus consider more intensively stream interstitial conditions on spawning grounds, including evaluating physical characteristics, fine sediment accumulation as well as bioindication with suitable incubation systems for cyprinids.     

Fish utilisation of managed realignments

Abstract  One area of ecological benefit not yet fully evaluated in European waters is the utilisation of restored saltmarsh habitats by fish species. This study examines the utilisation of managed realignments and relic saltmarsh by fish species. Factors affecting habitat heterogeneity and fish populations are discussed, and recommendations are made with respect to scheme design and management that will maximise the biological and socio-economic values. Fish populations in the high intertidal areas were assessed using a suite of techniques, including observations on feeding behaviour. Each microhabitat was discussed as a function of the extent of fish colonisation. A positive relationship between the degree of fish utilisation and habitat heterogeneity was ascertained using species richness, abundance and behavioural observations. This study will aid habitat valuation for economic justification of managed realignments, over and above existing drivers, such as compensatory habitat for encroachment, flood defence and the European Union Habitats Directive. The work now forms part of a wider European Interreg IIIb project, COMCOAST.     

Processes of collating a European fisheries database to meet the objectives of the European Union Water Framework Directive

Abstract  FIsh Database of European Streams, a common database for the FAME project, was merged using existing data on electric fishing and environmental data. FIsh Database of European Stream is a relational database with eight tables. Metrics based on classification of fish species into guilds were calculated, and provided in separate tables. FIsh Database of European Stream contained information about 150 freshwater fish species, from 12 countries, 17 ecoregions, 40 main river regions, 2651 rivers and 8228 sites. Examples of data coverage and use are given. Relationships between environmental variables were illustrated using principal component analysis, which resulted in three environmental components – latitude, size and altitude. Environmental component scores were correlated with fish metrics used in the European Fish Index. Results exemplify how fish guilds reflect gradients in environmental variation. Benefits and problems concerning standardisation and data availability at the global level are discussed.     

赣江下游丰城江段鱼类早期资源现状调查

对赣江鱼类早期资源的调查,可为赣江鱼类资源保护以及水利工程生态调度提供科学依据.2017年5-7月,在赣江丰城段使用圆锥网采集鱼卵和弶网采集仔鱼,对鱼类早期资源种类组成、产卵规模和产卵场进行分析.结果显示,调查期间共采集鱼卵11215粒,仔鱼12645尾,隶属于4目、8科、36种,其中产漂流性卵鱼类24种.估算调查期间通过丰城段卵苗径流量为66.66×１０^８粒(尾),其中鱼卵径流量63.84×10^8 粒,鱼苗径流量2.82×10^8 尾;“四大家鱼”卵苗径流量为0.11×10^8 粒(尾),其中鱼卵径流量0.07×10^8 粒,鱼苗径流量0.04×10^8 尾.调查期间出现3次产卵高峰,集中在6 月上、中旬.各类群鱼卵数量呈现出不同的时间动态,银鮈(Squalidusargentatus)产卵高峰期主要出现在5月,银鲴(Xenocyprisargentea)、鳊(Parabramispekinensis)、赤眼鳟(Squaliobarbuscurriculus)以及“四大家鱼”则主要出现在6月.研究表明,峡江水利枢纽运行后,邻近峡江水利枢纽的巴邱“四大家鱼”产卵场消失,但其下游的仁和、新干产卵场保存较完整,在离坝较远的大洋洲镇江段新调查到一处“四大家鱼”产卵场.建议开展生态调度及增殖放流活动,以保护赣江鱼类资源.     

Effect of habitat fragmentation on spawning migration of brown trout (Salmo trutta L.)

