集鱼船在水电工程应用的问题与建议

集运鱼系统为过鱼设施的一种,应用于高坝大库工程,正日益得到关注。过鱼设施的关键在于集鱼,而集运鱼系统一般利用集鱼船进行集鱼。目前,集鱼船在水电工程应用中存在成年鱼类集鱼难度大、诱集底栖鱼类效果较差和急流水域集鱼作业困难等问题。对此进行了探讨,提出了加强鱼类活动调查、深入鱼类习性研究、优化集鱼船体结构和构建适宜集鱼区域等建议,以期为水电工程集鱼船的应用提供参考。     

不同诱鱼方式在黄登升鱼机鱼道的诱鱼效果比较研究

以澜沧裂腹鱼和光唇裂腹鱼为研究对象,通过在鱼道内安装黄色集鱼灯和饵料袋,鱼道进口处安装PIT监测设备,采用饵料诱鱼、灯光诱鱼和综合诱鱼(饵料+灯光)等3种诱鱼方式进行诱鱼,记录标记鱼类进入鱼道的时间、频次和数量,研究澜沧江云南流域黄登水电站的升鱼机系统鱼道的诱鱼方式。结果表明,使用饵料诱鱼触发PIT天线的频次最高;综合诱鱼方式标记鱼触发PIT设备5次以下共计12尾,高于其他诱鱼方式;综合诱鱼的总诱鱼效率最高,总诱鱼效率为60%,饵料诱鱼总诱鱼效率为50%,灯光诱鱼总诱鱼效率为35%。研究认为综合诱鱼方式适用于黄登升鱼机工程鱼道诱鱼措施。     

VOF方法在升鱼机集诱鱼系统中的应用

为分析升鱼机集诱鱼系统水力要素的分布特性,利用有限体积法对控制方程进行离散,选用RNG k-ε模型封闭雷诺方程组,采用VOF方法和SLIC界面构造法进行自由表面的追踪和构建,模拟发电工况集诱鱼系统的三维自由水面和流速场。结果表明,通过运用VOF方法建立三维数学模型,可对升鱼机集诱鱼系统的水流条件进行较好的数值摸拟,可为升鱼机集诱鱼系统的设计、优化和管理提供参考和依据。     

乌东德水电站尾水集鱼平台集鱼效果影响因素分析

为研究乌东德水电站尾水集鱼平台集鱼效果与诱鱼措施、下游水文要素等影响因素之间的关系,通过分析2021年4～10月乌东德水电站右岸尾水集鱼平台运行数据以及同期水文数据,采用数据对比分析法初步提出了水文指标变化与集鱼效果之间的趋势关系。数据分析显示：金沙江中游江段投放肉食型饵料诱鱼增益效果更好;6～7月开启灯光诱鱼,可显著提升光照敏感鱼类的收集率;短时间的下泄流量增加对刺激鱼类洄游,增加集鱼数量没有明显作用,而超过5 d以上连续的下泄流量增加可以刺激鱼类洄游,提升集鱼数量。研究成果可为优化金沙江中游水电站生态调度以及提升集鱼系统集鱼效率提供支撑。     

基于VOF方法的升鱼机集诱鱼系统流场数值模拟

为分析升鱼机集诱鱼系统水力要素的分布特性,以国务院172项节水供水重大水利工程为背景,利用有限体积法对控制方程进行离散,选用RNG k-ε模型封闭雷诺方程组,采用VOF方法和SLIC界面构造法进行自由表面的追踪和构建,模拟发电工况集诱鱼系统的三维自由水面和流速场。结果表明,通过运用VOF方法建立三维数学模型,可对升鱼机集诱鱼系统的水流条件进行较好的数值摸拟,可为升鱼机集诱鱼系统的设计、优化和管理提供参考和依据。     

