Figure 3 - uploaded by George Jackman
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View of eel pass netting hanging over spillway on the Mianus River Dam in CT in an area of reduced flow created by the face-boards.
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Acanthocephalans of the globally distributed genus Pomphorhynchus have been intensively studied during the past decades. In Europe, Pomphorhynchus species have shown a certain degree of variability in their morphological characteristics and behavior. Nowadays two different Pomphorhynchus species, namely P. laevis and P. tereticollis, have been desc...
Accurate observation of hillslope groundwater storage and instantaneous recharge remains difficult due to limited monitoring and the complexity of mountainous landscapes. We introduce a novel storage‐discharge method to estimate hillslope recharge and the recharge ratio—the fraction of precipitation that recharges groundwater. The method, which rel...
The upstream movement of juvenile eels (median total length (TL) = 138 mm) in the Mondego River, Portugal, was analysed between January 2017 and August 2019. A total of 12,019 individuals (TL ranging from 60 to 287 mm) were counted and measured on an eel ladder at Coimbra weir, 44 km upstream from the river mouth, during their upstream movements. A...
Citations
... Eel passes comprise relatively steep ascent ramps that provide a wetted substrate designed to facilitate eel passage through crawling and swimming in nearboundary regions with lower flow velocities [14]. Historically, substrata were often cheap, robust items such as rocks, aggregates, branches [10] and burlap [15] or geotextile matting [10,16], but these were found to be too abrasive and caused passing eels to lose a considerable amount of mucus [17]. Purpose-built, synthetic substrates comprising small, more-or-less rigid, vertical cylinders or studs attached to a modular base that can be placed beside one another to create an eel pass have recently become available (e.g. ...
European eel populations have declined markedly in recent decades, caused in part by in-stream barriers, such as weirs and pumping stations, which disrupt the upstream migration of juvenile eels, or elvers, into rivers. Eel passes, narrow sloping channels lined with substrata that enable elvers to ascend, are one way to mitigate against these barriers. Currently, studded eel tiles are a popular substrate. This study is the first to evaluate the flow fields within studded eel tiles and to model the swimming performance of elvers using cellular automata (CA) and individual- (or agent-) based models. Velocities and flow depths predicted by a computational fluid dynamics model of studded eel tiles are first validated against published values for a single installation angle–discharge combination. The validated model is then used to compute three-dimensional flow fields for eel passes at five different installation angles and three inflow discharges. CA and individual-based models are employed to assess upstream passage efficiency for a range of elver sizes. The individual-based model approximates measured passage efficiencies better than the CA model. Passage efficiency is greatest for shallow slopes, low discharges and large elvers. Results are synthesized into an easy-to-understand graphic to help practitioners improve eel pass designs.
... The climbing ability of many migratory native fish and the inability of the current suite of invasive species to pass barriers >1 m high make vertical high-head barriers ideal for invasive fish exclusion in most parts of New Zealand. Native fish passage can be facilitated if necessary using ramps with brush material or other climbing material such as mussel spat ropes (David et al. 2009;Jackman 2009). ...