Abstract –  Human-induced habitat alteration is one of the main causes of the decline of freshwater fish populations. The watershed of the River Bidasoa (Spain) is an example of heavily fragmented habitat. The local brown trout ( Salmo trutta L.) population is disturbed, with evidence of poor recruitment as well as low adult densities in the main stem. Forty male and female adult migratory trout were tagged with external or internal radio transmitters and released. Fixed stations with data loggers and mobile antennae were used with daily surveys to track fish movements during the migration and spawning period (3 months). Migration distances did not exceed 10 km, and half of the fish never entered a tributary in the study area. Fragmentation because of weirs on the main stem apparently prevented fish from reaching their spawning destination. Fish that entered the tributaries were first confronted with an accessibility problem because of low discharge. However, each fish chose one tributary, without making attempts to run up in other tributaries. Once in the tributary, fish were restrained in their upstream movements by dams. The study area appeared to be isolated from the vast upper part of the watershed. Within the study area, upper parts of tributaries also seemed strongly disconnected from the main stem. This study illustrates the negative impact of river fragmentation on S. trutta migration pattern. Population sustainability can be directly affected through the low availability of spawning grounds for migratory fish. Long-term effects of fragmentation may cause reproductive isolation within watersheds, which in the case of trout also means isolated phenotypic population units.     

北极阿拉斯加水域鱼类生态特征及其重要性评价

为了对北极鱼类的生态特征进行研究,从而科学合理地开发和管理北极鱼类资源,以现有北极阿拉斯加水域鱼类生态科学信息为基础,针对北极阿拉斯加水域104种主要鱼类,从栖息深度、营养级、昼夜垂直移动及季节性洄游、生态重要性、传统文化重要性及商业重要性等多个方面进行了分析。结果显示,大多数北极阿拉斯加海洋鱼类为中上层鱼类或中层鱼类,栖息水域多在1 000 m以浅的陆架或陆坡水域;营养级范围为3.0～4.5,处于较高和较低营养级的鱼种较少;大部分鱼类的重要性知之甚少,目前仅少量鱼种在北极海域生态系统、传统文化以及商业性渔业中起到关键作用;具昼夜垂直移动及季节性洄游特性的鱼种各占一半左右;基于聚类分析,以栖息深度、垂直移动、季节性洄游及营养级4个指标作为变量,该水域属于5个生态类群,而以生态、传统文化以及商业重要性3个指标为变量,则该水域鱼类可划分为3个类群。本研究结果可为进一步开展北极鱼类生态学研究及北极渔业资源的开发潜力评价提供数据支持,并为我国参与北极鱼类资源潜力的开发及国家权益的争取提供参考信息。     

Evaluation of external fish injury caused by hydropower plants based on a novel field‐based protocol

Knowledge on the extent and mechanisms of fish damage caused by hydropower facilities is important for their ecological improvement. Herein, a novel field‐based fish injury assessment protocol is proposed that includes vitality and four general health criteria, as well as nine lethal and sub‐lethal injury types across 18 body parts. The protocol was validated using 3,087 specimens from four species of hatchery‐reared fish, as well as 2,262 specimens from 32 species of wild fish. The protocol allowed a detailed and systematic evaluation of different fish injury types in the field. Injuries related to handling and to contact with different parts of the hydropower structure could be distinguished applying multivariate statistics. This approach allows quantification and comparison of fish injuries across sites, and can help to identify the technologies and operational procedures that minimise damage to fish. It may also be useful to assess fish health in other contexts including aquaculture.     

Profile of the Marine Aquarium Fish Trade in Hong Kong

A market survey and review of government statistics were carried out to establish imports and exports of marine ornamental fishes into and out of Hong Kong, and to examine the local trade in terms of volume, value and species composition. Official government import figures for marine aquarium fishes were available from 1984 to 1991 and from 1997 and 1998. When compared with net imports, export and re-export volumes over the 15-year period were small, indicating that most imports entered the local market, or were exported unrecorded. The market survey of marine aquarium shops in Hong Kong was carried out between August 1996 and January 1997. From this survey, an annual estimate of 957,563 coral reef fish was calculated for the local trade, valued at HK$57,453,780, with a mean retail price of HK$60 per fish. These figures account for an estimated 2–3% of the global value and volume of marine aquarium fish trade, according to 1992 figures and, compared with government figures, indicate that official declarations of imports are underreported by at least 2–3 fold. A total of 342 marine aquarium fish species, from 49 families, were recorded with about 60% belonging to the families Labridae, Chaetodontidae, Pomacanthidae and Pomacentridae. It was estimated that a large proportion of the trade was in juvenile fishes and almost all fish were less than 10cm in standard length. It was common to see fishes in poor condition, species hard to maintain in captivity, or those listed for conservation concern, on sale. There are no regulations for local traders of live marine fishes other than those relating to either protected species or animal welfare. Licensing of traders in marine fishes could be introduced under existing Hong Kong legislation if fishes were to be re-classified as animals. This is strongly recommended as a step towards regulating and managing the trade in Hong Kong.     