基于坝下流场模拟的集鱼系统进口位置选择研究

集鱼系统进口位置的合理选择决定着鱼类能否顺利发现并进入集鱼系统,关系着过鱼设施的运行效果。为选择大坝过鱼设施集鱼系统进口位置,本文以长江流域某水力枢纽工程为例,对坝下尾水河道2.83 km范围内水流流场进行了二维数值模拟,以当地鱼类上溯洄游流速的偏好范围为评判指标,分析了不同发电工况下适宜鱼类上溯的水域范围,并针对不同发电工况给出了集鱼系统进口的适宜布置区域,可为过鱼设施集鱼系统的布置提供依据。研究结果表明:左右岸电站发电机组下泄流量比为1∶0和2∶1时,模拟区域适合鱼类上溯洄游区域的占比较大,这两种工况下,集鱼系统进口应布置在坝下右岸;其他工况下,适合鱼类上溯洄游区域难达坝下,集鱼系统进口或集运鱼船应布置在坝下稍远区域,以保证集鱼系统在不同工况下的集鱼效率。     

阿尔塔什水利枢纽工程过鱼系统设计

文章根据阿尔塔什水利枢纽工程高坝、水位变幅大、库岸陡等工程特点,设计选择了轨道升鱼机方案(生态电站尾水集诱鱼+坝后轨道运鱼+坝前回转投鱼),重点研究了该方案集诱鱼、运鱼和投鱼点选择及结构布置,研究成果可为相关高坝、高岸坡枢纽工程中的集诱鱼设施布置提供相关参考。     

鱼道进口水流对草鱼幼鱼上溯行为的影响研究

为使鱼类能够快速发现和顺利进入鱼道进口并成功过坝,设计了鱼道进口概化模型。以草鱼幼鱼为研究对象,在18±1℃的条件下研究了鱼道进口流速对鱼类上溯行为的影响。研究发现:鱼道进口水流存在一个最佳流速,在该流速下,鱼类进入鱼道进口的效率最高。利用诱鱼流道补水有助于进一步提高鱼道进鱼效率,诱鱼流道水流与鱼道进口水流之间存在一个最优流速比。针对草鱼幼鱼的鱼道进口最佳流速约为0.3 m/s,诱鱼流道水流与鱼道进口水流的最佳流速比约为2.3。通过对洄游区鱼类游泳轨迹以及流场耦合,可知草鱼幼鱼上溯的喜好流速范围是0.20~0.30 m/s。研究成果对于鱼道进口水力设计具有重要意义。     

小石峡水电站集鱼系统布置方案选择研究

已建水电站的集鱼系统布置方案选择不同于规划水电站的选择,其既要考虑过鱼系统的集诱鱼效果,又要考虑对已建电站的影响。以小石峡水电站集鱼系统布置为例,从集诱鱼水流条件、鱼类集群调查、发电尾水影响、行洪安全影响、施工期影响等角度,对拟定的4个集鱼系统布置方案进行了比选研究,推荐左岸集鱼槽型式(距尾水渠末端50 m)的集鱼系统布置方案。研究成果可为类似已建电站过鱼设计提供借鉴。     

辅助鱼类过闸的诱驱鱼灯光试验研究

为提高船闸的过鱼效率,参照葛洲坝1号船闸建立试验模型,以草鱼、鲢鱼、鳙鱼为试验对象,观察不同光色和闪光模式下的诱驱鱼效果,并选择合适的灯光开展诱驱鱼进出闸室试验。结果表明:红、黄、白、蓝、绿5种光色的诱鱼灯中,红色诱鱼效果最好;单闪、双闪和变闪3种闪光灯中,双闪驱鱼效果最好;通过在闸室内布置并运行红色诱鱼灯和双闪闪光灯,可有效提高船闸过鱼效率约10%,最高达16.7%。研究成果可为中低水头的水利枢纽船闸过鱼提供依据。     

Consequences of calamities and their management: The case of COVID-19 pandemic and flooding on inland capture fisheries in Kenya