A facial recognition tool and legislative changes for improved enforcement of the CITES Appendix II listing of the humphead wrasse,Cheilinus undulatus

1. Humphead, or Napoleon, wrasse, (Cheilinus undulatus), is a large reef fish naturally vulnerable to over‐exploitation and highly prized as luxury seafood. It is predominantly consumed in Hong Kong and mainland China. Hong Kong is the global trade hub for this species. In 2004 (effective 2005), the humphead wrasse was listed on the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) Appendix II that substantially improved understanding and management of the species although illegal, unregulated and/or undocumented trade (IUU) continues.
2. To understand patterns of trade in humphead wrasse, evaluate implementation of the CITES listing and identify ways to tackle IUU, especially in Hong Kong, data from multiple sources, including government databases between 1999 and 2017 and independent retail surveys between 2014 and 2017, were compiled.
3. IUU trade into and through Hong Kong was detected, but declined following increased government enforcement in 2016. Nonetheless, fish numbers on sale continue to exceed imports with CITES permits and mainland China only sparsely reports imports of the species. Approximately 0.5–1.5 metric tonnes were traded internationally annually.
4. Several legislative loopholes undermine enforcement into and within Hong Kong, including poor oversight of live fish carrier vessels and air imports, excessively long validity period for Licences to Possess in the city, non‐compliant traders, and legislative exemptions or omissions. The introduction of a ranched fish category in 2018 by Indonesia created additional challenges. More intelligence and risk analyses could help enforcers target their work.
5. A major enforcement challenge is the inability to distinguish legally from illegally imported fish within Hong Kong. To improve fish tracking, identifying individuals using their complex facial patterns as fingerprints was explored; proof‐of‐concept was demonstrated using a mobile phone application: Saving Face. Facial marks were determined to be long‐lasting and different enough to distinguish among multiple individuals.

     

Fish-based methods for assessing European running waters: a synthesis

Abstract  The European Union, Water Framework Directive (WFD) requires monitoring of riverine fish fauna. When the WFD came into force in 2000, most of the EU member states did not have fish-based assessment methods compliant to WFD requirements. Therefore, the objectives of FAME ( http://fame.boku.ac.at ), a project under the fifth R&D Framework Programme of the European Commission were to develop, evaluate and implement a standardised fish-based method for assessing the ecological status of European running waters. This paper synthesises the outputs of FAME and defines future research needs. Two different methodologies were used: the so-called spatially based modelling and the site-specific modelling, the latter leading to the European Fish Index (EFI). The advantage of the EFI is that, despite being a single index, it is applicable to a wide range of environmental conditions across Europe precluding the need for inter-calibration. The EFI will support the WFD towards harmonised/standardised assessment and management of running waters in Europe, thus enabling comparative analyses of the ecological status of running waters across Europe.     

Effects of natural rapids and waterfalls on fish assemblage structure in the Madeira River (Amazon Basin)

Abstract – Habitat connectivity is considered a central factor shaping ecological communities, and the effects of waterway barriers such as natural waterfalls on fish movements are expected to produce differing assemblage structures in riverine ecosystems. Here, we evaluate the influence of a sequence of waterfalls on the compositional dissimilarity of fish assemblages along the Madeira River, the largest tributary of the Amazon River. We found significant differences in species composition between rivers stretches located upstream and downstream of Teotônio waterfall and, to a less extent, Jirau waterfall, independently of the hydrological period. After accounting for the relative roles of local and regional factors in explaining fish compositional dissimilarity, we still observe a significant effect of the waterfalls. We conclude that these waterfalls act as natural ecological barriers limiting fish dispersal processes and discuss aspects of these ecological filters and the potential effects of two dams currently under construction in the Madeira River.     

Legislation and the capacity for rapid‐response management of nonindigenous species of fish in contiguous waters of Canada and the USA

• 1. The provision of Canadian and US hard, enforceable, law to authorize rapid response management of nonindigenous aquatic species originating from aquaculture, live fish sales, bait fish, and the pet trade was analysed at the provincial/state levels of government for the Atlantic, Laurentian Great Lakes, and Pacific regions of North America.
• 2. No federal legal capacity for rapid response management exists in either country. US state legislation is generally better developed than Canadian provincial laws to manage the exotic fish trade. However, much discrepancy exists among provincial and state law regarding provisions to restrict or prohibit potentially harmful species. Aquaculture and baitfish use is generally better regulated than live fish markets and the pet fish trade in both countries. Only the state of Maine has laws authorizing rapid‐response management to control escaped exotic fish.
• 3. Most species of nonindigenous fish arise from the aquarium, pet, and baitfish trades, and development of improved legislation containing provisions for rapid response management of escapees is warranted in all states and provinces.
• 4. It is recommended that Canada amends the Fisheries Act to create the appropriate enabling legislation to monitor, assess risk, and deploy rapid response management of nonindigenous aquatic species, including fish that enter federal fresh and sea waters. Two recently‐introduced US Bills, S. 725 and H.R. 1350, with their explicit measures for early detection and fast action response, could, if passed into law, create provisions to control introduced nuisance species throughout North American waters. They would also create precedents for states and provinces that have most jurisdiction over aquaculture and trade in exotic fish to amend and align their laws in a complementary manner.

Copyright © 2008 John Wiley & Sons, Ltd.     

Conservation of fish communities: Extending the ‘research life cycle’ by achieving practical effects

1. This article highlights the practical impact of our 2018 Aquatic Conservation: Marine and Freshwater Ecosystems publication, ‘Importance of peripheral basins: Implications for the conservation of fish assemblages’, which described fish communities in a Polish river.
2. Data on the fish assemblages of the Dniester River (Black Sea basin) are scarce; however, evidence indicates that the assemblages have declined. In our 2018 study, we hypothesized that the peripheral basin (the small basin on the edge) of the larger Upper Dniester River basin (the Strwi?? River) could maintain good ecological status and contained unique fish assemblages.
3. To examine the influence of historical factors and assess the role of peripheral basins on fish conservation, data from the Strwi?? basin were compared with the adjacent but unconnected Wiar basin (the Vistula basin; Baltic Sea basin). The Strwi?? River fish assemblages featured higher species richness and a greater number of native Ponto–Caspian species that function near the edge of their ranges.
4. This article focuses on four impacts of the 2018 publication: increasing awareness by various groups and organizations of the unique character of the surveyed river basin; highlighting important issues in assessing the ecological status of European rivers; driving the red‐listing of species and the development of stream fish conservation strategies; and identifying possible future impacts.
5. Our 2018 publication demonstrated the value of studying peripheral basins, which may affect conservation strategy development and encourage study of the importance of other peripheral basins and their role in aquatic resources conservation. Our article influenced the interpretation of fish‐based biotic indices and the conduct of monitoring work and its evaluation. It also strongly emphasized the native origin of the racer goby (Babka gymnotrachelus) in the Strwi?? River, which was important for subsequent works seeking to change the legal status of the species in Poland.