During the period February to June 2020, heavy rainfall caused increases in levels and flooding in many lakes in East Africa. This coincided with the COVID-19 pandemic. These calamities affected ecosystems and livelihoods, especially of fishers who depend on fisheries as their only source of livelihood. This study examined the effects of COVID-19 and flooding on the major inland capture fisheries in Kenya to illustrate the effect of such calamities on vulnerable communities to guide interventions. Socioeconomic data were collected across the fish value chains during the peak of COVID-19 pandemic and flooding in Kenya from May to early June 2020. The measures put in place to contain COVID-19 pandemic notably dusk to dawn curfew (66%) and lock-downs (28%) in major cities that act as main fish markets were cited as the main factors that influenced fishing and fishing trade. Negative consequences reported included livelihood losses from the COVID-19 pandemic. Reduced fishing time and trips as well as a decline in consumables such as boat fuel resulted in low fish catches. Although COVID-19 pandemic affected livelihoods, the fish stocks benefited from reduction in fishing effort. Similarly flooding led to livelihood and material losses but positively impacted on stocks through expansion of fish breeding and nursery areas. The respondents recommended that governments should have disaster preparedness programs in place to address such calamities. There is also need for more detailed research on calamities that are increasing in frequency to provide information and data to guide policy and interventions.     

Association between the Catches of Round Gobies and Smallmouth Bass on the Upper Niagara River

We wanted to confirm the presence of round gobies (Neogobius melanostomus) in the upper Niagara River and determine if there was a negative association between the catches of round gobies and smallmouth bass (Micropterus dolomieu). Our approach was to compare the catch rates of round gobies and smallmouth bass by anglers based on their method of fishing (from boat or from shore) and the fish they sought (anything or black bass). During 2003, both boat anglers and shore anglers caught round gobies in the upper Niagara River. The catch rates of round gobies and smallmouth bass for shore anglers who sought anything were positively and significantly correlated (r = 0 .081, P < 0.001). The catch rates of round gobies and smallmouth bass for shore anglers who sought black bass were negatively and significantly correlated (r = 0.141, P < 0.005). Correlations were not done using the catch rates of round gobies and smallmouth bass by boat anglers because they caught so few round gobies. Our results suggest that round gobies did not disrupt fishing for smallmouth bass on the upper Niagara River during 2003 if disruption is defined exclusively by the association between catch rates of smallmouth bass and round gobies. However, catching round gobies did lead to angler perceptions of poor fishing quality.     

Artisanal and commercial fishing gear and practices in the Lake Victoria basin drainage systems of Kenya: A photodiagrammatic verification

This study focused on providing a photodiagrammatic database illustrating various types of fishing gear and practical skills currently used in artisanal and commercial fishing in the shoreline, nearshore and offshore areas drainage systems of Kenya in the Lake Victoria drainage basin. It also identified the fish species typically caught by the fishing gear, and the gear catch per unit effort and selectivity. Four artisanal fishing gears (spear, trap, basket and hook) and two commercial gears (mosquito seine and purse seine) are used to fish in shoreline areas. Five commercial fishing gears (gill net, parallel tennis net, semicircular‐tennis net, sett net, long line) are used to fish in nearshore areas, while two commercial gears (drift net and offshore seine net) are used in offshore areas. For artisanal fishing, the basket is the most efficient gear for catching six fish species. The mosquito seine is the most efficient commercial fishing gear for catching 22 fish species. There is evidence for a chronological shift to more efficient artisanal and commercial fisher handmade fishing gear, resulting in overexploitation of diverse fish species. At the same time, the licensing and management policies for the use of various fishing gear are unclear, suggesting re‐evaluation of policies to cater for the use of handmade fishing gear.     

Identification of critical control points using water quality as an indicator of hygiene for artisanal fisheries on Lake Malawi

Fish are a highly perishable commodity, and unhygienic fresh fish supply chains have been documented over the past two decades in sub‐Saharan Africa. Fishers spend long hours on boats with no provision of sanitary facilities, and even after landing, they are often in environments without sanitary facilities. The purpose of the present study was to explore the impacts of water, sanitation and hygiene practices in an artisanal fishery on food safety by analysing water samples in close contact with fresh fish at various checkpoints from capture to sale at the local market along the shores of Lake Malawi (Malawi). The four checkpoints included (a) fishing boats at the fishing ground before fishing commenced (n = 85); (b) in the same boats at the landing site before offloading fresh fish (n = 85); (c) with fresh fish transporters at the landing site (n = 71); and (d) among vendors at the market (n = 63). Escherichia coli was found in a high percentage of samples at each of the four checkpoints during the dry, wet and cold seasons. The highest risk for contamination (represented by E. coli concentrations) was the transition from transport to vendor, regardless of the season during which the samples were taken. The product value chain demands food safety. The results of the present study have potential applications in informing future interventions to develop behavioural change strategies regarding handwashing and toileting practices, norms unique for highly mobile fishing communities through the integration of hardware and software solutions and using better‐quality water to store fish on the boat, in transport and at the market.     

Angler preferences for management of aquatic invasive species in the USA and Canada: A discrete choice experiment

Aquatic invasive species (AIS) management in the Great Lakes region of North America requires coordination between multiple agencies and stakeholder groups. Because the Great Lakes are an internationally managed entity, an understanding of policy preferences among stakeholders across borders is crucial for making both comprehensive and evidence-based decisions about fishery resources. We evaluated angler preferences for how future fishing scenarios are affected by aquatic invasive species in the Great Lakes region. Using a mixed-mode survey of anglers in Illinois, Michigan, Wisconsin, New York, and the Canadian province of Ontario, we conducted a stated choice experiment to understand and compare American and Canadian anglers. Results from a mixed multinomial logit model suggested fish habitat quality, amount of native fish species, impact of invasive species, availability of wash stations, and cost significantly influenced hypothetical scenarios chosen by survey respondents. Fish habitat and increased availability of boat wash stations had the greatest influence on the likelihood that a given scenario would be chosen by a survey respondent. We observed predominantly similar patterns across the border but did find that Canadians had stronger preferences for limiting AIS impacts and improving habitat quality. Our research thus suggests that an internationally consistent management approach would likely be well received among the anglers engaged in this study.     

池沼公鱼在关河水库,汾河水库的移植效果

本文主要从生物学、生态及渔业利用等方面阐述了关河水库与汾河水库的池沼公鱼移植效果，并对今后的发展提出一些建议。     

三峡水库运行后库区鱼类资源变化及保护研究

结合历史资料以及现状调查资料,分析了三峡库区形成后,库区江段鱼类资源变化的特征,以及造成库区鱼类资源变动的主要因素,并对库区鱼类所面临的主要生态环境问题进行了辨识。针对水利工程开发对鱼类生境造成的影响,提出了多种生态保护措施,如限制捕捞或全面禁捕、恢复洄游通道、栖息地生境保护等。指出大坝修建所导致的生境破碎化,是改变库区鱼类群落结构的重要因素;而不合理的人工捕捞是导致库区鱼类个体变小的直接原因。     

Fishing community preferences and willingness to pay for alternative developments of ecosystem‐based fisheries management (EBFM) for Lake Naivasha,Kenya

Ecosystem‐based fisheries management (EBFM) is an important complement to existing fisheries management approaches to maintain ecosystem health and function; to translate goals and aspirations for sustainability into operational objectives, the preferences of the fishing communities should be considered for successful implementation of EBFM. This study analysed the preferences of the fishing community for alternative EBFM developments for Lake Naivasha, Kenya, and estimated the willingness to pay, using a choice experiment approach. Protection of fish breeding grounds, improving tilapia fish abundance and accessibility of fishing zones were identified as relevant EBFM attributes for the choice experiment. A monetary attribute (payment for fishing permit) was also included. In addition to a conditional logit model, mixed logit models are estimated to account for heterogeneity in preferences. This study results indicated fishing communities are most concerned about tilapia fish abundance and protection of fish breeding grounds. The welfare measures reveal that members of the Lake Naivasha fishing community are willing to pay a considerable sum of money for ecosystem services improvement, relative to their low income derived from fishing. These study findings highlighted that evaluating the preferences of the fishing community and valuing the fishery at an ecosystem level are vital to prioritize and choose between alternative interventions for sound implementation of EBFM.