     

金沙江下游宜宾段产漂流性卵鱼类早期资源动态变化

为探讨金沙江下游溪洛渡、向家坝水电站蓄水运行对下游江段鱼类早期资源群聚动态的影响,本文基于2016-2020年宜宾江段鱼类早期资源调查数据,对鱼类早期资源种群结构和年际变化趋势进行了研究。宜宾江段共计采集鱼卵20种,主要优势种为吻鮈和寡鳞飘鱼；估算出鱼卵年平均径流量为15.07×10⁶粒,漂流性卵为9.89×10⁶粒,年际间总体呈增加趋势；推算采样点以上分布有产漂流性卵鱼类产卵场3处；从多样性指数和相似度指数看,宜宾江段鱼卵种类组成结构较为稳定,年际间变化不大。尽管受到金沙江下游水电工程开发的影响,宜宾江段作为长江上游珍稀特有鱼类国家级自然保护区的重要组成部分,仍是产漂流性卵鱼类产卵繁殖的重要分布区,但主要以产漂流性卵小型鱼类为主,圆口铜鱼、长鳍吻鮈等长距离洄游性鱼类鱼卵没有监测到。建议继续加强圆口铜鱼、长鳍吻鮈等鱼类的增殖放流,同时,针对产漂流性卵小型鱼类的生态需求,开展金沙江下游梯级水电开发对其生态效应影响的监测研究。     

Fish‐based assessment of ecological status of Finnish lakes loaded by diffuse nutrient pollution from agriculture

Abstract The European Union Water Framework Directive stipulates that pressures on surface waters due to diffuse loading of nutrients have to be taken into account in determination of their ecological status. A Finnish data set of fish communities in 178 lakes was used to assess the effects of agriculture‐induced nutrient loads on the ecological status of lakes. The lakes were divided to reference (n = 100) and impacted sites (n = 78) based on water quality, land use and nutrient load data. Fish sampling was conducted by standardised gill net test fishing. A fish‐based classification tool of the four parameters (EQR4) was applied to assess the ecological status of lakes. The parameters included were: mean total biomass of fish per gill net night, number of fish individuals per gill net night, biomass proportion of cyprinid fishes and the presence of indicator species. The analysis resulted in a median EQR4 value of 0.78 (good status) for reference lakes and 0.56 (moderate status) for affected lakes. Thus, the classification tool gave an acceptable output for different nutrient‐loaded lakes.     

Do recreational fisheries metrics vary on differently sized fishing grounds?

This study aimed to assess the relationship between basic metrics in recreational fishing and the size of the fishing ground. Data were obtained from individual angling logbooks collected by the Czech Fishing Union over 12 years on 212 fishing grounds located in the regions of Prague and Central Bohemia in the Czech Republic. Small fishing grounds had the highest catch, yield, numbers of fishing visits and numbers of angling guard controls per hectare. Medium‐sized fishing grounds had the highest catch, yield, and numbers of both fishing visits and angling guard controls per fishing ground. Anglers returned to medium‐sized fishing grounds most frequently. The percentage of anglers who caught and took home at least one fish decreased with increasing size of the fishing ground. In conclusion, basic metrics in recreational fishing are related to the size of the fishing ground, which thus plays an important role in fisheries management.     

Catch‐related fish injury and catch efficiency of stow‐net‐based fish recovery installations for fish‐monitoring at hydropower plants

Hydropower‐related damage to fish remains a great challenge, making objective monitoring of turbine‐related fish injury a necessity. The catch of fish at turbine outlets is currently realised by net fishing, but potential catch‐related injuries are largely unknown. Catch efficiency and fish‐friendliness in relation to fish handling, exposure time, floating debris and fish biomass of four fish recovery installations were assessed using seven species. Highly species‐specific lethal and sublethal effects were observed. Exposure time had the strongest effects on catch‐related damage, being up to 150‐fold increase after 12 hr compared to 1 hr. Up to 84% mortality occurred in the most sensitive species Thymallus thymallus L. Besides exposure time, higher current speed and biomass within the net resulted in greater fish damage. To minimise catch‐related effects, keeping emptying periods <1–2 hr and considering the effects of current speed, fish and debris biomass are crucial to increase data comparability among studies.